The Solar SystemThe Solar System

The The SolarSolar System System• According to Aug 24, 06

Resolution the Solar System is composed of:– Eight planets with their moons

– Three dwarf planets with their moons

– Small Solar System bodies

• The major features of the Solar System are:– The Sun– Terrestrial (inner) Planets– Inner Belt of Asteroids– Gas Giant (outer) Planets– Outer Belt of Small Bodies (Kuiper Belt)

Heliocentric Heliocentric SystemSystem• Nicolaus Copernicus

developed a sun-centered system called a heliocentric system.

• The Earth and the other planets revolve around the sun.

• Galileo was the first scientist to use a telescope to look at objects in the sky, which supported Copernicus’s theory.

• Johannes Kepler, a German mathematician, discovered that the orbit of each planet is an ellipse.

• Isaac Newton concluded that two factors- inertia and gravity - combine to keep the planets in orbit.

• The Sun (Sol) contains 99.8% of the Solar System’s known mass.

The The SunSun

• The Sun dominates the Solar System gravitationally.

• The Sun consists of 70% hydrogen, 28% helium, and 2% metals. It’s energy is sustained

by nuclear fusion reactions, converting hydrogen into helium and energy.

• The Sun releases enormous amounts of energy. Most is sent into space as radiation, including visible light.

• The Sun radiates a plasma known as solar wind.

• A “planet” is a celestial body that:– is in orbit around the Sun;– has sufficient mass for self-

gravity so it assumes a nearly round shape; and

– has cleared the neighborhood around its orbit.

Final International Astronomical Union Resolution, Aug 24 06

Definition of PlanetDefinition of Planet

• The four inner or terrestrial planets are dense, rocky, have few or no moons, and lack ring systems.

The The Inner Inner PlanetsPlanets

• Closest planet to the Sun and least massive of the planets. It has a very thin atmosphere and has no natural satellite.

MercuryMercury

• It’s atmosphere is 90 times as dense as Earth’s and composed of carbon dioxide. It has no natural satellite and is the hottest planet.

VenusVenus

• Largest and densest of the inner planets. Only inner planet with evidence of geological activity and liquid hydrosphere. Has one satellite, the Moon.

EarthEarth

• Less massive than Earth or Venus. Has a carbon dioxide atmosphere. It’s surface contains volcanoes and rift valleys. Has two satellites: Deimos and Phobos.

MarsMars

• Made of mostly small solar system bodies of rocky minerals. Occupies the orbit between Mars and Jupiter.

The The Inner Inner BeltBelt

• Small solar system bodies found mainly in the Asteroid Belt with elliptical orbits between Mars and Jupiter.

AsteroidsAsteroids

• Smaller than asteroids. A meteor is a meteoroid that has entered the Earth’s atmosphere. A meteor that survives impact is called a meteorite. Meteors can produce impact craters.

MeteoroidMeteoroid

• Largest body in the asteroid belt and only known dwarf planet in this region. It is spherical and contains a third of the belt’s total mass.

CeresCeres

• The four outer planets or gas giants together make up 99% of the mass known to orbit the Sun.

The The Outer Outer PlanetsPlanets

• All four of the gas giants have orbital debris rings. Only Saturn’s rings are observable from Earth.

The The Outer Outer PlanetsPlanets

• Is at 318 Earth masses. Composed of hydrogen and helium. Has large cloud bands and the Great Red Spot. It has 63 satellites, the largest is Ganymede.

JupiterJupiter

• Has an extensive ring system. Also composed of hydrogen and helium. Has 56 satellites and largely made of ice. Titan is larger than Mercury.

SaturnSaturn

• The lightest of the outer planets. It orbits the Sun on its side (axis is 97o to the ecliptic). Radiates very little heat. Has 27 satellites.

UranusUranus

• Smaller than Uranus but is denser and more massive. Radiates more heat than Uranus. Has 13 moons; the largest Triton revolves clockwise around Neptune.

NeptuneNeptune

• A great ring of debris, similar to the asteroid belt. Composed mainly of icy small solar system bodies. Often called the outer solar system or “trans-Neptunian region.”

The Kuiper BeltThe Kuiper Belt

• The Kuiper Belt is possibly the place of origin for short term comets, such as Halley’s comet. Some objects are affected by Neptune’s orbit.

• Small solar system bodies composed largely of ice. When a comet approaches the Sun the surface boils away creating a coma (tail of gas and dust).

CometsComets

• The largest known object in Kuiper Belt. Reclassified as a dwarf planet. Charon orbits Pluto more like a binary system. Nix and Hydra orbit Pluto and Charon.

PlutoPluto

• Largest known scattered disk object (overlaps the Kuiper Belt). 5% larger than Pluto. The largest known dwarf planet. Has one moon, Dysnomia.

ErisEris

The Solar SystemThe Solar System