00:00My colleagues from the Science Mission Directorate will go through the images in detail,
00:04but just to give you a peek, here's one of the images from the closest physical instrument we
00:08had to the comet, from the high-rise instrument on our Mars Reconnaissance Orbiter, taken on
00:12October 2nd as the comet sailed by at a distance of 19 million miles from the instrument.
00:17You can see that Comet 3i Atlas looks like a fuzzy white ball. That ball is a cloud of dust
00:22and ice called the coma, which is shed by the comet as it continues its trajectory towards the sun.
00:27The NASA-funded Atlas Survey Telescope, which made the discovery, is part of NASA's Planetary
00:33Defense Network. Our telescopes are always watching the skies to keep us safe, and in
00:39doing so, they occasionally make major scientifically interesting discoveries, just like this one.
00:45Right away, of course, NASA's Planetary Defense Coordination Office established, they studied
00:50it, and they established that 3i Atlas is not a danger to Earth. In fact, it's at least
00:57twice as far away as the distance between the Earth and our sun. On October 30th, the comet
01:05itself reached the closest it will ever be to the sun when it crossed just inside Mars' orbit, which
01:12is why the image that Ahmet just showed, he noted it was the closest instrument physically to the comet,
01:18because the comet was right inside the orbit of Mars. Earth was on the opposite side of the sun,
01:23which is about as far away as our planet can possibly be from Mars. It's been clear from the moment of
01:31discovery that the comet was going to pass on the opposite side of the sun from where the Earth is.
01:36However, it was also clear that its positioning behind the sun was going to make observations from Earth very,
01:42very, very difficult. NASA's Hubble Space Telescope celebrated its 35th birthday earlier this year.
01:48And not too long after that, in July, it looked at 3i Atlas, not long after we discovered it from the ground.
01:55At this point, 3i Atlas was about 277 million miles from Earth. And what Hubble's images revealed was a few things.
02:03First, a teardrop shaped coma of dust coming off that solid icy nucleus of the comet itself.
02:11From these data, astronomers were able to more accurately narrow a few things. Importantly, the size of the nucleus.
02:18We now know it's between, at that point actually, we knew it was between 1,400 feet in diameter up to as large as 3 and a half miles in diameter.
02:26And Hubble also saw that the comet was losing dust, and not just losing it, but losing it at a rate consistent with other previous sunbound comets that originated from within our solar system, consistent with the physics that we figured out from watching those objects.
02:41Now, the last thing Hubble did is it gave us a better understanding of the orbit of this object, tell us not just where it was, but where it was heading, so we could point other observatories at it, such as the James Webb Space Telescope.
02:53We added this to our fleet early in this decade. We didn't have it when the last two interstellar comets came around.
02:58Now, what James Webb did and its companion SPHERE-X, which we only launched at the beginning of this year, is it added infrared observations.
03:06The power of infrared observations is, these are colors we can't see. They're redder than what our eyes can detect.
03:13And infrared light is particularly good at helping us understand the composition of objects.
03:17We can see little molecular fingerprints from the things that the objects are made of.
03:22So with these infrared observations, with James Webb and SPHERE-X, we detected an abundance of carbon dioxide gas in the comet's coma
03:29and in the bright cloud of gas and dust surrounding that comet as it approaches the sun.
03:33Those molecular fingerprints I mentioned, those are the little, like, science wiggles you might see in the top right of these images.
03:39We now know from seeing those science wiggles, those fingerprints of those molecules, that the comet has a nucleus rich in carbon dioxide as well as the presence of water ice.
03:49Now, the ratio, like, we can not just say that these things are there.
03:53We can also say, what's the ratio of carbon dioxide to water?
03:56And we now know that. We know it's larger than what we usually see in solar system objects.
04:01But there's a lot of natural explanations for that.
04:04For one, the carbon dioxide is going to kind of bake off that comet earlier on when it's far away.
04:09But there's other well-understood processes that could also explain it.
04:13I'll just, to put this in context, there are, every time we look beyond our solar system and we look at the ratios of carbon dioxide to water,
04:22we see, whether it's a star or a planet, different ratios than we see in the solar system.
04:27And that's true for this comet as well.
04:30So it could mean, and this is the last theory of why those ratios could be different,
04:34that ices, these ices could have been exposed to higher levels of radiation than comets in our own system.
04:39Or, as I said before, it could be that the comet just formed from a region where carbon dioxide ice was particularly abundant
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