The skies above the Paranal Observatory
in Chile are among the clearest and
driest in the world. But occasionally the
atmosphere isn't quite good enough for
science observations.
That's when astronomers dig up cosmic
gems like this one. Welcome back to
Launch Pad, I'm Christian Ready, your
friendly neighborhood astronomer. The
European Southern Observatory released
the spectacular image of the spiral
galaxy NGC 3981. NGC 3981 is located in
the constellation Crater, the Cup. The
image was taken in May of 2018
with the FOcal Reducer and low
dispersion Spectrograph 2 - or FORS2 -
instrument on the European Southern
Observatory's Very Large Telescope.
FORS2 is mounted on the Unit One telescope
named Antu. This is one of the four
telescopes belonging to the Very Large
Telescope or VLT at ESO's Paranal
Observatory in Chile. FORS2 has been
dubbed the 'Swiss Army knife' of
instruments because it's able to study a
variety of astronomical objects in many
different ways, as well as being capable
of producing beautiful images like this
one. And that's a good thing because this
image is really a consolation prize of
sorts.
The weather at Paranal is on average
perfect for astronomy. But every once in
a while, the conditions aren't quite good
enough for scientific observations.
Rather than just let the telescopes sit
there, astronomers use that time to make
images like these as part of ESOs Cosmic
Gems program - a collection of visually
interesting images for public outreach
and education. But the image is more than
just a pretty picture. It tells us a
story of a galaxy that's inclined to our
line of sight from Earth. This allows us
to peer into the heart of the galaxy and
observe its bright center. Lurking
beneath is a supermassive black hole
some 70 million times the mass of our
Sun. Surrounding the galaxy's center are
a pair of tightly wound spiral arms,
strewn with bright bursts of star
formation. But the outer spiral arms
aren't quite so spiral-like; they're
disrupted and pulled
away from the rest of the galaxy. These
are the tell-tale signs that NGC 3981
was involved in a cosmic fender-bender
with another galaxy long ago. The
encounter disrupted NGC 3981's
spiral structure, flinging its outer
stars and gas into new orbits. Clouds of
gas, dust, and stars collided within the
arms, setting off waves of star formation
in the process.
In fact NGC 3981 belongs to a small
group of about 13 other galaxies; the
largest member of this group are
actually two galaxies called the
Antennae galaxies. These two were once
spiral galaxies that fell into an orbit
around one another. Their ongoing
collision is triggering new waves of
star formation. NGC 3981 is not the only
interesting feature captured in this
image. As well as several foreground
stars from our own galaxy the Milky Way,
FORS2 also captured a rogue asteroid
streaking across the sky. This particular
asteroid reveals how the image was made,
as three different exposures in blue,
green, and red filters were taken. These
images were then later combined to
create this full-color image of the
galaxy. I love how we get to see the
scale of the cosmos compressed like this,
with a tiny piece of our solar system
photobombing a galaxy containing
hundreds of billions of Suns tens of
millions of light years away. It's said
that every image tells a story, and this
image tells us several at once. If you'd
like to learn more stories about our
universe, please make sure to hit the
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out on any new videos. And until next
time, keep watching the skies