Astronomy has really big numbers

Distance between Earth and Sun 150000000000 meters 1500000000 kilometers This is the closest star.

Distance To Next Closest Star Alpha Centauri 41295206500000 kilometers Or 41295206500000000 meters Too big. Mind explosion.

What’s a better way? 4.12952065 × 1013 km Or 4.365 light years

Scientific Notation 2.75 x 103 A number is written in two parts: Just the digits (with the decimal point placed after the first digit), × 10 to a power Example: 2.75 x 103

x 103 = ???????? × 10 to a power puts the decimal point back where it should be (i.e. it shows how many places to move the decimal point). Examples: 2.75 x 103 = 2750.0

Another Example

How to do it Step 1 To figure out the power of 10, think "how many places do I move the decimal point?"

How to do it Step 2 If the number is 1 or greater the decimal place has to move to the left the power of 10 will be positive.   If the number is smaller than 1 then decimal place has to move to the right the power of 10 will be negative: 

Example 0.0055 would be written as 5.5 × 10-3 Because 0.0055 = 5.5 × 0.001 = 5.5 × 10-3

Why not just write the number? Scientific Notation is used for numbers that are HUGE or tiny For example it is easier to write (and read) 1.3 × 10-9 Than 0.0000000013

Which one is easier to read? So what do you think? The distance from the earth to the sun 150000000000 meters 1500000000 kilometers or 1.50 x 1011 m Which one is easier to read?