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Thu Sep 12, 2019, 05:43 PM

Astronomers Spot a Comet That Likely Came From a Different Solar System

For only the second time, astronomers believe they have detected a space rock that formed in some distant system before making the interstellar journey to fly through our own solar system. The object, a comet named C/2019 Q4 (Borisov), was recently verified by the Minor Planet Center. According to available observations of the comet, C/2019 Q4 is moving too fast, some 30.7 kilometers per second (68,700 miles per hour), to have origininated in our solar system.

The likely interstellar comet was first observed by Gennady Borisov, a Ukrainian amateur astronomer working at the Crimean Astrophysical Observatory, on August 30. The object is still inbound, and it will make its closest approach to the sun on December 7, and its closest approach to Earth—within 180 million miles—on December 29, as reported by Michael Greshko at National Geographic. Further observations by astronomers have determined that C/2019 Q4 is a comet stretching a couple miles wide, with a coma of gas and dust enveloping the object that forms when icy material is heated by the sun. (Asteroids have less icy material and do not develop comas.)

In addition to C/2019 Q4’s great speed, the object is on a hyperbolic trajectory through the solar system, meaning rather than circling the sun, it will fly in close—almost as close to the sun as Mars—and then sling back out into interstellar space. Astronomers use a measurement called eccentricity to determine how circular an object’s orbit is: An eccentricity of 0 is perfectly circular, while an eccentricity of 1 is highly elliptical, and anything greater than is hyperbolic. C/2019 Q4’s eccentricity is greater than 3.5, according to NASA JPL’s Small-Body Database.

“Based on the available observations, the orbit solution for this object has converged to the hyperbolic elements shown below, which would indicate an interstellar origin,” says a statement from the Minor Planet Center, part of the Smithsonian Astrophysical Observatory, that accompanies data about C/2019 Q4. “Further observations are clearly very desirable.”

Read more: https://www.smithsonianmag.com/smart-news/object-flying-through-our-solar-system-likely-interstellar-space-180973114/#lGGO7BZQ95ofh40h.99

Animation of its path:

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Reply Astronomers Spot a Comet That Likely Came From a Different Solar System (Original post)
muriel_volestrangler Sep 12 OP
PJMcK Sep 12 #1
Igel Sep 12 #2

Response to muriel_volestrangler (Original post)

Thu Sep 12, 2019, 05:50 PM

1. Fascinating

I wonder if there have been many such objects as C/2019 Q4 and Oumuamua but they weren't observed.

The gif is particularly interesting as the comet's trajectory seems nearly perpendicular to the orbital plane around the sun. Needless to say, it's a good thing it won't be near Earth!

The gif is cool and thanks for the link, muriel!

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Response to PJMcK (Reply #1)

Thu Sep 12, 2019, 06:31 PM

2. Probably.

Note that a good deal of the object's velocity is due to the Solar System's velocity as it moves. I'm pretty sure its direction is opposite that of the solar system's.

Planets and other objects were ejected from the solar system during its evolution--they were moving fast enough to become interstellar objects. It's not impossible that some object was on a distant trajectory but part of the solar system, ran into some other object's gravity well, and was slingshot back towards the inner system at speeds that now make it destined to never return.

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