Definition of a planet:

Orbits around the sun Has enough mass Has cleared its orbit of small celestial matter When the moon is between the sun and Earth, the moon casts a shadow, causing an eclipse.

Venus is the hottest planet in the solar system. The surface temperature of Venus reaches 500 degrees celsius.

Mars has a radius of only one half of Earth. Mars has the largest mountain in the solar system. Dust Storms can happen all over Mercury.

Jupiter is 2.5x more massive than all the planets in the solar system. In Jupiter, thunder can be seen from the sky. Jupiter also has 4 moons.

Astronomers began to discover exoplanets in 1990. Using the velocity method, 500 hot like Jupiter exoplanets were found in 10 years.

Normal matter has made up 5 percent of the universe. Dark Matter is invisible and makes up 27 percent of the universe.

Galaxies are building blocks of the universe and are made up of stars, interstellar medium, and dark matter.

The local group consists of 50 galaxies and has a diameter as long as ten million light years.