Astronomy Flashcards
Define astronomical unit.
The average distance between the sun and the Earth.
What is the definition of nebula?
A cloud of interstellar gas and dust.
What is a constellation?
A various group of stars that have definite names given to them.
What is the meaning of planetesimal?
One of the celestial bodies, according to the planetesimal hypothesis, were fused together to form the planets of the solar system.
What is protoplanetary?
The collection of matter, in the process of condensation.
Define nuclear fusion.
A thermonuclear reaction in which nuclei of light atoms join to form nuclei of heavier atoms.
What are terestrial planets?
The 4 planets closest to the sun.
(Mercury, Venus, Earth, Mars)
The gas giant planets are…
Planets that are mostly formed of various gases, with a supposed rocky center.
(These planets are farthest from the Sun)
What is a comet?
A celestial body moving towards the sun,usually in a high eccentric orbit.
An asteroid is…
A small body that revolves around the sun in orbit.
(Lies mostly between Mars & Jupiter)
What is a cosmologist?
Someone who studies the general structure and evolution of the universe.
Explain angular velocity.
The time rate of change of angular position of a rotating body.
Define orbit.
A curved, elliptical path around a celestial body.
(planets orbit Sun, satellite orbits Earth)
