The Truth About “Planetary Aligments”

Rare planetary alignment happening soon….

You probably read those words a lot if you pay attention to astronomy-related posts. But articles and posts about this rare event seem to happen every month, so what’s really happening here?

For starters, the graphics many of these news stories and social media posts use to represent planetary alignments are highly misleading. For example, this image below shows a recent graphic describing an upcoming rare planetary alignment.

An image from a news article depicting a planetary alignment. (with editorial commentary)

There are SO MANY things wrong with this image but let’s focus on the fact that no one in their lifetime is ever going to see all the planets in a straight line like this. At best we will see a couple of the planets appear near each other in the sky like the Great Conjunction of 2020 when Jupiter and Saturn were within a half a degree of each other. Having them all align like this could happen but would likely only happen once in millions of years. That would truly be rare, and spoiler alert, we are never going to see this in our lifetime (see diagram below of this “alignment” that is never going to happen in our lifetime)

The planets all in a line like this, is never going to happen in our lifetime.

However what these articles fail to convey is that our planets are almost ALWAYS aligned, just not in the way they are depicting.

All of the planets orbit in nearly the same plane around the sun. The plane of the Earth’s orbit is called the Plane of the Ecliptic, and all the other planetary orbits line within a few degrees of that plane. Mercury is the farthest off at a mere 7 degrees, and the remainder of the planets lie within or near 3 degrees of that plane (see diagram below of orbital variances). This makes them appear “aligned” in our night sky. (As a sidebar, Pluto’s orbital plane is inclined by 17° compared to Earth’s plane; another reason it’s an outlier among planets).

What these articles are typically referring to when talking about alignments, is that the planets are all or mostly on one side of the solar system, which allows us to view them all in one night. Planets spread across the solar system would mean some of them would be on our daytime side, and others on our night time side. Right now, all of the planets with the exception of Mercury are on our night time side, because of the Earth’s position in its orbit. This permits viewers to see them all during a window of a few overnight hours, some visible to the naked eye, and others like Uranus and Neptune, requiring binoculars or telescopes to see.

But they still appear aligned because they lie near the plane of Earth’s orbit (plane of the Ecliptic). This is more commonly, and correctly, referred to as a parade of planets, and due to the much slower orbits of the outer planets, Jupiter, Saturn, Uranus, and Neptune will remain on one side of our solar system for the next few years.

Currently, Mars, Jupiter, Saturn and Venus are all visible after sunset (although Venus sets within a couple hours). They sit within a 145 degree angle which allows them all to be seen at the same time (see next diagram). Neptune and Uranus are also within this 145 degree angle, but they require assistance to see, with binoculars or telescopes.

January 2025, almost all the planets are on one side of the solar system. This facilitates what is known as a “parade of planets”.

This will recur for at least several more years and the parade of planets will be visible as seen in the 2022 photo below taken at Alms Park in Cincinnati. The red line depicts the Plane of the Ecliptic, and shows how close all the planets lie near that plane.

Now you know how to read these stories about “rare planetary alignments”.

Get outside over the next few months and see this Parade of Planets and let us know when you see it.