The Solar 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 System 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 Sun

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 Definition of Planet

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

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

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. Venus

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

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. Mars

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

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

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. Meteoroid

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. Ceres

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

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

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. Jupiter

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

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

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

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 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). Comets

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. Pluto

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

The Solar System