Page 110 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

Core

Outer Arm

Sagittarius-Carina Arm
Norma Arm

Scutum-Crux Arm

Perseus Arm

Orion-Cygnus Arm
Solar System

THE MILKY WAY

DISCOVER THE HUGE ISLAND OF STARS THAT IS OUR HOME GALAXY

Our Galaxy, the Milky Way, created by the hundreds of afar, as shown in the image through the central bulge.
is one of the most magical thousands of faint, distant above, the view would look This means that the Milky
MARK GARLICK/SCIENCE PHOTO LIBRARY X 2, PETE LAWRENCE of light. It becomes clearly more to our Galaxy than is made up of somewhere known as the galactic disc,
Way is a member of the
much like a spinning
stars whose light combines
sights of the night. Away
class of galaxies known
to form this wonderful feature.
Catherine Wheel fi rework.
from light-polluted regions
However, there’s much
This particular ‘fi rework’
as barred spirals.
our Galaxy looks like a river
The arms form what’s
between 200 and 400 billion
visible every year as autumn
these stars, which are just
where the majority of stars
approaches, the brightest part
stars, and is believed to be
the visible part of it. The
around 3.2 billion years old.
of it adorning our skies.
term Milky Way is also used
live, including the Sun. And
From its bright, bulging
The term Milky Way can
because of all the dust and
to describe our entire Galaxy,
gas that fl oats about there, the
refer to several different
centre emanate several
a huge island of stars of
arms are also where new stars
arms, which spiral outwards.
objects, as well as a famous
which our Sun is a member,
chocolate bar. Some use it
A closer look reveals that
to refer to the weaving band
outside the main disc, there’s
we see. If we were to look
a halo that surrounds the Milky
the ends of a bar that runs
down at our Galaxy from
of light crossing the sky,
110 skyatnightmagazine.com 2012 and not just the band of light these spiral arms come out of are being born. Beyond that,