The Universe - Terms to definitions Flashcards
What is the universe?
Everything, including all space, matter, and energy.
What is the sun?
The star in the center of our solar system.
What is a planet?
A celestial body that orbits a star, has enough mass to form into a round shape, and has cleared its orbit of any objects of similar size.
What is an orbit?
The elliptical path of a celstial object or spacecraft around a star, planet, or moon.
What is a solar system?
A group of planets and other bodies that revolve around a star.
What is a galaxy?
A concentration of stars, gas, dust, and dark matter held together by gravity.
What is a moon?
An object that orbits a planet or something else that is not a star.
What is a star?
A large celestial body made mostly of hydrogen and helium which produces light and heat from the churning nuclear forces insied its core.
What is absolute magnitude
The brightness of a star as seen from 10 parsecs away.
What is apparent magnitude?
How bright a star looks from earth.
How much is a light year?
9.46 trillion km
The distance that light travels in a year
How much is an Astronomical Unit (AU)?
150 million km
The radius of earth’s orbit
How much is a parsec (PC)?
3.2 light years
206,265 AU
30.9 trillion km
The distance at which one AU subtends an angle of one arc second (1/3600°)
What is Hubble’s Law?
v = HD
H = hubble’s constant
D = distance
v = recessional velocity
Hubble’s law says that the further away an object, the faster it is moving away.
What is the doppler effect?
The shift in a wave’s frequency when its source is moving closer (higher) or away (lower).
