Remember Comet ‘Oumuamua? Another object apparently falling into the broad classification of Not from these parts has appeared, and is called Comet Borisov. Here’s a depiction of its trajectory from Jet Propulsion Laboratories:
In a press release:
The new comet, C/2019 Q4, is still inbound toward the Sun, but it will remain farther than the orbit of Mars and will approach no closer to Earth than about 190 million miles (300 million kilometers).
Spaceweather.com has more details:
There are thousands of comets in the Solar System, but this one is special. Comet Borisov is interstellar. The newly-discovered comet is following a hyperbolic orbit with an eccentricity greater than 3.7. This means it is unbound to the sun. Indeed, Comet Borisov is moving 30.7 km/s (68,700 mph) too fast for the sun’s gravity to hang onto it. It must have come from the stars.
This is the first time an interstellar visitor to our Solar System has clearly shown a tail due to outgassing. The only other known interstellar visitor was ‘Oumuamua in 2017-2018, a cigar-shaped object with no visible comet-like emissions.
Because Comet Borisov is still just entering the solar system, astronomers will have plenty of time to study it in the months ahead. Is it truly interstellar? What are comets from other solar systems made of? Answers to these and many other questions are forthcoming.
I’ll be looking forward to more details over the coming months, and while I assume there’s no space vehicles in position to approach it, we may be able to get a better view of it than we have so far.
