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Our Solar System • • • • The SunSun is the – center our solar The ourofvery ownsystem star The word “solar” means “of the sun” Our sun is a medium-sized star Our sun is medium-hot, and yellow The Sun dominates the Solar System The Inner Planets Terrestrial Planets • Mercury, Venus, Earth & Mars – “Earth-Like” Rocky Planets – Largest is Earth – Only in the inner solar system (0.4 to 1.5 AU) • Rocky Planets: small, dense and rocky – – – – Solid Surfaces Mostly Silicates and Iron High Density: (rock & metal) Earth, Venus, & Mars have atmospheres Spinning Planets • Period of Rotation: amount of time that an object takes to rotate once. (1 Day) • Period of Revolution: time it takes an object to revolve around the sun once. (1 year) http://www.youtube.com/watch?v=97Ob0x R0Ut8&feature=related Mercury • On Mercury you weigh only 38% of what you weigh on Earth. • Fastest orbiting planet • Planet nearest to the sun • One side of the planet can be 800 degrees Fahrenheit when the other can be -280 degree Fahrenheit at the same time. • Orbit Period 88 days • Rotation Period 59 days Mercury • The planet Mercury is the closest of the planets to the Sun, but it is not the hottest. • The surface of the planet Mercury is covered with craters. These craters have been created by eons of accidental encounters with asteroids and comets. This is because it does not have an atmosphere. • Mercury is just a little bit larger than Earth's moon. The surface of Mercury that faces the Sun can reach about 800 degrees Fahrenheit. On the other hand, the temperature on the nighttime side can plummet to almost -300 degrees Fahrenheit. This is because Mercury has little to no atmosphere to help regulate temperature. Venus • On Venus you weigh only 91% of what you weigh on Earth. • Venus has 90 times the pressure of Earth and it’s the hottest planet. • Venus has volcanoes like Earth • Rotates in the opposite direction of Earth. • One time there were oceans before they boiled away. • Orbit Period 224 days • Rotation Period 242 days Venus • Venus rotates in a prograde rotation. The sun comes up in the west and sets in the east. • Venus is the hottest planet because of its extremely thick atmosphere of carbon dioxide. • Venus is know as Earth’s twin. • Venus has no moons. Earth • 23 hours and 56 min=1 Earth day (rotation) • 365 days =1 Earth year (revolution) • Earth is warm enough to keep most of its water from freezing and cold enough to keep it’s water from boiling • Temperature is between –13 degrees Celsius and 37 degrees Celsius Earth • Earth is the only planet know to have life forms. • Earth has one natural satellite, the moon. • The ground you're walking on is recycled. Earth's rock cycle transforms igneous rocks to sedimentary rocks to metamorphic rocks and back again. • The oceans cover some 70 percent of Earth's surface, yet humans have only explored about 5 percent, meaning 95 percent of the planet's vast seas have never been seen. Mars • Air Pressure on Mars is the same as 30 km above the Earth’s surface • Mars is in the form of ice. • Evidence that water was there at one time • Volcanic history like Earth. • It has the tallest mount of the planets (Olympus Mons) 3x’s size of Mt. Everest. • Orbital Period 687 days • Rotation Period 24. 6 hours Mars • Mars’ red color is due to iron oxide, also known as rust, and has the consistency of talcum powder. Literally, the metallic rocks on Mars are rusting. • No human could survive the low pressure of Mars. If you went to Mars without an appropriate space suit, the oxygen in your blood would literally turn into bubbles, causing immediate death. • Mars has an enormous canyon named Valles Marineris (Mariner Valley) which is an astounding 2,500 miles long and four miles deep. As long as the continental United States, this gigantic canyon was likely formed by the tectonic “cracking” of Mars’ crust and is the longest known crevice in the solar system. • Although it is much colder on Mars than on Earth, the similar tilt of Earth’s and Mars’ axes means they have similar seasons. Like Earth's, Mars’ north and south polar caps shrink in the summer and grow in the winter. In addition, a day on Mars is 24 hours 37 minutes—nearly the same as Earth’s. No other planet shares such similar characteristics with Earth. Outer Planets The Jovian Planets or Gas Giants • Jupiter, Saturn, Uranus & Neptune – – – – Largest Planets: at least 15 times mass of Earth. Only in the outer solar system (5 to 30 AU) No solid surfaces (mostly atmosphere) Low density • Gas Giants: (Jupiter & Saturn) – Thick H/He atmosphere, liquid hydrogen mantle, ice core • Ice Giants: (Uranus & Neptune) – Ice/rock core & mantle, thin H/He atmosphere Jupiter • Largest planet in the Solar System • Has a Great Red Spot from a storm system that is more than 400 years old • Pressure is so great it would crush a spaceship. • Orbit Period 12 years • 9 hours and 54 min=1 Jupiter day (shortest day) Jupiter • Jupiter is the largest planet in our Solar system. • Jupiter has many storms raging on the surface, most notably the big red spot which is the largest hurricane in our Solar System. It's been raging for over three hundred years. • Jupiter has many moons circling around it. Four of these moons are bigger than Pluto. • Jupiter also has a number of rings similar to that of Saturn but much less noticeable. Saturn • 2nd Largest planet in the Solar System • 95 times more massive than earth. • Saturn has the largest rings of any planet, the rings are made of icy particles. • Most moons of any planets ( 47 known) • Orbit Period 12 years • Rotation Period 10 hours Saturn • Many astronomers consider Saturn the most beautiful planet in the solar system because of its stunning rings. In fact, Saturn’s nickname is “the jewel of the solar system. • Saturn is the least dense planet in the solar system, and if there were a body of water large enough to hold Saturn, the planet would float. • Saturn rotates so fast (6,200 miles per hour) that the planet bulges at its equator and its poles are flat. It is the flattest (oblate) planet in the solar system. • Because Saturn spins on a tilt, it has seasons. Summer on Saturn lasts about eight Earth years. Uranus • • • • Discovered in 1781 Uranus appears blue-green in color It’s axis of rotation is tilted 90 degrees Moons are named after Shakespearean plays and formed from other broken moons. • Orbit Period 84 years • Rotation Period 17 hours Uranus • Uranus spins lying on its side (like a barrel), this is perhaps due to a large collision early in its formation. • Uranus’s atmosphere is mostly hydrogen but it also contains large amounts of a gas called methane. Methane absorbs red light and scatters blue light so a blue-green methane haze hides the interior of the planet from view. • It has only been visited one time - It has 27 moons - It can be seen without a telescope or binoculars. Neptune • Discovered in 1846 • The atmosphere appears blue and is marked by large dark blue storms • Neptune has visual belts of clouds • It has a system of 5 rings and at least 13 moons • Orbit Period 165 years • Rotation Period 16 hours Neptune • Neptune suffers the most violent weather in our Solar System. • Storms have been spotted swirling around its surface and freezing winds that blow about ten times faster than hurricanes on Earth make it the windiest planet. • Neptune is a large, water planet with a blue hydrogen-methane atmosphere and faint rings. • Neptune is covered in thin wispy white clouds which stretch out around the planet. Pluto • • • • Discovered 1930 Mystery Planet Farthest from the sun Recently changed from a being considered a planet to a dwarf planet. • Orbit Period 248 years • Rotation Period 6.4 days Is Pluto a Planet? What to consider? • Size? • Shape? • Orbit? • What is it made of? IAU Definition of a Planet In 2006, the International Astronomical Union (IAU) came up with the following definition of a planet: orbits the Sun has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical), has cleared the neighborhood around its orbit, is not a satellite IAU Definition of a Dwarf Planet In 2006, the International Astronomical Union (IAU) came up with the following definition of a dwarf planet: orbits the Sun has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical), has not cleared the neighborhood around its orbit, is not a satellite st 21 Century Solar System If you traveled on a shuttle that’s going 28,000 mph it would take… Mercury 52d • Venus 100d • Mars 210d • Jupiter 1.9yr • • • • • Saturn 3.6yr Uranus 7.3yr Neptune 11.4yr Pluto 15.1yr Dwarf Planets • A dwarf planet is a celestial body massive enough to be spherical, in orbit around the Sun, which are not satellites. The crucial factor dividing a planet from a dwarf planet is that a planet must have succeeded in clearing the area of its orbit from debris and other objects, whereas a dwarf planet has not. Dwarf Planets Mimas Mercury Iapetus Miranda Proteus Tethys Dione Umbriel Europa Moon Pallas Ariel Io Hygeia Triton Titan Ganymede Vesta Oberon Callisto Ceres Rhea Titania Enceladus Pluto Charon Kuiper Belt • Class of icy bodies orbiting beyond Neptune. – Found only in the outer Solar System (>30AU) – Densities of 1.2 to 2 g/cc (mostly ices) • Examples: – – – – Pluto & Eris (icy dwarf planets) Kuiper Belt Objects (30-50AU) Charon, Pluto’s large moon Sedna & Quaor: distant large icy bodies Kuiper Belt The Giant Moons • Moon: any natural satellite orbiting a planet or dwarf planet • Giant Moons: – – – – Earth: The Moon (Luna) Jupiter: Io, Europa, Ganymede, & Callisto Saturn: Titan Neptune: Triton • Many smaller moons, both rocky & icy. • Only Mercury & Venus have no moons. The Giant Moons The Leftovers (small bodies) • Asteroids: – Made of rock & metal (density 2-3 g/cc) – Sizes: Few 100km to large boulders – Most are found in the Main Belt (2.1-3.2 AU) • Meteoroids: – Bits of rock and metal – Sizes: grains of sand to boulders • Comets: – Composite rock & ice “dirty snowballs” – Long tails of gas & dust are swept off them when they pass near the Sun. Asteroids 253 Mathilde 951 Gaspra 243 Ida Comets • A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. Comets are often referred to as "dirty snowballs." They are left over from the formation of stars and planets billions of years ago. Before zipping around the Sun with their characteristic big tails, comets that we see in our solar system start out as big chunks of rock and ice just floating around in something called the Oort Cloud. When the gravity from a large passing body, like a star, becomes strong enough, some large chunks of ice get pulled away from the cloud and head toward the Sun. As that ball of ice gets close enough to the Sun, its heat begins to melt some of the ice that makes up the comet. The melted ice becomes a gaseous tail that extends away from the source of the heat (in this case, the Sun). The tail is pushed out by the Sun's solar wind. Comet P/Halley Comet P/Wilt Comet Meteoroid, Meteorite and Meteor • A meteoroid is a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter (larger objects are usually referred to as asteroids). • A meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor. • A meteoroid that survives falling through the Earth’s atmosphere and colliding with the Earth’s surface is known as a meteorite. Meteor burning up in the atmosphere.