Artist’s impression of the collision of two neutron stars. Image credit: NSF/LIGO/SSU/A.Simonnet

On 16th October a huge team of astronomers announced to the world that they had detected, for the first time, gravitational waves and light from the same event. That event was the collision of two neutron stars in a galaxy around 130 million light year away. The signal was first detected by the LIGO and Virgo gravitational wave detectors, and less than two seconds later by the Fermi gamma ray satellite.

Neither of those initial detections pinpointed the location particularly well, but astronomers from over 70 observatories, including Edward’s Las Cumbres Observatory, went on the hunt. A matter of hours later a new object was spotted in galaxy NGC 4993 – the afterglow of the collision. Follow-up observations told us a huge amount more about this extremely violent event, which is thought to have created huge quantities of heavy elements such as gold and platinum.

The concepts involved in this are complex, and can be hard to articulate. Chris North and Edward Gomez are joined by Sarah Roberts. As well as working in the outreach team here in Cardiff Physics, Sarah writes “Space Scoop“, explaining astronomical stories to those with very little background, such as young children. Sarah is therefore the ideal person to help us explain this event, and how one goes about describing it to a 9 year old.

An extended edition of an original broadcast on 25th October 2017 as part of Pythagoras’ Trousers on Radio Cardiff.

For an archive of Pythagorean Astronomy, visit pythagastro.uk.