23.2 - The terrestrial planets

Videos http://www.youtube.com/watch?v=QTW2 YNj_4-U http://www.youtube.com/watch?v=qir- AngHoQU http://www.youtube.com/watch?v=XTXI2 nsSdPg http://www.youtube.com/watch?v=894Ae jo-R0U http://www.youtube.com/watch?v=LQqS hj6leq8

Do Now Put terrestrial planets in order from the Sun to Jupiter.

Do Now Put terrestrial planets in order from the Sun to Jupiter. Mercury Venus Earth Mars

Key Words Telescopic Prominent

The Terrestrial Planets Mercury The Innermost Planet Venus The Veiled Planet Earth The Blue Planet Mars The Red Planet

Mercury

Mercury Innermost Planet Smallest planet (not counting Pluto) Hardly larger than Earth’s moon Absorbs most of the sunlight and only reflects 6% back to space. Meaning no atmosphere.

Mercury’s Surface Features The surface looks similar to the moon with highlands and maria. Very dense planet, suggesting that there is a large iron core inside. Has very long scarps (deep slopes) that cut across the plains and craters alike. These scarps may have resulted from crustal changes as the planet cooled and shrank.

Mercury’s Surface Temperature Revolution is quick, but rotation is slow, about 59 Earth days. One night on Mercury lasts about three months and is followed by three months of daylight. Nighttime temperatures drop as low as -173 degrees. Noontime temperatures exceed 427 degrees (hot enough to melt lead). No chance of life ever being on Mercury.

Venus

Venus The Veiled Planet Second to the moon, in brilliance in the night sky. Similar to Earth in size, density, mass and location in the solar system. “Earth’s Twin” Possibly can tell us about Earth’s history.

Venus’ Surface Features Covered in thick clouds that visible light cannot penetrate. Varied topography that is similar to Earth and Mars. Basaltic volcanism and tectonic activity shape Venus’s surface. 80% of the surface is covered in these volcanoes. Only 8% of Venus’s surface consists of highlands, similar to Earth’s continents.

Venus’ Surface Temperatures The greenhouse effect has heated the planet’s atmosphere to 475 degrees. Hot enough to melt lead. This is considered a runaway greenhouse effect and the cause is due to the fact that the atmosphere is 97% carbon dioxide due to all the volcanic activity and lack of oceans which absorb carbon dioxide. In it’s history there were sources of water vapor but that helped speed up the greenhouse effect and all water vapor was lost.

Earth

Earth The Blue Planet The only planet in our solar system with life on it. Only planet with mostly water, roughly 75% covered in water.

Earth’s Surface Features Has a relatively thin atmosphere, where light can penetrate. Has various topographic features, and active plate tectonics.

Earth’s Surface Temperatures Due to the bearable temperatures on Earth, it is the only planet in our solar system that is able to sustain life. Due to global winds, temperature of Earth is well balanced.

Mars

Mars The Red Planet The only planet within telescopic range where we can view the surface from Earth. Known as the Red Planet since from the telescope it appears as a reddish ball. Has bright white ice caps on the poles. With current technology, NASA’s our robotic missions usually take about 8 months to travel to Mars. NASA is exploring options that will minimize the duration of a human trip to Mars. Earth's and Mars' orbit around the sun allow for an opportunity to embark to Mars about every 26 months. There are two scenarios for going to Mars and returning to Earth. The first requires astronauts to remain on Mars for only a few weeks before returning. The second scenario will see astronauts spending over a year on the Red Planet. The overall mission duration ranges from about a year to close to three years.

Martian Atmosphere Only 1% the density of Earth’s atmosphere. The oxygen content of the Martian atmosphere is only 0.13 percent, compared with 21 percent in Earth's atmosphere. Carbon dioxide makes up 95.3 percent of the gas in the atmosphere of Mars. It also contains nitrogen and argon and very small amounts of water and methane. Mostly carbon dioxide with traces of water vapor. The ice caps are made of water ice, covered by a thin layer of frozen carbon dioxide. As the temperatures drop to -125 in the winter, more carbon dioxide is deposited on the ice caps. Extensive dust storms occur and have hurricane-force winds up to 270 kilometers per hour and can last for weeks.

Mars’ Surface Features Numerous large volcanoes. Olympus Mons is one of these volcanoes (size of Ohio and 2 times taller than Mt. Everest) and looks like the shield volcanoes in Hawaii. Most of the surface is old in Earth standards. 3.5 - 4.5 billion years old “Fresh” volcanic activity – 1 billion years old Several canyons, that are much larger than the Grand Canyon on Earth. Rift Valleys similar to the one in Africa.

Water on Mars Some areas of Mars exhibit drainage patterns similar to those created by streams on Earth. Many scientists do not accept the theory that Mars once had an active water cycle like on Earth. Instead the stream-like features were created during the formation of Mars. New data shows that some areas of Mars were once “drenched” in water, but that data is still being analyzed.

Group Activity For each of the terrestrial planets you will need to draw what they look like; as well as describing features and temperatures on their surfaces. Including Earth!