Lore. Learning on any subject.
Lunar. Of, or having to do with the Moon.
Magnetic lines of force. The direction of the force of magnetism acting in and around a magnet.
Magnetic storm. The Earth is a great magnet and sometimes when sun spots of unusual size or numbers appear, the magnetic lines of force of the Earth are violently affected. This is called a magnetic storm.
Mass. (1) Amount of matter. (2) A lot of molecules or particles of matter brought and held together.
Matter. The substance of which a thing is formed. A molecule of matter is made up of atoms, and a mass is a lot of molecules held together by some attractive force.
Mercury. (1) The name of the planet nearest the Sun. (2) A silver white liquid metal.
Molecule. The smallest part of matter that can exist separately without the substance it forms being destroyed.
Morning Star. A planet which can be seen in the east just before the Sun rises.
Morse code. A telegraph code of dots and dashes invented by Samuel F. B. Morse. The Morse Code is used for telegraph and heliograph signaling.