Astronomy and related astronomical terms

The movement of a celestial body against the background of distant stars.

Time determined by the actual position of the sun in the sky which corresponds to time on most sundials.

A zodiacal constellation a little south of the celestial equator near Pegasus.

Aquarius is represented as a man pouring water from a jar. The sun passes through Aquarius from late February to early March.

Units for measuring small angles, used in astronomy.

An arc minute (symbol ') is one-sixtieth of a degree, and an arc second (symbol ") is one-sixtieth of an arc minute. Small distances in the sky, as between two close stars or the apparent width of a planet's disk, are expressed in minutes and seconds of arc.

Zodiacal constellation in the northern hemisphere between Pisces and Taurus, near Auriga, represented as the legendary ram whose golden fleece was sought by Jason and the Argonauts.

Its most distinctive feature is a curve of three stars of decreasing brightness. The brightest of these is Hamal or Alpha Arietis, 65 light-years from Earth.

1. A group of stars not belonging to any of the 88 recognized constellations.
2. A noticeable pattern of stars that makes up part of one or more constellations; not a constellation itself.

A soft layer of the upper mantle of the earth under the lithosphere.

The asthenosphere is a region in the upper mantle of the earth's interior, characterized by low-density, semiplastic (or partially molten) rock material chemically similar to the overlying lithosphere.

The upper part of the asthenosphere is believed to be the zone upon which the great rigid and brittle lithospheric plates of the earth's crust move around.

The asthenosphere is generally located between 45–155 miles (72–250 km) beneath the earth's surface, though under the oceans it is usually much nearer the surface and at mid-ocean ridges rises to within a few miles or kilometers of the ocean floor.

A reference to or pertaining to the stars.

The science concerning life or the potential for life on other planets.

1. A minor planet, smaller than any major planet in our solar system and not one of the satellites (moons) of a major planet; such as, the Earth or Jupiter.
2. A rocky object, smaller than a planet, that orbits the sun.

1. A type of star map developed by the ancient Greeks consisting of a horizon circle graduated in degrees, or azimuths, from the north point, and star altitude circles.

There is also a sighting bar to measure the altitudes of stars and other celestial bodies.

2. An ancient navigational instrument, forerunner of the sextant.

Astrolabes usually consisted of a flat disk with a sighting rod that could be pivoted to point at the sun or bright stars.

From the altitude of the sun or star above the horizon, the local time could be estimated.

1. The study of the positions and the movements of the stars, planets, and other heavenly bodies in the belief that these affect people's lives.
2. A nonscientific system that attempts to explain or predict human actions and events by the position of celestial objects.
3. The study of the relative positions of the sun, moon, and planets in order to estimate their supposed influences on human events.
4. A pseudoscience that claims to be able to predict one's destiny according to the position of celestial bodies when one was born and which has been widely discredited by science.

Despite modern science's lack of regard for astrology, the work of the early astrologers was of great value in the development of astronomy, principally because of their accurate obsersvations and records of star positions.

The problem is that the conclusions that those astrologers drew from their observations depended far more on supernatural beliefs than on scientific principles; for example, from calculations known only to themselves, they plotted charts called horoscopes, from which they attempted to predict and influence future events.

Purposes of astrology

Astrologers cast a horoscope by first determining for the given moment and locality the boundaries of the twelve places and the longitudes and latitudes of the seven planets.

They read this horoscope by examining the intricate geometric interrelationships of the signs and their parts and of the planets of varying computed strengths with the places and each other and by associating with each element in the horoscope its list of sublunary correspondences.

Any horoscopic diagram, of course, will yield a vast number of predictions, including many that are contradictory or extravagant.

So astrologers must rely on their knowledge of the client’s social, ethnic, and economic background and on their own experiences to guide them in avoiding errors and attaining credibility.

Despite criticisms, astrology continues to attract people from all walks of life; from the casual followers who read their horoscopes in the daily newspaper to those who have their star charts drafted by professional astrologers.

In short, even though it is regarded by many as devoid of intellectual value, astrology in its modern and historical forms remains of great interest to scholars and a wide spectrum of the general public.

1. Normally a scientist who specializes in the study of celestial bodies, including their sizes, features, compositions, motions, relative positions, etc.
2. Someone who has a knowledge of the laws of the heavenly orbs, or the principles by which their motions are regulated, with their various phenomena.

Fields of study include: astrophysics, celestial mechanics, and cosmology.

Astronomy is considered by some to be the oldest recorded science. This concept is based on records from ancient Babylonia, China, Egypt, and Mexico.

The first true astronomers are said to be the Greeks, who deduced the earth to be a sphere and attempted to measure its size. A summary of Greek astronomy came to us from Ptolemy of Alexandria's Almagest.

The Arabs developed the astrolabe and produced good star catalogs while in 1543, the Polish astronomer Copernicus demonstrated that the sun, not the earth, is the center of our planetary system

The Italian scientist Galileo was the first to use a telescope for astronomical study, 1609-1610.

The British astronomer William Herschel's suggestions on the shape of our galaxy were verified in 1923 by the U.S. astronomer Edwin Hubble's telescope at the Mount Wilson Observatory in California.

Recent extension of the powers of astronomy to explore the universe has been made possible in the use of rockets, satellites, space stations, and space probes, while the launching of the Hubble Space Telescope into permanent orbit in 1990 has made it possible for the detection of celestial phenomena seven times more distant than by any earth-based telescope.

1. The average distance from the earth to the sun, which equals 149,597,870 kilometers or 92,955,800 miles.

For simplicity, an AU is usually rounded off to 93,000,000 miles or 149,637,000 kilometers.

2. An astronomical unit is used to describe planetary distances.

Light travels this distance in approximately 8.3 minutes.