There are eight large celestial bodies called planets.
Each planet rotates on its own invisible axis.
Each planet also orbits the Sun. The planets can be classified into two groups: terrestrials and gas giants.
PLANETS & SATELLITES • Mercury, Venus, the Earth and Mars are the terrestrial planets. They are small, and mainly made up of rock. • Jupiter, Saturn, Uranus and Neptune are called gas giants because they are large and are made up of gases. • Natural satellites are smaller celestial bodies, such as moons, which orbit their planets.
Sometimes during their orbits, the Moon, the Earth and the Sun align, and an eclipse occurs.
During a lunar eclipse, the Earth passes between the Sun and the Moon, and blocks the Sun’s light.
The Earth’s shadow moves across the surface of the Moon.
During a solar eclipse, the Moon passes between the Earth and the Sun, blocks the Sun’s light, and projects a shadow on the Earth. When the Moon and Sun are in a perfect line, it is called a total eclipse.
Stars are divided into eighty-eight groups or constellations to make identification easier. The constellations have the names of characters from classical mythology or the names of animals and objects because of the shapes they form.
Some constellations, such as Ursa Major, can be seen all year.
However, Orion, for example, can only be seen in winter, and Hercules can only be seen in summer.