Comet 2I/Borisov Near and at Perihelion
These two images, taken by NASA's Hubble Space Telescope, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.
"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, whose team has captured the best and
sharpest look at this first confirmed interstellar comet. "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. 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."
Crimean amateur astronomer Gennady Borisov discovered the
comet on August 30, 2019 and reported the position measurements to the
International Astronomical Union's Minor Planet Center in Cambridge,
Massachusetts. The Center for Near-Earth Object Studies at the Jet
Propulsion Laboratory, working with the Minor Planet Center, computed an
orbit for the comet which shows that it came from elsewhere in our
Milky Way galaxy, point of origin unknown.
Nevertheless,
observations by numerous telescopes show that the comet's chemical
composition is similar to the comets found inside our solar system,
providing evidence that comets also form around other stars. By the
middle of 2020 the comet will have already zoomed past Jupiter's
distance of 500 million miles on its way back into the frozen abyss of
interstellar space.
[left] November 16, 2019 photo
The
comet appears in front of a distant background spiral galaxy (2MASX
J10500165-0152029). The galaxy's bright central core is smeared in the
image because Hubble was tracking the comet. Comet Borisov was
approximately 203 million miles from Earth in this exposure. Its tail of
ejected dust streaks off to the upper right. The comet has been
artificially colored blue to discriminate fine detail in the halo of
dust, or coma, surrounding the central nucleus. It also helps to
visually separate the comet from the background galaxy.
[right] December 9, 2019 photo
Hubble
revisited the comet shortly after its closest approach to the Sun where
it received maximum heating after spending most of its life in frigid
interstellar space. The comet also reached a breathtaking maximum speed
of about 100,000 miles per hour. Comet Borisov is 185 million miles from
Earth in this photo, near the inner edge of the asteroid belt but below
it. 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. The comet will make its closest approach to Earth
in late December at a distance of 180 million miles.
The Hubble
Space Telescope is a project of international cooperation between the
European Space Agency (ESA) and NASA. NASA's Goddard Space Flight Center
in Greenbelt, Maryland, manages the telescope. The Space Telescope
Science Institute (STScI) in Baltimore, Maryland, conducts Hubble
science operations. STScI is operated for NASA by the Association of
Universities for Research in Astronomy in Washington, D.C. The Minor
Planet Center and the Center for Near-Earth Orbit Studies are projects
of NASA’s Near-Earth Object Observations Program of the Planetary
Defense Coordination Office at NASA Headquarters.
Source: HubbleSite/News
Contact
Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
villard@stsci.edu
Stuart Wolpert
UCLA, Los Angeles, California
swolpert@stratcomm.ucla.edu
David Jewitt
UCLA, Los Angeles, California
jewitt@ucla.edu
Related Links
- NASA's Hubble Portal
- ESA/Hubble's Release
- UCLA's Release
- STScI's Comet 2I/Borisov Release (Oct. 16, 2019)
