The Hubble Space Telescope has shared the sharpest view of the interstellar comet 2I/Borisov moving at 160 934 km/h (100 000 mph) past the Sun. This is the second interstellar object recorded in our solar system, the first being Oumuamua in 2017.
“Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is likely no more than about 975 m (3 200 feet) across, about the length of nine football fields,” NASA said in a news release on December 12, 2019.
“Hubble gives us the best upper limit of the size of comet Borisov’s nucleus, which is the really important part of the comet,” said David Jewitt, a UCLA professor of planetary science and astronomy.
Jewitt’s team has captured the best and sharpest look at 2I/Borisov.
“Surprisingly, our Hubble images show that its nucleus is more than 15 times smaller than earlier investigations suggested it might be. Our Hubble images show that the radius is smaller than half-a-kilometer,” he added.
“Knowing the size is potentially useful for beginning to estimate how common such objects may be in the solar system and our galaxy. Borisov is the first known interstellar comet, and we would like to learn how many others there are.”
Image credit: NASA/ESA/D. Jewitt (UCLA)
Crimean amateur astronomer Gennady Borisov discovered the comet on August 30, 2019. He sent the reports on the position measurements to the International Astronomical Union’s Minor Planet Center in Cambridge, Massachusetts.
The image from November 16 shows that the comet in front of a distant background spiral galaxy. In this exposure, the comet was around 326 million km (203 million miles) from Earth.
“The comet has been artificially colored blue to discriminate fine detail in the halo of dust, or coma, surrounding the central nucleus,” NASA explained.
On the other hand, the image from December 9 shows the comet at its closest approach to the Sun. It reached a maximum speed of about 160 934 km/h (100 000 mph) and was positioned 297 million km (185 million miles) from Earth.
“The nucleus, an agglomeration of ices and dust, is still too small to be resolved. The bright central portion is a coma made up of dust leaving the surface,” said NASA.
The comet will make its nearest approach to Earth in late December at 289 million km (180 million miles).