D.1 Stellar quantities

… is a collection of planets, moons, asteroids, comets, and other rocky objects travelling in elliptical orbits around the Sun under the influence of its gravity.

Mercury, Venus, Earth, and Mars are classified into … group.

Jupiter, Saturn, Uranus, and Neptune are classified into … group.

Pluto used to be called “the ninth planet” but, in 2006, it was downgraded to a …

Asteroids are rocky objects orbiting the Sun – with millions of them contained in solar orbit in the asteroid belt situated between … and ...

Like the Sun, all stars initially form when gravity causes the gas in a nebula to condense. As the atoms move towards one another, they lose gravitational potential energy that is converted into kinetic energy and form a …

… is the condition when a radiation pressure that opposes the inward gravitational forces are balanced.

A … is a pattern formed by stars that are in the same general direction when viewed from the Earth.

Regions of intergalactic cloud of dust and gas are called …,

The Milky Way is part of a cluster of about 30 galaxies called the “… Group” which includes Andromeda and Triangulum.