WEBVTT FILE 1 00:00:01.070 --> 00:00:05.070 2 00:00:05.070 --> 00:00:00.000 Narrator: People have been hunting for sun grazing comets for well over 100 years, 3 00:00:00.000 --> 00:00:05.040 Narrator: People have been hunting for sungrazing comets 4 00:00:05.040 --> 00:00:09.040 for well over a hundred years, but up to 1979 5 00:00:09.040 --> 00:00:13.040 we only knew of less than a dozen. As of 2020, we have seen 6 00:00:13.040 --> 00:00:17.040 around 4,000 sungrazers. Why did the number increase? 7 00:00:17.040 --> 00:00:21.040 The answer lies along the route most sungrazers follow. 8 00:00:21.040 --> 00:00:25.040 In the late 1800s, Heinrich Kreutz observed that a few recent comets 9 00:00:25.040 --> 00:00:29.040 comets traveling near the Sun appeared to follow the same orbit. 10 00:00:29.040 --> 00:00:33.040 On this Kreutz sungrazer path, as we've come to call it, it takes 11 00:00:33.040 --> 00:00:37.040 the comet several hundred years to complete one loop around the Sun. 12 00:00:37.040 --> 00:00:41.040 While there are other orbits of sungrazers, Kreutz comets are the most common. 13 00:00:41.040 --> 00:00:45.040 All of the comets in this orbit came from a single comet that fell apart 14 00:00:45.040 --> 00:00:49.040 near the Sun thousands of years ago. 15 00:00:49.040 --> 00:00:53.040 As the comet moved closer to the sun, the ice binding it together evaporated, breaking it into 16 00:00:53.040 --> 00:00:57.040 smaller pieces that the Sun's gravity pulled apart. 17 00:00:57.040 --> 00:01:01.040 Every time a comet comes around the Kreutz path, this can happen again, resulting 18 00:01:01.040 --> 00:01:05.040 in a new generation of comets. It might sound 19 00:01:05.040 --> 00:01:09.040 like this would clutter the solar system full of comets, but that is not the case. 20 00:01:09.040 --> 00:01:13.040 Most of the new comets are small enough that they become completely vaporized as they approach 21 00:01:13.040 --> 00:01:17.040 the Sun. There are more comets observed in the last few decades, 22 00:01:17.040 --> 00:01:21.040 not because there are more in the solar system but because we have better ways 23 00:01:21.040 --> 00:01:25.040 to see them when they are close to the Sun. 24 00:01:25.040 --> 00:01:29.040 Spotting a sungrazer from the ground is almost impossible because of the blinding sunlight. 25 00:01:29.040 --> 00:01:33.040 Now, spacecraft uniquely design to look at the Sun can 26 00:01:33.040 --> 00:01:37.040 block the brightest sunlight, making the job a lot easier. 27 00:01:37.040 --> 00:01:41.040 Since the joint ESA/NASA mission SOHO launched in 1995, 28 00:01:41.040 --> 00:01:45.040 it has shown us thousands more comets than any tool before it. 29 00:01:45.040 --> 00:01:49.040 With SOHO we can now see the smaller, fainter comets 30 00:01:49.040 --> 00:01:53.040 close to the sun, just long enough to add them to our list of sungrazers 31 00:01:53.040 --> 00:01:57.040 before they vaporize. The spacecraft's data is available online, 32 00:01:57.040 --> 00:02:01.040 so now, anyone can discover a comet. 33 00:02:01.040 --> 00:02:05.040 Roughly 95% of these comets have been found by amateur astronomers. 34 00:02:05.040 --> 00:02:09.040 SOHO isn’t the only Sun-observing spacecraft to have surprised us 35 00:02:09.040 --> 00:02:13.040 with beautiful images of comets. NASA’s Solar Dynamics Observatory 36 00:02:13.040 --> 00:02:17.040 has spotted sungrazers, too, though less frequently than SOHO 37 00:02:17.040 --> 00:02:21.040 Now that we can observe comets better than ever - who knows? 38 00:02:21.040 --> 00:02:25.040 - maybe you will spot the next sungrazer. 39 00:02:25.040 --> 00:02:29.040 40 00:02:29.040 --> 00:02:34.005