Did I see 5 of Jupiter's moons tonight?

[MarkVIIIMarc]

Just coming in from observing. 

Using my 9mm and 6mm eyepieces it seemed I could see 5 moons around Jupiter and the red spot.

The moons were located 2 to "telescope left" of the planet and 3 to the right, two of those far out one above the other.

The red spot appeared to be near top and center on the planet.

Sounds like a silly question but did I see that right?  It could have been a star following the planet about.  FWIW, I followed it for the better part of an hour and it seemed to stay in place.  Also, was that where the red spot was or was I adding detail to what I could see?

Thanks in advance.

[Joe12345]

I think you might have been seeing a star. There were a few around Jupiter last night. I've posted a picture below, so take your pick. Remember that right will be left and left will be right.

[andyboy1970]

The moon Amalthea at mag +15 was showing on Stellarium last night, it was close in to the Planet.

[michael.h.f.wilkinson]

The next brightest moon after the Galilean quartet is Amalthea, which is close in to Jupiter and has an apparent magnitude of about 14.1 (max). Himalia is next at 14.6 (but is further out). In theory these magnitudes should allow them to be seen in largish amateur telescopes, but the glare from Jupiter would make that near impossible

[Stu]

From what you describe it was a background star, HD95848 which appears exactly where you say you thought the fifth moon was. It is showing as mag 7.2, a little dimmer than the moons themselves.

GRS appears to have been centre of the disk at around 11pm your time (23.08), does that tie up with when you were observing?

[Peder]

I had a chance to see the same thing through the 14" Celestron at the roof of the department of Astronomy at Lund University in Sweden Monday night. According to their PhDs it was a background star.

[Peter Drew]

Interestingly, whilst observing Jupiter last Saturday night I noticed that Jupiter had the appearance of having 5 moons. Now I'm an experienced observer and know full well that the 5th "moon" was a star. A little later, to my surprise, another faint star appeared next to Jupiter that I had somehow overlooked, as I watched it gradually brightened to reveal itself to be Io coming out of eclipse. What I had suspected of being the genuine 4th moon originally was in fact another star dead in line with the true moons. Just goes to show that you can always be mistaken if you're not carefull.  6 moons that night!   

[laudropb]

I had exactly the same experience Peter.

[Linda]

We saw the same phenomenon on Saturday night. I let my husband view Jupiter through the scope and he was convinced there we 5 moons, not matter what I said. But you can always check it afterwards in Stellarium and adjust the time to check what really was the matter.

If you have a bigger scope, you might be able to see the moons as small discs and the stars as pinpoints. 

[MarkVIIIMarc]

7 hours ago, Stu said:

From what you describe it was a background star, HD95848 which appears exactly where you say you thought the fifth moon was. It is showing as mag 7.2, a little dimmer than the moons themselves.

GRS appears to have been centre of the disk at around 11pm your time (23.08), does that tie up with when you were observing?

Yup, that lines up pretty well with what I saw!

Thanks everyone for taking the time to explain things to me.

[BeerMe]

8 hours ago, Linda said:

 

If you have a bigger scope, you might be able to see the moons as small discs and the stars as pinpoints. 

The 3 times I've observed Jupiter so far, the moons have always been very distinctive on my 130 even when stars have been in the vicinity.  As you say, they are small flat discs and very well defined when I get the focus spot on, and they are also brilliant white compared to the stars nearby.

I've yet to see all 4 moons at one time though, it's been 3 each time.  How often does it happen?

[Space Hopper]

Almost certainly the star HIP 54057

[Linda]

10 hours ago, BeerMe said:

The 3 times I've observed Jupiter so far, the moons have always been very distinctive on my 130 even when stars have been in the vicinity.  As you say, they are small flat discs and very well defined when I get the focus spot on, and they are also brilliant white compared to the stars nearby.

I've yet to see all 4 moons at one time though, it's been 3 each time.  How often does it happen?

You can install a phone app, jove moons or moons of Jupiter. There you can follow them and look ahead in time.

Edited April 14, 2016 by Linda

[Joe12345]

9 hours ago, BeerMe said:

The 3 times I've observed Jupiter so far, the moons have always been very distinctive on my 130 even when stars have been in the vicinity.  As you say, they are small flat discs and very well defined when I get the focus spot on, and they are also brilliant white compared to the stars nearby.

I've yet to see all 4 moons at one time though, it's been 3 each time.  How often does it happen?

If a moon's missing, it has to be somewhere - either behind Jupiter's shadow or disguised in its surface. If you keep watching, or coming back to Jupiter every 15mins, you might be able to catch either a shadow transit, or one of its moons appearing. I'm always more excited to see 2 or 3 of them! I think it's more likely for all the moons to be there than one missing, so it shouldn't be too long before you catch them all.

[rwilkey]

Amalthea, one of four inner moons is not large enough to pick up in an amatuer scope.  The only other moon besides the Galilean moons that can be picked up in an amatuer scope is Himalia, often found some distance from Jupiter.

[Owmuchonomy]

18 hours ago, BeerMe said:

The 3 times I've observed Jupiter so far, the moons have always been very distinctive on my 130 even when stars have been in the vicinity.  As you say, they are small flat discs and very well defined when I get the focus spot on, and they are also brilliant white compared to the stars nearby.

I've yet to see all 4 moons at one time though, it's been 3 each time.  How often does it happen?

Easily done because Callisto orbits much further out than the other 3 so can be at the edge or even out of the field of view depending upon what your kit is delivering.  Look slightly further afield in case its lurking out there. 

[Owmuchonomy]

21 hours ago, BeerMe said:

The 3 times I've observed Jupiter so far, the moons have always been very distinctive on my 130 even when stars have been in the vicinity.  As you say, they are small flat discs and very well defined when I get the focus spot on, and they are also brilliant white compared to the stars nearby.

I've yet to see all 4 moons at one time though, it's been 3 each time.  How often does it happen?

This is the view right now. See where Callisto is?

 

[LukeSkywatcher]

Very common mistake. Most people see 5 "moons" when observing Jupiter. Only 4 of them are actual moons and the 5th is just a background star.

[Relpet]

On 4/13/2016 at 11:33, laudropb said:

I had exactly the same experience Peter.

Now I know I'm in excellent company!