How many moon of Jupiter can I see through my telescope? I have an 11" SCT. Of course, the 4 Gallilean

Question

moons are visible but could some the the other points of light possibly be moons?

Answer 1

Luvlaket:  You can see the four Galilean satellites of Jupiter and that's it.  You actually can see more moons around Saturn on a good night.  

Jupiter is very bright but any star that is in the same brightness league as the Jupiter's moons will be visible as Jupiter goes by.   The moons themselves are magnitude 5-6 depending on  the moon and how far Jupiter is etc.   Seventh and eighth magnitude stars & brighter will as a rule not be blotted out (until they are very close).  At high power in your C11 however the four Galileans should show as resolved disks.   But if you're watching *all* four satellites in your narrow field C11 then odds are you're going to be at lower power (and a wider field of view).  That means your chances of viewing a star near Jupiter are increased.  Since Jupiter itself moves relative to the background, and since the Galilean satellites are moving, you can definitely get the impression that a star is slowly moving in relation to Jupiter and the other satellites.  

The best way to keep track of the stars is with a software program.  However, most people do that with Saturn not Jupiter because (a) Saturn is dimmer so more stars are visible around it and (b) the moons of Saturn don't resolve into disks the way the Galilean moons of Jupiter do.    But, in lower powers, as your field gets wider, you will see more stars around Jupiter and some of them will look like they're in the same plane as  the moons.  Most of these stars will eventually disappear in the glare of Jupiter which will illuminate the least bit of haze in the sky like a search light.   A very few stars are bright enough to be followed all the way till Jupiter runs over them and then you get an occultation, but there's usually lots of publicity for that.  

On August 14th from about 9:30 p.m. thorugh the 15th at 3:30 a.m. there will a magnitude 8.9 star and two magnitude  11.6 stars all within about two arc minutes of Jupiter--approximately the same distance as the moons.  They will be close but not occulted.  This is a good time to see how you do looking for extra "satellites."  My bet is you'll catch the mag 8.9 star but miss the other two.  The danse of the satellites will make that star look like "one of the crowd."  Jupiter will move relative to background stars at the apparent speed of about 1 arc minute every five hours.  By comparison Io will be moving about 1.5 arc minutes every five hours (relative to Jupiter).  

I can say that even though Jupiter is in the dense star field of Sagittarius right now, clicking through the hours one gets a strong sense that it's not all the time that a mag 8 or brighter star gets near Jupiter.   But the rich Sagittarian star field helps explain your sightings of extra stars.   Almost any bright star within 5 arc minutes of Jupiter will look like a moon to the unwary.    I suppose if the star were *real* bright than it would be obvious.  But the brighter they are, the less of 'em.  

Hope that helps,

GN

Answer 2

I think maybe the first answerer was just taking a wild, uneducated guess.

You should not be able to see any of Jupiter's other satellites.  The largest is less than 1/10 the size of Europa.  Two were discovered in the late 1800's with large telescopes, (like 36 inch.).   Several were discovered in the 1900's and most were discovered by probes in this century.  The best magnitude for any of these is 14, beyond the range of your telescope.

Answer 3

In my eight inch SCT I can always see 4 -- once in a while younger observers with better eyes say they can see 5.

But this old guy can only see 4. :)

Answer 4

the 4 closest ones in the west right now

with an 11 inch you'll see amazing shots!

here you go right in milford

https://www.highpointscientific.com/stor...

after you get your scope asktheastronomer will help you learn the night sky !

asktheastronomer for telescope and astronomy help !!

also teaches how to observe the night sky !

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Answer 5

About ten.  And Brant is wrong again.  Jupiter's moons include four Galilean satellites. They are named so because they were the only four moons that Galileo was able to see. They are also the largest of Jupiter's moons.  they are Ganymede, Callisto, Europa, and Io.  Ganymede is a very large moon, one of the largest in the solar system.  Sorry Brant, wrong again.

Answer 6

I have seen up to 6 but that took a 24 inch RC at a professional observatory on an exceptionally clear night.  It was unforgetable!