Gravitational waves have been in the news a lot lately.
Two weeks ago, the Nobel Prize in Physics went to three of the leading scientists behind the 1,000-strong international project which first detected these miniscule ripples in the fabric of space-time.
Now an international team of scientists has detected gravitational waves from a new source: the cataclysmic collision of neutron stars, the smallest and densest stars in the universe.
And this is much more than just the fifth in that historic series of detections.
Scientists say this is a game-changer, which arguably rivals the original Nobel Prize-winning detection.
Not only has it produced an unprecedented amount of data and opened a new window on the universe, it will revolutionise science for decades to come.
Here are six reasons why.
The first hint of gravitational waves came from neutron stars
Albert Einstein predicted that if you had two stars orbiting each other they would give off an intensifying burst of gravitational waves, just before they collided.
A neutron star is the small, heavy core left behind after a supernova explodes.
Because it packs the mass of up to two Suns into a ball the size of Adelaide, a neutron star is also a perfect laboratory for studying the extremes of gravity.
We only know of their existence through the discovery of pulsars — regular pulses of radiation created when these stars spin, incredibly fast.
In 1974, astronomers Russell Alan Hulse and Joseph Hooton Taylor Jr discovered radio pulsars coming from a pair of neutron stars circling each other.