M - N
the letter that (probably) leads off the word in question. Please
suggest new words or corrections.
The fourth planet from the Sun. It's reddish in appearance and
shows evidence of liquid water on its surface in the distant
A small, rocky planet closest to the Sun.
Charles (1730-1817): An 18th century comet hunter probably
best known for compiling a list of 110 celestial objects known
as the "Messier Catalog" that is still in use today.
A natural solar-system object that enters Earth's atmosphere
and is subsequently destroyed in a flash of light before reaching
the surface. Several regular meteor showers occur throughout
the year including the Leonids and Perseids to name two.
A meteoroid that has landed on the surface of Earth.
small rock in space consisting of rock and/or iron that is probably
a chip of an asteroid.
The large rocky body orbiting the Earth around every ~28 days.
A large cloud of gas and dust in space, much smaller than a
galaxy. They can actually be a star producing region. They can
emit, reflect, and/or absorb light and radiation from nearby
stellar radiation. Ex. M42 - The Orion Nebula.
An object only tens of miles across, but greater in mass than
The eighth planet from the Sun. It is a gas giant.
Also known as the "NGC", this catalog
was compiled by John Louis Emile Dreyer around 1887. It contains
a variety of objects with a detailed legend for descriptions
of each of them.
The process by which one celestial body passes in front of another,
blocking it from the view of an observer as seen from Earth.
Similar to an "eclipse".
cluster: Gravitationally bound concentrations of stars believed
to originate from large cosmic gas and dust clouds. Smaller
than a globular cluster and usually have a short lifespan as
a cluster. Also see "star cluster" and "globular cluster". Ex.
M45 - the Pleiades star cluster.
The positioning of two celestial bodies relative to a third
(usually the Sun, Earth, and a third celestial body) such that
they are 180 degrees apart in Right Ascension. Note that the
bodies need not actually lie on a straight line since they may
lie at different Declinations.
The path and process by which one object revolves or moves
around another, held together by their mutual gravitation.
Cloud: A theoretical region that surrounds the solar system
at about 50 to 100 astronomical units; the Oort Cloud is presumably
a remnant of the solar system's accretion disk and it is thought
to contain trillions comets.