انجمن علمی نجوم و نقشه برداری تفت

The angle between the plane of the celestial meridian and the plane of an initial meridian that is arbitrarily chosen. Astronomical longitude results directly from observations on celestial bodies, uncorrected for deflection of the vertical

The layer of gas which surrounds a celestial body. Stars, many planets, and a few satellites have atmospheres, and vary in their composition

The point at which the Sun crosses the celestial equator moving southward. It occurs around September 22 and marks the first day of autumn in the Northern Hemisphere

A spacecraft en route to Saturn, scheduled to arrive in 2004. Named after the astronomer who discovered the dark gap between the two main rings of Saturn

Any object beyond the Earth and visible in the sky

The imaginary line dividing the northern and southern hemispheres of the celestial sphere. Equivalent to the equator on the Earth

The two poles (north and south) of the celestial sphere. The stars rotate around the stationary poles

The imaginary sphere on which the stars and deep sky objects lie. Although an inaccurate representation of the three dimensional universe, the celestial sphere is a useful way to represent the night sky

Time counted from 0 hours at midnight at 0 degrees longitude (Greenwich). Central Standard Time (Wisconsin) is UTC minus 6 hours