Astronomy Flashcards

Front

Solar system

Back

A sun together with the group of celestial bodies that revolve around it

Front

Milky Way Galaxy

Back

A large spiral system of gas, dust, and billions of stars and their solar systems, all held together by gravity - our galaxy

Front

Nebula

Back

A rotating, interstellar cloud of gases and dust that collapsed due to gravity, forming a sun and orbiting planets

Front

Orbit

Back

A regular, repeating path one object takes around another object or center of gravity

Front

Kepler's 1st Law

Back

All planets move in elliptical orbits with the sun at one focus

Front

Ellipse (Kepler)

Back

An oval shape centered on two points instead of one

Front

Focus (Kepler)

Back

The two points that make up an ellipse

Front

Perihelion

Back

The point in the orbit of a planet, asteroid, or comet where they are closest to the sun

Front

Aphelion

Back

The point in the orbit of a planet, asteroid, or comet that is furthest from the sun.

Front

Ellipse Eccentricity

Back

The ratio of the distance between the foci to the major axis of the ellipse. The more eccentric an orbit, the more oval-shaped it is. The eccentricity is zero for a circle.