Get your telescopes ready, but don't count on a bright enough comet yet.
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An image of comet
C/2017 K2 PANSTARRS (K2) taken in June 2017 by the Hubble Space Telescope's
Wide Field Camera 3. (Image credit: NASA, ESA, and D. Jewitt (UCLA)) |
A comet first spotted in the distance in 2017 might finally be within view soon of amateur astronomers.
Comet C/2017 K2
(PANSTARRS), called K2 for short, was then the farthest active comet ever
spotted, a title it recently surrendered to megacomet Comet
Bernardinelli-Bernstein, detected last year. But even down one superlative, K2
is remarkable for activity. The comet began to spew gas and dust in the far
outer solar system, whereas it's more typical for comets to wake up around
Jupiter's orbit, much closer in.
Five years later,
the icy body is finally drawing within reach of Earth and its amateur
astronomers. K2's closest approach to our planet will be on July 14, and it
will get closest to the sun on Dec. 19.
Assuming K2
survives the heated journey and continues to brighten, EarthSky(opens in new
tab) predicts people with small telescopes will be able to spot the sojourner
soon.
"It should
brighten to magnitude 8 or even 7, still too dim for the unaided eye,"
EarthSky wrote.
Sharp-eyed viewers
can usually spot stars of magnitude 6 in dark-sky conditions with no aid. In
the case of this comet, you will also need areas away from light pollution to
spot it with a telescope.
"The darker
the skies, the better the contrast will be," EarthSky advised.
As the comet
approaches us, professional observatories may be able to figure out how big its
nucleus is. Early observations by the Canada–France–Hawaii Telescope (CFHT)
suggested K2's nucleus could be between 18 and 100 miles (30 to 160 kilometers)
wide; Hubble Space Telescope observations suggested it might be only 11 miles
(18 km) at most, EarthSky said.
In 2017, Hubble
imagery determined that the comet's coma (or fuzzy atmosphere) likely includes
oxygen, nitrogen, carbon dioxide and carbon monoxide, all turning from solid to
gas as the comet warmed.
An archival search
of CFHT imagery suggested K2 was active at least as far back as 2013, when it
was between the orbits of Uranus and Neptune, NASA said at the time.
All predictions
for comet activity are subject to change, however. Comets are prone to falling
apart or brightening unpredictably when the draw close to the intense heat and
gravity of our sun. That characteristic, however, makes them all the more
interesting to astronomers who want to understand how comets are put together.
Reference: Space.com
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