NASA's Hubble space telescope provided astronomers with the best look yet at Comet 2I/Borisov, the first confirmed interstellar comet, on October 12, 2019. The observation is the sharpest view ever of the said comet. Hubble showed a central concentration of dust around the icy nucleus.
Comet 2I/Borisov is the second interstellar object observed to have passed through our solar system. The first was dubbed 'Oumuamua' in 2017, which swung within 38 million km (24 million miles) of the Sun, before shooting out of the solar system.
"Whereas ‘Oumuamua looked like bare rock, Borisov is really active, more like a normal comet. It’s a puzzle why these two are so different," said David Jewitt of UCLA, leader of the Hubble team who observed the comet.
On October 12, 2019, the NASA/ESA Hubble Space Telescope observed Comet 2I/Borisov at a distance of approximately 420 million km (260 million miles) from Earth. The comet is believed to have arrived here from another planetary system elsewhere in our galaxy. Credit: NASA, ESA, D. Jewitt (UCLA)
The comet gives invaluable clues to the chemical composition, structure, and dust characteristics of planetary building blocks apparently forged in an alien star system far away from a long time ago.
"Because another star system could be quite different from our own, the comet could have experienced significant changes during its long interstellar journey. Yet its properties are very similar to those of the Solar System’s building blocks, and this is very remarkable," explained Amaya Moro-Martin of the Space Telescope Science Institute in Baltimore, Maryland.
Hubble telescope captured the comet at approximately 420 million km (261 million miles) from Earth. It is now heading towards the Sun and will make its closest approach on December 7, when it will be twice as far from the Sun as Earth. It is blazing along at the velocity of 150 000 km/h (93 206 mph).
By mid-2020, the comet will be traveling back into interstellar space where it will drift for million years before arriving at another star system.
This illustration shows the path of comet 2I/Borisov through our Solar System. This visitor came from interstellar space along a hyperbolic trajectory. It is only the second known intruder to zoom through our Solar System (the interstellar object ‘Oumuamua was detected in 2017). As the graphic shows, the comet’s straight path across interstellar space is slightly deflected by the gravitational pull of our Sun. The comet is traveling so fast, at over 155 000 km/h, it will eventually leave the Solar System. The panel on the right shows the comet’s position relative to Earth when the NASA/ESA Hubble Space Telescope observed it on 12 October 2019, when it was 420 million kilometers from Earth. Credit: NASA, ESA, J. Olmsted, F. Summers (STScI).
Astronomer Gennady Borisov discovered the comet on August 30, 2019. After a week of observations by astronomers worldwide, the International Astronomical Union's Minor Planet Center calculated an orbit for the comet which indicated that it was from interstellar space.
2I/Borisov and Oumuamua mark the start of the discoveries of our solar system's interstellar visitors. Future Hubble observations of Borisov are planned through January 2020.
Featured image credit: NASA, ESA, D. Jewitt (UCLA)