h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I saw Uranus for the first time last night, or i think i did, just next to Jupiter.

Hi there

Yes, Uranus is just above (north) of Jupiter at the moment. It's a bit more than a Moon's diameter seperation and has a blue-green tint about it. I can barely resolve it as a disc though, even with the scope.

I've also been trying to locate Neptune which is about 30 deg west of those two along the ecliptic. That's a bit more difficult as it doesn't move much and it's lower down. A good place to start looking is north-east of delta Capricorn

Deke

Hasn't Neptune just completed it's first complete orbit of the sun since it's discovery? I'm sure I heard this recently on one of the podcasts I listen to. Could have been Science Talk from Scientific American.

t.

Just been and looked on W*k*pedia and the orbital period is given as 164.79 years so that would confirm what I heard.

t.

Should have said - discovered in 1846.

I got my binos on Jupiter the other night, prob Wed, and made out one of the moons. you can see Uranus though

How do you tell whether you are seeing a moon or another star when looking at jupiter?

Do you mean moon or another planet? My binos are not high res enough to spot Uranus.

a moon of jupiter rather han another star. I read elsewhere on the internet you can just see uranus with binoculars

If you're referring to being able to tell Jupiter's moons from stars, then that's a good question.

Personally I've always had difficulties with the fainter objects, not least because I don't have a particularly dark sky around my way, and one point of light does look much like another. I have found that for me it's largely a waste of time just going out to look for something without a bit of planning beforehand. My methodology, for what it's worth, is to plan out what I'm looking for so that I can get the relative positions fixed beforehand.

I make a lot of use of one of the computerised night sky simulators, (Starry Night) which works in real time and can enlarge a patch of sky and identify any of the galaxies/stars/planets/moons/why therein. Also in the case of the Jovian moons there are published ephemeris in UK astro magazines that show their positions on any date that month.

'Frinstance, tonight 19/9/10, at around 12:30 am all four moons are on view. Io will be to the left of Jupiter, Europa and Ganymede fairly close together and about the same distance out on the right, and Callisto about twice that distance further out on the right. They are always in a relatively straight line so I'm fairly sure of what I'm looking at as there aren't any stars at the moment bright enough in that position, to register. They also have a 'look' about them which is hard to describe but they appear to be the same cream/tan colour that Jupiter appears in the scope.

Uranus has been a different kettle of fish. It's fairly obvious from its relative position to Jupiter being in the same binnie field of view, and according to 'Starry Night' there isn't another significant star between them at the moment. In the binnies it's only a point of light and as it happens the brightness of Jupiter is rather drowning it out. I've had the 'scope on it a few times but at around 125X magnification it still barely shows as a disc, but it does appear to have a bluish tint. If I get the chance this weekend I'll try a higher magnification, the trouble is that with my scope anything above 125X begins to lose definition.

It's at times like these I wish I had a more powerful telescope. 'Starry Night' shows that tonight, five of Uranus' moons are viewable. Oberon and Miranda to the south of the planet, while Umbriel, Ariel and Titania are to the north. so bearing in mind that Uranus' axial tilt is almost 90 degrees off the plane in which they orbit, they are at a right angle to that of Jupiter's, so the 'line' these moons describe illustrate the planet's axial tilt admirably.

Incidentally, you'll probably already know that the southern equatorial belt on Jupiter has all but disappeared. But the Great Red Spot that it contains has become darker. The aforesaid ephemeris predicts the GRS will be passing centre at 3:53am tonight (19th) and again at 11:45pm tomorrow evening. Or you could try on Wed 22nd at 1:22am or 9:14pm.

Deke

I have been watching Jupiter the past few nights, reckon I have seen at least three of Jupiters moons.

On a clear night here in North Wales I can see all 4 Galilean moons.

t.

Only 3 tonight though. Io is in front of Jupiter.

t.

I always found it easy to see Jupiters 4 main moons with binoculars.
they always line up in a "plane", east/weat I guess.

Maybe people actually can see them with the naked eye. Not in my light polluted city and with my ever dimishing eyesight

That's West, I guess...