According tomedia New Atlas, an interstellar visitor is currently passing through our solar system. The Hubble telescope has been observing the journey of interstellar comet 2I/Borisov through the solar system. The space telescope has captured new images of the comet, which has now bypassed the sun and is returning to interstellar space.
2I/Borisov was first discovered by astronomers on August 30, shortly after they calculated its trajectory – revealing that it was an interstellar comet. The comet comes from another star system, making it the second interstellar object ever discovered. The first interstellar object was Oumuamua, discovered in 2017.
As 2I/Borisov moved closer to the inner solar system, astronomers from around the world aimed telescopes and observatories at it to study this rare interstellar visitor. What they learned was that its composition and age were very similar to that of local comets.
Now, Hubble has taken two new photographs of 2I/Borisov, one of which was taken as it approached the sun and the other as it bypassed our star and began to return to the depths of interstellar space.
The lenses allowed the team to calculate the size of its comet core – ice and dust at the center. They found that it was actually much smaller than expected, at a diameter of only 3,200 feet (975 meters).
“The Hubble telescope gives us the best upper limit of the size of the comet’s nucleus, which is what really matters to the comet,” said lead researcher David Jewitt. “Surprisingly, our Hubble images show that its comet nucleus is 1/15 of what previous studies have shown. Knowing its size may help to begin to estimate how common such objects are in the solar system and the Milky Way. Borisov was the first known interstellar comet, and we wanted to know how many more. “
In both photos, Borisov’s color is artificially treated blue to make it stand out. The left image was taken on November 16, when the comet was about 203 million miles from Earth. The photo on the right was taken on December 9, when the comet was about 185 million miles from Earth. It had bypassed the sun and was approaching the asteroid belt. Through this “slingshot effect”, it also increases speed, moving at about 100,000 miles per hour.
Astronomers expect 2I/Borisov to be closest to Earth in late December, at a distance of 180 million miles. After that it will be far from earth and will never return.