The Universe Flashcards
The Universe
all existing matter and space considered as a whole; the cosmos. Has been constantly expanding since the big bang 13 billion years ago.
The observable universe
The observable universe is the ball shaped part of the universe that contains all matter that can be seen or detected from earth
constellation
a group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure.
Galaxy
a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction of a black hole
solar system
The solar system is made up of the sun and the 8 planet that orbit it
planet
a celestial body moving in an elliptical orbit round a star.
parsec
a unit of distance equal to 3.26156 light years
apparent magnitude
the brightness of an object relative to earth
star
A star is a luminous celestial body made up of hot gases, primarily hydrogen and helium, undergoing nuclear fusion to produce energy and light.
light year
A light year is the distance light would travel in a year
absolute magnitude
the brightness of an object at a distance from earth of 10 parsecs
speed of light
3.0 x 10^8 m/sec
The milky way galaxy
The milky way galaxy is large collection of gas, dust and billions of stars and their systems
Order of planets
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
HR-diagram
The Hertzsprung-Russell (HR) diagram is a chart that plots stars by their brightness and temperature, showing how they change and evolve over time.
Stellar Evolution
Stellar evolution is the process by which a star changes over time, from its formation to its death