The Solar System

Solar system – consists of the sun and, planets, and other objects that orbit the sun Nebular model – states that the sun and planets all formed at the same time from a cloud of gas and dust called nebula – Gravity forced this material together – Collision and pressure caused it to heat up – The sun and planets formed

Formation of planets These were formed at the outer materials – Early stages of formation are called planetesimals – These collided to form protoplanets – These two bodies collided to make the planets

Formation of Earth Gravity pulled heavy materials together Lots of pressure and heat made it stick together As elements were formed they differentiated into the three layers – core, mantle, and crust The least dense elements formed the atmosphere (originally hydrogen and helium) – H and He went into space – Volcanic gases were released (called outgassing) – As volcanic eruptions slowed, rain fell creating oceans – Producers formed and oxygen collected

Solar System models Geocentric model – Earth is the center of the solar system (Aristotle) Ptolemy model – The planets move in circles (epicycles) as they go around Earth Heliocentric models (Copernicus) – The sun is the center of the solar system and planets move at different speeds

Geocentric model

Ptolemy model

Heliocentric models (Copernicus)

Kepler’s Law First law – Law of ellipses – Planets move in ellipses not circles – Orbits vary in shape – As they become elongated they have greater eccentricity

Law of Ellipses - Eccentricity

Kepler’s Law Second law – Law of equal areas – Planets move faster when they are closest to the sun – However, the area it covers between it and the sun is always the same

Law of Equal Area

Third law – Law of periods – Orbit period – time needed for a body to make 1 orbit – Because a planets orbit is consistent, a formula can be used to determine its distance from the sun

Newton’s Law of planetary motion Objects stay in motion at the same speed unless acted on by an outside force (called inertia) The gravity of the sun is the force that keeps the planets from moving in a straight line

The farther away from sun, the less gravity there is so the orbits are larger and curved more gently

The inner planets Include – Mercury, Venus, Earth, Mars Called terrestrial Composed of solid rock and have metallic cores Have many impact craters due to collisions stem

Mercury Size: 2.6 times smaller than Earth Temperature: Great range due to no atmosphere Atmosphere: None No moons or rings Extra information Rotates: 59 days Revolves: 88 days Gravity :.39 times Earth (100 lbs = 39 lb)

Venus Size: Slightly smaller than Earth (1.1X) Temperature: Hottest planet Atmosphere : thick clouds of carbon dioxide and lots of sulfuric acid (greenhouse effect) No moons or rings Extra Information Rotates: 243 days but opposite than all other planets Revolves: 225 days Gravity :.91 that of Earth (only 91 lbs here) Brightest object in the night sky

Earth Size: km Temperature: Average 59 F Rotates: 24 hours Revolves: 365 days Gravity: 9.8 m/s 2 Atmosphere: oxygen, carbon dioxide, and nitrogen Water in all three states Has life 1 moon and no rings

Mars Size: 1.9 times smaller Temperature: below freezing - 74 F Atmosphere: mostly carbon dioxide 2 moons, no rings Has seasons like Earth due to tilt Surface: – Red due to all of the rust – Volcanoes (Largest is Olympus Mons over 100x larger than yellowstone) – Canyons (longest Valles Marineris same as width of US) – Use to have liquid water Extra information Rotates: 24 hours 37 minutes Revolves: 687 days Gravity:.38 times Earth (38 lbs)

Outer planets Include: Jupiter, Saturn, Uranus, and Neptune Separated from inner by asteroid belt Called Jovian planets or gas giants Massive atmospheres – never lost their original atmospheres Less dense than terrestrial planets Mostly hydrogen and helium All have rings of dust and ice

Jupiter (Larger) Size: Largest planet (11x) Temperature: -238 F Surface: appear to be banded with lots of orange and white Atmosphere: swirling clouds of mostly H and He (like sun) Storms: Like the Great red spot (2x Earth) – Winds over 700mph, thunder, lightning Greatest number of moons Has rings Extra Information: Rotates: 10 hours Revolves: 12 years Gravity: 2.6 times Earth (260 lbs)

Saturn (larger) Size: 9.4 times larger Temperature: Average -292 F Surface: Bands of orange and other colors Atmosphere: hydrogen and helium Many moons (largest is Titan) Over 1000 rings – of dust and ice Density is so little it would float on water Extra information: Rotation: 10.5 hours Revolves: 29.5 years Gravity: 1.01 times greater (107 lbs)

Uranus Size: 4 times greater Temperature: -347 F Atmosphere: thick layer of methane so it appears blue-green Many moons and rings Almost sideways (one side sun and one dark) Extra information: Rotates: 17 hours Revolves: 84 years Gravity:.9 times Earth (90 lbs)

Neptune (Larger) Size: 3.9 times larger Temperature: -365 F Atmosphere: hydrogen, helium, methane Weather: Great Dark Spot – size of earth with Strongest winds in Solar System of 1000 km/h Moons and rings Extra information: Rotates: 16 hours Revolves: 164 years Gravity: 1.15 (115 lbs)

Pluto Size: 5.6 times smaller Surface: frozen methane, rock and ice Atmosphere: thin layer of nitrogen Temperature: -235 C 1 moon (Charion) and no rings Sometimes it is the 8 th planet Extra information: Rotates: 6 days and 9 hours Revolves: 248 years Gravity:.01 times (1 lbs)

Beyond Pluto Kuiper belt – region beyond Pluto with objects made of ice – Quaoar ( half size of pluto) Sedna – 3x farther from Earth than Pluto Exoplanets – planets that circle other stars other than out sun – Only detected by the gravity tugs on star they orbit – All known are larger than Uranus