Astronomy: Solar System Vocabulary

apsis

either of two points on the orbit of a planet or satellite that are nearest to or furthest from the body around which it moves

apogee

farthest or highest point; culmination; zenith

accretion

growth in size or increase in amount

perigee

point in an orbit that is closest to the earth

irregular satellites

satellites having orbits of LARGE eccentricity, high inclination or both Captured from elsewhere

Regular Satellites

satellites having orbits of low eccentricity near the equatorial plane of their planet formed in the "sub-nebula" surrounding the planet

terminator

the dividing line between the light and dark part of a planetary body.

Perihelion

the point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.

Aphelion

the point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun.

angular momentum

the quantity of rotation of a body, which is the product of its moment of inertia and its angular velocity.

Magneteosphere

the region surrounding the Earth or another astronomical body in which its magnetic field is the predominant effective magnetic field

Hohmann Transfer

1. transfer between two coplanar circular orbits 2. requires two engine burns 3. lowest energy transfer if R'/R<12 4. assume impulsive thrust

comet

A ball of frozen dust and rock that orbits the sun and has a tail that glows

meteor

A streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere.

Albedo

Ability of a surface to reflect light

Jovian Planets

Jupiter, Saturn, Uranus, Neptune

terrestrial planets

Mercury, Venus, Earth, Mars

Planetesimal

One of the small asteroid-like bodies that formed the building blocks of the planets.

Occulation

The hiding of a celestial body when another celestial body passes in front of it.

umbra

The darkest part of a shadow

Penumbra

The part of a shadow surrounding the darkest part

dwarf planet

a celestial body resembling a small planet but lacking certain technical criteria that are required for it to be classed as such.

Protoplanets

a large body of matter in orbit around the sun or a star and thought to be developing into a planet.

Meteroite

a meteor that survives its passage through the earth's atmosphere such that part of it strikes the ground.

asteroid

any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)