What is a planet?

  • Orbits the sun

  • Has a spherical shape

  • Dosen’t share the space of its orbit with other objects of significant size, other than moons.

What is a Dwarf planet?

  • Orbits the sun

  • Has a rigid, almost spherical shape

  • Can share their orbits with other bodies

  • Are not satellites(moons)

What is a moon?

  • is a satellite

Small solar system body(SSSB)

  • Anything else in the solar system that isn’t a dwarf planet, or moon.

Terrestrial

  • similar in size and density to earth

  • Mercury, Mars, Venus, Earth

Jovian

  • Lower densities; are mostly made up of light elements, gases, and ices.

  • Jupiter, Saturn, Uranus, Neptune

  • “Gas Giants”

Inferior planets

  • closer to the sun than earth

  • mercury, venus

Superior planets

  • farther from the sun than the earth

  • Retrograde motion

Astronomical Unit(au)

A unit of length effectively euqals the average, or mean, distance between Earth and the Sun

Mercury

  • 0.39 au from the sun

  • Covered with craters & maria

  • smallest planet

Venus

  • 0.72 from the sun

  • opaque atmosphere

  • closest in size to earth

  • hot, dense atmosphere

  • extremely hot on the surface

Earth

  • 1 au from the sun

Mars

  • 1.52 au from the sun

  • reddish color

  • thin atmosphere, mostly carbon dioxide

  • two tiny moons

  • Has the longest volcano in the solar system(olympus Mons)

The gas giants

  • They emit up to 70% more energy than they receive from the sun. Uranus emits almost no excess energy.

Jupiter

  • 5.20 au from the sun

  • largest and most massive

  • noticeable equatorial bulge

  • Clouds and storms in its atmosphere

  • many moons

Saturn

  • 9.6 au from the sun

  • noticeable equatorial bulge

  • less dense than water

  • ring system

  • largest moon, titan, has its own atmosphere

Uranus

  • 19.2 au from the sun

  • discovered in 1781 by Sir William Herscel

  • third largest, but fourth in mass

  • Appears to be lying on its side

  • Strange madnectic field

  • five large moons, many smaller ones

Neptune

  • 30.1 au from the sun

  • discovered in 1846

  • resembles Uranus in a vairety of ways

  • two large moons