4.1 and 4.2 Key Terms (Astronomy)

Front

What is the Universe?

Back

All that exists everywhere, including all matter, energy, planets, stars, galaxies, and the space in which all of this exists.

Front

When did the universe begin?

Back

13.8 billion years ago.

Front

What is String Theory?

Back

A theory that unifies force and matter particles by suggesting that their fundamental units are one-dimensional filaments called strings.

Front

How many dimensions are theorized by physicists?

Back

11 dimensions.

Front

What does our place in the universe depend on?

Back

It depends on who we are, when we are, and what we know.

Front

What is the celestial sphere?

Back

An imaginary rotating sphere on which all objects of the night sky lie.

Front

How is the celestial sphere divided?

Back

It is divided into the northern and southern hemispheres.

Front

What can an observer see of the celestial sphere?

Back

An observer can see only half of the celestial sphere.

Front

What is the Ecliptic?

Back

The path that the Sun and some other celestial objects appear to take across the celestial sphere.

Front

What is Earth's rotation?

Back

The spinning of Earth on its axis, which causes objects to appear to move from east to west.