What does it mean when a planet 'goes retrograde'?

Mercury doesn't actually move backwards.

By Erin Cook

Disclaimer: If you're not into astrology, look away now — we're about to go all 'woo woo' you.

This month, the astrologers of the internet can't stop talking about the planets going retrograde. While Mercury retrograde usually gets the most attention, Mars retrograde is also shaking things up. (Just so you know, Mars is in retrograde until August 27.) Later this year, Uranus, Neptune, Pluto and Venus could also throw you off-kilter.

Planets in retrograde: what does it mean?

When a planet is in retrograde, it means that they're moving backwards. Well, sort of. While the planets can't technically switch directions, at certain times of the year, they appear to do just that.

As astrologer Hedy Damari explains, "Retrograde refers to when a planet appears to be moving backwards, in its orbital path. It isn't really [moving backwards], it just looks that way."

Why do the planets appear to move backwards?

It all comes down to the orbits. All planets orbit the sun, however, their individual orbits all vary in distance. As Susan Miller explains to Astrology Zone, Mercury is the planet closest to the sun, so its orbit is much shorter than Earth's. About three or four times per year, Mercury speeds past earth — but from our perspective, the planet appears to be moving backward.

"If you were in a car and another car passed you, you could tell it was going faster than you," Miller says. "But if it slowed down and you then passed it, it would appear that that car was actually going backward."