Jason Davis • September 13, 2019

It is likely that a newly discovered comet is indeed an interstellar intruder from outside our solar system.

Since its discovery on August 30, more and more measurements of C / 2019 Q4 (Borisov) – named after the amateur astronomer from the Crimea, who found it – suggest that it does not orbit our Sun. Even NASA now says that the extrasolar origin of the comet is promising.

If confirmed, C / 2019 Q4 (Borisov) would be the second interstellar object we saw in our solar system after the discovery of & # 39; oumuamua in 2017. The new object, which has a blurred coma in images, would be the first definitive interstellar comet; "Oumuamua looked like an asteroid and behaved a bit like a comet.

Comet 2019 Q4 (Borisov)

Canada-France-Hawaii telescope

Comet 2019 Q4 (Borisov)

Comet C / 2019 Q4 (Borisov) taken by Canada-France-Hawaii Telescope on September 10, 2019 on Hawaii's Big Island.

Comet C / 2019 Q4 (Borisov) will reach perihelion on December 8, 2019 – its closest point to the sun. To learn more about this comet and other interstellar objects, I spoke with Karl Battams, an astrophysicist and computer scientist at the Naval Research Laboratory in Washington, DC. Battams operates the NASA-funded Sungrazer Project, which uses space-based solar telescopes to search for comets is sought, which fly near the sun.

Why is it so important to study objects from outside our solar system? What can we learn about the cosmos and our own origins by studying them?

I think what matters is that one of the big questions we have in astronomy or even beyond astronomy is, "Are we alone?" Is our solar system and our planet completely unique? Is there something about us that is completely different from the rest of our galaxy and the universe? It is really impossible to fully answer the question, but the beauty of an interstellar object is that we can see how similar or dissimilar it is to objects in our own solar system. If it turns out that this comet is like a typical comet that we see in our own solar system, we'll think, "Okay, maybe we're not so unique in composition." Or maybe there will be a really bizarre chemistry and we'll say, "Wow, the things out there are wild!"

This object definitely seems to be a comet while Oumuamua had both asteroid and comet features. If this really is our first interstellar comet, how big will that be for astronomers? What kind of things will we try to learn from and how?

The beauty of comets is that they are active. The reason why comets have the diffuse coma and the tail behind it is that sunlight hits all the volatiles on the surface and makes them basically evaporate. When they lift off the surface, they also bring out other material. In other words, you cook the surface away.

While an asteroid is an inert rock and you can only study how light is reflected by it, a comet has many chemical processes. It's much more complex, so you'll understand a little more about the gases and dust released by the comet, and hopefully get a much better idea of ​​its composition.

Comets are also a bit easier to see. "Oumuamua was very small, weak and star-shaped in appearance, while this comet will be easier to see for people with a reasonably decent telescope – though it is by no means bright!

What does a comet close up look like?

"The Comet" is a short film shot with images from the mission of the spaceship Rosetta to the comet Churyumov-Gerasimenko. Find out more here.

Christian Stangl

More comet pictures can be found in our Bruce Murray Space Image Library.

This comet is called C / 2019 Q4 (Borisov). Can you decipher this name for us?

I suspect that the name does actually change a bit when it is officially classified as interstellar, but the C designation in the current name is the default for a comet. The year 2019 is pretty obvious – it's the year. The letter and number are just a continuous label that is applied. The very first comet of the year is A1, the next one is A2, and then they go every six months to the next letter of the alphabet. Borisov is the name of the object's discoverer, Gennady Borisov.

Will the comet come close to the earth? And can we see it without a telescope?

The next approach will be just outside Mars orbit, which is not very close, but in a few months it should be in a pretty good position to be seen from Earth. It will not be bright to the naked eye unless it does something unexpected. We assume that it is played according to the same rules our comets play, and if so, it will not be bright with the naked eye.

I think the current forecasts are on the order of 16, maybe 17, which definitely requires a decent telescope and some expertise, but it's not inappropriate that many amateur astronomers see it, as well as professional telescopes.

The way from C / 2019 Q4 (Borisov)

The planetary society

The way from C / 2019 Q4 (Borisov)

This graphic shows the way from C / 2019 Q4 (Borisov) on its way through our solar system.

Are the comet and Oumuamua related or are they from the same place? Suppose it's interstellar, do we know where the comet moves after it passes our solar system?

No, it has absolutely nothing to do with Oumuamua. The orbit of the comet is still being refined, so people are still reluctant to say it's definitely interstellar. This is partly because we are still trying to narrow the details of the orbit. It will be a few weeks before we get there.

But we generally know from which direction the comet came in interstellar space, and we generally know which direction it will go, and none of these directions has anything to do with the origin or origin of Oumuamua. They are completely different objects with completely different orbits, and there is absolutely no relationship between them.

How do we know that objects like & # 39; oumuamua and possibly this comet are interstellar? How important is it for amateur asteroid hunters to determine if an object has interstellar origin?

Basically, every comet we've discovered so far is somehow tied to our sun and our solar system. They meet the sun, bend and go out again, but you notice that they are gravitationally bound to our solar system. Interstellar objects follow an orbit that is still affected by the gravity of our Sun but is not bound to it. These objects can easily escape our solar system and return to interstellar space. Also, this comet moves much faster than a comet if it were bound to our sun – so its speed is another strong indication that we are dealing with some interstellar.

As for the role of amateurs, those who can provide very high-quality observations are certainly crucial. Determining the orbit for such objects is not so much about getting more observations this second, but about a week or two. This really enables us to get a better grip on the way it goes through space. When an object like this is discovered, many amateur astronomers look at celestial surveys that took months or even years of data because such things are sometimes overlooked.

At the moment, we have no way to send a spacecraft to see a comet like this close up. How do you like a mission? Comet interceptor ESAthat would start in 2028 and park in space until we discover an object like this, change that?

A space probe mission to this comet would be incredible! The scientific return we've received from the probes that have visited comets like Deep Impact and Rosetta has been absolutely phenomenal. So, if we could bring a probe close to an interstellar comet, it would be extraordinary, especially for what I've noticed before – that this is part of a completely different star system.

I think the Comet Interceptor concept developed by ESA is pretty much the right approach. They will literally park a satellite at a suitable point in space, hoping something will come within their reach and then intercept it. ESA has tweeted that this comet could actually have been a potential target for this mission.

"Oumuamua has theorized that it could be a huge alien spaceship, which is certainly the least likely explanation for these objects. Why do you think the public takes notice of such objects? Is it related to our desire to learn more about our own place in the cosmos?

I think because it forces you to think far beyond your bladder. When something comes from a completely different solar system and comes from another star, it broadens your horizons. I also think that this is science fiction, which often involves interstellar travel. And yes, that includes things like extraterrestrials, and I know you're trying to get around that angle. Nevertheless, people think about it because it goes back to the basic questions: "Are we alone? Are we unique? "I think that's why it attracts people's attention because it's something that is so strange compared to what we've seen before.

It's as if the stars are those distant points of light that are so far away that it's almost unimaginable. But when you hear of a piece of one of these stars in our neighborhood, the stars feel a little closer.

Precisely. The universe or galaxy just got a little smaller. As the neighbors have just sent us an apple pie.

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