Download 2.7 - 2.9a

4.1 – 4.3
What is space like?
 No air – vacuum
 No air friction – force
that resists motion
 Mostly black – absence
of light
 Extreme temperatures
Galactic Shapes
 spiral galaxies
 include the Milky Way (our galaxy)
 all have a central nucleus
have long curved arms
 contain a lot of gas and dust
 barred spirals
the spiral arms are attached to a
straight “bar” that runs through the
center of the galaxy

Spiral

Barred Spiral
Barred Spiral Galaxy
elliptical
galaxies
resemble an egg or a football
not as structured
irregular galaxies
groups of stars that have no
defined shapes
the Large Magellanic Cloud
and Small Magellanic Cloud
the two closest galaxies to
ours

Elliptical galaxy

Irregular galaxy
Celestial
Clouds
nebulae
large
clouds of gas and dust
floating in space
They are most common in
spiral and irregular galaxies
horse head nebula is one of
the most widely known
nebulae
Helix Nebula

Horsehead
nebula
Constellations
Group
of stars outlining an
imaginary picture
most have been identified since
ancient times
Constellations were once used to
navigate by travelers because
they appear to revolve around the
North Star
They
are also used to refer to 88
regions of the sky (celestial sphere)
North
Star
Polaris
is the scientific name for
the north star
It is located directly above the
Earth’s “axis of rotation”
The axis is the Imaginary line
that runs from the north pole to
the south pole on which the
Earth spins
 The
word constellation has two current
meanings
-The oldest refers to a pattern of stars
-The reference used by most current
astronomers refers to a section of sky.
-We will look at some of the patterns
or arrangements of stars.
The constellations seen in the Northern
Hemisphere are divided into groups
determined by the season in which
people can see them. So we call them:
Spring constellations
Autumn constellations

2 groups in the northern hemisphere
Spring Constellations
 Autumnal Constellation

Constellations of the
Northern Hemisphere
Ursa Major
The Great Bear
Contains the Big Dipper
Most familiar of all
constellations
 Ursa
Minor
The Little Bear
More commonly called the
Little Dipper
Polaris is at the point of Ursa
Minor
 Queen
Cassiopeia
Named after a mythical queen
of Ethiopia
Looks like a big “M” or “W”
 King
Cepheus
Looks like a house with a long
pointed roof
 Andromeda
Mythological
daughter of Cassiopeia
and Cepheus
Andromeda is also called “The Lady in
Chains”
Her head is part of the Great Square star
formation
Her “knee” contains the Andromeda
Galaxy
 Whale
Monster that was to devour Andromeda
This constellation is often located
beneath the horizon
Perseus
The
hero that rescues
Andromeda
Located above Andromeda
Contains the star Algol which
is a binary star
A binary star is actually two
stars that appear as one
because they are so close
 Pegasus
 The
Flying Horse
 Leo
 The
Lion
 Regulus
Brightest
star in the Leo constellation
(probably a white dwarf)
Found in the lion’s paw
 Sickle
The
outline of Leo’s head
Cygnus
or the Swan
It
is located on the opposite side
of the Big Dipper from Leo
Deneb
is the brightest star in
“The Swan”
Deneb is also the top of the
Northern Cross which is
part of the Swan
 Gemini
The
twins
Castor and Pollux are the
brightest stars in Gemini
Castor and Pollux are the
heads of the two boys
 Draco
The dragon
 Orion
The
Hunter
Orion is the brightest of the
constellations
 It contains two very large stars
Betelgeuse
Brightest star in the constellation
found at the right shoulder
Rigel is a blue supergiant type star
 If Betelgeuse was placed in the center of
our solar system, it would reach past
Mercury, Venus, Earth, and Mars
 Taurus
The
Bull
Pleiades
Large
group of stars at the horn of
Taurus
His eye is Aldebaran (a large star)
Canis
The
Major
Big Dog
Sirius is found in Canis Major
and is the brightest star in the
night sky
There
are some constellations
in the Southern Hemisphere
that we do not see
Scorpius
The scorpion
Antares is the brightest star
in Scorpius
means“Rival of Mars”
The star appears red in the sky
Antares
Sagittarius
The
Archer
It contains two other
constellations
The Milk Dipper
The Tea Pot
Centaurus
The
constellation is said to
resemble a creature that is half
man and half horse
It contains two stars that are
relatively close to our sun:
Alpha Centauri and Beta
Centauri
Alpha Centauri is the closest
star to the earth other than
our sun
Southern
It
Cross
is made up of the brightest
stars in the Southern Sky
It is found near beneath
Centaurus
Many countries have this
constellation in their flag