If we didn't correct for gravitational effects on the Earth's orbit, the winter solstice would shift backwards by a day every 72 years.
A black hole is an object with such a strong gravitational pull that nothing, not even light, can escape from it.
The comet 46P/Wirtanen is just 1.2km in size but it should be visible in the night sky this Saturday as it makes a close approach to Earth this year. And don't forget the Geminids meteor shower.
A bright comet visible in December provides an excellent viewing opportunity for night sky lovers – even potentially with the naked eye.
Expect a spectacular display of 120 or more meteors per hour – some of them brightly coloured.
More ripples in space-time have been detected from merging pairs of black holes, one of which was the most massive and distant gravitational-wave source ever observed.
We will never see 'Oumuamua again, and we may never know exactly what it is. But with the right kind of media coverage it could inspire some kids to take up a career in science.
A number of surrounding galaxies are slowly being devoured by the most luminous object in the sky.
The new planet is believed to be orbiting Barnard's Star, a red dwarf that's not visible to the naked eye but one of the closest stars to our Solar System.
Astronomers have suspected them for ages –now a team as finally spotted a 'fountain' in a galaxy far, far away.
The Gaia satellite has uncovered the remains of a galaxy buried deep in the Milky Way.
Are there stars other than the Sun that might explode soon close to us? Yes, there are! As long as by 'soon' we mean within a million years.
Astronomers think they've identified which galaxy was the source of a blast radio energy, over in a fraction of a second. And it's much closer to us than the others detected, so far.
There are lots of places where it's much, much hotter than the Sun. And the amazing thing is that this heat also makes new atoms - tiny particles that have made their way long ago from stars to us.
From sun dials to atomic clocks, we still don't have a perfect time measuring device.
Merging supermassive black holes would emit gravitational waves, allowing scientists to detect them.
Whether you call it Planet X or Planet Nine, talk of another planet lurking in our Solar system won't go away. So what does the discovery of a new object – nicknamed "The Goblin" – add to the debate?
The five planets visible to the naked eye since ancient times are putting on a dazzling display this month, in a night-sky dance along with the Moon.
We still don't know what causes these mysterious Fast Radio Bursts deep in the universe, but we've detected a whole new batch of them.
The 'oldest known nova' (a star explosion) in the sky was actually not a nova, astronomers show.