Can the Sun be closer to the Earth than any planet is to Earth? (Intermediate)

Are there times when the Sun is closer to Earth than any planet is to Earth? In other words, are there times when the distance between the Earth and the Sun is less than the distance from the Earth to any planet? If this can happen, when is the next time?

That is possible, and it will happen later this year (2012). From September 23 to October 28, the Sun will be closer to the Earth than any planet. On September 23, Venus will be closer to the Earth but will be moving away from us. On October 28, Mercury will be moving toward us and will become closer than the Sun.

Plot of the inner solar system on October 17, 2012 (courtesy NASA/JPL-Caltech)

The diagram above (originally from here, courtesy NASA/JPL-Caltech) shows the inner Solar System on October 17, 2012, when the Sun will be 1.00 AU from the Earth, and Mercury and Venus are both 1.17 AU from the Earth. AU is an abbreviation for Astronomical Unit, which is often used by astronomers and engineers to express interplanetary distances. The average distance from the Earth to the Sun is almost exactly 1 AU.

I only discuss the inner planets, because Jupiter (and the other outer planets) can never be closer than Mars.

The NASA/JPL Solar System Simulator lets you see the positions of the planets (and more) at any time between 1990 and 2025. If you want the actual numbers, visit the NASA/JPL HORIZONS System.

This page was last updated on September 7, 2015.

About the Author

Sean Marshall

Sean is a sixth-year astronomy graduate student at Cornell who works with Professor Donald Campbell to study physical properties of near-Earth asteroids using radar and infrared data. Sean currently manages the "Ask an Astronomer" website.

 Website:  http://astro.cornell.edu/~seanm/

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