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STARS &
GALAXIES


Galaxies – billions of star
groups
 more than 100 billion
galaxies, each
containing billions of
stars.
Galaxies have different
shapes:
 Spiral Galaxies –
pinwheel-shaped:
 spiral arms that
rotate
 nucleus in the
center
 30% of all galaxies,
including the Milky
Way (our galaxy)
 The oldest stars
are located
near the
nucleus.
Galaxies and Stars
Types of Galaxies
Elliptical Galaxies:
spherical or oval
shape:
 contain little dust
and gas
 60% of all galaxies
 very old stars and
very little nebulae
(a cloud of gas
and/or dust in
space)
 Irregular Galaxies: no
orderly shape and are
very rare.
 10% of all galaxies

Big Bang Theory

At one time, the universe was a dense, hot,
supermassive ball.

About 13.7 billion years ago, a violent explosion
occurred sending material in all directions into
space.

This marked the beginning of the universe.

Eventually, matter cooled and condensed into
galaxies, stars, and planets.
Support for the Big Bang Theory
 Red
shifts
 Cosmic
background radiation
Radio
signals coming from
every direction in space.
Believed
to be created by the
big bang explosion.
The Expanding Universe

1929 – Edwin Hubble found
that the universe is expanding

Estimated distances,
relative brightness,
Doppler red shifts

Dimmer galaxies had
greater red shifts  farthest
from Earth

Hubble’s Law: the more
distant the galaxies have
greater red shifts, therefore
they are moving away at
faster speeds.
The End of the Universe

Some scientists believe the universe will continue to expand.


The stars will slowly burn out creating invisible matter and
black holes that continue to travel outward.
Other scientists believe the universe will end in the “big
crunch.”

Gravity will pull galaxies together.

Galaxies will collide, creating a high-energy, high-density
mass – the opposite of the big bang.
Evidence for the End of the
Universe

The evidence leads to the belief of
an ever-expanding universe.

There may be uncertainties (such
as undetected matter) that
scientists do not know about that
may provide evidence that the big
crunch can actually happen.
Solar System

Until recently, there have been 9 planets in our solar
system.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
Neptune, and Pluto

In 2003, scientists discovered more planets orbiting in
our solar system. Pluto is not anymore a planet!!!!
The Sun
Terrestrial Planets
Mercury
Earth
Venus
Mars
Jovian Planets
Jupiter
Saturn
Neptune
Uranus
The New “Dwarf” Planets
Sedna
(2003
UB 313)
Charon
Ceres
Asteroid
Pluto
Assignment

Solar System
Assignment
Solar System assignment

1. Each group will be assigned a planet.

2. Follow the directions on the blue WS:
 Do
****
step I
DO NOT Do step II
3. Use Construction papers or white paper to illustrate your
planet.
Make sure you planet is on scale
4. Put you planet on the navy blue poster

3. Part III is your homework…… I will post it on my weebly
The solar system