Meet the Oddball Planets

The planet Uranus is often called the oddball of the Solar System because it’s tipped over sideways.

Uranus’s axis of rotation is tilted approximately 98° relative to its orbital path around the Sun, but Uranus isn’t the only planetary body with an “odd” axial tilt.

Just recently, we learned that Enceladus, one of Saturn’s icy moons, may have been knocked on its side by an asteroid impact at some point in its history. If that’s true, Enceladus has since reoriented itself. Being sideways was only a temporary thing in that case.

But then there’s Pluto. Pluto is also tipped on its side, as is Charon, Pluto’s largest moon.

In fact with an axial tilt of 122° relative to their orbital path around the Sun, you could argue that the Pluto/Charon pair is almost upside down.

Which brings us to Venus. Venus’s axial tilt can be defined in two different ways. You could say Venus is rotating backwards, clockwise where the other planets rotate counterclockwise, with a modest axial tilt of about 3°. But it’s equally valid to say Venus’s rotation is normal (i.e.: counterclockwise) but that the planet is flipped upside down, with its axis of rotation tilted 177°.

Of course there’s really no such thing as up, down, or sideways in space. Directions are relative to your point of view. The planets simply are the way they are, a result of each planet having its own unique history, without regard for what we humans might consider “normal.”

Maybe we should keep that in mind before we start labeling planets oddballs.

8 thoughts on “Meet the Oddball Planets

  1. Wow. Cool post. Good going pointing out that Venus might be going backward or it might be upside down. It’s another one of those things that I think maybe you and I have traded comments about (or maybe I’m misremembering) about how there’s always, and with reason, a geocentric attitude toward things. Maybe we’ve got it all wrong. I’ve had an idea for a while for a post that crosses over this one. So, if it’s okay, I might nod back to you if I ever get around to writing it.

    Liked by 1 person

    1. Please do! Sounds cool, and I look forward to reading your post.

      I think you’re right. We probably have talked about this before. I have sort of mixed feelings about geocentrism. In some ways, it makes sense. We live on Earth, and therefore when we look out on the rest of the universe our perspective is understandably and unavoidably Earth-centric.

      If we all moved to Mars, then our perspective would be unavoidably Mars-centric (areocentric?). I guess my point is that we need to remember these things are all a matter of perspective, not absolute truths.

      Liked by 1 person

      1. Absolutely. It’s important to remember that it’s just our view from here. I like to tell people there’s always some place where the Moon is full and always somewhere the Sun’s eclipsed. We take value from our perspective, but our view isn’t necessarily the universe’s.

        By the by, sorry I never followed through on the award you gave me in the spring. I very much appreciate it, but just haven’t had the chance to tend to it.

        Liked by 1 person

      2. Hey, no worries about that. I got another one recently, and I just haven’t had time to do anything with it either. I think those kind of awards can be fun, but space blogging must come first!

        Liked by 1 person

  2. Orientation in space is indeed a tricky thing. Most of the matter in the solar system is concentrated along the ecliptic plane, and everything more or less orbits in the same direction, with their rotation roughly in the same direction as well, except for the oddballs.

    Once we get to the Kuiper Belt, having orbits modestly off the ecliptic becomes more common, so Pluto and Charon’s orbits seem to “fit in” out there. I suspect their axis of rotation won’t be that unusual for KBOs either.

    But even Earth’s axis is skewed, making the celestial equator 23 degrees off the ecliptic, so it’s all matters of degree rather than sharp distinction.

    And of course, the solar system ecliptic itself is 60 degrees out of whack with the galactic plane. So ultimately we’re all oddballs!

    Liked by 2 people

    1. You raise a good point about Earth. Earth’s tilt is extremely important. Without it, we wouldn’t have seasons, and maybe this planet wouldn’t be such a nice place to live.

      In fact the only planet that’s close to “normal” in regard to axial tilt is Mercury, and that’s one of the things that makes Mercury kind of odd.

      Liked by 1 person

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