Earth And Space

Question 1

Galaxies

Answer 1

a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

Question 2

Solar system

Answer 2

the collection of eight planets and their moons in orbit round the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets. The planets of the solar system are (in order of distance from the sun) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Question 3

Astronomer

Answer 3

an expert in or student of astronomy

Question 4

Expanding universe

Answer 4

the increase in distance between any two given gravitationally unbound parts of the observable universe with time.

Question 5

Gravity

Answer 5

the force that attracts a body towards the centre of the earth, or towards any other physical body having mass.

Question 6

Singularity

Answer 6

a point at which a function takes an infinite value, especially in space–time when matter is infinitely dense, such as at the centre of a black hole.