# Lengths From Very Small to Very Large

Our Universe has very small things (like atoms), and very large things (like galaxies).

And this is where metric prefixes like milli- and kilo- can be very useful.

Example: the distance between London and New York is about 5,580,000 meters.

But it is easier to use 5,580 kilometers.

Here is an illustration of sizes, from the very small (a Quark) to the very large (the known Universe):

The sizes are in meters using metric numbers.
(Just add the word "meter" after them, so you get "millimeter", "terameter", etc.)

The numbers (like 10-18) use Scientific Notation to show how big the value is.

Example: 106 is 10 used in a multiplication 6 times, which is a 1 followed by 6 zeros: 1,000,000.

It is also called a million.

The prefix is mega-, so a megameter is a million meters.

Example: 10-9 is a 1 moved nine places the other side of the decimal: 0.000 000 001

It is also called a billionth.

The prefix is nano-, so a nanometer is a billionth of a meter.

Looking at the illustration you can see that a person is about 1 meter in size, a mountain is about 103 (one thousand) meters in size, and the diameter of the Sun is about 109 (one billion) meters.

Example: We could also say the Sun is about a "gigameter" in size

It's diameter is actually 1.392×109 meters, or 1.392 gigameters, or simply 1.392 Gm

More Interesting facts:

• Quarks are very very small
• Molecules are around the billionths of a meter in size. That is 0.000000001 meters. Some molecules are smaller and some bigger, though.
• People are a little over a meter tall,
• Mountains are kilometers in size.
• The Earth is megameters in size (a megameter is a thousand kilometers, and the Earth's Diameter is actually 12,000 km)
• A Light Year is about 10 petameters in size (a petameter is 1,000,000,000,000,000 meters, which is a 1 followed by 15 zeros)
• The Milky Way is about 1 zetameter across (1,000,000,000,000,000,000,000 meters, which is a 1 followed by 21 zeros)
• The Universe is very very big