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

2. 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

4. 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

5. 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

6. 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.

7. 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.

8. STARS!

9. 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

10. 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

11. 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

12. 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

13. 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