1. The Milky Way

2. Sum up Introduction: the Milky Way’s identity
View from Earth: a few explications
Size and mass
Age
Spiral arms
Environment
Velocity
Some order of magnitude

3. Introduction
The Milky Way galaxy is visible from Earth as a band of light in the night sky, and it is the appearance of this band of light which has inspired the name for our galaxy.

4. View from Earth

5. Size and mass Mass: about 5.8×10^11
Size: approximately 10×10^4 light years in diameter, and about 10×10^2 light years thick.

6. Age
About 13.2×10^9 years

7. There are four major spiral arms in the Milky way.

8. Environment
The Milky Way and the Andromeda Galaxy are a binary system of giant spiral galaxies. Together with their companion galaxies they form the Local Group, a group of some 50 closely limited galaxies.
Andromeda Galaxy

9. velocity
Many astronomers believe that the Milky Way is moving at approximately 600 km per second.

10. Some order of magnitude
10^23 m: 10 million light years away from the Milky Way
10^21 m: our galaxy, the Milky Way
10^20 m: stars at the rim of the Milky Way galaxy
10^19 m: stars in the Milky Way galaxy
10^18 m: 100 light years from earth and nothing but stars
10^13 m: our solar system
10^9 m: the earth and the orbit of the moon

11. The end Our references: Images: Google Text: Wikipédia
Nwnw.gsfc.nasa.gov/-5k-