2. Planet The International Astronomical Union (IAU) defines a planet as a body that: is in orbit around the sun has sufficient mass for its self-gravity to assume nearly round shape, and has cleared the neighborhood around its orbit. Source: IAU Resolution 5B

3. Why should we study the planets? Learning about the other planets helps us understand a lot about Earth.

4. Inner Planets Also called the terrestrial planets Near to the sun Small planets Composed primarily of rocks and iron Includes Mercury, Venus, Earth and Mars Source: Encarta encyclopedia 2009

5. Inner Planets (except Pluto)

6. Mercury

7. Mercury Closest planet to the sun Smallest planet in solar system Has many craters and looks more like Earth’s moon Has a very thin atmosphere The temperature varies from 330°C to 750°C Dry, hot and virtually airless.

8. Venus

9. Second planet from the sun Known as Earth’s twin One Venus day is longer than one Venus year Hottest planet in the solar system with temperatures reaching 860°C It’s atmosphere is composed mainly of carbon dioxideVenus

10. Appears to have phases like the moon and Mercury The “morning and evening star” Third brightest object in the skyVenus

11. Venus

12. Third planet from the sun The only planet known to support life Atmosphere is composed of 78% nitrogen, 21% oxygen The surface is about 70% waterEarth

13. Earth

14. Mars

15. Mars Also known as the “red planet” Has polar ice caps that vary during seasons Has many craters Has the largest volcano, the Olympus Mons Atmosphere consists predominantly of carbon dioxide

16. Mars

17. That’s all for now! Source of planetary images: www.nasa.gov