QG
QUANTUM
GRAVITY
EVERYTHING YOU NEED TO KNOW ABOUT THE UNIVERSE THIS MONTH...8 ASTRONOMY • APRIL 2018SNAPSHOTThe first
interstellar
asteroid
A strange, cigar-shaped
rock reminds us that the
solar system is not alone
in our galaxy.At first, astronomers were
intrigued when they detected,
in October 2017, a high-speed
object moving through the
solar system. Upon investigat-
ing the object, researchers using
the Pan-STARRS 1 telescope in
Hawaii found it was not an
ordinary fast-moving asteroid.
Its orbit suggested it came from
outside the solar system.
Amazingly, the rock is elon-
gated, some 10 times longer
than it is wide. This interstellar
cigar measures around a quar-
ter of a mile (400 meters) long,
or four football fields.
Planetary scientists were
elated. They had their first evi-
dence of an interstellar asteroid
moving through our neighbor-
hood. Others on social media
were less circumspect: “C’mon,
Dave,” some friends teased. “It
looks like a rocky spaceship
from Star Trek. You have to be
able to see that, right?”HOT BYTES >>
TRENDING
TO THE TOPCERES’ SHEEN
The mysterious bright
spots observed on the
dwarf planet Ceres have
changed over time,
indicating the world is
still surprisingly active.SUPERNOVA STEW
A new image taken
by the Chandra X-ray
Observatory maps the
distribution of four ele-
ments in the supernova
remnant Cassiopeia A.RED ROVER
Mars 2020 will seek out
sites on the Red Planet
that were likely habit-
able in the distant past
and search for evidence
of ancient microbial life.But the object — known as
1l/2017 U1 and nicknamed
‘Oumuamua, Hawaiian for
“scout” — is amazing just as a
wandering asteroid. The dark,
reddish object is unique among
asteroids, tumbling as it moves
along its path, dimly glowing at
27th magnitude when astrono-
mers made their follow-up obser-
vations, and heading away from
the Sun and out of the solarsystem. The object’s color suggests
coatings of molecules decomposed
by cosmic rays. It rotates about
once every 7.3 hours. Actually, it
tumbles because it’s not rotating
around one of its two main axes.
Scientists detected no dust around
the object at all, and they think its
composition is dense, with pos-
sibly a rocky or a high metallic
content. The asteroid came from
the general direction of the starVega, in the constellation Lyra.
Planetary scientists believe an
interstellar asteroid probably zips
through the solar system about
once per year. They are faint,
however. ‘Oumuamua’s brief
showing reminds us that the
solar system is not isolated from
the rest of our galaxy: It is one
big universe out there, and
many things can affect us.
— David J. EicherThe long, narrow asteroid ‘Oumuamua startled everyone who found out about an interstellar visitor with such an unusual shape.
Planetary scientists believe it to be a quarter-mile (400 m) long and 131 feet (40 m) wide.ESO/M. KORNMESSER; TOP FROM LEFT: NASA/JPL-CALTECH/UCLA/MPS/DLR/IDA; NASA/CXC/SAO; NASA