The third planet from the Sun, and the planet that you are living
The condition in which the Sun or the Moon is blocked from our
view, either partially or fully. Also see "annular
eclipse" and "total eclipse". In a "solar eclipse" the Moon passes in front of the Sun, and in a "lunar eclipse" the Earth's shadow passes between the Sun and the Moon, blocking the Moon from Earth's view.
The apparent path of the Sun across the sky as it travels across
the constellations from Earth's perspective.
galaxy: An ellipsoidally shaped galaxy that does not contain
much interstellar matter. They appear as small "wads"
or orbs in a telescope.
angular distance between two celestial bodies as seen from Earth.
gas and dust that glows as a result of atoms being excited by
high energy radiation from hot, massive, young stars.
gap or "division" located in Saturn's A ring first
named after J. Encke (possibly the discoverer).
table giving the coordinates of a celestial body at a number
of specific times during a given period.
instant in time that is arbitrarily selected as a point of reference.
Commonly used as the reference point in time when creating stellar
maps. Ex. Epoch 2000.0
A moon of Jupiter's discovered by Galileo in 1610. There is
strong evidence that underneath its surface there may exist
The part of a visual telescope that is used to provide different
magnifications of the image the viewer is seeing. Usually measured
in millimeters. The lower the number of millimeters the higher
The distance between the lens of an eyepiece and the point behind
the eyepiece where all the light rays of the exit pupil come
to a focus and the image is formed. It is the distance from
the eyepiece at which the eye can be held and correctly see
the image produced by the eyepiece.