1. 28 Sep 2000ASTR103, GMU, Dr. Correll1 Ch 06--Other Terrestrial Planets

2. 28 Sep 2000ASTR103, GMU, Dr. Correll2 Terrestrial Planets Is the temperature on Mercury, the closest planet to the Sun, higher than the temperature on Earth? What planet is most similar to Earth? What is the composition of the clouds surrounding Venus? Does Mars have liquid water on its surface today? Is life known to exist on Mars today?

3. 28 Sep 2000ASTR103, GMU, Dr. Correll3 Terrestrial Planets

4. 28 Sep 2000ASTR103, GMU, Dr. Correll4 Mercury

5. 28 Sep 2000ASTR103, GMU, Dr. Correll5 Mercury Proximity to Sun makes for a hot planet –daytime 700 K (800 F) –nighttime 100 K (-280 F) (actually quite cold) Some regions of Mercury’s poles are permanently shaded –Water ice on the poles! Magnetic field similar to Earth, therefore, must have an iron core

6. 28 Sep 2000ASTR103, GMU, Dr. Correll6 Mercury’s Interior

7. 28 Sep 2000ASTR103, GMU, Dr. Correll7 Mercury’s Violent Past

8. 28 Sep 2000ASTR103, GMU, Dr. Correll8 Venus

9. 28 Sep 2000ASTR103, GMU, Dr. Correll9 Venus Atmosphere Greenhouse effect-- carbon dioxide prevents infrared light from escaping, thus heating up the atmosphere Mostly sulfuric acid clouds shrouding the planet’s surface

10. 28 Sep 2000ASTR103, GMU, Dr. Correll10 Venus Atmosphere

11. 28 Sep 2000ASTR103, GMU, Dr. Correll11 Venus Mapped by the Magellan spacecraft in 1990--radar!

12. 28 Sep 2000ASTR103, GMU, Dr. Correll12 Venus Mapped by the Magellan spacecraft in 1990--radar!

13. 28 Sep 2000ASTR103, GMU, Dr. Correll13 Mars

14. 28 Sep 2000ASTR103, GMU, Dr. Correll14 Mars--Martians?! 1877, Schiaparelli reports seeing “canali” (channels, not canals) –some thought these were a planetary irrigation system 1898, H. G. Wells “War of the Worlds” 1938, Orson Wells radio broadcast 1976, Viking Orbiter 1 photo

15. 28 Sep 2000ASTR103, GMU, Dr. Correll15 Mars Life? Probably not.

16. 28 Sep 2000ASTR103, GMU, Dr. Correll16 Mars Life? Maybe in the past. –There was abundant water!

17. 28 Sep 2000ASTR103, GMU, Dr. Correll17 Mars--Recent Discoveries Life? Maybe in the past. –There still may be abundant water! –Images from Mars Global Surveyor

18. 28 Sep 2000ASTR103, GMU, Dr. Correll18 Mars 1997, Analysis of pieces of Mars found in Antarctica suggest fossil remains of microbial life! (maybe) 1979, Viking 1 lander had inconclusive (controversial) results regarding organic material

19. 28 Sep 2000ASTR103, GMU, Dr. Correll19 Mars Mars atmosphere often active: –~1% as dense as Earth’s –95% CO 2 Oxygen reacted with iron (rust colored surface!) –Dust storms seasonally –Snow fall near the poles

20. 28 Sep 2000ASTR103, GMU, Dr. Correll20 Terrestrial Planets Is the temperature on Mercury, the closest planet to the Sun, higher than the temperature on Earth? –Higher in the day side, colder in the night side What planet is most similar to Earth? –Venus in size, chemistry, and distance. Mars in length of day and seasons What is the composition of the clouds surrounding Venus? –Primarily sulfuric acid Does Mars have liquid water on its surface today? –No, some water ice, though. Probably lots of water in the past Is life known to exist on Mars today? –No, but not ruled out. Hints that it may have had life in the past

21. 28 Sep 2000ASTR103, GMU, Dr. Correll21 Questions for thought Discuss the existence of life on Mars, in the past and at the present time.