1 00:00:03,780 --> 00:00:07,040 Astronomers using a fleet of ESO telescopes 2 00:00:07,040 --> 00:00:11,520 have observed a visible counterpart to gravitational waves for the first time: 3 00:00:11,960 --> 00:00:15,000 a kilonova from merging neutron stars. 4 00:00:26,560 --> 00:00:30,080 Episode 133 // ESO Telescopes Observe First Light from Gravitational Wave Source 5 00:00:30,320 --> 00:00:32,640 On August the 17th 2017, 6 00:00:32,920 --> 00:00:40,380 the LIGO–Virgo collaboration detected gravitational waves rippling through the fabric of space-time. 7 00:00:41,040 --> 00:00:45,500 Just two seconds later two space telescopes from ESA and NASA 8 00:00:45,960 --> 00:00:50,940 also detected a short gamma-ray burst coming from the same area of the sky. 9 00:00:52,480 --> 00:00:55,900 This coincidence had never been seen before 10 00:00:55,900 --> 00:01:00,200 and raised hopes that astronomers had witnessed a cataclysmic event — 11 00:01:00,640 --> 00:01:04,900 two neutron stars combining in an explosive merger. 12 00:01:05,740 --> 00:01:11,840 If so a visible-light counterpart known as a kilonova was expected to follow. 13 00:01:11,840 --> 00:01:13,360 The hunt was on! 14 00:01:17,020 --> 00:01:19,520 ESO and ESO-partnered telescopes in Chile 15 00:01:20,220 --> 00:01:23,820 joined other observatories to search for a new light source. 16 00:01:24,340 --> 00:01:26,340 They were looking for a needle in a haystack — 17 00:01:26,850 --> 00:01:30,119 a faint new glimmer amid millions of stars. 18 00:01:30,780 --> 00:01:34,320 But amazingly, they found it just a few hours later — 19 00:01:35,000 --> 00:01:38,520 in the galaxy NGC 4993, 20 00:01:38,520 --> 00:01:41,780 130 million light years from Earth. 21 00:01:44,560 --> 00:01:46,680 Over the next few weeks, 22 00:01:46,680 --> 00:01:53,520 astronomers used a host of ESO telescopes with more than 10 different instruments to record the kilonova. 23 00:01:55,360 --> 00:02:01,680 Neutron star mergers are the furnaces where most of the chemical elements heavier than iron are forged. 24 00:02:02,020 --> 00:02:06,640 The kilonova, an event 1000 times brighter than a typical nova, 25 00:02:07,060 --> 00:02:10,300 spreads the newly-formed elements into the surrounding space. 26 00:02:11,020 --> 00:02:16,720 These include the gold in jewelry, the platinum in catalytic converters in cars, 27 00:02:16,720 --> 00:02:19,280 and uranium in nuclear reactors. 28 00:02:21,080 --> 00:02:24,400 Such an explosion had never been confirmed before, 29 00:02:25,040 --> 00:02:27,940 but now one could be studied in great detail! 30 00:02:28,820 --> 00:02:36,760 The ESO observations revealed an extraordinary and rapidly changing event, closely mirroring theory. 31 00:02:37,420 --> 00:02:43,180 Heavy, radioactive elements were shot into space at one-fifth of the speed of light. 32 00:02:44,000 --> 00:02:49,720 In just a matter of days the kilonova’s colour changed rapidly from blue to red, 33 00:02:50,120 --> 00:02:53,940 faster than any other observed stellar explosion. 34 00:02:57,740 --> 00:03:04,040 Thanks to the rapid reaction of groups of skilled scientists and ESO's very wide array of instruments, 35 00:03:04,040 --> 00:03:10,520 this kilonova was located and studied across a swath of wavelengths in a matter of days. 36 00:03:11,140 --> 00:03:16,760 This event marks the start of a new era of multi-messenger astronomy. 37 00:03:17,140 --> 00:03:23,320 For the first time in history we can now combine light signals with gravitational waves 38 00:03:23,320 --> 00:03:27,520 to provide a totally new way to probe the Universe. 39 00:03:33,400 --> 00:03:38,240 Transcripted by ESO. Translated by — .