A - B
the letter that (probably) leads off the word in question. Please
suggest new words or corrections.
Abbr. See astronomical unit.
quantity giving an astronomical object's intrinsic brightness
defined by the apparent magnitude (see below) of an object placed
at a distance of 10 Parsecs.
disk: The theoretical nebular cloud from which the planets
and the Sun coalesced into the solar system.
System by which a telescope utlizes computer technology to correct
for atmospheric effects on its image.
disk: A disk of light seen through a telescope with about
80% of all the light from the star. It is surrounded by concentric
rings, each fainter and fainter. Often used as a benchmark for
determining the quality of a telescope's image. The better and
more defined the disk is, the better the optical quality.
system for celestial navigation. Rather than having a telescope
who's center of rotation is centered on the celestial north
pole, the telescope simply relies on an up-down, right-left
bearing system, allowing it to move freely in any direction.
eclipse: This is a partial solar eclipse in which the Moon
is not close enough to the Earth to completely block out the
Sun's light. When the Moon is centered on the Sun there is still
an uncovered ring of sunlight.
The diameter of a telescope's light collecting surface (either
a lens or mirror).
apoapsis of an object orbiting around the Sun.
point in an orbit farthest from the body being orbited.
apoapsis of an object, commonly used for objects orbiting Earth.
apparent brightness of an object as viewed from Earth, regardless
of its intrinsic magnitude value.
Units of measurement in the sky based on a full circle of 360
degrees. Each degree is divided into 60 arc minutes (symbol
is ' ) and each arc minute (symbol is " ) is divided into 60
arc seconds. For reference, the Full Moon is about 30 arc minutes
(or 30' ) in diameter when viewed from Earth.
named collection of stars in the sky that is not part an official
constellation. Ex. the Big Dipper.
A small, rocky, celestial body that revolves around the
Sun with characteristic diameters between a few and several
hundred kilometers. Also called minor planet, planetoid.
collection of asteroids in orbit about the Sun lying between
Mars and Jupiter. It is believed that this belt formed as the
result of a planet breaking apart or failing to coalesce at
unit: A unit of measurement based on the average distance
Earth is from the Sun in its orbit. One astronomical unit is
equal to about 93 million miles.
The scientific study of matter in outer space, especially the
positions, dimensions, distribution, motion, composition, energy,
and evolution of celestial bodies and phenomena.
"seeing": This term describes the observing conditions
through which astronomers view the heavens. Bad "seeing"
indicates that the atmosphere is not good for observing because
of high winds, fluctuating temperatures, turbulence, haze, etc.
Beads: phenomenon that occurs during a solar eclipse by
which sunlight shines through the gaps produced by Moon craters,
mountains, etc. The sunlight produces bright areas that appear
type of galaxy in which there appears to be a "bar".
The purpose and origin of the bar is not well understood, but
they are often very active.
star system in which two or more stars orbit each other around
a center of mass. They can share material between themselves.
hole: An object in space who's gravity is so strong that
nothing inside can escape, not even a ray of light. The center
of the Milky Way (and many other galaxies) is thought to be
a large black hole. A theory of their origin is that they are
term for the second full Moon in a single month. This usually
happens a couple times a year.
star which does not have enough mass to ignite thermonuclear
fusion in the core.
Division: A major gap between the A and B rings around Saturn.
It was first discovered by Giovanni Domenico Cassini in the
Jupiter's second largest moon. It is composed of about 40% ice
and 60% rock. It was discovered by Galileo in 1610.
see "charged-coupled device"
Of or relating to the sky or heavens.
equator in the sky that corresponds to the equator on Earth.
Any of a class of intrinsically variable stars with exceptionally
regular periods of light pulsation. Commonly used to determine
oxide: A polishing agent commonly used for polishing and
figuring optical surfaces.
A highly sensitive digital imaging device used to collect light
data through a telescope.
The only known moon of the planet Pluto.
An incandescent, transparent layer of gas, primarily hydrogen,
several thousand miles in depth, lying above and surrounding
the photosphere of a star, such as the sun, but distinctly separate
from the corona.
system object in orbit around the Sun that is composed of ice,
rock, and other chemicals. They are often described as a "snowball"
position of two celestial bodies (very often one of them being
the Sun) when they have the same celestial longitude (right
ascension) when viewed from Earth.
group of stars that are used as a system of mapping the night
sky. The entire sky is broken up into multiple constellations,
such as Andromeda, Perseus, and Draco to name a few.
The luminous, irregular envelope of highly ionized gas outside
the chromosphere of the Sun.
telescope or an attachment for a telescope equipped with a disk
that blacks out most of the Sun, used to photograph the Sun's
dust that makes up much of the matter in galaxies.
force that pushes debris and cosmic dust along through galaxies.
A depression on a body's (planet, moon, asteroid, etc.) surface
originating from, among other things, the collision of another