Download Ch. 3 Sec. 3 Notes

Ch. 3 Sec. 3 Notes
The Inner Planets
*Mercury, Venus, Earth, and Mars are the 4 inner planets
*The four inner planets are small and dense and have rocky surfaces
*The inner planets are often called the terrestrial planets
Earth
*Earth has 3 main layers: crust, mantle, and core
Water
*Earth is unique in our solar system in having liquid water at is surface
*70% of Earth is covered in water
*Earth is able to have water in liquid, solid, or air form
Atmosphere
*Earth is the only planet that has an atmosphere rich in oxygen
*All the rest of the atmosphere is mainly nitrogen
Mercury
*Mercury is the smallest terrestrial planet and the planet closest to the sun
-Size of Earth's moon
*Planet is made of mostly iron
Exploring Mercury
*Scientists know most about what's on Mercury because of a single probe, Mariner
10 that flew by 3 times in 1974 and 1975
*Scientists recently sent MESSENGER to orbit Mercury in 2009
*The probe shows that Mercury has many plains and craters
Mercury's Atmosphere
*Has almost no atmosphere because temperatures are too high for gas particles to
stay on planet
*Scientists have discovered some trace of sodium
*Temperature ranges from 430 C in day to -170 C at night
Venus
*Venus's density and internal structure are similar to Earth's
-Nicknamed "Earth's Twin"
Venus Rotation
*Takes 7.5 Earth months to revolve around the sun
*Takes 8 Earth months to revolve once on its axis
-Its day is longer than its year
Venus's Atmosphere
*Atmosphere is so thick that it's always cloudy
-Made of sulfuric acid
*Its air pressure is 90x greater than ours and would crush us instantly if we
stepped on Venus
*Venus's atmosphere is so dense that it traps in all the sun's heat
-Temperature stays around 460 C
*This trapping of heat by the atmosphere is called the greenhouse effect
Exploring Venus
*The first probe to explore Venus was Venera 7 in 1970
*The second probe, Magellan in 1990 discovered that Venus is rocky with lots of
rocks and volcanoes
Mars
*Known as the "red planet" because of the iron-rich rocks that cover the planet
Mar's Atmosphere
*95% carbon dioxide
*You can walk around on Mars but need an airtight suit and oxygen (like a scuba
diver)
*Temperature ranges from -140 C to 20 C
Water on Mars
*Scientists think that a large amount of liquid water flowed on Mars's surface in
the distant past
*Water cannot exist as liquid today because of Mars's too thin atmosphere
Seasons on Mars
*Mars is tilted like Earth so it experiences seasons
*Ice caps grow over one pole in the winter while the ice cap at the other pole
shrinks in the summer at the same time
Exploring Mars
*Many space probes have visited Mars
*NASA's Spirit and Opportunity are the most recent probes that discovered the
water was once present on Mars
Volcanoes on Mars
*Volcano lava has greatly shaped Mars's landscape
*Olympus Mons is the largest volcano in the solar system
-3 times taller than Mount Everest
Mars's Moon
*Mars has two small moons
*Phobos and Deimos
*Phobos is slowing spiraling closer to Mars and will crash into its surface in 40
million years