2016: The year In Space And Astronomy

The discovery of the year was the first detection of gravitational waves. LIGO/T. Pyle

Kristy Hamilton 29 Dec 2016, 19:08

The Conversation

The achievements of astrophysicists this year were as groundbreaking as they were varied. From reuniting a lander with a mothership on a comet, to seeing the most extreme cosmic events with gravitational waves, 2016 was truly out of this world for science.

Here are some of the highlights of the year that was.

1. Gravitational Waves

The spectacular announcement that ripples in the very fabric of spacetime itself had been found (and from surprisingly massive black holes colliding) sent similarly massive ripples through the scientific community. The discovery was made using the Laser Interferometer Gravitational-Wave Observatory (LIGO) and represents a fundamentally new sense with which to see the universe.

Animation showing how colliding black holes cause a ripple in spacetime that moves outwards into the universe as a gravitational wave.

The gravitational waves cause one arm of the LIGO detector to stretch relative to the other by less than a thousandth of the width of a proton in the centre of the atom. Relatively speaking, that’s like measuring a hair’s-width change in the distance to the nearest star.

This discovery was the end of a century-long quest to prove Einstein’s final prediction that these gravitational waves are real. It also allows us to directly “see” that famously and fundamentally invisible entity: the black hole (as well as definitively proving its existence). The fact that the two black holes collided 1.3 billion years ago and the waves swept through Earth just days after turning the detector on only add to the incredible story of this discovery.

The ‘sound’ of the black holes colliding where the measured signal from LIGO is converted to audio, the rising chirp sound towards the end is the two black holes spiralling together ever more quickly. A surprisingly wimpy sound for the most extreme collision ever detected.

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