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Jupiter's moons through binoculars


SpaceBug
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Hi :smiley:. A few days ago I went out with a pair of 10x50 binoculars for some stargazing. I've read on several forums and articles that you are easily able to see Jupiter's four largest moons through binoculars. However, when I looked at Jupiter, at first I was not able to make out any moons at all. I tried to use averted vision and I was able to see only one faint dot that I suspect was a moon. A bit earlier, I also looked at Venus, as I had read that you could see the crescent shape of the planet with binoculars. But no shape was visible and all I could see was a bright point of light :sad:.

I suspect that perhaps my binos are out of focus or something? But that would be weird, since I can see the moon very crisp and clear. Or could it be light pollution, since I live in a fairly polluted area (Bortle 6 or 7)?

Thanks!

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Should be easy enough to see, can vary from 2 to 4 as some hide behind Jupiter.

They are not overly bright but visible, I use 8x42's and can see them as small bright points, also usually looked at from the front door in the town I live at. So also have light pollution to contend with.

Best I can think is there was some high thin cloud or mist that was just sufficent to lose the light from the moons.

I suppose there is the slight chance that you had the moons either in front of or behind Jupiter so they just were not visible at that time but I think that the chances of that are small.

Never seen much of Venus other then a bright blob. Would really not have expected detail down to cresent level. Also it is low and the atmosphere could easily make decent viewing difficult.

Which night were you looking at Jupiter and the time, just thinking there must be something to show the positions of the moons and just maybe they were in line with Jupiter, either in front or behind.

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Hi. I have a pair of cheap 8x60's and I can see the 4 moons with my binoculars. I think it will depend on seeing as well as light pollution because I have found that I can't always see them. It helps to hold the binos steady by leaning against a wall as the moons are very small points of light with such small magnification.

Michael

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You need good binoculars to see Venus as a crescent, average ones won't show it crisply enough.

As for not seeing Jupiter's moons, they appear quite close in at 10x. Anything to steady the binoculars helps, whether it's a tripod, an upturned broom, or just a better holding technique. If they're actually too dim to see, I'd check the following in order:

The binocular coatings. Faint blues or greens are fine. Intense reds or oranges are bad, they cut out a lot of light.

The binocular exit pupils. Point the binoculars at a well-lit surface and hold them at arms length. Circles of light over the eyepieces are good. Cats-eye shapes are bad, that means the prisms are misaligned, again losing light.

The sky. Thin cloud will make stuff look dimmer.

The binocular objectives when you're using them. Dew will make stuff look dimmer.

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You need good binoculars to see Venus as a crescent, average ones won't show it crisply enough.

As for not seeing Jupiter's moons, they appear quite close in at 10x. Anything to steady the binoculars helps, whether it's a tripod, an upturned broom, or just a better holding technique. If they're actually too dim to see, I'd check the following in order:

The binocular coatings. Faint blues or greens are fine. Intense reds or oranges are bad, they cut out a lot of light.

The binocular exit pupils. Point the binoculars at a well-lit surface and hold them at arms length. Circles of light over the eyepieces are good. Cats-eye shapes are bad, that means the prisms are misaligned, again losing light.

The sky. Thin cloud will make stuff look dimmer.

The binocular objectives when you're using them. Dew will make stuff look dimmer.

Unfortunately, the coating has a pretty intense orange colour :/

The exit pupils are perfectly round circles, but I can see a small grain of dust in there. I don't know how it made it in there though, as I have never opened them up...

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Unfortunately, the coating has a pretty intense orange colour :/

That probably accounts for your viewing troubles then. The odd bit of dust in the optics is no big deal, and as for air bubbles, while a sign of poor quality I don't know what effect they have on the views. But the orange coatings are not good.

You could try figuring out just what your limiting magnitude with them is, to quantify just how they're performing. But if you come to look for a new pair (quite probably), http://binocularsky.com/ has good advice and the site admin's a regular here.

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Hmm, I also have an old pair of 8x42's. I suspect they are better, since they have no colour on the coating. They also seem to be of an overall better quality  :p. I simply chose the 10x50's because of their larger aperture, but it seems like they are not supposed to be used for astronomy :Envy:.

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Hi :smiley:. A few days ago I went out with a pair of 10x50 binoculars for some stargazing. I've read on several forums and articles that you are easily able to see Jupiter's four largest moons through binoculars. However, when I looked at Jupiter, at first I was not able to make out any moons at all. I tried to use averted vision and I was able to see only one faint dot that I suspect was a moon. A bit earlier, I also looked at Venus, as I had read that you could see the crescent shape of the planet with binoculars. But no shape was visible and all I could see was a bright point of light :sad:.

I suspect that perhaps my binos are out of focus or something? But that would be weird, since I can see the moon very crisp and clear. Or could it be light pollution, since I live in a fairly polluted area (Bortle 6 or 7)?

Thanks!

I also have a pair of old 10x50's and I have never been able to make out the moons either so your not the only one. I will say though they are old, left to us by my grandad who died in 1988 & I live in a very LP area as well so these factors probably dont help.

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Jupiters moons are quite easy to spot. I was looking at jupiter with my 90mm mak from my living room and my kid was "looking" at stars with his yellow plastic toy binoculars. I wondered if he could see _anything_ with that toy. I tried and I saw the jupiter and it's 4 moons fine with that toy. For a while I had this sensation of "If only Galileo would know", our kids get plastic toys which are on par with his scientific instruments. 

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I also have a pair of 10x50 binoculars and I can see Jupiter's Galilean moons with them, as well as (just) Saturn's shape with the rings, good views of the Orion Nebula and the Andromeda galaxy. I don't live in a heavily light polluted area but there is some so the higher in the sky, the later at night it is, I've found the viewing to be clearer/brighter (also weather depending, of course).

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