Couple of days ago I was asked, if I know how far is the Sun from the Earth. I realized that I have no idea and I don’t even know if it is half a million, one million, hundred million miles or more. My answer was: “I don’t know” but, after a while, … hey, hey I’m able to estimate the distance between Earth and Sun!
I know that the Sun’s light travels to Earth about 8-9 minutes and I know that the speed of light is about 300,000,000 meters per second. By the way, it’s easier to remember the speed of light in metric system because it’s almost round number (exactly 299,792,458 m/s), in miles per second it is 186,282 (about 671 million miles per hour).
So, let’s calculate: (you can use our Online Speed Calculator - Earth To Sun Distance Calculation)
8.5 minutes is equal to 8.5*60 seconds = 510 seconds (let’s make it 500, will be easier to multiply)
Every second light can travel 300,000 kilometers (1 km=1000 meters).
So, the Sun is 500*300,000 kilometers away from the Earth. That gives us 150,000,000 (150 million kilometers)
which is 93,210,000 miles (1 km is equal to 0.6214).
That was the estimation and what is the exact distance from Earth to the Sun?
As we can read in wikipedia Earth’s aphelion (farthest distance beetwen two astronomical objects) is 152,097,701 km, perihelion (closest distance) is 147,098,074 km and the semi-major axis (average distance) is equal to 149,597,887.5 km. So, as you can see, our calculation is very good and approximation error is small.
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