The Andromeda Galaxy
By: Briana Larson
Constellation
• The Andromeda constellation are in the
northern sky
• It was cataloged by a Greek astronomer
Ptolemy in the second century
• The constellation was named after the
mythical princess Andromeda who is known
as the wife of Greek hero Perseus
Andromeda constellation
Cetus the sea monster
Myth
Queen Cassiopeia
King Cephus
The myth is about Andromeda, daughter of King Cepheus and
Queen Cassiopeia of Ethiopia. The Queen offended the sea nymphs by
saying that she was more beautiful than they were. The nymphs
complained to Poseidon and he sent Cetus (the sea monster) to
destroy King Cepheus’ lands as punishment. The king got advice from
the Oracle of Ammon on how to prevent his land’s destruction. The
oracle told them that the only way was to sacrifice Andromeda to
Cetus. Cepheus and Cassiopeia had Andromeda be chained to a rock
on a cliff. Perseus intervened when he was riding home on Pegasus and
heard Andromeda’s screams as Cetus was getting closer to her. Perseus
charged towards Cetus with Medusa’s head and turned Cetus to stone
making sure Andromeda didn’t get turned to stone too. Perseus
unchained Andromeda and the two fell in love and had 6 children.
Pegasus
Perseus
Collisions with other galaxies
• The Andromeda Galaxy has collided with
many other galaxies including M32
• In about 3 to 5 billion years (about the lifetime
of our sun) Andromeda and our Milky Way will
collide
• When our Milky Way and the Andromeda
Galaxy collide it will form an elliptical galaxy
Messier 32
Elliptical Galaxies
• An elliptical galaxy is a circular galaxy
• Elliptical galaxies have very little gas and dust
• Elliptical galaxies also have little star formation
because stars form from gas
• Most of the stars on elliptical galaxies are old
and red
Elliptical galaxies
Messier 87 (elliptical galaxy)
The Triangulum galaxy/M33
Triangulum Galaxy
• The Trinagulum Galaxy/M33 is Andromeda’s
satellite
• M33 will join the collision between
Andromeda and the Milky Way
• It might merge with the Andromeda-Milky
Way galaxy later
• There is a small chance that M33 will hit the
Milky Way first
Distance and Size compared to our
Milky Way
• The Andromeda Galaxy is about 2.5 million
light years away from the Milky Way
• Andromeda is the closest galaxy to our Milky
Way
• The Andromeda Galaxy is over twice as long as
the Milky Way
Andromeda
The Spitzer Space Telescope
• The Spitzer Space Telescope has seen the
Andromeda Galaxy
• It has shown that Andromeda is no longer a
spiral galaxy but more of a galaxy that looks
like a ring
The Spitzer
Space
Telescope
Spitzer’s image
of Andromeda
Stars and Planets
• The Andromeda Galaxy is the home to a
trillion stars
• Andromeda is too far away that we can’t see
any planets in Andromeda
• On the Andromeda Galaxy there has been a
discovery of an “asymptotic giant branch” star
• This type of star is short lived and can be also
found in the Milky Way
What Astronomers first thought
• The Andromeda Galaxy was first thought to be
a nebula
• Charles Messier guessed that it was about
2,000 times further out than Sirius the star
• Heber Curtis said that Andromeda was
500,000 light years away and was a separate
“island universe”
• Edwin Hubble calculated that the galaxy was
actually 1.5 million light years away in 1925