Can someone explain the apparent erratic movement of Jupiter?
  • I was watching what I think was Jupiter tonight (11/17). It was very bright, and appeared to be moving somewhat erratically. Is this possible? It would be in one spot for awhile, then slowly begin moving one direction, then back in a different direction. Was this an optical illusion or is there another explanation?
  • Hi Starbird, Jupiter will not move in the sky to the unaided eye. Probably some kind of optical illusion from clouds or something.

    The International Space Station is very bright and can look like Jupiter, it moves across the sky quite fast.

    Jupiter is in the east early to mid evening, it gets higher in the south, then sets in the west by morning. Have you tried looking at it with binoculars? (10x40 upwards) Look very carefully and you'll see the four moons.
  • Thanks, Betelgeuse, for your reply to my question about Jupiter. I'm obviously not an experienced night sky gazer, but I'm pretty sure what I was watching was Jupiter. I think it was around 7:30 Central time when I first noticed it. I was looking east, and it was already fairly high in the sky. Over the next 2-3 hours it moved more to the southern sky. I was very perplexed when it appeared to be drifting one way, and then another, but if it was Jupiter, what appeared to be movement had to be an optical illusion. I'll try looking at it with binoculars, and see if I can detect the moons -- that will confirm that it is Jupiter, at least.
  • Hi,
    That definitely sounds to me like you were looking at Jupiter,rise in the east,move to south,set in west. But if Jupiter is moving and drifting about all over the place in its orbit I think we're all in trouble :-)

    Some times moving clouds can really have an effect on the eyes making you think something is really moving when it actually isn't. Try your binoculars on Jupiter Starbird to see those moons,it's pretty cool.
  • Hi Starbird,
    I have bouts of low blood pressure and what I have noticed sometimes is that tossing my head back and looking up at the stars can result in what appears to be slight movement in the stars. The seem to drift from left to right quite slowly and then sometime come back again until my balance restores.... This is especially true if I have a bit of a head cold (or possibly a couple of beers!!). Maybe what you are seeing is something similar to this.
    Obviously the orbit of any of the planet is (more or less) fixed around the sun. They can't change suddenly from this unless disturbed by excessively large amounts of energy. Even when comet SL9 hit jupiter some years ago there was no visible change in Jupiter orbit despite SL9 having more energy than the worlds nuclear arsenal by a factor of 600.

    I hope that help :o)

    S