An extinction level comet has just been spotted

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The International Astronomical Union confirmed that the object formally known as C/2019 Q4 (Borisov) is indeed from another solar system, giving it the proper name of 21/Borisov on Tuesday. It is the second-ever object from beyond our solar system, following Ouamuamua’s discovery in October 2017.

21/Borisov was discovered on Aug. 30 by astronomer Gennady Borisov and, unlike its predecessor, Ouamuamua, will be observable for an extended period of time. It is likely a comet, given its short tail and "fuzzy" appearance, a description backed up by NASA JPL researcher Davide Farnocchia.

"The comet's current velocity is high, about 93,000 mph [150,000 kph], which is well above the typical velocities of objects orbiting the Sun at that distance," said Farnocchia in a statement posted to NASA's website on Sept. 12. "The high velocity indicates not only that the object likely originated from outside our solar system, but also that it will leave and head back to interstellar space."

Earlier this month, NASA JPL said 21/Borisov is approximately 260 million miles from the Sun and will reach its closest point, known as perihelion, on Dec. 8, 2019, when it gets within 190 million miles of the Sun.

Source: Mysterious, second interstellar object ever spotted is confirmed

So perhaps the real question is why within a short period of geological time has two of these objects suddenly appeared? Is it a trend? Has an event happened outside our solar system to propel these objects towards Earth? How many more might appear in the near future? Or is this just due to improvements in our detection systems?

There was an interesting article about the first interstellar asteroid/comet that was spotted now called "Oumuamua" back in 2017. Why was 'Oumuamua so weird? New research tries to track its origins.

I mentioned that the second such interstellar object (C/2019 Q4 (Borisov)) appeared this year in October and it was of such a size that had it hit Earth it would have produced an extinction level event. So I wrote:

So perhaps the real question is why within a short period of geological time has two of these objects suddenly appeared? Is it a trend? Has an event happened outside our solar system to propel these objects towards Earth? How many more might appear in the near future? Or is this just due to improvements in our detection systems?

In the article they tried to addressed this point.

And the biggest puzzle regarding 'Oumuamua is that we even saw it at all. Consider the scale of time and space at work in a galaxy. Stars live and die over the course of millions or billions of years. The formation of a system takes hundreds of millions of years. It takes tens of thousands of years for even the fastest-moving objects to hop from star to star.

In contrast, we've only been searching the heavens with telescopes for about 400 years. That's basically nothing; a thin sliver of time to monitor the cosmos. And it's only within the past few decades — and even a few years — that we've had the technology to spot and track small, dim, fast-moving objects like 'Oumuamua.

So, the fact that we saw 'Oumuamua at all is a giant clue. Ejections from solar systems must be common. Common enough that the galaxy may just be swimming in these transient objects with enough frequency that they can swing through our neck of the woods in the brief amount of time that we've been looking for them.

Either rocks like 'Oumuamua are very common, or we got astronomically lucky with our detections. Those odds are pretty hard to swallow, so we'll go for common for now.

So why is this important?

In 1998, NASA formally embraced the goal of finding and cataloging, by 2008, 90% of all near-Earth objects (NEOs) with diameters of 1 km or larger that could represent a collision risk to Earth. The 1 km diameter metric was chosen after considerable study indicated that an impact of an object smaller than 1 km could cause significant local or regional damage but is unlikely to cause a worldwide catastrophe. The impact of an object much larger than 1 km diameter could well result in worldwide damage up to, and potentially including, extinction of the human species.

Source: Asteroid impact avoidance

And indeed many of these NEOs have been identified and their orbits determined. None so far presents a danger of collision with Earth. Governments eased back into their comfortable chairs saying we can put off for another year, decade, millennium and do nothing towards mitigating the threat and just wait until one does appear.

But there is a weakness to this approach. Interstellar objects are a wildcard. They appear out of nowhere with incredible speed and great mass. Should one appear suddenly, there is nothing that anyone could do to stop the next mass extinction, because the technology to destroy or deflect the object was never given a priority and never moved forward.

I hope the comet doesn't make climate change worse.

Many years ago, in the time of the ancient Greeks, there was belief that the heavens were some kind of divine realm, where things didn’t change. Some kind of perfect world. When they saw a comet in the sky, the ancients were stricken with dread. A ball of fire half the size of the moon, with a tail stretching across the sky, obviously boded no good for somebody. The skies were the home of capricious gods and such a disturbance in the heavens meant danger on earth.

Comets destroyed that perfection. Well into Christian times, comets were regarded as bad omens. There was something new in the sky, and people took them as omens of disaster. Many ascribe the fall of Jerusalem in 70 A.D. to the appearance of Halley’s Comet. In 1066 a comet was seen as William the Conqueror was preparing to invade England. Soon after, Harold, the Saxon king, was defeated by William and wise men nodded. It was only to be expected after such a portent, and many thought the comet was actually responsible.

Not all the omens were bad. In 1301, Giotto painted Halley’s Comet, which he had seen 10 years earlier, as the Star of Bethlehem and his "Adoration of the Magi". There are thousands, perhaps millions of comets, but Halley’s is the best known, because in 1682 Edmund Halley applied the laws of gravity discovered by his friend Isaac Newton. He predicted that the comet he had seen would return, and it did 12 years after his death.

Gennady Borisov, an amateur astronomer working with his own telescope in Crimea, first spotted the interstellar comet on Aug. 30. His find made the object the first interstellar visitor discovered since oblong 'Oumuamua flashed through our solar neighborhood back in 2017. Now, in a new paper, a team of Polish researchers has calculated the path this new comet — known as Comet 2I/Borisov or (in early descriptions) as C/2019 Q4 — took to arrive in our sun's gravity well. And that path leads back to a binary red dwarf star system 13.15 light-years away, known as Kruger 60.

When you rewind Comet Borisov's path through space, you'll find that 1 million years ago, the object passed just 5.7 light-years from the center of Kruger 60, moving just 2.13 miles per second (3.43 kilometers per second), the researchers wrote.

And the researchers found that if the comet were really moving that slowly at a distance of no more than 6 light-years from Kruger 60, it probably wasn't just passing by. That's probably the star system it came from, they said. At some point in the distant past, Comet Borisov lively orbited those stars the way comets in our system orbit ours.

"If you have an interstellar comet and you want to know where it came from, then you want to check two things," he said. "First, has this comet had a small pass distance from a planetary system? Because if it's coming from there, then its trajectory must intersect with the location of that system."

Source: A Second Interstellar Visitor Has Arrived in Our Solar System. This Time, Astronomers Think They Know Where It Came From

I'm ready! Sock it to me, baby!

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As the comet approaches our sun, the heat striking the comet cause the ices that make up the comet to outgas which produces the comet tail.

Currently,

The comet tail is nearly 100,000 miles long.

In September, NASA JPL said 2I/Borisov is approximately 260 million miles from the sun and will reach its closest point, known as perihelion, on Dec. 8, 2019, when it gets within 190 million miles of the sun.

Researchers believe the comet's nucleus is 1 mile wide.

Source: Interstellar comet Borisov spotted in new image, has 'ghostly' appearance