How many of the 4 galilean moons are visible now(in august)?

Question

how many of the 4 galilean moons can be seen in august.

I mean, how many of the 4 galilean moons are not behind or not infront of jupiter. They should be at the side of the jupiter, so that they can be seen from earth with a small telescope.

Answer 1

All 4 are visible.  Occasionally one will orbit the other side of Jupiter but it only takes a day or two to get back around to where you can see it again.  Sometimes they are in front of Jupiter and you see them as a black dot on the surface of Jupiter.  We call that a transit.  

  

Answer 2

All four moons are visible almost all the time (at least 95%). Once every orbit each moon passes in front of and behind Jupiter for a couple of hours, with the exception of Callisto which sometimes passes above or below Jupiter's disk. When the moons cast their shadows on Jupiter, these shadows are readily visible in small telescopes as tiny black dots. When Io and Europa pass in front of Jupiter, they usually disappear into the background. When Ganymede and Callisto pass in front, they usually appear as grey spots which need about a 5 or 6" scope to resolve.

The phenomena of Jupiter's moons are predicted in the RASC Observer's Handbook and Sky & Telescope, or can be seen in any good planetarium software.

Answer 3

All four were visible last night when I observed, though it looked as if Europa was about to go behind Jupiter. But the orbits on those little guys are so fast that it only takes a few days for them to come back out again. If your lucky, you get to see the transit... where a moon is passing in front of Jupiter. I saw Europa's transit once.

So tonight you can probably catch all four. And if not, then wait a few days and they will all be out.

None of the Galilean moons are in front of Jupiter currently, so your good to go.  

Answer 4

all of them, almost all the time.

in addition to the references geoff cited, like the rasc observer's handbook and sky & telescope, any decent astronomy program will predict their positions.

i watch ganymede transit jupiter a couple of weeks ago. it was really cool.

Answer 5

They are all visable!