To answer this tricky question, we have to look back in time to when the Earth was born, 4.5 billion years ago.
Images from New Horizons spacecraft provide more evidence about the surface of Pluto.
When NASA first started planning the Kepler mission, no one knew if the universe held any planets outside our solar system. Thousands of exoplanets later, the search enters a new phase.
A new trajectory means the mission to uncover core facts about the asteroid belt will happen sooner than planned.
Simulations in a special chamber suggest how the Mars landscape could have been shaped under certain conditions.
Planetary protection protocols try to make sure we don't seed places like Mars with life from our planet. An astrobiologist argues they're misguided – especially with human astronauts on the horizon.
Imagine the Earth pulling everything it is made up of, all of its mass, towards its centre. This happens evenly all over the Earth, causing it to take on a round shape.
How exactly do the stars twinkle in the night sky? As it turns out, the answer is full of hot air... and cold air.
While we on Earth are familiar with our own star, the Sun, the European Space Agency's PLATO mission will explore solar systems similar to ours as well as those that are more exotic.
The planets closer to the Sun are indeed hotter than the Earth is. But they are still not hot enough to melt the rocks they are made from.
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.
What caused the Big Bang is still a mystery. And that's just one of the many unanswered questions, in spite of everything we do know about the birth of the Universe.
The images are in from the Juno probe's closest flyby so far of Jupiter's Great Red Spot. Citizen scientists are now getting involved in processing those images.
Researchers recently discovered the hottest planet known. But which one is the coldest? And the biggest?
We may need to re-think our models of Jupiter’s formation thanks to the first results from Juno probe orbiting the planet, and new observations from Earth.
Australia's new partnership with the European Southern Observatory will give our astronomers access to much bigger telescopes.
Plants on other planets are bound to be even weirder than the strangest ones we find on Earth – if they even exist.
With the probe now on its 'Grand Finale,' a Cassini team member describes the amazing discoveries it made about the ringed planet and its many moons.
A group of astronomers are trying to reclassify Pluto as full 'planet'. But there are good reasons to leave our classification system alone, and this doesn't mean Pluto is any less interesting.
Scientists have discovered seven Earth-sized planets packed around a dim star.