WEBVTT FILE ﻿1 00:00:00.000 --> 00:00:04.100 Music 2 00:00:04.120 --> 00:00:08.200 People have been 3 00:00:08.220 --> 00:00:12.320 hunting for sungrazing comets for hundreds of years, but as of 4 00:00:12.340 --> 00:00:16.390 1979 we only knew of less than a dozen. Today. 5 00:00:16.410 --> 00:00:20.500 we have seen about 2,500. Why did the number increase? 6 00:00:20.520 --> 00:00:24.550 Understanding this starts with the Kreutz path. In the 7 00:00:24.570 --> 00:00:28.580 late 1800s, Heinrich Kreutz observed that many recent comets 8 00:00:28.600 --> 00:00:32.760 traveling near the sun appeared to follow the same orbit. On this Kreutz 9 00:00:32.780 --> 00:00:36.820 path, as we've come to call it, it takes the comet about 800 years 10 00:00:36.840 --> 00:00:40.930 to complete one loop around the sun. While there are other orbits of 11 00:00:40.950 --> 00:00:45.040 sungrazers, Kreutz comets are the most common. All of the comets 12 00:00:45.060 --> 00:00:49.120 in this orbit came from a single comet, observed thousands of years ago. 13 00:00:49.140 --> 00:00:53.180 As the comet moved closer to the sun, the ice binding it 14 00:00:53.200 --> 00:00:57.240 together evaporated, breaking it into smaller pieces that the sun's gravity 15 00:00:57.260 --> 00:01:01.309 pulled apart. Every time the comet comes around the Kreutz path, this can 16 00:01:01.330 --> 00:01:05.420 happened again, resulting in a new generation of comets. It might 17 00:01:05.440 --> 00:01:09.530 sound like this would clutter the solar system full of comets, but that is not the case. 18 00:01:09.550 --> 00:01:13.580 Some of the new comets are small enough that they become completely vaporized 19 00:01:13.600 --> 00:01:17.649 as they approach the sun. There are more comets observed, not because 20 00:01:17.670 --> 00:01:21.680 there are more in the solar system but because we have better ways to see them. 21 00:01:21.700 --> 00:01:25.890 Spotting a sungrazer from the ground is difficult because of the blinding sunlight. 22 00:01:25.910 --> 00:01:29.920 Now, spacecraft designed to observe the sun make the job a lot 23 00:01:29.940 --> 00:01:34.120 easier. Since the joint ESA/NASA mission SOHO launched in 1995, 24 00:01:34.140 --> 00:01:38.180 it has shown us thousands more comets than any tool before. 25 00:01:38.200 --> 00:01:42.270 To date, it has found 2,387 comets. 26 00:01:42.290 --> 00:01:46.370 With SOHO we can now see the smaller, fainter comets 27 00:01:46.390 --> 00:01:50.480 close to the sun, just long enough to ad them to our list of sungrazers 28 00:01:50.500 --> 00:01:54.670 before they vaporize. The spacecraft's data is available online, 29 00:01:54.690 --> 00:01:58.700 so now, anyone can discover a comet. Roughly 75% 30 00:01:58.720 --> 00:02:02.789 of these comets have been found by amateur astronomers. 31 00:02:02.810 --> 00:02:06.880 Other solar observatories, such as NASA's SDO, weren't expected to provide 32 00:02:06.900 --> 00:02:10.910 good comet observations, but they captured some beautiful images, creating 33 00:02:10.930 --> 00:02:14.960 more possibilities for comet research using unexpected tools. Now 34 00:02:14.980 --> 00:02:19.019 that we can observe comets better than ever - who knows? - maybe you 35 00:02:19.040 --> 00:02:23.060 will spot the next sungrazer. 36 00:02:23.080 --> 00:02:27.130 beeping 37 00:02:27.150 --> 00:02:31.190 beeping 38 00:02:31.210 --> 00:02:35.220 39 00:02:35.240 --> 00:02:36.480