How do you get the average time it takes for light to reach an object in space?

Question

And I am only 13 so I I would appreciate it if you said it in a little more simple terms. (sorry)

Answer 1

In space, light travels at a fixed speed.
Approximately 300,000 km/s (187,500 mph).

If you know the distance from the object to Earth in km, then you divide the distance by the speed to get the time.

"average" is when the distance varies in a cyclical way, around a mean value. For example, Earth's orbit around the Sun is not a perfect circle. In January, we are a bit closer to the Sun than in July.
Our average distance to the Sun is approximately 150,000,000 km.

150,000,000 km divided by 300,000 km/s gives 500 seconds. This is the average time that light takes to come from the Sun.
-----

The real speed of light is 299,792.458 km/s
The real average distance from Earth to the Sun is 149,597,870.1 km (centre to centre)
The light leaves from the surface, not the centre.

The real average time light takes to come from the Sun to Earth is 499 seconds.

Answer 2

Light always travels through space at the same speed. It is therefore assumed that the time for light to reach something is half the time it takes for light to travel from an observer to the object and back to the observer.
For most objects in space the time to wait for the light to travel round trip is greater than the length of any persons life. Some of those objects are close enough that we can determine the distance between the object and the Earth. We can then calculate the time it would take for light to travel between the object and the Earth. The distance to the object divided by the speed of light determines the time that it takes light to travel between the object and the Earth. The units of measure are important in this situation. If the distance is measured in feet then the speed must be measured in feet. If the speed is measured in days then the time of transit will be measured in days. Usually astronomers use convenient distance measures for the distance to the object to be reasonable in size. In the solar system it is possible to use kilometers. For distances to things outside our solar system light years are a better unit of measure.

Answer 3

There is no "average time." The speed of light in space is a constant. If you know the distance from the light source (sun) to the object (planet) the time will be the same each time you calculate it.

Divide the distance by the speed of light and you get the time. There is no "average" as there is only one right answer.

Answer 4

If the distance to the object is given in light years, that also tells you how long it takes light to reach it.

So if something is 20 lightyears away, it takes light 20 years to travel that distance (makes it nice and simple).

Most scientists use light years when discussing the distances to objects outside our solar system (like stars and galaxies).

Answer 5

Divide the distance (in meters) by the speed of light which is
300,000,000 meters per second.
So... To go 1 kilometer (1000 meters) takes light abut
1000/300000000 = .00000333 seconds.

Doug