Select the first letter of the word from the list above to jump to appropriate section of the glossary.
If the term you are looking for starts with a digit or symbol, choose the '#' link.
- A -
- absolute magnitude
The apparent magnitude of brightness a celestial body would have if it were
to be viewed from a distance of 10 parsecs. This brightness is calculated on a logarithmic scale.
The reflecting ability of a planet or other non-luminous body.
The Anasazi were cliff-dwelling Indians of the American Southwest. Their name means "ancient enemy",
or "ancient people who are not us", inflection depending, in the Navaho, who otherwise don't seem to
remember anything about them. From the celestial perspective, however, they did leave behind some intriguingly-aligned
artifacts. They resided in the region for about 1200 years, until somewhat before 1300 C.E. The height of their
culture began in 700 C.E., lasting until their sudden departure in the 13th century.
- Andromeda Galaxy
Largest galaxy in the Local Group, a small
collection of galaxies which includes our own Milky Way. It is a spiral galaxy
about 2.25 million light years away. It is viewable in the constellation of
Andromeda, near Pisces. Also known as the galaxy M31.
The point in its orbit around the Sun at which an object is
furthest from the Sun.
The point in its orbit around the Earth at which an object is furthest from the Earth.
- apparent magnitude
The apparent visual brightness of a celestial body from the viewpoint of Earth (or from wherever one
happens to be...). This brightness is calculated on a logarithmic scale.
The eleventh constellation in the Greek-based zodiac.
Aquarius the Water Bearer.
A small constellation south of Cygnus, its name refers to the Eagle. It is recorded
as early as 1200 BCE as an eagle in a Mesopotamian stone relief. Altair, whose name means eagle in Arabic, is its
The study of old relics and their alignments, in order to determine how the ancients may have represented celestial
events and objects.
First constellation in the Zodiac since
at least the time of the Greeks, it is also considered to be the first sign of the Zodiac. Named Aries the Ram.
In the time of the ancient Greeks, this constellation heralded the position of the Sun at the vernal equinox.
One of the thousands of small solid objects in orbit around the Sun, mostly located between Mars
and Jupiter. Also known as a "minor planet" or "planetoid".
- astronomical unit
The average distance between the Earth and the Sun, approximately 93 million miles. A useful unit to measure distances
within the solar system.
The study of the stars and other celestial objects and events.
Horizontal arc from the north point of the horizon measured clockwise to the object's position projected on the
Created by Searles and Deborah O'Dubhain,
Copyright 1996 by The Summerlands, Inc., All rights reserved
Page last updated: 08/30/98
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