How Many Miles is the Earth From the Sun?

The terrestrial planets
The Earth is the third planet from the Sun, and the largest of the terrestrial planets. But how many miles is the Earth from the Sun? The Earth’s average distance from the Sun, which astronomers call the semimajor axis, is 92.96 million miles.
But remember that this is an average number. The Earth actually follows an elliptical path around the Sun. At the closest point of its orbit, called perihelion, the Earth is only 91.40 million miles. And then when it’s out at the most distant point of its orbit, called aphelion, the Earth reaches 94.51 million miles.
Astronomers use the Earth’s average distance from the Sun as a standard yardstick for measuring distances in the Solar System. This Earth Sun distance is called an astronomical unit. So, the average distance from the Earth to the Sun is 1 astronomical unit, or 1 AU; and the distance from Mars to the Sun is 1.524 AU, on average. And the average distance from Pluto to the Sun is 39.48 AU.
We have written many articles about Earth for Universe Today. Here’s an article about the temperature of Earth, and here’s an article about why the Earth has seasons.

The shape of the earth is spherical in shape

Distances in the Solar System
Ancient astronomers, especially the Greeks, tried estimating the distance to the Sun in several different ways: measuring the length of shadows on Earth, or comparing the size of the Moon and its orbit to the Sun. Unfortunately, their estimates were off at least by a factor of 10.
The key to figuring out the distance to the Sun came from observing Venus as it passed directly in front of the Sun. This rare event, known as a Transit of Venus, happens only twice every 108 years. Once devised, the best opportunities for taking this precise measurement came during the Venus transits of 1761 and 1769. Astronomers were dispatched to remote corners of the globe to observe the precise moment when Venus began to move in front of the Sun, and when it had moved completely across the surface.
By comparing these measurements, astronomers could use geometry to calculate exactly how far away the Sun is. Their initial calculations put the distance at 24,000 times the radius of the Earth. Not bad considering our modern measurement of 23,455 times the radius of the Earth.
Modern astronomers can use radar and laser pulses to calculate the distance to objects in the Solar System. For example, they fire an intense beam of radio waves at a distant object, like Mercury, and then calculate how long it takes for the waves to bounce off the planet and return to Earth. Since the speed of light is well known, the return travel time tells you how far away the planet is.
Astronomy has truly helped us find our place in the Universe. It nice to be living in a time when many of these big mysteries have been solved. I don’t know about you, but I can’t wait to see what’s around the corner of the next discovery.

Venus Transit