Planets, dwarf planets, moons, and asteroids The Solar System Planets, dwarf planets, moons, and asteroids

Our Solar System What is a Solar System? A group of objects in space that orbit a star in the center The sun is the star in the center of our solar system – the largest object in our solar system Our solar system includes 8 planets, dwarf planets, moons, and asteroids Planet: A large object that revolves around a star in orbit Dwarf Planet: Also revolves around star, but not in a clear path Moon: Smaller object that revolves around a planet Asteroid: Small and rocky object in space

The Inner Planets The inner planets are the planets closest to the sun In order: Mercury, Venus, Earth, and Mars. How are these planets similar? Rocky surfaces Smaller than most of the outer planets None have more than 2 moons Earth is the most unusual planet Only one with liquid water on surface Only one with a large amount of oxygen in the atmosphere

The Outer Planets – the “Gas Giants” The outer and inner planets are separated by a ring of asteroids orbiting the sun In Order: Jupiter, Saturn, Uranus, and Neptune How are these planets similar? Huge Made up of gas and no solid surface All have many moons and have rings made of dust, ice, or rock

Dwarf Planets Is Pluto a planet or a dwarf planet? Pluto was discovered in 1930 and considered a planet until 2006, when it was reclassified as a “dwarf planet.” Pluto’s orbit was different than other planets. It would orbit in a long orbit, cutting into the orbit of Neptune. For this reason, it was no longer considered a planet. There are 5 known dwarf planets in our solar system, but scientists think there may be hundreds more in our solar system.

Other objects in our Solar System Asteroids: Bits of rock and metal, most often in the asteroid belt that separates the inner and outer planets Comets: Balls or rock, ice, and frozen gas. Sometimes looks like a fiery ball when visible from Earth.

STARS!

The Sun and Other Stars Star: A huge ball of superheated gases The sun is a star at the center of our solar system Largest object in our solar system Source of most of the energy on Earth

How are stars classified? By color – Blue – hottest Red – coolest By brightness – depends on how far it is from Earth and how bright it actually is

What are the stages of a star? Form from clouds of spinning dust and gas Gravity squeezes the cloud and changes take place, forming a star The mass of the star changes into light and heat

Constellations Constellation A group of stars that form an imaginary picture in the sky are called constellations Serve as landmarks in the sky Big dipper, Ursa Major, Orion, Polaris, just to name a few! Named by ancient people, such as Galileo We see different constellations at different times of the year due to Earth’s movement

Galaxies Galaxy Everything that exists in space is called The Universe A galaxy is a huge system of gas, dust, and stars. Contain billions of stars Our galaxy is the Milky Way Galaxy Some galaxies are spiral (Milky Way), look like a ball, egg, or have no clear shape Everything that exists in space is called The Universe