A question about Jupiter for ATS??

Okay, I just had a random question about the planet Jupiter. I just downloaded an app for google chrome called "Planeterium". I like it alot. I just want to know if any ATS'ers have the app. Jupiter goes into Gemini in around January headed one direction then in april-may in turns around to exit gemini in the same direction it entered. I am a novice observer and my first thought was, this is where jupiter is making somewhat of a turn, back towards the sun??. Just a noob question????
Sry if this is in the wrong place.?

reply to post by AKINOFTHEFIRSSTARS


From what you're describing, it sounds like you're talking about what's called retrograde..

www.universetoday.com...

reply to post by AKINOFTHEFIRSSTARS


We, the planey earth, are passing around the sun in a way that makes it appear to be moving in that manner. In fact, Jupiter is moving soooo much slower than the earth that it's virtually standing still, in comparison to us, and as we swing around the sun, Jupiter will seem to move back the other way. Hope I'm explaining this in a way that you can understand me.


Let's say that We are on one side of the sun and jupiter on the other. As we move in one direction, jupiter will seem to move in our perspective in one direction. When we swing around to end up on the same side of the sun as jupiter, it will seem to move the other direction because we will be moving faster than it and at some point pass it up.

Thanks guys.
Great information.

reply to post by AKINOFTHEFIRSSTARS


ok - a very heavily simplified depiction of retrograde :

earth has an orbital period of 1 year , the orbital period of Jupiter = 12 years . thus over stylised 6 month period

earth has " moved " 180 degrees on its orbital path - but Jupiter has only " moved " 15 degrees

hence - when Jupiter is viewed against the stellar background :



simples - Jupiter appears to move backwards

reply to post by AKINOFTHEFIRSSTARS


Looks like you got some good posts explaining why Jupiter appears to do this. Mars is a better example as it's closer to us and orbits the sun faster, so you'll see it do the same thing.

All of the planet's past Earth will appear to do this, with the planets further away taking longer to do so.

Venus and Mercury being closer to the sun than us will not appear to do this, because they are over taking us (the Earth). If you could be on Venus and watch the Earth, it would appear to turn around and reverse direction too, then reverse again and continue on.

Copernicus explained the physics of retrograde motion, and then Kepler discovered that the orbits of the planets were not perfectly circular.
Taken together, these discoveries complement each other and resulted in our true understanding of how planetary bodies are observed as they orbit the sun.