1 00:00:00,000 --> 00:00:05,040 Narrator: People have been hunting for sungrazing comets 2 00:00:05,040 --> 00:00:09,040 for well over a hundred years, but up to 1979 3 00:00:09,040 --> 00:00:13,040 we only knew of less than a dozen. As of 2020, we have seen 4 00:00:13,040 --> 00:00:17,040 around 4,000 sungrazers. Why did the number increase? 5 00:00:17,040 --> 00:00:21,040 The answer lies along the route most sungrazers follow. 6 00:00:21,040 --> 00:00:25,040 In the late 1800s, Heinrich Kreutz observed that a few recent comets 7 00:00:25,040 --> 00:00:29,040 comets traveling near the Sun appeared to follow the same orbit. 8 00:00:29,040 --> 00:00:33,040 On this Kreutz sungrazer path, as we've come to call it, it takes 9 00:00:33,040 --> 00:00:37,040 the comet several hundred years to complete one loop around the Sun. 10 00:00:37,040 --> 00:00:41,040 While there are other orbits of sungrazers, Kreutz comets are the most common. 11 00:00:41,040 --> 00:00:45,040 All of the comets in this orbit came from a single comet that fell apart 12 00:00:45,040 --> 00:00:49,040 near the Sun thousands of years ago. 13 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 14 00:00:53,040 --> 00:00:57,040 smaller pieces that the Sun's gravity pulled apart. 15 00:00:57,040 --> 00:01:01,040 Every time a comet comes around the Kreutz path, this can happen again, resulting 16 00:01:01,040 --> 00:01:05,040 in a new generation of comets. It might sound 17 00:01:05,040 --> 00:01:09,040 like this would clutter the solar system full of comets, but that is not the case. 18 00:01:09,040 --> 00:01:13,040 Most of the new comets are small enough that they become completely vaporized as they approach 19 00:01:13,040 --> 00:01:17,040 the Sun. There are more comets observed in the last few decades, 20 00:01:17,040 --> 00:01:21,040 not because there are more in the solar system but because we have better ways 21 00:01:21,040 --> 00:01:25,040 to see them when they are close to the Sun. 22 00:01:25,040 --> 00:01:29,040 Spotting a sungrazer from the ground is almost impossible because of the blinding sunlight. 23 00:01:29,040 --> 00:01:33,040 Now, spacecraft uniquely design to look at the Sun can 24 00:01:33,040 --> 00:01:37,040 block the brightest sunlight, making the job a lot easier. 25 00:01:37,040 --> 00:01:41,040 Since the joint ESA/NASA mission SOHO launched in 1995, 26 00:01:41,040 --> 00:01:45,040 it has shown us thousands more comets than any tool before it. 27 00:01:45,040 --> 00:01:49,040 With SOHO we can now see the smaller, fainter comets 28 00:01:49,040 --> 00:01:53,040 close to the sun, just long enough to add them to our list of sungrazers 29 00:01:53,040 --> 00:01:57,040 before they vaporize. The spacecraft's data is available online, 30 00:01:57,040 --> 00:02:01,040 so now, anyone can discover a comet. 31 00:02:01,040 --> 00:02:05,040 Roughly 95% of these comets have been found by amateur astronomers. 32 00:02:05,040 --> 00:02:09,040 SOHO isn’t the only Sun-observing spacecraft to have surprised us 33 00:02:09,040 --> 00:02:13,040 with beautiful images of comets. NASA’s Solar Dynamics Observatory 34 00:02:13,040 --> 00:02:17,040 has spotted sungrazers, too, though less frequently than SOHO 35 00:02:17,040 --> 00:02:21,040 Now that we can observe comets better than ever - who knows? 36 00:02:21,040 --> 00:02:25,040 - maybe you will spot the next sungrazer. 37 00:02:25,040 --> 00:02:29,040 38 00:02:29,040 --> 00:02:34,005