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)