The APL Astronomy Club
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Learning about Astronomy
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Phases -
As the objects in our solar system orbit the Sun, the angle of the Sun light also changes and we can observe this change. The Moon completes it's phases in approximately 29 1/2 days. The phases of Venus can also be seen with the aid of a low power telescope.
New Moon -
The Moon can not be seen since it's position is in between the Earth and the Sun.
Cresent -
The Moon is less than quarter lighten by the Sun, as seen from the Earth and seen near the rising or setting Sun.
Quarter -
When the Moon is half lighted, called first quarter or last quarter and can either be Waxing or Waning.
Gibbous -
The Moon is more than quarter lighten by the Sun, as seen from the Earth. It's called either Waxing or Waning and seen mostly all night.
Full -
Completed lighted by the Sun and lasting for only a single night. It is usually difficult to see details of feature while Full.
Terminator -
The transition line between the Sun lit side of the Moon or Planet and the dark side. The Lunar terminator can change longitudital position due to small whobbles in the Moon's rotation.
Orbit -
New moons occur every 29.5 days at 240,000 miles from Earth. The orbit is increasing, since the Apollo missions to the Moon the orbit has increased ~3ft. The Earth stretchs towards the Moon, this stretching produces a net transfer in the rotation and causes the Moon the accelerate into a higher orbit.
Draconic month -
The time it takes for the Moon to return to a node (about 27.2 days) in the Moon's orbit.
Anomalistic month -
The time it takes (about 27.6 days) for the Moon to travel from apogee to perigee and back again.
MORE INFORMATION WILL BE ADDED SOON!
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Visitors since 11/19/98
This web site was updated on 08/10/99
For additional information contact
Bernie Kluga President, Mark Simpson VP , Carol Bates, Treasurer, Nick Beser, Secretary
APL Amateur Astronomy Club, 443-778-7257 or 240-228-7257
Copyright 1996, 1997, 1998,1999 by JHU/APL Amateur Astronomy Club. All rights reserved.
