WWW.ASTRONOMY.COM 9A GALACTIC
COLLISION
Merging galaxies
can create
familiar shapes
in the sky, but
only for a short
cosmic time.
Each time astronomers image
merging galaxies, they’re
capturing a single moment in a
process that can last hundreds
of millions to billions of years.
NGC 5394 and NGC 5395,
featured in this new photo
from the Gemini Observatory’s
telescope in Hawaii, have already
collided at least once. The pair
is located about 160 million
light-years away and is also
known collectively as Arp 84 or
the Heron Galaxy. (The larger
galaxy forms the bird’s body,
while the smaller galaxy is its
head and beak.)
Because the galaxies’ stars are
so far apart, smash-ups between
individual suns are unlikely.
Instead, turbulence caused by
the initial pass has triggered gas
in the two galaxies to collapse,
resulting in numerous regions
of star formation, visible here as
pinkish-red clumps. Over time,
gravity will twist and bend
these galaxies out of shape as
the merger progresses, erasing
this bird from the sky. — ERIK A K.
CARLSON, ALISON KLESMANNEW MYSTERIES
NASA’s Parker Solar
Probe has revealed that
the Sun’s magnetic field,
solar wind, and outer
atmosphere appear
different at close range
than models predicted,
hinting there is much
we still don’t understand
about the Sun.BLACK HOLE TWOFER
A UCLA-led team
suggests that the Milky
Way’s 4-million-solar-
mass supermassive
black hole, Sagittarius
A*, may have a smaller,
100,000-solar-mass
supermassive black
hole companion in
orbit around it.DUST BUSTER
Lunar dust sticks to
everything, causing
problems for astronauts
and equipment alike. A
new, super-thin coating
of indium tin oxide
developed by NASA
may prevent Moon dust
from electrostatically
clinging to surfaces.HOT
BYTESSNAPSHOTQUANTUM GRAVITY
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