The Universe Flashcards
The totality of all matter energy and space
Universe
The apparent sphere of the sky on which all the stars seem to appear
Celestial Sphere
The apparent path the sun traces annually along the celestial sphere
Ecliptic
A coordinate for measuring the east-west positions of celestial objects the angle is measured eastward from the vernal equinox
Right Ascension
The angular measure of a celestial object in degrees
Declination
The distance to a star when the star exhibits a parallax of one second of arc where one second of arc is defined to be 1/3600 of 1 degree
Parsec
The bright visible surface of the sun
Photosphere
The brightness of a star as observed from earth
Apparent Magnitude
The brightness a star would have if it were placed at a standard distance of 10 pc from the earth
Absolute Magnitude
A plot of the absolute magnitude of stars versus the temperature of their photospheres
H-R Diagram
The narrow band of stars going from the lower right to the upper left on the H-R diagram; most stars fall into this category
Main Sequence
A relatively cool very bright star that has a diameter ten to a hundred times larger than the sun
Red Giants
A hot white star that has a much smaller diameter and much higher density than average It is believed to be the final stage of a low mass star
White Dwarfs
Cool dense clouds of interstellar gas and dust
Nebulae
A luminous shell of gas ejected from an old low mass star
Planetary Nebula
