The Universe
The Big Bang Theory
• Scientists believe that our universe began with
a big explosion of gas and dust in space. This
explosion is called the Big Bang.
• All of this matter and energy in space was
concentrated at one point before the Big Bang.
• They believe this explosion occurred about 15
billion years ago.
• Since that time, the universe has been
expanding (getting bigger and more spread
out).
animation of the formation of the
universe:
• http://resources.schoolscience.co.uk/PPARC/b
ang/bang.htm
our solar system
• Our solar system consists of the sun, planets,
dwarf planets (or plutoids), moons, an
asteroid belt, comets, meteors, and other
objects.
• The sun is the center of our solar system; the
planets, over 61 moons, the asteroids, comets,
meteoroids and other rocks and gas all orbit
the Sun.
This is the compostion of our solar
system:
Sun: 99.85%
Planets: 0.135%
Comets: 0.01% ?
Satellites: 0.00005%
Minor Planets: 0.0000002% ?
Meteoroids: 0.0000001% ?
Interplanetary Medium:
0.0000001% ?
animation of our solar system.
• http://janus.astro.umd.edu/javadir/orbits/ssv.
html
galaxy
• Definition: A cluster of hundreds of billions of
stars.
• Our galaxy is the Milky Way.
• The Milky Way is a spiral galaxy.
• Our solar system is on a spiral arm of the
Milky Way.
The Milky Way Galaxy
Types of Galaxies: Elliptical galaxies
Huge; contain
stars, gas, and dust
Held together by gravity
Round-to-oval shape
Mainly old stars are
present
Types of Galaxies: Spiral galaxies
• Huge; contain stars,
gas, and dust
• Held together by
gravity
• Pinwheel shape
• Young and old stars
are present
Types of Galaxies: Irregular galaxies
• No regular shape
• May show signs of a
disk and/or a bulge;
• halo is present
• Usually rich in gas and
dust
• Young and old stars
are present
formation of our solar system
• http://www.metacafe.com/watch/1111454/fo
rmation_of_the_solar_system_great_animatio
n/