August 21 is the Great American Eclipse the first total solar eclipse in American history exclusive to the US. Elsewhere on Earth, though, a total solar eclipse occurs roughly every 18 months. But what about other planets? Can they happen there?

Mercury No. In a total solar eclipse, a moon slides between a planet and its sun, blocking the suns light and casting a shadow on the world below. But Mercury doesnt have a moon, making eclipses there impossible.

Venus No. Venus doesnt have a moon either. But that doesnt mean there arent eclipses. Venus has planetary eclipses or transits caused by Mercury orbiting between Venus and the Sun. Earth experiences transits, too, every time Mercury or Venus pass between the Sun and Earth. But theyre rare. Mercury and Venus transit Earth 8 years apart, then it takes over a century for the cycle to start over. The next planetary eclipse here on Earth is December 11, 2117.

Mars No. Mars has two moons, Phobos and Deimos, so solar eclipses are totally possible they just arent total. Theyre annular. Just like a total solar eclipse, the moon passes between its planet and the Sun, covering the Suns center. But when a moons too far from the planet to cover the Sun or as with Phobos and Deimos too small, the rest of the Sun sticks out around the sides. See one for yourself in this video Curiosity Rover took on Mars September 13, 2012:

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Total eclipse of a planet | Astronomy.com - Astronomy Magazine