Download Astronomy

Astronomy
Astronomy
What is Astronomy?
1. Astronomy is the study of the universe.
• This includes planets, stars, galaxies,
black holes, moons, meteors, comets,
asteroids and all of the matter that exists
in space.
2. Astronomers are people who observe and
study space.
Modern Calendar
1. Our modern calendar is based on
the observations of bodies in our
solar system.
2. A year is the time it takes for the
Earth to orbit the sun.
3. A month is the time it takes for the
moon to orbit the Earth.
4. A day is the time it takes for the
Earth to rotate once on its axis.
The Size and Scale of our Universe
1. It is important to consider scale
when we think about the universe.
2. Stars appear to be very small when
viewed from Earth, but they are
actually very large, some, like our
sun, are bigger than Earth.
The Scale of our Solar System
Earth
Scale of the Universe
SUN
Mercury
Our Galaxy and Scale
• Our Milky Way galaxy is simply huge. Just how
big is our galaxy?
• Let's now pretend that our galaxy is a kid's
sandbox, and our sun is a grain of sand in a
sandbox.
• The Earth is a miniscule dust speck near the
grain of sand, too small to be seen without a
microscope.
• If our sun were a grain of sand in this sandbox
representing the Milky Way galaxy, the sandbox
would be somewhat oval and yet flat, and would
be about 20 feet in diameter.
• The sand would be about 12 inches thick in the
center, and thinner towards the edges.
Milky Way Galaxy
Distance in Space
1. Distance in space is measured in light
years.
2. A light year is used to measure large
differences in space.
3. A light year is the distance light travels
in a year, 5.88 trillion miles.
4. Light travels at 186,000 miles per
second.
THE MILKY WAY
GALAXY
•Each swirling object
you see is a galaxy in
our universe.
1. We can estimate that
there are about 100
billion stars in our
galaxy.
2. Andromeda is the
nearest major galaxy to
our own Milky Way
Galaxy.
3. Most scientists
believe that Andromeda
is about 2 million light
years away from the
Milky Way.
What is a Galaxy?
1. A large group of stars, gas, and
dust held together by gravitational
attraction.
2. A system of about 100 billion stars.
3. There are billions of galaxies in the
observable universe.
3 Types of Galaxies
1. Spiral
 2. Elliptical
 3. Irregular

Spiral Galaxy
1. Spiral galaxies
consist of a flat,
rotating disk of
stars, gas and
dust, and a
central
concentration of
stars known as
the bulge.
2. The Milky Way
galaxy is a
spiral galaxy.
Irregular Galaxy
1. These are galaxies
that feature
neither spiral nor
elliptical
morphology.
2. They are often
chaotic in
appearance, with
neither a nuclear
bulge nor any
trace of spiral arm
structure.
Elliptical Galaxy
1. Elliptical galaxies
have smooth,
featureless lightprofiles.
2. There is very little
interstellar matter
(neither gas nor
dust), which results
in low rates of star
formation.
3. Elliptical galaxies
are dominated by
old stellar
populations, or old
stars.
FLASHCARDS FOR THIS PPT PRESENTATION
http://www.flashcardmachine.com/180371/x18g