P - Q
the letter that (probably) leads off the word in question. Please
suggest new words or corrections.
point nearest the sun in the orbit of a planet or other celestial
One of two small moons orbiting Mars discovered in 1877
by American astronomer Asaph Hall.
The visible outer layer of a star, especially of the Sun.
A large, round object, larger than an asteroid, that is formed
inside an accretion disk. Unlike a star, a planet does not produce
its own energy via nuclear reactions. There are nine planets
in our solar system. Ex. Earth.
An expanding gas cloud that was created as the result of gas
being expelled from a sunlike star in the later stages of its
life. Ex. M57 - The Ring Nebula.
The ninth and final known planet from the Sun. Pluto is the
smallest planet in diameter. It is rocky and orbited by one
moon named Charon.
longitude on Earth from which the 24 hour UTC clock is centered.
It runs through Greenwich, England, among other places. Also
see "Universal Coordinated Time".
A very fast-spinning and highly dense object that emits light,
radio and/or X-rays in very tight beams, similar to a lighthouse.
A large, red sunlike star in its latter stages of life.
An measurement of the increase in the wavelength of light often
due to the Doppler effect. It is used as a means of more accurately
predicting the distances to cosmic objects. Objects with higher
observed redshifts are farther away than those with lower redshifts.
The coordinate system in the sky that corresponds to longitude
on Earth. It is measured eastward from the vernal equinox. Also
see "vernal equinox".