Q1. Complete the following definitions:
a. A star is … is a sphere of gas.
b. A planet is … a celestial body that orbits a star.
c. A satellite is … a celestial body that orbits a planet.
d. An asteroid is … small celestial body that revolves around the Sun.
e. A galaxy is … a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
f. A comet is … a celestial object consisting of a nucleus of ice and dust and a tail of gas and dust particles.
