It’s more than 100 times Earth’s distance from our sun, and it takes 1,000
earthly years to orbit the sun once. Astronomers have labeled it 2018 VG18, but
nicknamed it Farout!
View larger. | Solar system
distances to scale showing the newly discovered 2018 VG18 – nicknamed Farout
– compared to other known solar system objects. Illustration via Roberto Molar
Candanosa/Scott S. Sheppard/Carnegie Institution for Science.
Astronomers have discovered another small object in the outer solar system,
the most distant solar system object yet known. Another first … it’s the first
solar system object to be detected at a distance of more than 100 times Earth’s
distance from the sun. The new object has been given the provisional
designation 2018 VG18. Astronomers have given it the nickname Farout.
Scott S. Sheppard of the
Carnegie Institution of Science, David Tholen of the University of Hawaii and Chad Trujillo of Northern Arizona University
co-discovered the object. The discovery images of 2018 VG18 were taken at the
Japanese Subaru 8-meter telescope located atop Mauna Kea in Hawaii on November
10, 2018. By tracking its movement through space, the astronomers can calculate
that 2018 VG18 lies at a distance of about 120 astronomical units, or Earth-sun units. A
statement from these astronomers explained:
The second-most-distant observed solar system object is Eris, at about 96 AU. Pluto is currently at about
34 AU, making 2018 VG18 more than 3 1/2 times more distant than the solar
system’s most-famous dwarf planet.
2018 VG18 was discovered as part of the team’s continuing search for
extremely distant solar system objects, including a suspected Planet X (with
the X standing for unknown), also sometimes called Planet 9.
Discovery images of 2018 VG18
aka Farout, from the Subaru Telescope on November 10, 2018. Farout moves
between the two discovery images while the background stars and galaxies do not
move over the one hour between images. Image via Scott S. Sheppard/David
Tholen/Carnegie Institution for Science.
Indeed, it’s the Planet 9 possibility that makes this new discovery of
another small object in the outer solar system so tantalizing. After all, there
must be many small outer solar system bodies, moving through space,
unknown to earthly astronomers. Finding them is a big deal to the Planet 9
search because the orbits of these small, outer bodies are clues to Planet 9’s
whereabouts, if, indeed, it exists.
This same group of astronomers – Sheppard, Tholen and Trujillo – recently
discovered another small, outer body that’s been labeled 2015 TG387 and
nicknamed The Goblin, because it was first seen near Halloween 2018. Their
statement explained:
The Goblin was discovered at about 80 AU and has an orbit that is
consistent with it being influenced by an unseen super-Earth-sized Planet X on
the solar system’s very distant fringes …
2015 TG387 and 2012 VP113 never get close enough to the solar
system’s giant planets, like Neptune and Jupiter, to have significant
gravitational interactions with them. This means that these extremely distant
objects can be probes of what is happening in the solar system’s outer reaches.
The team doesn’t know 2018 VG18’s orbit very well yet, so they have not
been able to determine if it shows signs of being shaped by Planet X.
How long will it take to learn more about 2018 VG18’s orbit? Years! That’s
because 2018 VG18 is so distant. Remember your Astronomy 101? The more distant
the object from our sun, the slower it moves in orbit around the sun. As the
most distant object yet found in our solar system, 2018 VG18 has the
distinction of being slower-moving than any other observed solar system object.
So, Sheppard explained:
… it will take a few years to fully determine its orbit. But it was found
in a similar location on the sky to the other known extreme solar system
objects, suggesting it might have the same type of orbit that most of them do.
Tholen added:
All that we currently know about 2018 VG18 is its extreme distance from the
sun, its approximate diameter, and its color. Because 2018 VG18 is so distant,
it orbits very slowly, likely taking more than 1,000 years to take one trip
around the sun.
Bottom line: 2018 VG18 is the most distant object yet known in our solar
system. It’s a small body, 120 times Earth’s distance from the sun, but it may
have a big role to play in the discovery of a large, as-yet-unknown Planet X
(aka Planet 9).
EarthSky By Deborah Byrd
in Space | December 17, 2018
No comments:
Post a Comment