ESCI A.S1.O2.A2 Size and Composition of the Solar System

• Relate the composition of objects in the solar system to their distance from the Sun.
• Compare the size of the solar system to the Milky Way galaxy. 
• Compare the size and scale of objects within the solar system.

So, space is, like, really big. And spacey. Space is mostly made of space. This means it's mostly just an area where stuff can be, but probably just ends up being empty. Take our solar system form example. Often we see pictures like this:

See how the planets all fit nicely crammed together in that little rectangle? This couldn't be further from the truth. Remember, space is mostly nothing. We make diagrams like this because if we made them accurately the image would stretch for hundreds of pages in a book and most of those pages would be blank. To give you an idea of the true scale of the solar system check this animation out:

If the Moon Were Only One Pixel Links to an external site. 

One of the things you may have noticed about the planets is that there is a pattern. Small, rocky planets are found close to the Sun while large gassy planets are farther from the Sun. To understand why we see this pattern we can go back to the nebular theory. Remember the big spinny disk of stuff that eventually formed our solar system? This disk was full of atoms. Some of them heavy and some light. In the center, we have a huge amount of matter that eventually becomes a star. A star is born when it starts fusion. When a star begins to fuse it gives off a lot of light and spews tons of particles into space. This is called the solar wind. The solar wind begins to push the lightest particles away from the Sun to the outer parts of the system. So we get a buildup of light elements like hydrogen and helium in the outer planets and a lack of these particles near the Sun. For a more detailed explanation and animations read the information at this site:

How Planets Form Links to an external site.

And watch this video:

ESCI A.S1.O2.A2 Seeing the Formation of Planets VID   Links to an external site.

Lastly, use this interactive animation Links to an external site. to look at the size and scale of things. Find the following objects, identify what they are (you may have to do a search), and arrange them in order from smallest to largest. List all of the objects this way, and in order, in the textbox:  Object name - Type of object

Object List

Jupiter

Io

Kuiper Belt

Cruithne

Milky Way Galaxy

Hailey's Comet

Observable Universe

Earth

Deimos

Oort Cloud

The Sun

Eagle Nebula