Contributors in Miscellaneous
Miscellaneous > 
aplanatic system
Astronomy; General astronomy
A system of three lenses which, taken together, correct for spherical aberration, chromatic aberration, and coma.
apocenter
Astronomy; General astronomy
The point in the orbit of one component of a binary system which is farthest from the center of mass of the system.
apogalacticon
Astronomy; General astronomy
The point in a star's orbit farthest from the Galactic center.
apogee
Astronomy; General astronomy
The point at which a body in orbit around the Earth reaches its farthest distance from the Earth.
apparent magnitude
Astronomy; General astronomy
1) A measure of how bright a star looks in the sky. The brighter the star, the smaller the apparent magnitude. A star that is one magnitude brighter than another (e.g., +1 versus ...
apsidal motion
Astronomy; General astronomy
Rotation of the line of apsides in the plane of the orbit; (in a binary) precession of the line of apsides due to mutual tidal distortion.
