Articles on Sun

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A total solar eclipse will be visible across parts of the United States Aug. 21, treating amateur and professional astronomers alike to sights similar to this NASA’s Solar Dynamics Observatory ultraviolet image of the moon eclipsing the sun on Jan. 31, 2014. (NASA)

How to safely watch an eclipse: Advice from an astronomer

If you've ever wondered why you can look at a solar eclipse and why it can harm your eyes, the answer is in the sun's rays.
A solar eclipse observed over Grand Canyon National Park in May 2012. Grand Canyon National Park

How eclipses were regarded as omens in the ancient world

More than 2,000 years ago, the Babylonians understood the cycle of eclipses. They also regarded them as signs that could foretell the death of a king.
Earth, shot from space, as it absorbs and reflects rays of light coming from the Sun - the same white-looking rays that give our sky its colour. NASA

Curious Kids: Why is the sky blue and where does it start?

Some people think the sky is blue because of sunlight reflected off the ocean and back into the sky. But that's not the real reason.
An artist’s illustration of Kappa Ceti whose stellar winds are 50 times stronger than our sun’s. Any Earth-like planet would need a magnetic field to protect its atmosphere if it was to stand a chance of hosting life. M. Weiss/CfA

What the ‘weather’ is like on a star can help in the search for life

In the search for life on other planets in the universe we need to find the right kind of star, and it needs to have the right kind of space weather.
Artist’s impression: Looking back 12.9-billion km towards the sun and the inner solar system from Sedna, one of the recently discovered minor planets in the Kuiper belt. NASA, ESA and Adolf Schaller

The long hunt for new objects in our expanding solar system

The search for new objects, including new planets, in our solar system has turned up some interesting finds. There have been a few failures over the years too.
The UV Index was created last century largely for North American and European conditions, which rarely reach the ‘extreme’ range. Andy Cross/Flickr

Health Check: what does the UV Index mean?

Alongside the day's high and low, weather reports generally contain a UV alert for a particular time. But what does it actually mean – and what should you do about it?

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