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Chapter 19.2 . The Inner and Outer Planets. Objectives…. By the end of this section you WILL be able to do the following… Explain how the inner planets are all similar to each other Identify what makes a planet a gas giant Identify and describe bodies that lie beyond the gas giants. Lets
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Chapter 19.2 The Inner and Outer Planets
Objectives… • By the end of this section you WILL be able to do the following… • Explain how the inner planets are all similar to each other • Identify what makes a planet a gas giant • Identify and describe bodies that lie beyond the gas giants
Lets look at the inner planets first!
The Inner Planets • The inner planets include Mercury, Venus, Earth, and Mars • These planets are also known as the terrestrial planets • They are relatively small and have solid rocky surfaces, metallic cores, and terrain (hence they are terrestrial)
Mercury • Scientists sent a space probe named Mariner 10 to investigate Mercury • Distances in the solar system are usually measured in Astronomical Units (AU) • This is the distance from the earth to the Sun • Mercury’s distance is roughly .4 AU • Mercury’s surface can reach more than 720 Kelvin • How hot is that in Fahrenheit?
Mercury contd… • One day on Mercury lasts about 59 Earth days • However one year on Mercury is only 88 Earth days long
Venus • Venus is .7 Au from the sun • Venus is also known as the morning/evening star because of its appearance near sunrise or sunset. Misnomer? • Venus has mountains and plains and spins very slowly in the opposite direction of most other planets and the sun • One day on Venus is 243 Earth days
Venus Contd… • Venus is extremely hot and its atmosphere contains large amounts of sulfuric acid • Atmospheric pressure is also more than 90 times the pressure on earth. • Carbon dioxide, a major greenhouse gas, absorbs the radiation from the sun and keeps the surface temperature more than 700k • http://video.google.com/videoplay?docid=-1640455400367692862&ei=z6CtSu-6O5WmlQfkqpGzAw&q=venus+planet&hl=en&client=firefox-a
Earth… • Earth is the 3rd planet from the sun • How many AU is the earth from the sun? • Earth is the only planet scientists are aware of that supports life • It has large amounts of liquid and solid water known as the hydrosphere • The hydrosphere is responsible for keeping Earth’s temperatures moderate
Earth cont’d… • Earth’s atmosphere protects us from radiation • The atmosphere is composed of 78% N2, 21%O2, and 1% Ar, CO2 and other gases • The atmosphere also protects us from harmful UV rays • The atmosphere also protects us from debris in space • How?
Earth’s atmosphere has changed over the years • It used to be made up mainly of CO2, methane, and ammonia
Mars • Humans have not yet visited Mars in person, but have sent probes to explore it • Viking 1 and Viking 2 sent landers to the surface in 1976 • In 2004 two Mars rovers landed on Mars • http://video.google.com/videoplay?docid=1814981743437079182&ei=q18fStHnCIOMrwLe15HHBA&q=mars+rover&hl=en&client=firefox-a#
Polar ice caps on mars are made of frozen CO2 and maybe some frozen water • Other features on the planet suggest that water once flowed across the surface of the planet • Mars has a thin atmosphere composed mainly of CO2 • Mars is 1.5 AU from the sun and has two small satellites. Remember their names? • Phobos and Deimos
The largest mountain in the solar system is Olympus Mons, it is roughly 3 times the height of Mount Everest • Unlike the Earth, Mars has no plate tectonics • Mars’ surface is riddled with craters due to its extremely thin atmosphere • The surface of Mars is red from iron oxide (rust) in its soil