ASTRONEWS
FAST
FAC T2,080 feet tall
(634 meters)1,670 feet wide
(510 meters)3,000 feet wide
(900 meters)1,454 feet tall
(443.2 meters)5001,1,2,2,3,0To k y o
Sky TreeAsteroid BennuAsteroid RyuguEmpire State
Fee BuildingtWWW.ASTRONOMY.COM 13CHILL OUT. NASA’s Cold Atom Laboratory on the International Space Station is slowing down atoms for study
by producing ultra-cold clouds that reach just a fraction of a degree above absolute zero.HOW BIG IS ASTEROID BENNU?
Astronomers discovered the most
“far out” object ever observed
in our solar system: a pink dwarf
planet called 2018 VG 18 , aptly
nicknamed “Farout.”
The dwarf planet, whose
discovery was announced by
the International Astronomical
Union’s Minor Planet Center on
December 17, is about 120 astro-
nomical units away. (An astro-
nomical unit is the average
distance between Earth and the
Sun.) That makes it over three-
and-a-half times farther than
the famous dwarf planet Pluto.
Discovered using the
Japanese Subaru 8-meter tele-
scope in Hawaii, and further
investigated using the 6.5-meter
Magellan Telescope at Carnegie’sLas Campanas Observatory in
Chile, researchers found that
Farout is fairly sizable, about
310 miles (500 kilometers) in
diameter, or roughly a third the
diameter of Pluto. The dwarf
planet also has a pinkish hue,
likely because it is rich in ice.
While a significant discovery
on its own, finding Farout might
also support the search for
“Planet X,” a theoretical massive
planet beyond Neptune that is
often employed to explain the
strange orbital harmony found
in other distant bodies. But it
will be at least a year, and likely
more, before researchers under-
stand Farout’s orbit enough to
say whether it actually provides
evidence for Planet X.While the team’s main focus
is looking for Planet X, they
continue to keep their eyes
peeled for other objects in the
same general vicinity. Earlier
this year, “The Goblin” was dis-
covered by the same team,
which includes Carnegie’s Scott
S. Sheppard, the University of
Hawaii’s David Tholen, and
Northern Arizona University’s
Chad Trujillo.
Further study of our system’s
outer edge, along with the likely
discovery of more objects like
Farout, will continue to inform
the search for Planet X. “We are
finally exploring our solar sys-
tem’s fringes, far beyond Pluto,”
Sheppard said in a press release.
— C.G., J.P.The most distant dwarf planet yet
Infant stars host
planets early on
Bennu’s density
(about 1 g/cm^3 ) is lower than
that of solid rock, suggesting
it may be a porous “rubble
pile” with voids throughout.
ASTRONOMY:^ ROENKELLYSPACE ROCKS. On December 31, NASA’s
OSIRIS-REx mission entered orbit around asteroid
Bennu. The roughly 0.3-mile-wide (510 meters)
asteroid is diamond-shaped, much like the
asteroid Ryugu, which the Japanese Hayabusa
spacecraft is currently studying. However, at
0.6 mile wide (900 m), Ryugu is about twice the
size of Bennu, winning Bennu the title as the
smallest object ever orbited by a spacecraft.
— A.K.MIND THE GAP. A recent survey by Chile’s
Atacama Large Millimeter/submillimeter Array
(ALMA) captured 20 infant stars and the
intricate planet-forming disks that surround
them, a sample of which appears above.
The dust and gas that fill these disks gradually
start to collide and form the cores of planets,
which are thought to then carve out gaps
within them. Researchers thought this process
took millions of years, but ALMA’s observations
suggest otherwise. These young stars, some
only 300,000 or so years old, already seem to
have tiny planets orbiting around them,
sweeping up material in their disk. Researchers
now think the planets’ early formation is
enabled by the disks’ extreme densities, which
could cause large dust grains to condense
instead of falling toward the star. — A.J.ALMA^ (ESO/NAOJ/NRAO);^S.^ ANDREWS^ ETAL.;^ NRAO/AUI/NSF;^S.^ DAGNELLOILLUSTRATION^ BY^ ROBERTOMOLARCANDANOSA,^ COURTESY^ OF^ THE^ CARNEGIE^ INSTITUTIONFOR^ SCIENCEPRETTY IN PINK.
The newly discovered dwarf
planet — 2018 VG 18 , or “Farout” —
is shown in this artist’s concept
with the Sun in the background.