Astronomy & telescopes glossary - M

Astronomy & Telescopes Glossary - M

Magnification - Magnification is determined by dividing the focal length of a telescope by the focal length of the eyepiece.

Magnitude - A measure of brightness of celestial objects. Smaller values represent brighter objects than larger values. The magnitude scale is logarithmic whereby a difference in magnitude of 5 is a 100X increase in brightness.

Maksutov-Cassegrain telescope (MCT) - A type of compound telescope that uses both lenses and mirrors. Also called a Mak-Cass telescope.

Meridian - The imaginary north-south line in the sky that passes through the observer's zenith overhead.

Messier objects - The list of 110 deep-sky objects first cataloged by Messier.

Meteor - The bright flash of light when a meteor burns up in the earth's atmosphere, also called a shooting star. When a piece of this material which reaches the ground, it is called a meteorite. It is sometimes called a shooting star.

Meteor shower - Where lots of meteors fall through the atmosphere in a relatively short time. Meteor showers occur when the Earth passes through a comet's orbit and occur at predictable dates each year.

Milky Way galaxy - The galaxy that our Solar System resides in. Most of the stars that can be seen through amateur telescopes are in the Milky Way Galaxy. The Milky Way looks like a faint band of light across the night sky.

Minor planet - Another name for an asteroid.

Mirror - A highly polished surface made to reflect light in a telescope. Primary telescope mirrors are usually made spherical or parabolic to focus light rays properly.

Mirror diagonal - A star diagonal that uses a mirror instead of a glass prism.

Monocular - A type of spotting scope, which consists of a single lens and resembles half a binocular.