Quiz 1: The Celestial Sphere

Astronomical Terms

celestial sphere

an imaginary sphere that turns around the Earth once every 24 hours.

horizon

horizontal plane through the eyes of the observer that extends to the celestial sphere.

zenith

the point on the celestial sphere directly above the observer.

cardinal points (north and south)

points where the celestial meridian intersects the horizon.

cardinal points (east and west)

90* east or west of the north and south cardinal points.

celestial meridian

the portion through the celestial poles and the observer’s zenith which lies above the horizon.

transit (upper transit)

the passage of a celestial object across the celestial meridian.

anti-meridian

the portion through the celestial poles and the observer’s zenith which lies below the horizon.

nadir

the point on the celestial sphere opposite the zenith.

constellations

“patches” of sky that are divided by the celestial sphere.

asterisms

patterns formed by stars of one or more constellations.

dust tail

white tail of a comet

ion tail

blue tail of a comet

Capella

largest star of Auriga

Vega

largest star of Lyra

Deneb

largest star of Northern Cross

sublimate

going from a solid to a gas; happens to comets

M31

Andromeda Galaxy, closest largest galaxy to us

Beta Aquarii

brightest star in Aquarius

lightyear

how far light can travel in a year

Cygnus

constellation where Northern Cross is located

Delta Cephei

4th brightest star in Cepheus; pulsating variable star

open star clusters

recently “born”; eventually move away

Algol

beta star in Perseus; variable star

eclipsing binary star system

2 stars that orbit each other; Algol

red star

cooler

blue star

hotter

light curve

a plot of intensity vs. time