Why don't scientists use kilometers to measure in space?

Answer 1

They use Km if the distance is close if it is very far they use an astronomical unit of the distance between the earth and sun, they also use light years which is the distance light travels in one year.

Answer 2

All astronomical distances in km are difficult to read because they are so big. Using a large unit like a light year makes the numbers manageable, and easier to compare.

To illustrate this point, consider how far, in kilometers, light actually travels in one year:

Light travels at a speed of 299,792.458 kilometers a second!

So let's calculate how many kilometers light travels in one year:

Speed per second: 299,792.458 kilometers

seconds to minutes: x 60

minutes to hours: x 60

hours to days: x 24

days to years: x 365.25

So, in one year, light will travel:

299,792.458 x 60 x 60 x 24 x 365.25 = 9,460,730,472,580.8 kilometers! (say 9.5 million million!)

But but most people would much rather say 1 light year!

And when you take account of the fact that the Andromeda Galaxy is some 2.5 million light years away from the earth, it is no wonder that people would rather say 2.5 million light years than give the result of the calculation 2,500,000 x 9,460,730,472,580.8, which is 23,651,826,181,452,000,000 kilometers (exactly!)

Answer 3

Because a distance measured in kilometers is too long for a conveniently writting !

...a distance is always the same length regardless of the unit of measure...They tend to use astronomical units within the solar system and light years outside because the vastness of space means that kilometers are too small a measure to be practical. It's basically for the same reason that a car's speedometer reads km/hour rather than mm/hour.

Answer 4

It can be measured, of course, but it's just not feasible because the distances are too great to be measured in kilometers. Lightyears are more feasible in this case.

<><><><><>

Actually, AU's (Astronomical Units) are appropriate for measuring distances within the Solar System. One AU is the distance from the Earth to the Sun, about 8 light minutes.

Answer 5

For exactly the same reason that we use miles instead of inches to describe the distance

between New York and Chicago.

Using a unit that's too small gives you a number that's so big it's inconvenient.

The number you get when you measure something has to be easy to write down,

remember, and tell other people about.

The distance from New York to Chicago is about 49,357,440 inches, which is a pain

to try and remember. So we use a bigger unit and say "779 miles" instead.

The distance from Earth to the nearest star outside the solar system is about

39,707,870,000,000 kilometers, which is a pain to try and remember. So we use

a bigger unit and say "4.2 light years" instead.

Answer 6

Because it's easier to remember 1 AU than 93,000,000 miles (and a lot less typing)

Jupiter is 5 AU from the Sun or 780.000.000 kilometers - which is easier to remember? That's why!

Answer 7

It is a relatively too small unit to be used in astronomy measures.

Answer 8

They do not.

What they do use is 149,597,870.7 km (just a factor of a million out!) which is the mean distance from the earth to the sun.