The Solar System

Models of the Solar System People have noticed the stars and objects in the sky for 1000’s of years. People have noticed the stars and objects in the sky for 1000’s of years. There are two models of how the universe was thought to be structured There are two models of how the universe was thought to be structured

Geocentric Model Geocentric Model- Earth is stationary while objects in the sky move around it. Began with ancient Greeks. Updated by Egyptian Ptolemy (accepted for almost 1500 years).

Heliocentric Model Heliocentric Model- Earth and other planets revolve around the sun. Heliocentric Model- Earth and other planets revolve around the sun. Developed by Greek astronomer Aristarchus (not accepted at the time). Became accepted model in 1500’s when it was supported by Nicolaus Copernicus and Galileo Galilei.

Components of the Solar System The planets orbit in an elliptical pattern (stretched oval), not a circle. The planets orbit in an elliptical pattern (stretched oval), not a circle. Gravity and inertia combine to keep the planets in orbit around the sun. Gravity and inertia combine to keep the planets in orbit around the sun. Astronomical Unit- (AU) equals the distance from the Earth to the sun(150,000,000 km) Pluto is 40 AU from the sun. The Oort Cloud is 50,000+ AU from the sun (furthest points of the solar system) 1 AU=150,000,000 km

25.2 Earth & Moon System

Earth’s Moon Average distance=384,000km Average distance=384,000km The moon has no atmosphere, which explains the great variation in temperatures. The moon has no atmosphere, which explains the great variation in temperatures. Low=-180 Celsius/-310 F Low=-180 Celsius/-310 F High=130 Celsius/265 F High=130 Celsius/265 F No atmosphere means water cannot exist on the moon (evaporation). No atmosphere means water cannot exist on the moon (evaporation). The moon is a natural satellite. One of 96 moons in our solar system. Earth has 1 1/6 the gravity on Earth

Formation of the Moon “Born” 4-5 billion years ago (4.6 billion). “Born” 4-5 billion years ago (4.6 billion). Formed from impact of Mars-sized “planetesimal” on Earth. Formed from impact of Mars-sized “planetesimal” on Earth. Debris from both objects melted together to form the Moon. Debris from both objects melted together to form the Moon.

Surface Features Lunar Highlands cover most of the moons surface. Lunar Highlands cover most of the moons surface. Mountains up to 7500 meters (25,000 ft) tall. Mountains up to 7500 meters (25,000 ft) tall. Rilles- trench like valleys Rilles- trench like valleys

Surface Features Maria-low flat plains formed by ancient lunar lava flows. They cover 15% of the moons surface. Galileo thought the dark spots resembed seas, hence Maria. Dark spots on moon

Surface Features Craters-round depressions in the surface caused by the impact of high-speed meteroids. Chunks of rock that move through the solar system. Some formed by volcanic action inside the moon. Up to 2500km (1,553 miles) across. These craters are evidence that the moon is geologically dead.

Phases of the Moon The moon does not produce its own light. The moon does not produce its own light. You see the reflected light from the sun. You see the reflected light from the sun. Phases-different shapes of the moon visible from Earth. Phases-different shapes of the moon visible from Earth. These are caused due to the position of moon, sun, and Earth. These are caused due to the position of moon, sun, and Earth. Lunar Month-the time it takes the moon complete a full cycle of phases days The same side of the moon always faces the Earth. Due to making one full rotation (axis) while making one full revolution around Earth. Far side of moon has different features-more craters, few maria, and thick crust.

Phases

Eclipses Eclipses occur when the shadow of one body in space, such as a planet or moon, falls on another. Eclipses occur when the shadow of one body in space, such as a planet or moon, falls on another. Only happen once in a while due to varying ecliptic planes. Only happen once in a while due to varying ecliptic planes. 2 types: 2 types: Solar Solar Lunar Lunar

Tides Tides are the regular rise and fall of the oceans water. Tides are the regular rise and fall of the oceans water. Tides are mainly caused by gravitational pull (differences) between the moon and Earth. Tides are mainly caused by gravitational pull (differences) between the moon and Earth. Depends on distance Depends on distance High and low tides High and low tides Typically 2 of each a day per coast. Typically 2 of each a day per coast. Spring tide is when the change in high/low tide is the greatest. Due to the moon, sun, and Earth being in a straight line. New or full moons Neap tide is when the change in tides is smallest. Moon and sun at right angles. 1 st or 3 rd quarter moon.

The Inner Solar System The four inner planets are all relatively small and dense, and have rocky surfaces. The four inner planets are all relatively small and dense, and have rocky surfaces. The terrestrial planets are planets similar in structure to Earth. The terrestrial planets are planets similar in structure to Earth. Mercury, Venus, Earth, and Mars are called the terrestrial planets. Mercury, Venus, Earth, and Mars are called the terrestrial planets.

Mercury Mercury is the smallest of the terrestrial planets and the closest planet to the sun. Mercury is the smallest of the terrestrial planets and the closest planet to the sun. Mercury is a dense planet with a very large iron core. Mercury is a dense planet with a very large iron core. Mercury is geologically dead. Mercury is geologically dead. There is no mantle convection within the planet and little erosion on its surface. There is no mantle convection within the planet and little erosion on its surface. Temperature can fluctuate from 430 to -170 Celsius. Temperature can fluctuate from 430 to -170 Celsius.

Venus Venus’s thick atmosphere is composed mostly of carbon dioxide, which traps heat and raises the planet’s temperature. Venus’s atmosphere contains droplets of sulfuric acid. Average surface temperature 460 degrees.

Mars Mars is the most Earthlike of all of the planets. The weathering of iron rock on its surface gives the planet a reddish color. This is why Mars is called the “Red Planet.” Mars is the most Earthlike of all of the planets. The weathering of iron rock on its surface gives the planet a reddish color. This is why Mars is called the “Red Planet.” Olympus Mons is the largest volcano in the solar system. Olympus Mons is the largest volcano in the solar system. 3 times larger than Mt. everest. 3 times larger than Mt. everest. Cleveland to D.C wide at its base. Cleveland to D.C wide at its base.

Asteroids Beyond Mars is a region of small, rocky bodies called asteroids that orbit the sun. This region is referred as the asteroid belt Scientist now hypothesize that asteroids are remnants of the early solar system that never came together to form a planet

Outer Planets The outer planets consist of the four gas giants. Pluto, formerly considered a planet, was reclassified as a dwarf planet in Gas giants have many moons, most of which revolve in the same direction that the planets rotate. Gas giants have many moons, most of which revolve in the same direction that the planets rotate. Each of the gas giants is surrounded by rings. A ring is a disk made of many small particles of rock and ice in orbit around a planet. Each of the gas giants is surrounded by rings. A ring is a disk made of many small particles of rock and ice in orbit around a planet. Rings are so close to the planet that gravitational forces are very large, which may have prevented the ring particles from clumping together to form moons. Rings are so close to the planet that gravitational forces are very large, which may have prevented the ring particles from clumping together to form moons.

Jupiter Jupiter is the largest and most massive planet in our solar system. Jupiter is the largest and most massive planet in our solar system. Sometimes storms occur at the boundaries between these brown and white bands. The Great Red Spot is a huge storm that rotates around its own center like a hurricane. It is caught between two bands of winds blowing in opposite directions. Jupiter has 63 moons.

Giants

Saturn Saturn, the second largest planet in the solar system, is best known for its rings. Saturn, the second largest planet in the solar system, is best known for its rings. The rings are made of particles of ice and ice-coated rock. The rings are made of particles of ice and ice-coated rock. These particles are generally between a few micrometers and 10 meters across, with most particles being snowball-sized. These particles are generally between a few micrometers and 10 meters across, with most particles being snowball-sized. The rings are about 274,000 kilometers in diameter, yet are only tens of meters thick. The rings are about 274,000 kilometers in diameter, yet are only tens of meters thick.

Uranus A Tilted Planet The most unusual characteristic of Uranus is that it lies nearly on its side. Uranus rotates in a direction opposite to the direction of its revolution around the sun. Uranus’s rings and moons revolve about the same tilted axis.

Neptune Neptune is so far from the sun that it takes a very long time—165 Earth years—for it to make one revolution. Neptune is so far from the sun that it takes a very long time—165 Earth years—for it to make one revolution. Neptune has about the same composition and is about the same size as Uranus. Neptune has about the same composition and is about the same size as Uranus.

Dwarf Planets In 2006, astronomers established a new classification for certain objects in the solar system that share some, but not all, of the characteristics of a planet. In 2006, astronomers established a new classification for certain objects in the solar system that share some, but not all, of the characteristics of a planet. Pluto, which for many years had been considered the ninth and most distant planet in the solar system, was reclassified as a dwarf planet. Pluto, which for many years had been considered the ninth and most distant planet in the solar system, was reclassified as a dwarf planet.