1 00:00:02,980 --> 00:00:06,480 Astronomers using the NASA/ESA Hubble Space Telescope 2 00:00:06,480 --> 00:00:11,600 have observed a visible counterpart to gravitational waves for the first time: 3 00:00:12,080 --> 00:00:15,440 a kilonova from merging neutron stars. 4 00:00:21,640 --> 00:00:25,860 Hubble observes source of gravitational waves for the first time 5 00:00:26,220 --> 00:00:28,680 On August the 17th, 2017 6 00:00:28,760 --> 00:00:36,280 the LIGO–Virgo collaboration detected gravitational waves rippling through the fabric of space-time. 7 00:00:37,560 --> 00:00:41,700 Just two seconds later, two space telescopes from ESA and NASA 8 00:00:41,700 --> 00:00:47,680 also detected a short gamma-ray burst coming from the same area of the sky. 9 00:00:48,460 --> 00:00:51,560 This coincidence had never been seen before 10 00:00:51,900 --> 00:00:56,020 and raised hopes that astronomers had witnessed a cataclysmic event — 11 00:00:57,500 --> 00:01:02,040 two neutron stars combining in an explosive merger. 12 00:01:02,580 --> 00:01:08,240 If so, a visible-light counterpart known as a kilonova was expected to follow. 13 00:01:09,300 --> 00:01:10,880 The hunt was on! 14 00:01:11,720 --> 00:01:16,200 Hubble joined a host of telescopes from the European Southern Observatory 15 00:01:16,200 --> 00:01:20,380 and other observatories around the world to search for a new light source. 16 00:01:21,500 --> 00:01:24,120 They were looking for a needle in a haystack — 17 00:01:24,120 --> 00:01:27,540 a faint new glimmer amid millions of stars. 18 00:01:28,640 --> 00:01:32,300 But amazingly, they found it just a few hours later — 19 00:01:32,300 --> 00:01:35,920 in the galaxy NGC 4993, 20 00:01:35,920 --> 00:01:40,320 130 million light-years from Earth. 21 00:01:42,660 --> 00:01:48,820 Over the next few weeks, astronomers used a host of telescopes to record the kilonova. 22 00:01:51,920 --> 00:01:58,700 Neutron star mergers are the furnaces where most of the chemical elements heavier than iron are forged. 23 00:01:59,160 --> 00:02:03,360 The kilonova, an event 1000 times brighter than a typical nova, 24 00:02:03,360 --> 00:02:07,620 spreads the newly-formed elements into the surrounding space. 25 00:02:08,400 --> 00:02:14,080 These include the gold in jewelry, the platinum in catalytic converters in cars 26 00:02:14,080 --> 00:02:16,400 and uranium in nuclear reactors. 27 00:02:20,120 --> 00:02:27,680 Such an explosion had never been confirmed before, but now one could be studied in great detail! 28 00:02:28,720 --> 00:02:36,040 The observations revealed an extraordinary and rapidly changing event, closely mirroring theory. 29 00:02:36,920 --> 00:02:42,420 Heavy, radioactive elements were shot into space at one-fifth of the speed of light. 30 00:02:43,760 --> 00:02:49,540 In just a matter of days the kilonova’s colour changed rapidly from blue to red, 31 00:02:49,540 --> 00:02:53,720 faster than any other observed stellar explosion. 32 00:02:57,400 --> 00:03:02,880 This event marks the start of a new era of multi-messenger astronomy. 33 00:03:05,380 --> 00:03:11,440 For the first time in history we can now combine light signals with gravitational waves, 34 00:03:11,440 --> 00:03:15,740 to provide a totally new way to probe the Universe. 35 00:03:26,060 --> 00:03:30,400 Transcribed by ESO. Translated by --.