Glossary M

Magnification: The increase in the apparent angular size of an object when viewed through an optical instrument, such as a telescope.

Magnitude (Apparent): The measure of the brightness of an object as seen in the night sky.

Magnitude (Absolute): The apparent magnitude a star would have it were located at a standard distance of 10 parsecs (32.6 light-years) from Earth.

Main Belt: See asteroid

Main Sequence: A term given to the point in a star’s lifecycle, such as the Sun, that shine by converting hydrogen in their cores to helium.

Meridian: A great circle on the surface of the Earth or another astronomical body that passes through the north and south poles and crosses the equator at right angles.

Messier Catalogue: A widely used catalogue of celestial Charles Messier in 1781. For example M31 the Andromeda Galaxy.

Meteor: The short-lived streak of light seen when a meteoroid plunges into the Earth’s atmosphere and is heated by friction.

Meteor Shower: A substantial number of meteors that app[ear to radiate from a common point in the sky.

Meteorite: A rocky or metallic meteoroid that survives passage through the Earth’s atmosphere and reaches the Erath’s surface in one piece or fragments.

Meteoroid: A lump or small particle of rock, metal or ice orbiting the Sun.

Milky Way: (i) The spiral galaxy that contains the Sun. (ii) A faint misty band of light that stretches across the night sky.

Multiple Star: A system consisting of two or more stars bound together by gravity.