Oxford Discover 4 unit 2

Front

An expert who studies stars and planets.

Back

an astronomer

Front

___ travel through space and send information to us.

Back

Space probes

Front

The center or the most important part of something.

Back

core

Front

The moon has weaker __ than Earth.

Back

gravity

Front

The curved path of a planet round the sun.

Back

orbit

Front

The sun has the most of the ______ in the solar system.

Back

matter

Front

The ________ of Earth is 12,700 km.

Back

diameter

Front

If there is only one of something, it is _____

Back

unique

Front

The _____ of the desk is hard.

Back

surface

Front

There are lots of ______ on the moon.

Back

craters