The Outer Planets 2012 The Outer Planets The outer planets are made of gases. The outer planets are very large. Gas Giants Separated from the 1st zone by the asteroid belt, the 2nd Zone contains the gas giants. Made of the lightweight elements Hydrogen, Helium, Carbon, Oxygen, and Nitrogen. All are much larger than the Earth, with 15-300 times the mass, and 4-11 times the diameter. Not believed to have solid surfaces. Have rings and many satellites. Gas Giants Atmospheres Since they have so much mass, their strong gravity can keep even light gases from escaping. Atmosphere tends to resemble the sun (75% H, 24% He, 1% other gases). No well defined surface. Gases just get denser and denser as you go deeper. Becomes liquid metallic hydrogen, which has properties of liquids and metals. Exist only under high pressure. Causes Jupiter's magnetic field. Gas Giants Cores Gas giants are believed to have solid cores made of rock,, ice, frozen carbon dioxide, and other compounds. Cores would be several times the size of the Earth. Jupiter, King of the Roman Gods Named for Jove, the King of the Roman Gods. Roman name for the Greek god Zeus. Often the term Jovian is used to describe things pertaining to Jupiter. Example: the Jovian moons. Jupiter Believed to be a failed star, lacking the mass to become a small star. Most massive planet in solar system. Has over 60 satellites. Density is 1.33g/cm3. Rotates every 10 hours. Takes 12 years to orbit the sun. Gravity almost 2.5 times that of the Earth. Jupiter Atmosphere Mainly hydrogen with some helium. Very active weather systems. Forms colorful bands and swirls. Has hurricanes that last for 100’s of years. Great Red Spot The red spot is a huge storm that has been continuously going on Jupiter for over 400 years. Winds inside this storm reach speeds of about 270 mph. With a diameter of 15,400 miles, this storm is almost twice the size of the entire Earth. Jupiter's Moons Galileo discovered the four largest. Io, Ganymede, and Callisto are larger than our own moon. Europa has a icy crust and is believed to have liquid water oceans below the frozen surface. Io has many active volcanoes. Has 63 moons, most of any planet in our solar system. Ganymede is the largest moon in our solar system. Missions to Jupiter http://www.window s.ucar.edu/tour/link =/jupiter/space_mis sions.html http://www.solarvie ws.com/eng/craft2. htm#jupiter Shoemaker Levy 9 In July 1994, Comet Shoemaker-Levy 9 collided with Jupiter with spectacular results (left). The effects were clearly visible even with amateur telescopes. The debris from the collision was visible for nearly a year afterward with HST. Captured by Jupiter's strong gravity, the comet was torn into over 20 fragments that struck Jupiter, each with a force of millions of megatons of energy. This has renewed NASA’s interest in tracking objects that might get close to Earth one day. Jupiter Facts Diameter: 11 earth's Distance: 5 Au Atmosphere: mainly hydrogen with some helium Features: active weather with storms that last for 100s of years (GRS) Largest planet Over 60 moons, most in our solar system Life: none as we know it. Cold, no known surface. Saturn the God Saturn was the Roman God of the Harvest and of Time. Father of Jupiter, Neptune, and Pluto. The Roman name for the Greek god Cronos. Saturnalia was the midwinter festival in Saturn's honor. It lasted seven days, and there was much merrymaking. Public business was suspended and schools were closed. Parents gave presents to their children. Saturn Facts 2nd largest planet in solar system. A “day” on Saturn is a little over 10 hours long! It takes 29 years to orbit the sun. Almost 10 times larger than Earth. Most visible rings of any planet. Density is 0.69 g/cm3. If a large enough ocean could be found, Saturn would float in it! Saturn’s Atmosphere Similar to Jupiter’s, mostly hydrogen with some helium. Storms not as large or as long lived as Jupiter's. Clouds are thicker, blocking views to lower layers. Explains the lack of banding compared to Jupiter. Saturn’s Moons Has over 40 moons, 15 or so that are large enough to be called major moons. Titan Titan has an atmosphere made of about 99% nitrogen and 1% methane. Has a pressure of 1.6 atmospheres. Completely covered by thick clouds that are similar to smog on Earth. The second largest moon, it is larger than Pluto and Mercury. CassiniHuygens The Huygens probe actually parachuted into the atmosphere of Titan on 14 January 2005. It took pictures and collected data all the way to the surface. It survived the landing and sent back pictures of the surface it landed on. Saturn’s Rings Very spectacular. Not at all solid. Made of tiny bits of ice, dust, and rock. A few are up to a kilometer across. Only about a kilometer thick. The Cassini space probe actually passed through the outer ring as it slowed down to enter orbit. Saturn Facts Diameter: 9 times larger than Earth Distance: 10 Au Atmosphere: 96% Hydrogen 4% Helium Features: Has short storms, brilliant rings orbit it that are made up of bits of ice, dust, and rock 2nd largest planet Life: no life likely, although Titan and Enceladus have possibilities. Uranus the God URANUS: Great primeval God of the Sky. Born of GAIA, the Earth, he covered the world in the form of a vast bronze dome and ruled over everything. Uranus Facts Diameter is like 4 Earth’s. Mass is 14.5 Earth’s. Takes 84 years to revolve around the sun. Day is a little over 17 hours long. Has more than 20 moons. Uranus Axis Uranus is considered unusual because the planet is tipped on its side. The poles actually point towards the Sun. its magnetic field is tilted 60 degrees from the axis of rotation. It is believed that Uranus was struck by a large object that knocked Uranus on its side. Uranus Seasons Uranus Atmosphere First, there is absolutely no detail in the cloud cover. Only when pushed to the maximum level of color enhancement and contrast on computers do scientists start to see small swirls in the atmosphere. Uranus Moons 5 large and many small moons. Titania is the biggest moon of Uranus. It is about half the size of our moon. Titania is covered by many small craters, a few huge impact basins ice cliffs, and fault lines. Ariel: The brightest moon of Uranus. Youngest surface of Uranus' moons, the least cratered. Has long valleys and canyons. Uranus Diameter:4 Earth’s Distance:19 AU Atmosphere:82% Hydrogen 15% Helium Features: extreme seasons because axis is tipped on its side and no detail in cloud cover Life: no life, too cold, atmosphere and surface would not allow life as we know it. Neptune the God Neptune is the Roman god of the sea. The Romans modeled him after the Greek god Poseidon. Neptune Neptune revolves on its axis every 18 hours. It takes 165 years to revolve around the sun once. Has the mass of 17 Earths. Has 13 moons. Diameter is almost 4 times larger than Earths. Blue-green color is from the methane in the atmosphere. At times it is the furthest planet from the sun. Neptune Atmosphere 80% hydrogen, 19% helium, and 1.5% methane. Has icy clouds and enormous storms. Has the fastest winds in our solar system. Triton Neptune's largest moon is named Triton. Triton is much larger than any of the planet's other moons. Triton is a very cold place, so the moon is covered with ice. Even though Triton is cold there is a lot going on there. It has geysers like the ones at Yellowstone Park on Earth. The geysers shoot ice 8 km (5 miles) high into Triton's thin atmosphere! There may be water under the ice at Triton. It is even possible that there might be life in that water. The interior of Triton is probably geologically active. Neptune’s Rings Neptune's rings are much darker than Saturn's bright rings. Saturn's rings are made of ice, which reflects lots of light. Neptune's rings are probably made of rocks and dust. Rocks and dust don't reflect as much light. Neptune Facts Diameter: 4 times the size of Earth Distance: 30 Au Atmosphere: 80% Hydrogen 19% Helium 1.5% Methane Features: At times it is the furthest planet from the sun. Icy clouds and enormous storms, one called the Great Dark Spot. Life: possible life on one of its moons called Triton Pluto the God Pluto was the Roman name for Hades, the Greek god of the Underworld. Discovered in 1930 by Clyde Tombaugh using a blink comparator. This allowed astronomers to quickly look for differences in two photographs shot on different nights of the same part of the sky. Pluto Once thought of as usually the furthest planet from the sun. 2/3rds the size of our moon. Has one large moon, Charon, and two smaller ones, Nix and Hydra. So cold that oxygen and nitrogen in its atmosphere is frozen solid except when Pluto is nearer the Sun. Only planet not visited by a spacecraft. Pluto takes 248 years to make one orbit around the sun! Pluto’s Atmosphere When Pluto comes close enough to the sun, the surface of solid Nitrogen sublimates to produce a substantial atmosphere with winds and clouds. Because the planet is so small, however, it does not have enough gravity to bind an atmosphere for very long. Thus Pluto's atmosphere is being rapidly produced and rapidly lost at the same time. This means that the atmosphere is not in equilibrium. Similar to comets when they get close to the Sun. Pluto’s Orbit Pluto has the most eccentric orbit of all the planets in the solar system. Its orbit takes it to 49.5 AU at its farthest point from the Sun. And its orbit takes it as close as 29 AU to the Sun. That means that Pluto's orbit draws within the orbit of Neptune, as can be seen in this drawing, making Pluto the 8th planet rather than the 9th planet for roughly 20 years at a time. Pluto was the 8th planet from January 1979 to February 1999. Neptune is now the 8th planet for over 200 years!