Structure of Our Solar System

Navigate the knowledge tree: 🌿 Earth & Space Science ➡ Astronomy ➡ Our Place in Space

Learning Intentions

By the end of this topic, you should be able to:

Describe where planets, asteroids, and comets can be found within the Solar System.
State the difference between an asteroid and comet.
State the difference between a planet and a dwarf planet.

Glossary

Key terms and definitions.

asteroid: The force that pulls things towards each other.

Asteroid Belt: The amount of matter in an object.

comet: The path one object takes as it moves around another object in space.

dwarf planet: The force that pulls things towards each other.

Kuiper Belt: The amount of matter in an object.

Oort Cloud: The path one object takes as it moves around another object in space.

planet: A large ball-shaped collection of gas and/or other materials. It does not create its own heat and light.

shooting star: A collection of planets that orbit a star or set of stars.

solar system: A collection of planets that orbit a star or set of stars.

Exploring Objects in the Solar System

Name as many objects in our Solar System as you can!

Activity: Solar System Lab

Use the interactive below or click on this link to open it in a new window: https://www.earthspacelab.com

Activity: Solar System Scope

Use the interactive below or click on this link to open it in a new window: https://www.solarsystemscope.com/ and click "START"

Take a moment to zoom all the way out and remind yourself of where we are in the rest of space.
Now zoom back in again, and note where there are things like:
- - Rings of "debris" or small rocky objects
  - How many planets are closer to te Rā than the first ring of debris
  - How many planets are farther than te Rā than the first ring of debris.
Click and drag the Solar System so you can see it from the side, then drag it to the right or left.
Notice that the signs of the zodiac that we saw in lesson 10 are the constellations that are in line with the rest of the Solar System. We call this plane the "ecliptic."

Planets

A planet is a round object in space that orbits around a star. Planets in our Solar System orbit the Sun. They are large collections of matter that orbit the Sun and do not give off their own light. Many planets have moons; small objects that orbit sround them. There are hundreds of moons in our Solar System.

Dwarf Planets

Dwarf planets are small rocky worlds that orbit the Sun like the planets. But they have strange orbits, are much smaller and have less mass than planets. This means that they have less gravity and therefore tend to have a lot of debris in their orbit.

Plut is an example of a dwarf planet, and there are other dwarf planets in our Solar System.

Ceres is a dwarf planet, and the dwarf planets that are past Neptune are called plutoids. We now have four objects that we call plutoids, and they are Pluto, Eris, Haumea, and Makemake. Some of the other things shown here might be called dwarf planets or plutoids in the future.

The sizes of the planets and dwarf planets in our Solar System (but the distance is NOT to-scale).

Asteroids, Comets and Meteors

Other particles never gathered enough material to become planets or dwarf planets. Instead, they remained orbiting around the Sun as other kinds of objects., such as asteroids and comets.

Between the orbits of Mars and Jupiter is a ring of small, rocky objects that orbit the Sun. These are asteroids, and these are left over from the earliest days of the Solar System's formation.

Most dwarf planets are found in a ring of objects past Netptune, called the Kuiper Belt. The Kuiper Belt is also full of thousands of comets, which are objects made out of rock and different types of ices. These materials burn into a tail when the comet's long, elliptical orbits take them close to the Sun.

Out past the Kuiper Belt is a spherical cloud of even more comets, called the Oort Cloud. The Oort Cloud stretches out to more than 50,000 AU.

Pieces of asteroids, comets and other things are constantly flying around our Solar System. When these hit our atmosphere, the friction with the air causes enough heat to burn them up as they fall. We see this as a shooting star.