The Solar System

The Sun The Sun contains more than 99.8% of the total mass of the Solar System Chemical composition: Hydrogen 92.1% Helium 7.8% A yellow star in the prime of its life

There are 8 planets in the solar system –In 2006, Pluto was disqualified as a normal planet They are common in: -Orbiting the Sun in the same direction -Orbits in almost the same plane -Nearly circular orbits

Two Categories of Planets 1.Terrestrial planets: the four inner planets resembling the Earth 2. Gas Giants: the four outer planets resembling Jupiter

The two types of planets Differ in Physical properties –Diameter: small versus large –Mass: small versus large –Density: high versus low –State: solid versus gaseous

The Terrestrial Planets Small in size Small in mass High density Composed of heavy elements: Fe, Ni, Si Solid Mercury VenusEarth Mars

Mercury Size and comp. – small, solid(iron core – weak magnetic field), and rocky Atmosphere – none Temperature - 425°C– (-170°) C (740° F – (-273)° F) Surface Features – craters and cliffs (moon like) Space Probes – Mariner 10, Messenger

Mercury (cont.) MASS – x 10^23 kg Rotation – 59 Earth days Revolution –.24 Earth years

Why are its conditions so extreme?

Venus Size and comp. – small, solid, and rocky Atmosphere – dense CO₂ and drops of sulfuric acid (greenhouse effect) Temperature - 450°C– 475°C (842° F – 887° F) Surface Features – craters, cracks, and volcanoes Space Probes – Mariner 2, Venera 7, Magellan Retrograde rotation

MASS – x 10^24 kg rotation– retrograde 243 Earth days Revolution -.62 Earth years

Greenhouse effect – trapped heat under dense cloud cover AAyc AAyc

Earth Size and comp. – small, solid, and rocky Atmosphere – Nitrogen, Oxygen, and others Temperature – H₂O in solid, liquid, and gas Surface Features – oceans, landmasses, ice caps Moons – 1

Earth cont. MASS – x 10^24 kg Rotation – 1 earth day (24 hours) Revolution – 1 earth year (365 days)

Mars Size and comp. – small, solid, and rocky Atmosphere – thin CO₂, Nitrogen, and Argon Temperature – (-125)°C – 35°C (-193)°F – 95°F Surface Features- red-yellow rocks. Rifts, craters, polar ice caps Moons – 2 (Phobos and Deimos) Space Probes – Mariner 9, Viking 1 and 2, Spirit, Opportunity, and Curiosity

Mars MASS – 6.42 x 10^23 kg Rotation – 1.03 earth days Revolution – 1.9 earth years Dormant volcanoes and craters Largest volcano – Olympus Mons

Why is Mars red? 7uY

The Gas Giants Large in size Large in mass Low density Composed of light elements: H, He Gaseous Jupiter NeptuneUranus Saturn

Jupiter Size and Composition – large and gaseous Atmosphere – Hydrogen, Helium, Ammonia, Methane and H₂O Below the atmosphere – ocean of H and He, core of rock Notable features – Great Red Spot, faint rings Moons – at least 61 (Io, Europa, Ganymede, and Callisto) Space Probes – Voyager 1 and 2, Galileo, Cassini

Jupiter MASS – x 10^27 kg Rotation -.41 earth days Revolution – 12 earth years

Why does Jupiter have so many moons?

Saturn Size and Composition – large and gaseous Atmosphere – Hydrogen, Helium, Ammonia, Methane and H₂O Below the atmosphere – ocean of H and He, core of rock Notable features – 100s of rings, lowest density Moons – 47 - Titan Space Probes – Voyager 1 and 2

Saturn MASS x 10^26 kg Rotation -.43 earth days Revolution – 29 earth years Rings composed of rock and ice (own orbits around Saturn)

Uranus Size and Composition – large and gaseous Atmosphere – Hydrogen, Helium, Methane Below the atmosphere – H₂O, Methane, Ammonia, rocky core? Notable features – thin, dark rings, blue- green in color, sideways rotation (90° tilt) Moons – 27 - Titania Space Probes – Voyager 1 and 2

Uranus MASS – 8.68 x 10^25 kg Rotation -.72 earth days Revolution – 84 earth years

Neptune Size and Composition – large and gaseous Atmosphere – Hydrogen, Helium, Methane Below the atmosphere – H₂O, Methane, Ammonia, rocky core? Notable features – Great Dark Spot, deep blue Moons – at least 13 (Triton!) Space Probes – Voyager 1 and 2

Neptune x 10^26 kg (8)Rotation -.67 earth days – 16.1 hours Revolution – 165 earth years

Asteroids Small and rocky objects orbiting the Sun Asteroids belt: most asteroids orbit the Sun between Mars and Jupiter There are thousands of kilometer-sized asteroids and millions of meter-sized asteroids The largest asteroid, Ceres, is about 900 km They are debris in the inner solar system Eros33 km long and 13 km wide NEAR Shoemaker spacecraft landed on it in March 2000

Trans-Neptune Objects Trans-Neptunian objects: small and icy objects orbiting the Sun beyond the orbit of Neptune in what is known as the Kuiperbelt >900 such objects have been found. Pluto is one of this category. They are debris in the outer solar system

Comets Comets are chunks of dirty ice They have highly elongated orbit. When close to the Sun, solar radiation vaporizes some of the ice material, forming a bluish tail of gas and a white tail of dust both tails can extend for tens of millions of kilometers