Light rays need time to travel distance. To calculate how long sunlight takes to travel from the sun to the earth, you have to take into account the distance between the sun and planet earth.

 

 

How far is the sun from the earth?

 

The distance between the Sun and the Earth varies because the Earth orbits the Sun in an elliptical shape. In the perihelion phase, the Sun is closest to the Earth, which is in January. The Sun is then about 147 million kilometres from the Earth.

In the aphelion phase, the sun is farthest away from the earth. This phase is in July. The sun is then about 152 million kilometres away.

 

How fast is light?

 

In a vacuum like space, light rays travel 299,792.458 km per second. 

 

To calculate the time it takes for the sun's rays to travel between the sun and the earth, divide the distance by the speed of light.

 

147,000,000 km / 299,792.458 km per sec = 490.339 seconds

 

In January, when the sun is closest to the earth, it takes 490 seconds (8 minutes 10 seconds) for the sun's rays to reach the earth.

 

 

152,000,000 km / 299,792.458 km per sec = 507.017 seconds

 

In July, when the Sun is farthest from Earth, it takes 507 seconds (8 minutes 27 seconds) for the Sun's rays to reach Earth.