Why the Sky
Changes with the Seasons
You might have noticed that during different seasons,
some constellations are visible, but others you can
see all year round.
Why does this happen?
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Why the Sky Changes with the Seasons
To better understand this, we’ll start by talking about
constellations you can see all year round.
You can see the Big Dipper any night, and is pretty easy to
find. It looks like a giant spoon, and can be used to find the North
Star. If you extend a line from the line that makes up the very
end of the Big Dippers cup, it will guide to the North Star, which
also named Polaris. Polaris is the star found on the very end
of the Little Dipper’s handle. Next, extend that same line past
the North Star to find Cassiopeia’s throne, which looks like the
letter W.
These three constellations are called circumpolar
constellations because they rotate around Polaris. They can
be during any season.
The appearance of the sky rotating is actually caused by
the Rotation of the Earth. This is what causes our Day
and Night cycle. As the Earth rotates, the half without
light moves to face the sun, creating daytime. Just like how
the Sun rises in the East and sets in the West, so does the
whole night-time sky.
Not only does the earth rotate, but it also Orbits around the
Sun. Where the Earth is located in its yearly orbit determines its
seasonal constellations, because our perspective of the sky has
changed.
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Why the Sky Changes with the Seasons
During Iowa’s summer months of July
and August, we revolve to be on the
side of the sun where we can easily see
the Summer Triangle and
Scorpius.
You can find the Summer Triangle in
the Northern part of the sky, outlined by
three bright stars. You can find Scorpio
in the Eastern part of the sky, outlined
by a fish hook shape.
During Iowa’s winter months December
and January, when we’re on the other
side of the sun, we can’t see them as
well. These constellations don’t disap-
pear, they’re just in the sky at the same
time as the sun. The light from the sun
lights up our daytime sky, making it hard
to see the stars that make up these
constellations.
We can however, see Orion in the
winter, because we have rotated to be
facing it during the night. You can find
Orion in the Southern half of the sky. It’s
easy to spot because of his bright belt,
outlined by three stars.
These constellations are all called
seasonal constellations, because they
can only be seen during only certain
seasons!
What constellations will you be able to
see tonight?
What constellations do other parts of
the world see during the same time of
year?
All images rendered using E&S Digistar 5
