Another measure of distance you may come across when learning astronomy is the parsec. It is equal to 3. 26 light years. It is another way to simplify the numbers used to calculate and discuss astronomical distances. [3] X Research source
If you want to know the distance of a light year in kilometers, you will need to find the speed of light in kilometers per second. If you want miles, you will need the speed of light in miles per second. You need to know the number of seconds in one Earth year for this calculation.
For this calculation we will use the speed of light, c, equals 186,000 miles per second. This can be rewritten in scientific notation as 1. 86 x 105 miles per second.
1 year x 365 days/year x 24 hours/day x 60 minutes/hour x 60 seconds/minute = 31,536,000 seconds. [6] X Research source Again, we can rewrite this large number using scientific notation as 3. 154 x 107.
d = c x t d = (1. 86 x 105) x (3. 154 x 107 seconds) d = 5. 8 x 1012 or 5. 8 trillion miles.
d = c x t d = (3. 00 x 105) x (3. 154 x 107 seconds) d = 9. 46 x 1012 or 9. 5 trillion kilometers.
To convert feet into miles, remember that there are 5,280 feet in a mile: x ft (1 mile/5280 ft) = miles. [9] X Research source To convert meters into kilometers, simply divide by 1000: x m (1 km/1000 m) = km.
To convert from kilometers to light years, you will use: 1 light year/(9. 46 x 1012 km). [10] X Research source To convert from miles to light years, you will use: 1 light year/(5. 88 x 1012 miles). [11] X Research source
For example: If you knew that an object was approximately 14. 2 x 1014 miles away from Earth, how many light years would that be? Use the miles conversion factor: 1/(5. 88 x 1012) Multiply: (14. 2 x 1014) x (1/(5. 88 x 1012)) = 2. 41 x 102 = 241 light years. The object is 241 light years away.
Remember, there are always multiple ways to get help when looking for an answer.
