This presentation was used during 6th grade. Most of the source are from a book. Pictures from google ;) Please enjoy!

3. Galaxies
Are group of star clusters held
together by gravity.
Could contain more than 200
billion stars.

5. MAIN GROUPS OF GALAXIES
1. Spiral Galaxy
Looks like a whirlpool

6. MAIN GROUPS OF GALAXIES
2. Elliptical Galaxy
Shape is similar to a football
Has no spiral arms and little or
no dust.

7. MAIN GROUPS OF GALAXIES
3. Irregular Galaxy
Has no recognizable shape
May have been caused by collisions
with other galaxies

8. STARBURST GALAXY

10. MILKY WAY GALAXY
Our home galaxy
Is a spiral galaxy
To find the center of the galaxy:
1. Look in the center of the constellation
Sagittarius, the archer.

12. SPECTRUM
• When light passes through water
droplets, it separates into a band of
colors.
• This is because white light is a
combination of all the colors of the
rainbow.

13. • Astronomers think the galaxies must
have been closer to each other in the
past.
• At the beginning moment, the universe
was extremely tiny, hot, and dense.

14. • From this tiny beginning, the universe
expand rapidly.
This expansion called the big bang,
sent matter out in all directions.

15. BIG BANG THEORY
• The universe is expanding, and its
temperature are decreasing.
• Gravity has caused matter to collect
into clumps, forming stars and
galaxies.

16. BIG BANG THEORY
• Background radiation is radiation that
is left over from the beginning
moments of the universe.

18. FORMATION OF THE SOLAR
SYSTEM
• Scientists believe that billions of years
after the big bang, dust and gas in a
part of the Milky Way gathered into a
nebula massive enough to rotate.

20. HOW ARE SOLAR SYSTEM FORMED
1. A rotating cloud of gas and dust begin to
contract.
2.Protoplanets form, and they orbit a
protostar, the Sun.
3.The solar system as it is today emerged.

21. EARTH
• Scientists think that Earth is about 4.6
billion years old. Astronomers think
that Earth and its atmosphere
developed in a series of stages.

24. *For those who listened