# Tag Info

19

Every Galilean moon and inner moon go into lunar eclipse once per orbit. How often is there a lunar eclipse of the Jovian moons? I set up a little animation of the Galilean moons (I didn't include the inner moons), and made a few assumptions (negligible moon size, sun at infinity, perfectly circular orbits) and found that there is a lunar eclipse in the ...

15

The orbits of the Galilean satellites have a roughly 2° incline. Based on their distance from Jupiter and on the radius of Jupiter, I computed the apparent diameter of Jupiter from these satellites. The apparent diameter of Jupiter from each of these satellites is 19°, 12°, 7.5° and 4.3° for Io, Europa, Ganymede and Callisto respectively. Therefore, the ...

9

You can simply startup Stellarium and have a look yourself. Choose any locations you are interested in. The Galilean satellites of Jupiter are inside the default list of locations. The attached image shows Jupiter as viewed from Io at the given time, Europa is the bright object to the right; with -9 mag it is considerably brighter than Venus when viewed ...

4

As in real estate, so in astronomy: Location, Location, Location Where an object forms in a system will significantly impact its makeup. For example, during the stage of planet(esimal) formation, due to the radiation of the (proto-)star, various chemicals and atoms will be expelled from the innermost areas, but may stay around long enough to be part of ...

4

They might escape from the solar system, if the angles are right. If not, they'll probably wind up in elliptical orbits around the Sun. We'll use a simplifying assumption that the orbits are circular to make the calculations easier; All objects mentioned have orbital eccentricity of less than 0.05. The mean orbital velocity of Jupiter is 13.1 km/s, which ...

4

I've noted before that the IAU naming critera are guidelines rather than laws of nature. If applied to Jupiter's moons the four Galilean satellites would probably be "planets" (they don't share their orbits with anything else of comparable size and are large enought to be in hydrostatic equilibrium) There is a mean-motion resonance 4:2:1 between ...

4

For what it's worth, I just got a shot of what looked like a 5th Galilean moon near Ganymede tonight (from South Florida). Here's a quick, unprocessed image. I thought I was going crazy seeing an extra moon (in the correct plane) that kept showing up. But looks like it's HIP 99314 (2nd dot to the upper left of Jupiter).

3

The answer is a strong maybe. The International Occultation Timing Association (IOTA) produces predictions for such events. Their webpage Major Planet Occultation Predictions lists the occultation of HIP 99314 by Jupiter, but it does not list an occultation by its moon Ganymede. Date U.T. Durn Star Star Planet y m d h m ...

2

Some time back, I made a jupyter notebook (in French, but the names of the satellites are similar enough) that compares the angular diameter of Jupiter as seen from its moons to the angular diameter of our own Moon seen from Earth. This way, you can get an idea of how big Jupiter would look in comparison to a more familiar sight. For instance, if the Moon (...

1

I did not find any Richter-scale numbers for Io, probably since there are no direct measurements yet, or how atmosphericprisonescape puts it: Nobody put a seismometer on Io yet, so we don't know. The only other bodies except for Earth, where seismometers have been placed so far are the Moon and Mars. But I found some interesting comparison at on NASA's ...

1

The need to distinguish between these potato-shaped and spherical moons hasn't arisen. As such, there aren't two different words to designate these two types of moons. And as long as the community of astronomers who study natural satellites doesn't feel the need for there to be an extra category, there likely won't be one created preemptively. Perhaps, one ...

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