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[Music throughout] My name is

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Karl Battams, I’m a computational scientist at the Naval Research Lab, and for nearly 17 years

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I’ve been in charge of NASA’s Sungrazer Project. The Sungrazer Project is

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a citizen science project that allows anyone in the world to discover new comets

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that are seen in images recorded by the joint ESA/NASA SOHO satellite.

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Recently, the project has reached a very special milestone: 

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SOHO has found 4000 previously unknown comets in nearly

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25 years. So I want to share with you my favorite comets

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that SOHO has discovered. [#4 Twin Comets] These were a pair of bright comets,

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both members of what’s known as the Kreutz group, which is a very large

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family of comets that all follow the same path in space.

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Unfortunately, and like nearly all of SOHO’s comets, these guys were completely 

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vaporized by the Sun’s radiation. [#3 SOHO 422] Most of

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SOHO’s comets are what we call sungrazers, which means they follow an orbit that almost

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grazes the surface of the Sun. But we’ve also discovered a lot of comets

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that stay just a bit further away from the Sun, and, unlike sungrazers, 

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manage to at least partially survive passing by the Sun. This comet,

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SOHO’s 422nd discovery, was found back in 

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2002. Here we see it swinging around the sun at a seemingly safe

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distance. Unfortunately, it kind of looks to me like this comet may

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have turned entirely to dust towards the end of the movie.

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It can be hard to know the exact fates of comets like this because

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they’re often impossible to locate from Earth because they’re so close to the Sun.

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[#2 C2015 D1] One of the great things about SOHO’s comet discoveries

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is they also teach us things about the Sun. Here we see what looks like a 

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typical bright sungrazer racing through the LASCO cameras and in this case disappearing

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behind LASCO’s solar occulting disk. And normally this is

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the last we see of them. But this comet, to our absolute astonishment,

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was also visible in images recorded by NASA’s 

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Solar Dynamics Observatory, which looks at the Sun’s million-degree atmosphere

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in extreme ultraviolet light. This was the first time anyone had ever

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seen something like this. We were completely blown away by this result. And

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we can use comets like this almost like remote probes. They

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allow us to learn about the environment close to the Sun

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by watching how the comet is reacting within that

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really extreme environment. [#1 The 4,000th] Finally, this is certainly not

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the biggest or brightest comet SOHO has ever found, but for me it’s

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absolutely one of the most important. This is SOHO’s 4000th

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comet discovery. That’s a truly remarkable milestone for this mission to reach.

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Particularly as it was never designed to look at 

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or discover comets. This milestone is also a huge testament to

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the NASA and ESA scientists and engineers in support

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teams that have kept SOHO running so well all these years.

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And of course, probably most of all, it’s a testament to the 

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army of citizen scientists who have contributed so much

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free time to scouring the SOHO images and

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helping us realize all of this incredible science that we’ve gained so far.

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Here’s hoping for another 4000 comets.

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[Music fades]

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[Music]

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[Music]