Astronomy - USA (2020-01)

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EXTENDED OBSERVATIONS
2I/Borisov offers astronomers a some-
what more leisurely pace for discovery
than its predecessor. ‘Oumuamua was
discovered nearly two months after it
had passed perihelion, as it was already
f leeing the inner solar system. That gave
astronomers just four months to study
it before ‘Oumuamua grew too faint to
track. 2I/Borisov was spotted while still
on its way into the inner solar system,
meaning it will only grow brighter
through December. In fact, 2I/Borisov is
expected to reach magnitude 15 by the
time it passes closest to Earth, putting
it potentially within reach of amateur
scopes larger than 10 inches under excel-
lent viewing conditions. It should remain
visible to the largest telescopes through
October 2020, when it slips behind the
Sun from our viewpoint on Earth.
As with ‘Oumuamua, however,
astronomers can’t guess yet which star
system 2I/Borisov came from. But as
observations of its motion improve,
they may be able to rewind its track, as
well as trace backward the motions of


stars in the Sun’s vicinity, to determine
where it might have originated.
Regardless of whether it’s tracked to
its home, 2I/Borisov has much to tell
us in the coming months. “We really
wanted to know what [‘Oumuamua]
was made of. We wanted to know
its chemistry. And that experiment
couldn’t be done well. But it will be
done well for 2I,” says Karen Meech
of the Institute for Astronomy at the
University of Hawai‘i. Meech is part of
the team that discovered ‘Oumuamua,
as well as the group that spotted CN gas
on 2I/Borisov.
And as more surveys chart the sky
and bigger, better telescopes open their
domes, more interstellar objects are
likely to pop up each year. “Hopefully,
observing this one and the previous
interstellar object, ‘Oumuamua, and
more to come, will help us understand
not only how our comets and asteroids
compare to other solar systems’ comets
and asteroids, but also about this jour-
ney that they do through the galaxy,”
Kelley says. — A.K., MARA JOHNSON-GROH

EXPLOSIVE ORIGIN
Models suggest climate change
on Saturn’s moon Titan may
have triggered explosions of
underground nitrogen pockets,
forming the craters that now harbor
Titan’s liquid-hydrocarbon lakes.

SPACE PASTE
Astronauts recently mixed
cement — a primary ingredient of
concrete — in space for the first
time. By proving cement can
solidify in a microgravity
environment, the success helps
pave the way for construction of
colonies on other worlds.

LUNAR CUBE
NASA is partnering with
aerospace company Advanced
Space to develop a CubeSat that
will circle the Moon to test the
orbit of the proposed lunar
Gateway space station.

COLD FRONT
A new study suggests debris
from an asteroid collision in
space rained dust on Earth for
millions of years, possibly
triggering a global ice age some
466 million years ago.

PREPARE FOR LAUNCH
After years of delays, engineers
have finally connected the two
halves of NASA’s James Webb
Space Telescope, which is
scheduled to launch in 2021.

BOLSTERING BONES
New research suggests the
sleep-regulating hormone
melatonin may help prevent bone
loss in astronauts by both
suppressing the breakdown
of bones (resorption) and
encouraging new growth.

INVISIBLE RING
Physicists captured gravitational
waves “ringing” after two black
holes merged into one. They
found that the pattern
corresponds to the resulting
black hole’s mass and spin — just
as predicted by Einstein. — J.P.

QUICK
TAKE S

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Hubble’s latest snap of Saturn


Saturn recently sat for its annual yearbook photo. As part of the Outer Planets
Atmospheres Legacy project, the Hubble Space Telescope takes a series of snapshots
of our solar system’s gas and ice giant planets each year to monitor changes in their
atmospheres. Hubble captured this image June 20, 2019, a few weeks before the
ringed planet reached opposition — its closest approach to Earth. The giant storm
observed raging near Saturn’s north pole in 2018 has since disappeared. But the bizarre,
hexagon-shaped structure at the planet’s north pole is still going strong. — JAKE PARKS


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