What does it mean when planets are in retrograde?

At the start of 2022, Venus and Uranus are both in retrograde. And on January 14, Mercury is in retrograde.

Speedy Mercury is going to be in retrograde a grand total of 4 times in 2022. Uranus? Twice. And Mars, Jupiter, Saturn, and Pluto all have one retrograde period this year.

Whew! That’s a lot of backward action!

But what does it mean when a planet is in retrograde? It means that as viewed from Planet Earth, the planet in retrograde appears to be moving backward as it travels across the night sky.

This is called an apparent retrograde, because the planets don’t really change direction. It’s an illusion. It’s all about how they appear to be moving in relationship to Planet Earth.

All planets and Pluto orbit the sun in a counterclockwise direction as viewed from the sun's north pole. When we see planets at night on Earth, they usually seem to move from west to east.

This is called prograde. This word has Latin roots: pro means “forward” and “gradus” means step.

Retrograde is the opposite. In Latin, “retro” means “backward.” So retrograde means “backward step.” It means the planets appear to go from east to west.

And then, after a while, the planets appear to switch back to prograde again. But why does this illusion of apparent retrograde happen?

An apparent retrograde will happen when a planet that moves faster in a solar orbit passes a planet that moves more slowly. At first, the planet may appear to slow or stop in the sky. Then, as it passes by, it appears to change direction before appearing to go prograde again.

For planets slower than Earth, think of it this way. Let’s say you’re in a race with a friend. They’re allowed to walk, but you’re allowed to racewalk. So you give your friend a head start.

When you first start racing, your friend will appear to be ahead. But you’re faster, so you’re going to catch up and pass your friend.

As you catch up, your perspective changes. For a few moments, your friend appears to be moving backwards in relationship to you! Then, as you race ahead, your friend once again appears to be moving forward.

However, you’re both still moving forward. No one ever changed direction. It’s an illusion of relative perception.

The same thing happens when Earth passes the 5 slower outer planets and Pluto. When the Earth passes them, they appear to go backwards from the perspective of someone on Earth.

But the two inner planets - Mercury and Venus - are faster than Earth. To understand how those of us on Earth perceive their retrograde motion, think of yourself watching a race on an oval track.

You’re in the stands, walking slowly from left to right. You represent Planet Earth.

There are only two racers on the track. They represent Mercury and Venus. Mercury has the inside lane and is a fast runner. Venus has the outside lane and is also slower than Mercury.

At the start of the race, you see Mercury and Venus take off from the left. As Mercury rounds the track, it will appear to slow and even briefly stop. Then, it will appear to go left as it goes around the track.

Even though Venus is slower than Mercury and in the outer lane, it’s still faster than Earth. Venus will keep moving forward on its orbit around the track. But from your Earth perspective, it will appear to slow then change direction as it goes around the curve.

Some people like to believe that planetary retrogrades influence human life on Earth. They assign special meaning to this natural visual phenomenon.

For example, many people like to blame the Mercury retrograde for their personal or professional problems. Supply chain disruptions or traffic bottlenecks? Wifi drops or credit card won’t swipe? An argument with a friend or an autocorrect mishap? They’ll blame it on the Mercury retrograde.

But these kinds of mishaps happen all the time! So why blame it on a retrograde?

This notion comes from the idea that Mercury -- the mythical messenger God and the planet’s Roman namesake — has lost his way. Because the God Mercury is going backwards in the sky, he has lost command over his spheres of influence: communication and transportation. 

Scientists, though, have shown no relationship to the movement of planets and stars that can significantly impact your personal or professional life on earth. When someone says that a planetary retrograde is affecting them personally, you can say “it’s just an illusion!”

But it’s a fun one!

Visual illusions like retrogrades can inspire lots of artistic interpretation. They get us to think about history and the evolution of our understanding of the natural world. They inspire centuries old myths and legends. 

A retrograde can also get us to think more deeply about our perceptions of what we observe. Scientific methods can help us design experiments and explanations for the unusual phenomenon we see.

How may things not be what they seem? And what stories can you tell to explain what you see?