tag:theconversation.com,2011:/global/topics/southern-hemisphere-18560/articlesSouthern hemisphere – The Conversation2023-07-10T20:11:22Ztag:theconversation.com,2011:article/2087612023-07-10T20:11:22Z2023-07-10T20:11:22ZDoes the direction water rotates down the drain depend on which hemisphere you’re in? Debunking the Coriolis effect in your sink<figure><img src="https://images.theconversation.com/files/534774/original/file-20230629-15-plnypv.jpg?ixlib=rb-1.1.0&rect=581%2C1032%2C4218%2C2604&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The idea that the Coriolis force influences how water drains frequently appears in popular culture and urban legends.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-photo/jet-water-flows-into-sink-concept-1399159301">frantic00 / Shutterstock</a></span></figcaption></figure><p>In countries near the Earth’s equator, tourists are often dazzled by a demonstration of a mysterious physical phenomenon. A presenter will position three buckets of water – one in the Northern Hemisphere, one in the Southern Hemisphere, and one directly on the equator – and let the water drain out.</p>
<p>Tourists are shown that, as the water drains, the water in the northern bucket rotates in one direction, the water in the southern bucket rotates in the other direction, and the water at the equator doesn’t rotate at all.</p>
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<figcaption><span class="caption">Tourists in countries near the equator, like Uganda and Ecuador, are amazed by attractions that claim to demonstrate the Coriolis effect.</span></figcaption>
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<p>The demonstrator might claim that this strange phenomenon is governed by physics, that it’s an example of the <a href="https://education.nationalgeographic.org/resource/coriolis-effect/">Coriolis effect</a>.</p>
<p>The intriguing nature of the Coriolis effect has led to its frequent appearances in urban legends and popular culture, from <a href="http://www.lghs.net/ourpages/users/dburns/ScienceOnSimpsons/Clips_files/Coriolis.m4v">TV shows</a> to <a href="http://www.gamefaqs.com/boards/939217-call-of-duty-4-modern-warfare/43834255/480093367">video games</a>.</p>
<p>The Coriolis effect is based on the idea that the spinning of the Earth introduces a physical force, known as the Coriolis force, which affects the way objects appear to move to us Earthbound observers. The Coriolis force causes objects on the Earth’s surface to be deflected in different directions depending on whether they are above or below the equator. The effect is strongest near the poles and weakest at the equator.</p>
<p>The Coriolis effect is legitimately responsible for the behavior of some natural phenomena, like hurricanes, that meterologists and physical oceanographers like <a href="https://scholar.google.com/citations?user=YdRRHIQAAAAJ">the two</a> <a href="https://0-scholar-google-com.brum.beds.ac.uk/citations?user=cQOa614AAAAJ&hl=fr">of us</a> study. But in domestic settings, the spinning of the Earth actually has very little effect on how water behaves. Math can explain how this works – or doesn’t work – in a kitchen sink.</p>
<h2>The math behind the phenomenon</h2>
<p>Geophysicists use certain mathematical equations, known as the <a href="https://www.britannica.com/science/Navier-Stokes-equation">Navier-Stokes equations</a>, to describe the behavior of fluids. Roughly, the Navier-Stokes equations relate the change of fluid velocity – how the fluid moves – to the forces acting on the fluid, subject to a few physical constraints. For example, the equations assume that the overall amount of fluid in the system doesn’t change over time.</p>
<p>But just because physicists and mathematicians can write down these equations, it doesn’t mean we can solve them. In fact, these equations are so difficult to solve that you would <a href="https://theconversation.com/millennium-prize-the-navier-stokes-existence-and-uniqueness-problem-4244">win a Millennium Prize and US$1 million</a> if you could do it.</p>
<p>Although there is no known complete solution to Navier-Stokes equations, meteorologists and physical oceanographers can still obtain useful partial solutions. One way to obtain these partial solutions is to compare various terms in the Navier-Stokes equations to determine which ones are most important. </p>
<p>These comparisons are often recorded as ratios and have no associated physical unit, thereby earning them the name “<a href="https://www.sciencedirect.com/topics/chemistry/dimensionless-number">dimensionless numbers</a>.”</p>
<h2>What happens in your sink?</h2>
<p>In the context of the Coriolis effect, perhaps the most important dimensionless number is the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/rossby-number">Rossby number</a>, named for the early 20th-century meteorologist <a href="https://www.britannica.com/biography/Carl-Gustaf-Arvid-Rossby">Carl-Gustav Rossby</a>. The Rossby number compares the dynamics of the fluid with the Earth’s rotation rate, taking into account how big the system is and how fast it’s moving. </p>
<p>A small Rossby number indicates that the Coriolis force has a strong effect on the system, while a large Rossby number signifies that the Coriolis force has a negligible effect. For example, the Rossby number for an average hurricane is of the order of 1, indicating that the dynamics of the fluid and the Earth’s rotation rate are of similar relevance. It is <a href="https://education.nationalgeographic.org/resource/coriolis-effect-1/">true that hurricanes</a> tend to rotate clockwise in the Southern Hemisphere and counterclockwise in the Northern Hemisphere.</p>
<p>The same math that applies to large-scale phenomena like hurricanes also applies to the water in your bathroom sink. In this setting, the system is relatively small, and so the Rossby number will be much larger than 1 – more than 10,000 times larger. This observation indicates that the Coriolis force is negligible on water draining in a bathroom sink.</p>
<p>In fact, the Rossby number predicts that the water would need to move at an almost imperceptible speed for the Coriolis force to become significant. So even though the way water swirls down the drain may be consistent, that isn’t due to the Coriolis effect.</p>
<h2>So what did the tourists see?</h2>
<p>The same logic applies to the equatorial attractions. Given the size of the system, physical oceanographers can comfortably conclude that the Coriolis force is not responsible for what the tourists see in those buckets or bowls. </p>
<p>This conclusion is also supported by examining the same kind of presentation in different countries. </p>
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<figcaption><span class="caption">Different videos of the Coriolis effect show the water spinning in different directions in the same hemisphere.</span></figcaption>
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<p>The water in the Northern Hemisphere rotates counterclockwise in one video but clockwise in another video. If the rotation were due to the Coriolis effect, the result would be the same in both videos. </p>
<p>Although physical oceanographers can’t deny what the tourists see, we know that the magic trick isn’t due to the Coriolis effect at such a small scale.</p><img src="https://counter.theconversation.com/content/208761/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Las personas firmantes no son asalariadas, ni consultoras, ni poseen acciones, ni reciben financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y han declarado carecer de vínculos relevantes más allá del cargo académico citado anteriormente.</span></em></p>This physical effect does explain how some massive natural phenomena like hurricanes behave. But on the scale of water in your sink – not so much.Francisco José Machín Jiménez, Profesor Titular de Universidad. Oceanógrafo Físico, Universidad de Las Palmas de Gran CanariaBorja Aguiar González, Personal Docente e Investigador, Universidad de Las Palmas de Gran CanariaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1778262022-03-16T19:28:41Z2022-03-16T19:28:41ZFlu, COVID and flurona: what we can and can’t expect this winter<figure><img src="https://images.theconversation.com/files/452341/original/file-20220316-28-dvj9zq.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/black-woman-feeling-sick-seasonal-flu-1201292887">Shutterstock</a></span></figcaption></figure><p>When it comes to respiratory viruses, COVID has been our greatest concern over the past two winters. So you might feel some aspects of <em>déjà vu</em> as winter 2022 approaches in Australia. </p>
<p>But this year is different. With relaxed public health measures and the opening of international borders, we will likely see a rise in flu cases. This is on top of a predicted rise in COVID.</p>
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<p>The potential double-whammy has prompted the federal government to announce <a href="https://www.abc.net.au/news/2022-03-11/health-package-to-target-expected-covid-and-flu-spike/100901242">A$2.1 billion</a> to target these expected spikes. The funding has <a href="https://www.health.gov.au/ministers/the-hon-greg-hunt-mp/media/canberra-press-conference-11-march-2022-on-kimberley-kitching-japanese-encephalitis-extensions-to-vaccinationbooster-plan-winter-preparedness-plan-for-covid-and-flu">been earmarked</a> for measures including vaccination, testing and measures to protect aged care.</p>
<p>Here’s what to expect and how to protect yourself ahead of winter.</p>
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Read more:
<a href="https://theconversation.com/heres-why-you-might-need-a-4th-covid-vaccine-dose-this-winter-177811">Here's why you might need a 4th COVID vaccine dose this winter</a>
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<h2>Why can we expect more flu?</h2>
<p>The main reason behind the expected rise in flu in 2022 is the opening of Australia’s international borders. </p>
<p>Tourists and returning residents can arrive without quarantining, provided they have the required COVID vaccinations and have had a COVID test beforehand. However, new arrivals don’t have to be tested for the flu virus, which they may inadvertently bring with them.</p>
<p>Flu, a little like COVID, can be spread by infected others before symptoms arise or even if symptoms don’t appear, something we regularly see in children. So once flu arrives, it will inevitably spread, regardless of whether we use masks, hand sanitiser or other measures.</p>
<p>In the past two years, for instance, we’ve seen large outbreaks of <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/covid-19-surveillance-report-20220107.pdf">other common respiratory viruses</a>. These include <a href="https://pubmed.ncbi.nlm.nih.gov/33735388/">respiratory syncytial virus</a>, <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/covid-19-surveillance-report-20220107.pdf">human metapneumovirus</a>, <a href="https://www.cdc.gov/adenovirus/about/symptoms.html">adenoviruses</a> and <a href="https://www.healthychildren.org/English/health-issues/conditions/ear-nose-throat/Pages/Rhinovirus-Infections.aspx">rhinovirus</a>. We’ve seen these even with strict COVID measures in Victoria, New South Wales and Queensland during 2020-2021.</p>
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Read more:
<a href="https://theconversation.com/we-can-expect-more-colds-and-flu-as-covid-restrictions-lift-5-germs-to-look-out-for-170263">We can expect more colds and flu as COVID restrictions lift. 5 germs to look out for</a>
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<h2>How bad will it get?</h2>
<p>It’s highly likely we’ll see COVID and influenza circulating at the same time this winter. But less certain is the more catastrophic predictions in the media of a so-called twindemic or syndemic.</p>
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<p>COVID is more likely to persist and increase during the winter, and sometime during this period influenza will pop up. But we’re uncertain about the details.</p>
<p>Will flu be mild or more concerning in 2022? Will we see a rise in cases during the usual June-September period, peaking normally in August? The answers to these questions rely on history, the current situation and a good deal of speculation.</p>
<p>History tells us that after two seasons of low or no influenza circulating, we should expect a more severe season. That’s because the majority of people are not vaccinated against influenza each year and peoples’ natural immunity after infection will have waned.</p>
<p>However, <a href="https://www.who.int/teams/global-influenza-programme/surveillance-and-monitoring/influenza-updates/current-influenza-update">current evidence</a> argues against this. In the Northern Hemisphere, there have been low levels of flu circulating in most countries, with shorter outbreaks, compared with pre-pandemic years. </p>
<p>We’ve also seen a number of countries in the Southern Hemisphere – including <a href="https://www.who.int/tools/flunet">South Africa, Brazil and Chile</a> – having out-of-season flu outbreaks, during their 2021-2022 summer.</p>
<p>So this may mean the timing of Australia’s normal influenza season might be delayed until spring or even later in 2022.</p>
<h2>Will I get ‘flurona’?</h2>
<p>We may also see dual infections – when someone has COVID and influenza at the same time – sometimes dubbed “flurona”.</p>
<p>While this has occurred, the rates of dual infections globally have been low. Generally, <a href="https://www.frontiersin.org/articles/10.3389/fmed.2021.681469/full">under 1% of people</a> with COVID also have influenza at the same time. Even with dual infections, people do not seem to be sicker than if they had COVID alone.</p>
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<p>We’ll have a better idea of how many people will be infected with both viruses at once with the use of broader laboratory tests now available at many sites. These so called <a href="https://www.health.gov.au/ministers/the-hon-greg-hunt-mp/media/canberra-press-conference-11-march-2022-on-kimberley-kitching-japanese-encephalitis-extensions-to-vaccinationbooster-plan-winter-preparedness-plan-for-covid-and-flu">multiplex tests</a> will detect a range of respiratory diseases, including COVID and flu, in a single test.</p>
<p>Fortunately, there is no way a new “hybrid virus” can emerge containing parts of SARS-CoV-2 (the virus that causes COVID) and the influenza virus in people with dual infections. These are distinct viruses that cannot combine.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/alpha-then-delta-and-now-omicron-6-questions-answered-as-covid-19-cases-once-again-surge-across-the-globe-174703">Alpha then delta and now omicron – 6 questions answered as COVID-19 cases once again surge across the globe</a>
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<h2>How can I protect myself?</h2>
<p>Despite the uncertainties around flu in Australia in 2022, the best way to protect yourself is to get your flu vaccine.</p>
<p>Everyone is susceptible to flu, no matter your age, health or lifestyle. However, some age groups and some people with underlying disease are likely to suffer more severe consequences if infected with influenza. </p>
<p>These include young children (especially those under two years old), people aged 65 and over, pregnant women, people with chronic lung and heart disease, those with asthma, diabetes and people who are obese.</p>
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Read more:
<a href="https://theconversation.com/you-cant-get-influenza-from-a-flu-shot-heres-how-it-works-118916">You can't get influenza from a flu shot – here's how it works</a>
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<p>Different flu vaccines target different age groups with different formulations. These vaccines have a <a href="https://ausvaxsafety.org.au/safety-data/influenza-vaccine">proven safety record</a> and usually only cause very mild reactions, such as soreness at the injection site, mild fever or headache. These may last for a 12-24 hours and are easily treated with paracetamol or similar medications.</p>
<p><a href="https://www.health.gov.au/health-topics/immunisation/when-to-get-vaccinated/national-immunisation-program-schedule">Flu vaccines are free</a> for children aged six months to under five years of age, people aged 65 or older, pregnant women and all Aboriginal and Torres Strait Islander people six months and older. People not eligible for free vaccines can still get them via their GP or some pharmacies.</p>
<p>This year you won’t have to schedule different visits for your influenza and COVID vaccinations. If needed, you can get them <a href="https://www.health.gov.au/sites/default/files/documents/2022/02/atagi-advice-on-seasonal-influenza-vaccines-in-2022.pdf">at the same time</a>.</p>
<p>Influenza vaccines will be available from late March and <a href="https://www.cdc.gov/flu/prevent/keyfacts.htm">will provide protection</a> for at least 6-12 months. While these vaccines are not perfect they help prevent infection and the more serious consequences of the flu, such as hospitalisation and even death. So in April to May this year, as the cool days and nights return, think about booking in and getting your flu shot.</p><img src="https://counter.theconversation.com/content/177826/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Barr owns shares in a vaccine producing company. His Centre receives funding from the Australian Government Department of Health as well as a number of commercial pharmaceutical companies.</span></em></p>Flu vaccines will soon be available. And this year, you can get your COVID shot at the same time.Ian Barr, Deputy Director, WHO Collaborating Centre for Reference and Research on InfluenzaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1734032022-01-10T13:36:59Z2022-01-10T13:36:59ZHow the Earth’s tilt creates short, cold January days<figure><img src="https://images.theconversation.com/files/439145/original/file-20220102-17-1b3kzl8.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C4163%2C2765&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Sun rises in Midland, Michigan, shortly after 8a.m. on Jan. 13, 2017.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/Q6LNQ5">Christian Collins/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>Above the equator, winter officially <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/seasons/winter/when-does-winter-start">begins in December</a>. But in many areas, January is when it really takes hold. Atmospheric scientist <a href="https://scholar.google.com/citations?user=B5TfCvMAAAAJ&hl=en">Deanna Hence</a> explains the weather and climate factors that combine to produce wintry conditions at the turn of the year.</em></p>
<h2>How does the Earth’s orbit influence our daylight and temperatures?</h2>
<p>As the Earth orbits the sun, it spins around an axis – picture a stick going through the Earth, from the North Pole to the South Pole. During the 24 hours that it takes for the Earth to rotate once around its axis, every point on its surface faces toward the Sun for part of the time and away from it for part of the time. This is what causes daily changes in sunlight and temperature. </p>
<p>There are two other important factors: First, the Earth is round, although it’s <a href="https://oceanservice.noaa.gov/facts/earth-round.html">not a perfect sphere</a>. Second, its axis is tilted about 23.5 degrees relative to its path around the Sun. As a result, light falls directly on its equator but strikes the North and South poles at angles. </p>
<p>When one of the poles points more toward the Sun than the other pole, that half of the planet gets more sunlight than the other half, and it’s summer in that hemisphere. When that pole tilts away from the Sun, that half of the Earth gets less sunlight and it’s winter there.</p>
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<a href="https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic of Earth tilting on its axis, with Northern Hemisphere toward the sun." src="https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438275/original/file-20211217-23072-g37bxk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Earth’s tilt as it orbits around the Sun puts that one part of the planet more directly exposed to the Sun’s rays.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/tilt-of-the-earths-axis-and-earths-season-royalty-free-illustration/695485360">iStock via Getty Images</a></span>
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<p>Seasonal changes are the most dramatic at the poles, where the changes in light are most extreme. During the summer, a pole receives 24 hours of sunlight and the Sun never sets. In the winter, the Sun never rises at all.</p>
<p>At the equator, which gets consistent direct sunlight, there’s very little change in day length or temperature year-round. People who live in high and middle latitudes, closer to the poles, can have very different ideas about seasons from those who live in the tropics.</p>
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<figcaption><span class="caption">As the Earth orbits the Sun, sunlight strikes the surface at varying angles because of the planet’s tilt. This creates seasons.</span></figcaption>
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<h2>There’s an old saying, “As the days lengthen, the cold strengthens.” Why does it often get colder in January even though we’re gaining daylight?</h2>
<p>It depends on where you are in the world and where your air is coming from. </p>
<p>Earth’s surface constantly absorbs energy from the Sun and stores it as heat. It also emits heat back into space. Whether the surface is warming or cooling depends on the balance between how much solar radiation the planet is absorbing and how much it is radiating away. </p>
<p>But Earth’s surface isn’t uniform. Land typically heats up and cools off much faster than water. Water requires more energy to raise and lower its temperature, so it warms and cools more slowly. Because of this difference, water is a better heat reservoir than land – especially big bodies of water, like oceans. That’s why we tend to see bigger swings between warm and cold inland than in coastal areas.</p>
<p>The farther north you live, the longer it takes for the amount and intensity of daylight to start significantly increasing in midwinter, since your location is tilting away from the Sun. In the meantime, those areas that are getting little sunlight keep radiating heat out to space. As long as they receive less sunlight than the heat they emit, they will keep getting colder. This is especially true over land, which loses heat much more easily than water. </p>
<p>As the Earth rotates, air circulates around it in the atmosphere. If air moving into your area comes largely from places like the Arctic that don’t get much sun in winter, you may be on the receiving end of bitterly cold air for a long time. That happens in the Great Plains and Midwest when cold air swoops down from Canada.</p>
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<p>But if your air comes across a body of water that keeps a more even temperature through the year, these swings can be significantly evened out. Seattle is downwind from an ocean, which is why it is many degrees warmer than Boston in the winter even though it’s farther north than Boston.</p>
<h2>How quickly do we lose daylight before the solstice and gain it back afterward?</h2>
<p>This depends strongly on your location. The closer you are to one of the poles, the faster the rate of change in daylight is. That’s why Alaska can go from having hardly any daylight in the winter to hardly any darkness in the summer. </p>
<p>Even for a particular location, the change is not constant through the year. The rate of change in daylight is slowest at the solstices – December in winter, June in summer – and <a href="https://www.bostonglobe.com/metro/2019/09/11/why-losing-daylight-quickly-and-what-know-about-autumnal-equinox/ooZUrhowvIUpSgV1LfOUoO/story.html">fastest at the equinoxes</a>, in mid-March and mid-September. This change occurs as the area on Earth receiving direct sunlight swings from 23.5 N latitude – about as far north of the equator as Miami – to 23.5 S latitude, about as far south of the equator as Asunción, Paraguay. </p>
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<figcaption><span class="caption">This satellite view captures the four changes of seasons. On the equinoxes, March 20 and Sept. 20, the line between night and day is a straight north-south line, and the sun appears to sit directly above the equator. Earth’s axis is tilted away from the Sun at the December solstice and toward the Sun at the June solstice, spreading more and less light on each hemisphere. At the equinoxes, the tilt is at a right angle to the Sun and the light is spread evenly.</span></figcaption>
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<h2>What’s happening on the opposite side of the planet right now?</h2>
<p>In terms of daylight, folks on the other side of the planet are seeing the exact opposite of what we’re seeing. Right now, they’re at the peak of their summer and are enjoying the largest amounts of daylight that they’re going to get for the year. I do research on <a href="https://www.nsf.gov/news/news_summ.jsp?cntn_id=296639&org=NSF&from=news">Argentinian hailstorms</a> and <a href="https://www.researchgate.net/profile/Deanna-Hence-2">Indian Ocean tropical cyclones</a>, and both of those warm-weather storm seasons are well into their peaks right now.</p>
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<p>But there’s a key difference: The Southern Hemisphere has a lot less land and a lot more water than the Northern Hemisphere. Thanks to the influence of the southern oceans, land masses in the Southern Hemisphere tend to have fewer very extreme temperatures than land in the Northern Hemisphere does.</p>
<p>So even though a spot on the <a href="https://www.geodatos.net/en/antipodes">opposite side of the planet from your location</a> may receive exactly as much sunlight now as your area does in summer, the weather there may be different from the summer conditions you are used to. But it still can be fun to imagine a warm summer breeze on the far side of the Earth – especially in a snowy January.</p><img src="https://counter.theconversation.com/content/173403/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Deanna Hence receives funding from NASA, the National Science Foundation, and the Illinois Campus Research Board.</span></em></p>The winter solstice is past, but bundle up – January is when winter really arrives in many parts of the Northern Hemisphere.Deanna Hence, Assistant Professor of Atmospheric Sciences, University of Illinois at Urbana-ChampaignLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1527772021-01-12T15:07:36Z2021-01-12T15:07:36ZSouth African astronomy has a long, rich history of discovery – and a promising future<figure><img src="https://images.theconversation.com/files/377956/original/file-20210111-23-12bfk2d.jpg?ixlib=rb-1.1.0&rect=4%2C492%2C2748%2C1655&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Southern African Large Telescope has been a key part of South Africa's astronomical contributions.</span> <span class="attribution"><span class="source">SAAO</span></span></figcaption></figure><p>The <a href="https://www.saao.ac.za/">South African Astronomical Observatory</a> in Cape Town is the oldest permanent observatory in the southern hemisphere: it turned 200 in 2020. </p>
<p>This observatory is a fundamental part of South Africa’s long history of astronomical research, which began when French academic <a href="https://academic.oup.com/astrogeo/article/43/2/2.25/281196">Nicolas-Louis de La Caille</a> visited Cape Town from 1751 to 1753. He undertook a careful examination of every square degree of the southern sky. This resulted in the first comprehensive sky survey ever made, in either hemisphere.</p>
<p>The Royal Observatory, Cape Town of Good Hope (today the South African Astronomical Observatory) was established in 1820. It became – and remained for 150 years – the most important source of star positions in the southern hemisphere sky. This was in terms of both accuracy and the number of measurements made. In the years that followed its foundation, the observatory’s laborious work led to important scientific discoveries. </p>
<p>Cape astronomers were responsible for, among other things, the first measurement of the distance to a star; the first photographic sky survey and the accurate measurement of the distance to the sun. They were at the forefront of developments in stellar spectroscopy. This is the detailed analysis of a star’s light to find out its composition and movement towards or away from the sun. They also determined the shape of the earth in the southern hemisphere and conducted the first accurate country-wide survey measurements of southern Africa. </p>
<h2>Measuring stellar distances</h2>
<p>In 1543 the mathematician and astronomer <a href="https://plato.stanford.edu/entries/copernicus/">Nicolaus Copernicus</a> asserted that the earth orbits the sun. This meant that people should be able to observe the apparent shift in the position of the nearest stars from different points in the earth’s orbit. But that had not been observed in the centuries that followed. The reason was, of course, that even the nearest stars are incredibly far away and the effect being looked for is very small. </p>
<p>When the Royal Observatory was founded in 1820, it was equipped with the most accurate star position measuring devices available. Eleven years later Thomas Henderson used those devices to make the first believable measurements of this effect, known as “<a href="https://www.space.com/30417-parallax.html">parallax</a>”. By observing the angular “movement” of Alpha Centauri – still the second-closest star known to us – and knowing also the size of the earth’s orbit, this gave the distance to the star by simple trigonometry. </p>
<p>A different technology, photography, would lead to more important astronomical discoveries at the Cape. All observatories in the 19th century made precise observations of star positions one by one and published catalogues of these. In 1882 the head of the Royal Observatory, David Gill, was surprised to receive a letter from a Mr Simpson, an amateur photographer in Aberdeen, a town elsewhere in the Cape. </p>
<p>Simpson had managed to photograph a bright comet that had just appeared. His photographic plates were sensitive enough to register stars in the background. This led to a “lightbulb” moment for Gill: he realised that the positions of stars could now be recorded in quantity on a permanent medium, more reliably than any visual observer could ever hope to do. </p>
<p>So he set up a special photographic telescope using the largest lens that he could find and set about making the first photographic star catalogue. This was called the <a href="http://adsabs.harvard.edu/full/1896AnCap...3....1G">Cape Photographic Durchmusterung</a> after its much more laboriously compiled northern hemisphere equivalent, put together in Bonn, Germany. </p>
<p>But it wasn’t just Cape Town that hosted an important astronomical site.</p>
<p>In 1903, the <a href="https://www.saasta.ac.za/johannesburg-observatory/">Johannesburg Observatory</a> was established. It achieved its greatest success in 1915 when its director, Robert Innes, discovered a very faint star near Alpha Centauri. </p>
<p>On various grounds he claimed it to be the nearest star to Earth; it took many years of investigation before this could be verified. The new discovery was named “Proxima Centauri”, meaning the nearest in the constellation Centaurus. Not only was it the nearest star but at that time of discovery it was the least luminous star ever discovered. Other dimmer stars have been found since, but Proxima still retains its nearest star status and its distance has been thoroughly verified from space satellites. </p>
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Read more:
<a href="https://theconversation.com/seti-new-signal-excites-alien-hunters-heres-how-we-could-find-out-if-its-real-152498">SETI: new signal excites alien hunters – here's how we could find out if it's real</a>
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<h2>Doubling the size of the Universe</h2>
<p>In 1948 the private Radcliffe Foundation in the United Kingdom set up in Pretoria what was for a time the largest telescope in the southern hemisphere and joint fourth largest in the world. This is a title currently held by the <a href="https://www.salt.ac.za/">Southern African Large Telescope</a>. </p>
<p>Early on in the Radcliffe’s existence the then director, David Thackeray, and his colleague Adriaan Wesselink discovered in our neighbouring galaxy, the Large Magellanic Cloud, a number of RR Lyrae variable stars that astronomers using smaller telescopes could not detect. These are stars that change their brightness in a well-defined manner over a cycle of a few days and whose average “wattage” is completely predictable.</p>
<p>By measuring the Magellanic Cloud stars’ average apparent brightnesses and comparing them to other RR Lyrae stars at known distances they determined that the cosmic distance scale originally published two decades before by Edwin Hubble and others was underestimated by about a factor of two. In effect, they doubled the size of the Universe. This result was announced to great acclaim at the triennial meeting of the <a href="http://adsabs.harvard.edu/full/1952JRASC..46..217D">International Astronomical Union in 1952</a>. </p>
<h2>More to come</h2>
<p>Today South African astronomy remains at the forefront of many initiatives and discoveries. It has become a leader in the field of radio astronomy with the MeerKAT telescope near Carnarvon and will within a decade be the host of an international project, the <a href="https://www.skatelescope.org/">Square Kilometre Array</a>.</p>
<p><em>This article is adapted from <a href="https://www.nrf.ac.za/sites/default/files/documents/04%20NRF%20SMM%20V3%20Issue3%20Highlights%20of%20Astronomy%20in%20South%20Africa%20Before%201972.pdf">a piece</a> that initially appeared in the South African National Research Foundation’s Science Matters Magazine.</em></p><img src="https://counter.theconversation.com/content/152777/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Glass does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Cape astronomers were responsible for, among other things, the first measurement of the distance to a star; the first photographic sky survey and the accurate measurement of the distance to the sun.Ian Glass, Associate Research Astronomer, South African Astronomical ObservatoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1487722020-10-27T21:12:37Z2020-10-27T21:12:37ZGiant ‘toothed’ birds flew over Antarctica 40 million to 50 million years ago<figure><img src="https://images.theconversation.com/files/365550/original/file-20201026-21-t2z6hk.png?ixlib=rb-1.1.0&rect=9%2C14%2C3249%2C2013&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fossil remains indicate these birds had a wingspan of over 20 feet.</span> <span class="attribution"><span class="source">Brian Choo</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Picture Antarctica today and what comes to mind? Large ice floes bobbing in the Southern Ocean? Maybe a remote outpost populated with scientists from around the world? Or perhaps colonies of penguins puttering amid vast open tracts of snow?</p>
<p>Fossils from Seymour Island, just off the Antarctic Peninsula, are painting a very different picture of what Antarctica looked like 40 to 50 million years ago – a time when the ecosystem was lusher and more diverse. Fossils of <a href="https://doi.org/10.1038/s41598-020-61973-5">frogs</a> and <a href="https://doi.org/10.1080/03115518.2011.565214">plants</a> such as ferns and conifers indicate Seymour Island was much warmer and less icy, while fossil remains from <a href="https://doi.org/10.7717/peerj.8268">marsupials and distant relatives of armadillos and anteaters</a> hint at the previous connections between Antarctica and other continents in the Southern Hemisphere.</p>
<p>There were also birds. Penguins were present then, as they are now, but fossil relatives of <a href="http://dx.doi.org/10.13679/j.advps.2019.0014">ducks, falcons and albatrosses</a> have also been found in Antarctica. My <a href="https://scholar.google.com/citations?user=5CGShQUAAAAJ&hl=en&oi=ao">colleagues</a> and <a href="https://scholar.google.com/citations?user=XlyfD9QAAAAJ&hl=en&oi=ao">I</a> published an <a href="https://doi.org/10.1038/s41598-020-75248-6">article in 2020</a> revealing new information about the fossil group that would have dwarfed all the other birds on Seymour Island: the pelagornithids, or “bony-toothed” birds. </p>
<h2>Giants of the sky</h2>
<p>As their name suggests, these ancient birds had sharp, bony spikes protruding from sawlike jaws. Resembling teeth, these spikes would have helped them catch squid or fish. We also studied another remarkable feature of the pelagornithids – their imposing size.</p>
<p>The largest flying bird alive today is the <a href="https://www.nationalgeographic.com/animals/birds/group/albatrosses/">wandering albatross</a>, which has a wingspan that reaches 11 ½ feet. The Antarctic pelagornithids fossils we studied have a wingspan nearly double that – about 21 feet across. If you tipped a two-story building on its side, that’s about 20 feet.</p>
<p>Across Earth’s history, very few groups of vertebrates have achieved powered flight – and only two reached truly giant sizes: birds and a group of <a href="https://www.amnh.org/exhibitions/pterosaurs-flight-in-the-age-of-dinosaurs/what-is-a-pterosaur">reptiles called pterosaurs</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A model of an enormous prehistoric bird is mounted outdoor in the middle of a river. The wingspan reaches from bank to bank." src="https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/365561/original/file-20201026-23-p2l76b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Full-size model of a Quetzalcoatlus on display at JuraPark in Baltow, Poland.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/5/5c/Kecalkoatl_%28Quetzalcoatlus%29_-_Baltow_%281%29.JPG">Aneta Leszkiewicz/Wikimedia</a></span>
</figcaption>
</figure>
<p>Pterosaurs ruled the skies during the Mesozoic Era (252 million to 66 million years ago), the same period that dinosaurs roamed the planet, and they reached hard-to-believe dimensions. <a href="https://www.wired.com/2013/11/absurd-creature-of-the-week-quetz/">Quetzalcoatlus</a> stood 16 feet tall and had a colossal 33-foot wingspan.</p>
<h2>Birds get their opportunity</h2>
<p>Birds originated while dinosaurs and pterosaurs were still roaming the planet. But when an <a href="https://www.smithsonianmag.com/science-nature/dinosaur-killing-asteroid-impact-chicxulub-crater-timeline-destruction-180973075/">asteroid struck the Yucatan Peninsula 66 million years ago</a>, dinosaurs and pterosaurs both perished. Some <a href="https://www.audubon.org/news/how-birds-survived-asteroid-impact-wiped-out-dinosaurs">select birds survived</a>, though. These survivors diversified into the thousands of bird species alive today. Pelagornithids evolved in the period right after dinosaur and pterosaur extinction, when competition for food was lessened. </p>
<p><a href="https://doi.org/10.1002/spp2.1284">The earliest pelagornithid remains</a>, recovered from 62-million-year-old sediments in New Zealand, were about the size of modern gulls. The first giant pelagornithids, the ones in our study, <a href="https://doi.org/10.1038/s41598-020-75248-6">took flight over Antarctica about 10 million years later</a>, in a period called the Eocene Epoch (56 million to 33.9 million years ago). In addition to these specimens, fossilized remains from other pelagornithids have been found on every continent. </p>
<p>Pelagornithids lasted for about 60 million years before going extinct just before the Pleistocene Epoch (2.5 million to 11,700 years ago). No one knows exactly why, though, because few fossil records have been recovered from the period at the end of their reign. Some paleontologists cite <a href="https://doi.org/10.1080/02724634.2011.562268">climate change as a possible factor</a>.</p>
<h2>Piecing it together</h2>
<p>The fossils we studied are fragments of whole bones collected by paleontologists from the University of California at Riverside in the 1980s. In 2003, the specimens were transferred to Berkeley, where they now reside in the <a href="https://ucmp.berkeley.edu/">University of California Museum of Paleontology</a>. </p>
<p>There isn’t enough material from Antarctica to rebuild an entire skeleton, but by comparing the fossil fragments with similar elements from more complete individuals, we were able to assess their size. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of a fossil fragment of a jawbone section that has worn toothlike projections. Line drawing around it illustrates where in the jaw it would have fit." src="https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=573&fit=crop&dpr=1 600w, https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=573&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=573&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=720&fit=crop&dpr=1 754w, https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=720&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/365552/original/file-20201026-17-1koc1h3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=720&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In life, the pelagornithid would have had numerous ‘teeth,’ making it a formidable predator.</span>
<span class="attribution"><span class="source">Peter Kloess</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>We estimate the pelagornithid’s skull would have been about 2 feet long. A fragment of one bird’s lower jaw preserves some of the “pseudoteeth” that would have each measured up to an inch tall. The spacing of those “teeth” and other measurements of the jaw show this fragment came from an individual as big as, if not bigger than, the largest known pelagornithids. </p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>Further evidence of the size of these Antarctic birds comes from a second pelagornithid fossil, from a different location on Seymour Island. A section of a foot bone, called a tarsometatarsus, is the largest specimen known for the entire extinct group. </p>
<p>These pelagornithid fossil findings emphasize the importance of natural history collections. Successful field expeditions result in a wealth of material brought back to a museum or repository – but the time required to prepare, study and publish on fossils means these institutions typically <a href="https://theconversation.com/digitizing-the-vast-dark-data-in-museum-fossil-collections-102833">hold many more specimens than they can display</a>. Important discoveries can be made by collecting specimens on expeditions in remote locations, no doubt. But equally important discoveries can be made by simply processing the backlog of specimens already on hand.</p><img src="https://counter.theconversation.com/content/148772/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter A. Kloess does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Paleontologists have discovered fossil remains belonging to an enormous ‘toothed’ bird that lived for a period of about 60 million years after dinosaurs.Peter A. Kloess, Doctoral Candidate, Integrative Biology, University of California, BerkeleyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1226642019-10-06T09:04:00Z2019-10-06T09:04:00ZLiterature sheds light on the history and mystery of the Southern Ocean<figure><img src="https://images.theconversation.com/files/295442/original/file-20191003-52796-1763ajl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>If you look at a globe, you’ll see that the Southern Hemisphere is bluer than the Northern Hemisphere. A <a href="http://www.ces.fau.edu/nasa/module-3/regional-temperature/explanation-2.php">huge 80%</a> of it is ocean compared to 60% of the North.</p>
<p>The Southern Ocean is the only ocean in which waves circulate without encountering intervening landmasses. It’s gargantuan in size and ferocity. The roaring, furious, and screaming latitudes are daunting to maritime traffic. </p>
<p>The Antarctic Convergence – where icy currents meet warmer sub-Antarctic waters – supports an abundance of marine life. There’s no northern equivalent to this phenomenon. But, like the icebound continent itself, no humans live there.</p>
<p>Because it uniquely flows into the Atlantic, Indian, and Pacific Oceans, the Southern Ocean opens up possibilities for tracking the intersecting currents and itineraries that compose the global South. As do writers and artists, we’re calling for the global South to be thought of alongside the Southern Ocean, what we call <a href="https://read.dukeupress.edu/english-language-notes/article/57/1/37/137694/The-Oceanic-South">the oceanic South</a>. </p>
<p>The global South makes you think mostly of an unequal present but the oceanic South brings to the fore pasts of maritime imperialism, as well as what the future might bring. It draws together the dispersed landmasses of the settler South, the decolonised and still colonised countries of the Southern Hemisphere, the “sea of islands” comprising Indigenous Oceania, and the frozen continent of Antarctica. </p>
<p>A <a href="https://www.oceanichumanities.com/people">research group</a>, that we are a part of, based at the University of the Witwatersrand, Oceanic Humanities for the Global South has turned its attention to cultural representations of the ocean by exploring literature and the arts across different scales of time and place. This includes the Southern Ocean.</p>
<h2>Reviewing the literature</h2>
<p>Many writers and artists have represented the Southern Ocean in ways that layer possible futures over diverse pasts – illuminating the links between them. </p>
<p>Two examples we discussed in a <a href="https://read.dukeupress.edu/english-language-notes/article/57/1/37/137694/The-Oceanic-South">recent paper</a> are Witi Ihaemera’s <em>The Whale Rider</em> from Aotearoa New Zealand and Zakes Mda’s <em>The Whale Caller</em> from South Africa. </p>
<p>Both novels register the catastrophic slaughter of whales that took place during roughly the same period as European colonialism. Both explore the interrelationship between genocidal and extractive projects and how humans and whales interlock as they journey together through the southern seas.</p>
<p>This is the term that Ihimaera uses to describe “the knowledge of whalespeaking” that the ancients once had. It was also this knowledge and with which the Maori ancestor Paikea asked a whale to carry him to the land that lay far to the south.</p>
<p>The novel shows how the interlocking of land inhabitants and ocean inhabitants that articulates the origin story of Aotearoa is sundered when the whalekilling begins.</p>
<p>Mda’s novel <em>The Whale Caller</em> sketches out similarly intersecting itineraries of land and ocean inhabitants from the vantage point of the southern tip of Africa. The Whale Caller had learned the songs of migrating whales during his own peregrinations in which he</p>
<blockquote>
<p>spent many years walking westwards along the coast of the Indian Ocean, until he reached the point where the two oceans met, and then proceeded northwards along the Atlantic Ocean coast.</p>
</blockquote>
<p>The Whale Caller surmises that – like the Australasians he has read about – the indigenous inhabitants of these African shores had feasted on stranded whales and that their expressions of gratitude for the bounty delivered by the sea included also mourning for the loss of companion species.</p>
<p>Other literature that’s been explored includes poetry by South African-born poet and novelist <a href="https://www.tandfonline.com/doi/abs/10.1080/23277408.2014.941751">Yvette Christiansë</a>. She links the Indian and Atlantic Oceans by following “Liberated Africans” from Mozambique to St Helena. This one of the forgotten afterlives of slavery, <a href="https://fordham.universitypressscholarship.com/view/10.5422/fordham/9780823277872.001.0001/upso-9780823277872-chapter-005">centred in the South</a>. </p>
<h2>The journeys of books</h2>
<p>The Oceanic Humanities for the Global South is also taking into account the entire hydrological cycle. This links evaporation from the surrounding oceans to rainfall on the watershed of the Witwatersrand – ridge of white waters in Gauteng. Isabel Hofmeyr, a Professor of African Literature at the University of the Witwatersrand and New York University, has <a href="https://read.dukeupress.edu/english-language-notes/article/57/1/11/137697/Provisional-Notes-on-Hydrocolonialism">proposed the rubric</a> “hydrocolonialism” to link sea and land, empire and environment. </p>
<p>In provisional notes on the topic she discusses hydrocolonial book history and sets out what can be learnt from tracing books on their oceanic journeys. </p>
<p>The Oceanic Humanities for the global South team is involved in a range of other research too. The subjects include undertaking a cultural history of seaweed harvesters, abalone poachers, black whalers and other underwater workers. Members of the team are also exploring representations of water spirits in local literature and culture and tracing links between black aesthetics and the deep ocean.</p><img src="https://counter.theconversation.com/content/122664/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Southern Ocean, as artists have uncovered, is also a treasure trove of cultural narratives.Charne Lavery, Lecturer and Research Associate, University of the WitwatersrandMeg Samuelson, Associate Professor, English and Creative Writing, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/828492017-09-14T16:47:59Z2017-09-14T16:47:59ZGhana is boosting Africa’s ascent to astronomical heights<figure><img src="https://images.theconversation.com/files/185644/original/file-20170912-19546-1n7hkdm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The refurbished radio telescope in Kutunse, Ghana paves the way for astronomy in Africa.</span> <span class="attribution"><span class="source">SKA</span></span></figcaption></figure><p><em>The <a href="https://theconversation.com/the-science-behind-the-square-kilometre-array-40870">Square Kilometre Array (SKA)</a> is the world’s largest radio telescope project, which will collect data over one million square kilometres from radio astronomy telescopes on the African and Australian continents.
In the long run the two-phased SKA could possibly help scientists answer questions in astrophysics, cosmology and fundamental physics. Phase one of the project entailed setting radio telescopes in <a href="http://www.ska.ac.za/about/the-project/">South Africa</a> and <a href="http://www.ska.gov.au/Pages/default.aspx">Australia</a>. Phase two will include more telescopes being added by partner countries, New Zealand and the eight African countries namely: Botswana, Ghana, Kenya, Mauritius, Madagascar, Mozambique, Namibia and Zambia. The full array should be up and running by 2030, but the first phase is expected to be operational by 2023. The launch of Ghana’s radio telescope is a critical part of this process. Dr Bernard Duah Asabere explained its significance.</em></p>
<p><strong>How did Ghana get involved in the project and how does it fit in?</strong></p>
<p>Ghana has had a redundant satellite communication antenna in Kutunse – a suburb 25 kilometres north-west of the capital, Accra.</p>
<p>Between 2011 and 2017 this antenna has been undergoing refurbishment for use as a radio astronomy telescope. At the end of the first engineering phase, the refurbished telescope is capable of participating in global network observations using a technique known as <a href="http://www.ska.ac.za/science-engineering/avn/">Very Long Baseline Interferometry</a> (VLBI). It also be used in single dish or standalone operational mode.</p>
<p>Interferometry is a technique in which collections of telescopes scattered over a large area function as a single radio telescope. The Very Long Baseline Interferometry technique is most well-known for:</p>
<ul>
<li><p>imaging distant cosmic radio sources, </p></li>
<li><p>tracking spacecraft, and </p></li>
<li><p>for applications in astrometry. </p></li>
</ul>
<p>But the technique can also measure the time differences between the arrival of radio waves from separate antennas to the same source in the sky. This helps astronomers get a better image resolution of an object or a region in the universe. </p>
<p>Put simply, if different telescopes at different locations are all tuned to observe the same source in the sky at the same time, astronomers can get fine details of the specific object being observed.</p>
<p>The countries that make up the African SKA project are each building their own radio telescopes or converting redundant telecommunication dishes so that they function as a network known as the African VLBI Network (AVN). </p>
<p>Ghana now becomes the first country in the African SKA partners besides South Africa to have a <a href="http://www.ska.ac.za/media-releases/ghana-and-south-africa-celebrate-first-success-of-african-network-of-telescopes/">telecommunication antenna</a> converted to realise the African VLBI Network. With Ghana’s telescope now operational, it means that South Africa and Ghana will be able to do joint observations. When the other seven African SKA partner countries get theirs ready, they will join the African’s network. </p>
<p>Kenya, Mozambique and Zambia are contending to add the <a href="https://furtherafrica.com/2017/08/28/eight-african-countries-commit-to-developing-radio-astronomy/">next </a>telescope to the network.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185643/original/file-20170912-19550-ts7kx9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A full view of the refurbished radio telescope in Ghana that forms part of the Square Kilometre Array project.</span>
<span class="attribution"><span class="source">supplied</span></span>
</figcaption>
</figure>
<p><strong>How did we know the Ghanaian telescope was ready and what will it do?</strong> </p>
<p>Across the globe there are several very long base interferometry networks: Europe has one, as does Australia and America. Any telescope across the world is able to join an observation in one of these networks.</p>
<p>After Ghana re-engineered the antenna into a functional radio astronomy telescope, it needed to do a science commissioning of the facility to see if the refurbishment was successful and it could track and observe astronomical sources in the sky and join international observations. </p>
<p>When Ghana tested its telescope it was able to detect methanol masers, observe pulsars and also succeeded in participating in an observation with 15 other telescopes which form part of the European very long base interferometry network. </p>
<p>Until now South Africa has been the only country on the continent that had been joining in VLBI observations with other countries’ networks because it was the only country with a radio telescope on the continent. </p>
<p>With radio telescopes in Ghana and South Africa, an African network is now given birth to. Aside being a part of the African network, Ghana could join other telescopes on the globe to do science observations. </p>
<p><strong>What is the significance of Ghana’s telescope for astronomy in Africa?</strong></p>
<p>There are many celestial objects to observe in the Universe: planets, masers, galaxies, meteorites, stars and even regions in the sky. And there are global questions that astronomy community is interested in addressing. This includes questions like: is there any life outside earth? Are there other stars that are as prominent as the sun? How did the universe come into being? These are questions that the SKA will attempt to address. </p>
<p>If Africa has its own network, astronomers on the continent can choose what celestial objects and regions it wants to observe. </p>
<p>If we look at most of the existing telescopes across the world, there has been a hole in Africa. Telescopes situated in the Northern hemisphere are unable to see the region of the sky in the southern hemisphere. With an African very long base interferometry network set up, astronomers in Africa can now observe both the northern and southern hemispheres of the sky from the continent. </p>
<p><strong>What is Ghana bringing to the party and what does it hope to get out of this SKA collaboration?</strong></p>
<p>The facility at Kutunse will be used as a science instrument but also as a training facility. Ghana will help the other seven countries that form part of the African network refurbish their unused antennae. </p>
<p>Although this technology is not new and has been done in Australia, Peru, Japan and the UK, no other country in Africa has done this. </p>
<p>For Ghana, developing the skills, regulations and institutional capacity in the partner countries is a vital part of building the square kilometre array on the continent over the next decade. This is because it will optimise African participation in the SKA.</p>
<p>Ghana will build it robust research community in a field never before accessible to the country.</p>
<p>But there is also the prospect of improving the radio astronomy capacity in the country. <a href="http://skatelescope.ca/wp-content/uploads/2017/05/01_asabere.pdf">Ghana’s radio astronomy development strategy</a> forms part of the broader Ghana Science, Technology and Innovation Development Plan.</p><img src="https://counter.theconversation.com/content/82849/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bernard Duah Asabere is the manager and lead local scientist of the Radio Astronomy Observatory. </span></em></p>Astronomy on the continent has been given a much needed boost with Ghana’s converted radio telescope between it and South Africa, to conduct scientific observations.Dr. Bernard Duah Asabere, Manager of the Ghana Radio Telescope Observatory, Ghana Space Science and Technology InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/643012016-08-24T20:27:15Z2016-08-24T20:27:15ZThe Industrial Revolution kick-started global warming much earlier than we realised<figure><img src="https://images.theconversation.com/files/135283/original/image-20160824-30259-wgdjb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Britain's industrial pioneers couldn't have known how they would affect the climate.</span> <span class="attribution"><span class="source">Henry Gastineau</span></span></figcaption></figure><p>In the early days of the Industrial Revolution, no one would have thought that their burning of fossil fuels would have an almost immediate effect on the climate. But our new study, <a href="http://nature.com/articles/doi:10.1038/nature19082">published today in Nature</a>, reveals that warming in some regions actually began as early as the 1830s. </p>
<p>That is much earlier than previously thought, so our discovery redefines our understanding of when human activity began to influence our climate. </p>
<p>Determining when global warming began, and how quickly the planet has warmed since then, is essential for understanding how much we have altered the climate in different parts of the world. Our study helps to answer the question of whether our climate is already operating outside thresholds that are considered safe for human society and functional ecosystems. </p>
<p>Our findings show that warming did not develop at the same time across the planet. The tropical oceans and the Arctic were the first regions to begin warming, in the 1830s. Europe, North America and Asia followed roughly two decades later. </p>
<p>Surprisingly, the results show that the southern hemisphere began warming much later, with Australasia and South America starting to warm from the early 20th century. This continental-scale time lag is still evident today: while some parts of Antarctica have begun to warm, a clear warming signal over the entire continent is still not detectable. </p>
<p>The warming in most regions reversed what would otherwise have been a cooling trend related to high volcanic activity during the preceding centuries. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kKPFUdcrLP0?wmode=transparent&start=40" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Global warming got underway much earlier in the north.</span></figcaption>
</figure>
<p>By pinpointing the date when human-induced climate change started, we can then begin to work out when the warming trend broke through the boundaries of the climate’s natural fluctuations, because it takes some decades for the global warming signal to “emerge” above the natural climate variability.</p>
<p>According to our evidence, in all regions except for Antarctica, we are now well and truly operating in a greenhouse-influenced world. We know this because the only climate models that can reproduce the results seen in our records of past climate are those models that factor in the effect of the carbon dioxide released into the atmosphere by humans.</p>
<p>These remarkable findings were pieced together from the most unusual of sources – not thermometers or satellites, but rather from natural climate archives. These include coral skeletons, ice cores, tree rings, cave deposits and ocean and lake sediment layers, all of which record the climate as they grow or accumulate. </p>
<p>These archives provide long records that extend back 500 years – well before the Industrial Revolution – and provide a critical baseline for the planet’s past climate, one that is impossible to obtain otherwise. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/135282/original/image-20160824-30228-gvuwcc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Corals can help reveal the climate of centuries past, long before weather records began.</span>
<span class="attribution"><span class="source">Eric Matson/AIMS</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But why is there no clear warming fingerprint yet seen across Antarctica? The answer most likely lies in the vast Southern Ocean, which isolates the frozen continent from the warming happening elsewhere. </p>
<p>The westerly winds that circulate through the Southern Ocean around Antarctica keep warm air masses from lower latitudes at bay. Ozone depletion and rising greenhouse gas concentrations during the 20th century have also caused this wind barrier to get stronger. </p>
<p>The Southern Ocean currents that flow around Antarctica also tend to <a href="http://www.nature.com/ngeo/journal/v9/n7/full/ngeo2731.html">move warmer surface waters away from the continent</a>, to be replaced with cold deeper water that hasn’t yet been affected by surface greenhouse warming. This process could potentially delay Antarctica’s warming by centuries.</p>
<h2>Ocean insulation</h2>
<p>The delay in warming observed in the rest of the southern hemisphere is something we do not yet fully understand. It could simply be because fewer records are available from the southern hemisphere, meaning that we still don’t have a full picture of what is happening. </p>
<p>Alternatively, like Antarctica, the southern hemisphere’s oceans could be holding back warming – partly through winds and currents, but perhaps also because of “thermal inertia”, whereby the ocean can absorb far more heat energy than the atmosphere or the land before its temperature markedly increases. Bear in mind that the southern half of the globe has much more ocean than the north.</p>
<p>Essentially, then, the coolness of the southern hemisphere’s vast oceans could be “insulating” Australasia and South America from the impact of global warming. The question is, for how long?</p>
<p>If our evidence of delayed warming in the southern hemisphere holds true, it could mean we are in in for more climate surprises as global warming begins to overcome the thermal inertia of our surrounding oceans. Could the <a href="https://theconversation.com/this-summers-sea-temperatures-were-the-hottest-on-record-for-australia-heres-why-56906">recent record warming of Australian waters</a>, and the <a href="https://theconversation.com/how-will-the-barrier-reef-recover-from-the-death-of-one-third-of-its-northern-corals-60186">subsequent damage to the Great Barrier Reef</a>, be an early sign that this is already occurring? </p>
<p>Recent research suggest that the mass bleaching event of the reef was made <a href="https://theconversation.com/great-barrier-reef-bleaching-would-be-almost-impossible-without-climate-change-58408">175 times more likely by climate change</a>. Following the recent severity of such extremes, a better understanding of how anthropogenic greenhouse warming is already impacting the southern hemisphere is critical. </p>
<h2>What to do about it</h2>
<p>Leading scientists from around the world <a href="https://www.ipcc.ch/report/sr15/">met in Geneva</a> last week to discuss the goal of limiting average global warming to 1.5°C – the more ambitious of the two targets enshrined in the <a href="https://theconversation.com/the-paris-climate-agreement-at-a-glance-50465">Paris climate agreement</a>. </p>
<p>Last year, global temperatures crossed the <a href="https://www.ncdc.noaa.gov/bams">1°C threshold</a>, and 2016 is <a href="http://climate.nasa.gov/news/2465/2016-climate-trends-continue-to-break-records/">on track to be 1.2-1.3°C above our climate baseline</a>.</p>
<p>But here’s the kicker. That baseline is relative to 1850–1900, when most of our thermometer-based temperature records began. What our study shows is that for many parts of the world that estimate isn’t good enough, because global warming was already under way, so the real baseline would be lower.</p>
<p>The small increases in greenhouse gases during the 19th century had a small effect on Earth’s temperatures, but with the longer perspective we get from our natural climate records we see that big changes occurred. These fractions of a degree of extra warming might seem insignificant at first, but as we nudge ever closer to the 1.5°C guardrail (and <a href="https://theconversation.com/we-have-almost-certainly-blown-the-1-5-degree-global-warming-target-63720">potentially beyond</a>), the past tells us that <a href="https://theconversation.com/without-a-longer-term-view-the-paris-agreement-will-lock-in-warming-for-centuries-64169">small changes matter</a>.</p>
<hr>
<p><em>Helen McGregor will be online to answer your questions from 2pm AEST today. Post a query in the comments below.</em></p><img src="https://counter.theconversation.com/content/64301/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen McGregor receives funding from the Australian Research Council and the University of Wollongong, Australia. </span></em></p><p class="fine-print"><em><span>Joelle Gergis receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Nerilie Abram receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Steven Phipps receives funding from the Australian Antarctic Science Program, the Australian Research Council, the International Union for Quaternary Research, the National Computational Infrastructure Merit Allocation Scheme, the New Zealand Marsden Fund, the University of Tasmania and UNSW Australia.</span></em></p>The first signs that humans were warming the climate appeared much earlier in the northern hemisphere - way back in the 1830s. But now the trend is emerging all over the globe.Helen McGregor, ARC Future Fellow, University of WollongongJoelle Gergis, ARC DECRA Climate Research Fellow, School of Earth Sciences, The University of MelbourneNerilie Abram, QEII Research Fellow, Australian National UniversitySteven Phipps, Paleo Ice Sheet Modeller, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.