Constellations are stars in the sky, and when you "connect the dots", it will make a shape.
You can see these constellations if you go outside at night.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto are planets. Some people say Pluto isn't a planet.
Pluto is the smallest planet, and is a dwarf planet. It used to be a planet, but now scientists say it isn't.
Earth is our home planet. It is the perfect temperature, and distance from the sun for us Humans to live in. If Earth was closer to the sun, then we would burn. If we were farther, then we would freeze. Some scientists sat that there might be life on Mars!
The sun is a middle aged star, that keeps our planet warm. The sun very hot, and even though it may seem big to us, it is only a middle sized star.
Some scientists think that about 1 million years from now, the sun will explode, and Earth will be destroyed, along with all the other planets.