The Bridge V Learning Edition 1 ; our solar system | Page 18

Even the star nearest to us, Proxima Centauri, is 4.22 light years (i.e., over 40 trillion km) away
from us. This is so distant that a journey there would take generations of human lives.
Jupiter
Neptune
Venus
Mercury
Earth
Mars
Pluto
Saturn
Rocky Planets
Uranus
Gas Giants
Credit: UNAWE / C.Provot
Planets that orbit other stars than our Sun are called extrasolar planets or exoplanets for short.
Astronomers have already discovered more than 900 of these exoplanets.
We can categorise the planets of our Solar System into two types: the rocky planets, which are
nearest to the Sun and have a solid surface, and the gas giants, which are farther from the Sun
and are more massive and mainly composed of gas. Mercury, Venus, Earth and Mars appear in
the former category, and Jupiter, Saturn, Uranus and Neptune make up the latter. Pluto, our
formerly outermost planet, has been considered one of the dwarf planets since 2006. Between
Mars and Jupiter is a so-called asteroid belt, which circles the Sun like a ring. It consists of
thousands of smaller and larger boulders. The largest of these have their own names, just like
the planets. One of them, Vesta, is so large that it is considered a dwarf planet.
1 Know Your Planets
Brief Description