Jupiter's moons?

Question

Have you ever seen any of Jupiters 4 largest moons thru a telescope? What do they look like? I know there are internet pictures of them but I was wondering what kind of telescope gives you a good picture of them.

Answer 1

I'm quite surprised at how some of the regulars here are going astray on this question. First of all, while one certainly can spend a few thousand dollars on an eight inch telescope, there are many that are available for a few hundred (Newtonians on Dobs such as the Orion XTs for about $500.) One can also spend about $1000 for an 8" Celestron SCT or $18,000 for an eight inch TEC apo. Second of all, the question of resolving detail on the moons has to be broken up into two parts.

1. Do you mean, at the eyepiece?
2. Do you mean, photographically?

1. At the eyepiece the yellow color of Io is very readily seen. Much more difficult are the dark markings of Ganymede, but these can be seen too. There are tricks to all these things, such as waiting for the moon to be crossing in front of a light colored part of the Jovian disk. Anyhow the dark markings of Ganymede are occasionally viewable in the best amateur telescopes in the best conditions.

A complicating factor in the question is that Jupiter is very fussy. Its 12 year orbit at times makes it a difficult object in the N. hemisphere and much easier in the S. hemisphere. Right now we are in a period of poor N. hemisphere viewing. So "more likely than not" it doesn't matter what telescope you're using, you're not going to see as much with Jupiter low to the horizon (and thick layers of atmosphere to look through) than you will when it is very high. It's going to be four or five years before it starts getting respectable altitude.

But generally speaking everything about the telescope and especially the atmosphere must be optimal before one can observe a few details on the Jovian moons. However, the yellow color of Io shows pretty easily when Jupiter is high. When it is low, however, the planet tends to get engulfed in red-blue diffraction effects that are associated with objects low to the horizon--this is color that is not in the scope, but comes from the position of the object and is an atmospheric side effect. To have the best shot at resolving details in an amateur instrument, the best bet would be a 14 inch or larger telescope in a place like Barbados or Florida where the air is reputed steady. Or high mountains like Chile.

2. Photographically, images of details on Ganymede and Io are achieved fairly often by the most advanced photographers. The secret is using a WEBCAM which takes thousands of frames in a few minutes. You use a program called registax which throws out the bad seeing frames and keeps all the rest, then aligns them all using a statistical technique in a process called STACKING. The result is extraordinary detail. One of the most accomplished amateur planetary imagers in the world is Damian Peach and his work is rather stunning. I've provided a link to one of his pages which has, among other things, details on Io and Ganymede.

It certainly is not EASY to capture details on Jupiter's moons, but it certainly isn't as impossible as some of the earlier messages suggest. Another way of looking at it is this way: if one is asking the question HERE, it is because one is not already a member of a more dedicated discussion group of amateur astronomers. And if one is NOT part of such a group, the odds are high that the kind of telescope one has, or is thinking about getting, and the way one would operate it, are such that I would not bet on success in getting detail off the moons. However, it's not impossible, and there are some people I can think of who might be able to pull it off with an inexpensive Newtonian instrument in the 10-14 inch range. That's because the experience matters: in knowing how to fine tune an instrument, and also it matters in terms of observational acuity.

Hope that helps,

GN

Answer 2

The larger the aperture (hole at the front) of a telescope, the more light it can collect. This means you can magnify an image more without the image becoming so dim you can't see it.

Jupiter itself can be seen clearly with an 8-inch aperture telescope (which might cost a few thousand dollars). Jupiter's moons are much smaller, and smaller objects are even harder to see clearly because of atmospheric distortion. You would have a hard time buying (or even finding) a ground-based telescope that could see individual features of Jupiter's moons.

The best bet for taking photos of Jupiter's moons is a space-based telescope, like the Hubble, or else sending a probe (like the Voyager craft) armed with a camera near the moons themselves.

Answer 3

I have seen Jupiter and its moons myself many times since I was 8 years old. (many moons ago)

I currently have a Meade 4.5" reflector which I bought at Wal-Mart for about $250. I just like to take it out and look every once in a while when I'm interested, so not being an "avid" amateur astronomer, this scope suits my needs. With this, using a 9mm focal length eyepiece and a 2x barlow lens, I can see Jupiter, can barely make out the bands, and can quite plainly see the 4 Galilean satellites of Jupiter.

The viewing conditions where I am are horrible - only in large cities like Chicago and NYC would they be worse. The humidity here is always very high, and the light pollution is very very bad. I can barely make out many constellations that as a kid were hidden among many other stars visible before the lights got so bad around here. Even with these bad conditions and my humble cheap scope, viewing Jupiter and its moons is very enjoyable and fascinating.

I personally cannot tell which moon is which - they simply appear as 4 points of light. They look very different to me than stars do through the scope, so they're obviously moons to anyone looking through my scope. I haven't ever done things such as view Jupiter night after night, watching the moons change their positions, but it would be pretty easy to do if you were so inclined.

As far as making out surface details of the moons, even on the damianpeach.com site referenced in a previous answer, you can't really make anything out other than different colored blothches, and this guy obviously knows what he's doing and works hard at obtaining his images. As a casual observer, you'll best be prepared to see the moons simply as clear points of light.

Be all that as it may - get a telescope and find a dark place out in the country to go stargazing. The heavens are wonderful to behold!

Answer 4

I've seen all the Galilean moons many, many times with big and small telescopes of just about any description you can think of. In the telescope they are not star like pips of light, they are tiny disks of different sizes and color. Ganymede and Callisto are noticably bigger than Io and Europa. Io tends to look reddish, Europa a creamy white, and the larger moons a sort of gray to me. To see them as disks, you need high magnification and steady air, or little or no turbulence in the atmosphere above your telescope. I've seen the moons like this through my 6 and 10-inch reflectors at magnifications of 200X and more. Very big telescopes have shown faint markings, but overall the moons are very tiny featureless disks. That is why it took the Voyager then Galileo probes to really begin to learn what these planet sized moons are like. You can also watch the moons pass in front of or behind the planet, and sometimes one or more of them casts a shadow on the planet. Io is the fast moving moon, with an orbital period of 43 hours, and thus you can actually watch it move in it's orbit over a period of a couple of hours. The moons always change position from night to night, and even binoculars are enough to follow their movements around the planet. A good 6-inch reflecting telescope will show the moons, and lots of details on Jupiter too with good eyepieces, a steady sky and patience. It will also get you started in astronomy and enable you to see galaxies, nebula and star clusters too as well as the other planets.

Answer 5

Yes i can see Jupiter larges moons every night through my 114mm reflector. It looks like a big colorful baned circle with four much smaller circles. A good telescope to see jupiter would be a 6-8 reflecting telescope. But if you go somewhere really nice and dark the picture should be even better. hope that helps

Answer 6

I own an 8 inch telescope and they are very clear to see with it. Through this telescope they look like bright stars. It is quite interesting to watch their positions as they are constantly changing. No other characteristics can be seen with this scope.

Answer 7

nasa has a space web site and you can also google Jupiters moons and see pictures of the moons. Most larger tripod mounted telescopes work ok - buy a cheap one $50.00 to $100.00 and if you like it sell that one and buy a better one. The photos I've seen make them look entirely different from our moon.