SOLAR SYSTEM BEFORE WE GO ON… Cosmologist – scientist who studies how the world was formed. In the beginning… • Ptolemy (Greek) proposed a theory that planets orbited the earth (geocentric). • Copernicus (Polish) changed the theory to planets orbiting the sun (heliocentric). • Kepler proved that the planets orbited in ellipses counterclockwise and not complete circles. • Newton explained planet motion as a result of inertia and gravity. Gravity keeps them close to the sun and inertia keeps them moving. Rotation versus Revolution • Rotation – the time it takes a planet to make a complete circle on its own axis. (Equal to one day) • Revolution – the time it takes a planet to circle the sun completely. (equal to one year) Shoulder Partner • Come up with a rhyme or quick saying to help you remember the difference between rotation and revolution. Did you know…? • The four inner planets are also referred to as rocky or terrestrial planets. MERCURY • Mercury – rocky, almost no atmosphere, sun is 9 times closer, moves around the sun faster than all other planets. Year = 88 days. No weather. All volcanoes now dormant. Day = 175 Earth days. Temp. range 427°C to –170°C. Day longer than its year. Face partner • Why couldn’t we survive on Mercury? Give at least 3 reasons. VENUS • Venus – Earth’s sister planet. Atmosphere is mostly CO2 and thick cloud cover. Windy 350 km/hr. Stormy. Deep canyons, vast plains. Mountains as tall as those on Earth. Huge channel some believe was once an ocean. Retrograde motion (sun rises in west…) Day = 243 earth days. Year = 224 earth days. Scientists believe ocean dried up due to greenhouse effect. Table Talk… • Why do you think they call Venus the sister planet to Earth? EARTH • A year on Earth is exactly 365.26 days. This is the reason for a leap year every four years. Seasons are caused by the tilt of the Earth on its own axis. When the N hemisphere is tilted toward the sun it is summer for us; when the S hemisphere is tilted toward the sun it is their summer. During an equinox (spring/fall) neither is tilted toward the sun. Shoulder partner • Where do you think our moon came from? What theories are there on its origin? MARS • Mars – Red in color, has two tiny moons Phobos and Deimos meaning fear and terror. Rocks found in Antarctica had live bacteria comparable to our bacteria. Has an enormous dormant volcano named Olympus Mons (3 times size of Mt. Everest). Windstorms that are up to 200 km/hr. Dust from these storms cause sky to look pink. UHHH…HELLO? ASTEROID BELT • Located between Mars and Jupiter. • Meteoroid – chunk of metal/stone that orbits the sun. • Meteor – streak of light produced by a burning meteoroid. • Meteorite – a meteor that strikes the Earth’s surface. Meteors… What would happen… • If the Earth crossed the asteroid belt? Is there any evidence that this has occurred in the past? NOW FOR THE OUTER PLANETS! JUPITER • Jupiter – day = less than 10 hours. Composed of hydrogen and helium. Belts – low, dark colored clouds. Zones – high, lightly colored clouds. Red Spot is a hurricane-like storm that has been rotating for more than 300 years. Has 4 main moons.(Io, Callista, Europa, and Ganymede) SATURN • Saturn – made mostly of hydrogen and helium. Has ammonia ice near top of its clouds. Has 18 known moons, giant one named Titan. May have methane (gas, liquid, and solid “ice”) similar to water on earth. URANUS • Uranus – discovered in 1781. Blue in color. Has 18 moons, 2 big ones named Oberon and Titania. Has 10 rings. Because it is tilted on its side; each pole spends 42 Earth years in darkness and 42 years in sunlight. It has a constant temperature of –215°C because of its atmosphere. NEPTUNE • Neptune – discovered in 1846. Slightly smaller than Uranus but same blue color. Considered the twin giants. Has clouds and belts like other gas giants. Once had a great dark spot like Jupiter but it disappeared in 1994. Has 8 moons, largest is Triton. Has nitrogen geysers. Also, has a retrograde motion. PLUTO • Pluto – discovered in 1930. Named after the Roman god for the underworld. Pluto is a little more than moon-sized and may be an escaped moon of Neptune. It has a moon named Charon that is roughly the same size as Pluto. So, the question remains: What should Pluto be classified as? PLANET X • Planet X – Scientists assume there is another planet; a big planet on the other side of Pluto. They think it is this planet or an object massive enough to pull Uranus on its side. May be the sister star to the sun because most stars are in pairs or threes, rarely are they single. Does the government think there is life outside the Earth? This picture is floating around in outer space on a satellite to let anyone looking for life find us. WHEW! WE’RE FINALLY DONE.