This picture purports to show what Jupiter would look like in Earth’s sky if it were the same distance from us as the Moon. Of course, I have no idea if the size is correct, but it’s still a very striking image and brings to my mind the question; what effects would Earth experience if another planet’s orbit really did bring it that close to us?
https://twitter.com/Earth_Pics/status/321480132189626368/photo/1
Well, I’ll leave stuff like the massive tides (unless Earth is tidally locked) and crazy radiation and probable loss of atmosphere to the experts and confine myself to saying:
Religion would be even weirder than it is already! Sun-worship would be eclipsed (pun intended of course) in a big way by Jupiter-worship; would we even be able to see stars to build gods around, or the other planets, with something like that lording (heh) over our night sky? So no sun-gods, no morning star, no gods made of constellations… just one big angry red eye staring down at humanity from (presumably) the dawn of time until now. Hmmm… makes one wonder.
That’s a really cool pic, thanks for sharing! Do they do pictures like this all the time, or is this a one-off?
Very nice pic. Running the numbers, Jupiter is about forty times as large as the Moon and the Moon subtends about one half of a degree, then Jupiter would span twenty degrees. (Your fist held at arm’s length is about ten degrees.)
Of course, perspective can change everything. Look at how gigantic the Moon looks in this video shot from about a mile away from the silhouetted people.
Here’s the video showing almost all the planets. link.
Sorry, I cannot answer your question.
The book The Story of Earth discusses the effects of an older, closer Earth’s Moon and its drastic impacts on tides and geology. Interesting read, and I suppose Jupiter would have even more drastic effects.
Also, it seems like having two planets that size so close together would just lead to them eventually smashing into each other, maybe a little at a time, but over the years they ought to violently fuse into one single planet? My guess.
Given the relative sizes of the earth and Jupiter, the Earth would orbit Jupiter as a satellite, rather than the other way around. Presumably the earth would have to travel at quite a clip for the orbit to be stable, given the enormous gravitational attraction of Jupiter, and the short distance between them. My guess is that the Earth would have one face permanently turned towards Jupiter, as the moon does to earth.
Since the Earth would be a satellite of Jupiter, the Earth’s year would be the same as Jupiter’s, which (in Jupiter’s current locaction) is 12 terrestrial years. However if, instead of moving the Earth to Jupiter’s current location, we move Jupiter to the Earth’s, presumably Jupiter’s orbital period in that location would be much smaller than Earth’s, given its much greater mass.
So, in this scenario, a year on Earth-the-satellite-of-Jupiter would be either very much longer, or very much shorter, than the year we now experience.
If we moved Jupiter to where the Earth is now, its orbital period would be the same, i.e. one current standard Earth year, 3.15 x 10^7 seconds. Kepler’s Third Law
Intuitively, these things spring to my mind, that a) a gas giant that close to the sun must be tidally locked to it; and b) the only way for a small rockball like the Earth to remain in a stable orbit is to sit in one of the Lagrangean points, but I will be happy to be corrected by someone with a better knowledge of astrophysics.
The earth would be in Jupiter’s shadow about half the time, so it would be a lot colder than it is now.
Oh, it would be much more interesting than that. Those who live on the Jupiter side would do all of the Jupiter mythologies and such, sure. But those on the non-Jupiter side (who would indeed see a typical night sky) would have no inkling that this huge orb fills the sky of the other hemisphere; when they get to doing some serious exploring of the other side of the planet (moon actually) at long last, imagine their utter shock and awe when they first behold it as it crests the horizon.
Plus, all those Riddick monsters…
If I did the math right, the Earth would orbit around Jupiter once every 1.5 days. Over each period, since Jupiter covers 20° in the sky we’d have 2 hours of solar eclipse. If the Earth was tidally locked, the solar eclipse would only occur for the side of the Earth that’s facing Jupiter. That would probably make that side substantially colder and subject to rather chaotic weather patterns.
Only if it were orbiting in the same plane as the orbit of Jupiter around the sun. If the orbit of earth were inclined, you could have frequent eclipses, or no eclipses depending on the angle of inclination. Of course, you could still have long periods of day and night if the earth were tidally locked, so a day would last the period of orbit around Jupiter. Unless my mental picture of this is off. 
Several good points:
Earth would be tidally locked, one face always toward Jupiter (like the moon with us). Whereever you see jupiter, it does not move, it just hangs in the sky.
The damned of the world would live on the side where they could not see the great planet of God hanging in the sky. That sort of messed up astronomy would probably result, as others mentioned, in a very different worldview, where the sun(god) is so bright and powerful but subordinate to the great stationary planet.
No tides. But unless our orbit was very neat and round (most orbits are a bit elliptical) the stress on the crustal plates would probably mean more frequent active earthquake zones. Would the continental plates eventually congregate at the closest and furthest points form Jupiter?
For a significant part of the day/orbit, earth would have an eclipse (on the Jupiter side). Possily reflection of a massive fully lit jupiter in the night sky would somehow reduce the effects of that.
Interesting to speculate on the effects of strong sunlight on Jupiter, since it’s basically hydrogen and helium - the rocky inner plantes either (a) all that stuff boiled away or (b) it was too hot, it never condensed on these planets. Jupiter likely wouldn’t be Jupiter if it was this close to the sun.
Jupiter has an extremely strong magnetic field. Not sure if our atmosphere and van Allen belts would protect us on the ground from the radiation of energetic particles in Jupiter’s belts, but space travel with current tech would be impossible. (From what I read, the big Jovian satellites are pretty much off limits for this reason. I suppose the aurora would be spectacular in a lot of places…
What about those Jovian satellites? Is it a package deal? That would certainly liven up astronomy/astrology having all those “planets” zipping around the sky. WOuld we even notice Venus or Mars? Not that they’d likely survive in their current location with Jupiter’s gravitational influence.
I suspect that in such a world, with the Earth tidally locked to Jupiter, there would not have been a Longitude Prize, at least if London was in the Jupiter-ward side.
Wow. Gives new meaning to the APP song:
I am the eye in the sky
Look at you
If the Earth was the same distance from Jupiter as it is from our moon right now, how fast would it have to travel around Jupiter to stay in orbit?
This pic was Tweeted by Twitter user @Earth_Pics. This Tweeter posts a variety of interesting and beautiful pictures of cool stuff from around the world. Highly recommended. The photos are usually the real deal and only occasionally do they use a manipulated image like this Earth/Jupiter picture.
I’m glad I brought it here. As usual, Dopers are providing some fascinating food for thought.
I notice that Io orbits Jupiter at approximately the same distance as Luna orbits Earth:
Semi-major axis (km):
Moon: 384,399
Io: 421,700
There are lots of artists conceptions of the view of Jupiter from Io. I agree that it would be quite pretty, however…
ICRP recommends limiting artificial irradiation of the public to an average of 100 mrem (1 mSv) of effective dose per year. Io receives about 3,600 rem (36 Sv) of radiation per day. So there’s that.