Symbolic Forest

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Blog : Posts tagged with ‘planets’

The old gods (redux)

Or, looking at the sky again

Back in August I talked about how Jupiter and Saturn were nicely visible in the sky, but not until well after The Children were in bed. Last night, though, we had a rare family conjunction of myself and The Children being in the same place, on a night when it was dark well before their bedtime, with a largely clear sky. So, the telescope came out.

This was the first time The Children had been able to use the telescope this autumn, the first time since a few abortive attempts just after moving house in February. I was impressed, to be honest, how over nine months they have grown that bit more mature to be able to use the telescope a bit better. Last winter, it was difficult to get them to stand still long enough to look through a telescope properly, difficult to get them to look through the eyepiece without grabbing onto it and swinging it out of position, and difficult to get them to wait patiently whilst I aimed and focused it. Now, though, they managed to do that with a few different things. FIrst we looked at Saturn, its rings angled and nicely visible; then at Jupiter and the four Galilean Moons. I couldn’t really see any cloud bands on Jupiter this time, unlike in August, but nevertheless the children were pretty excited.

There was a fair amount of patchy cloud; some constellations were visible but nothing exciting enough to hold The Children’s interest. In any case, it was almost bedtime. I left the telescope set up, though, and after a few hours the clouds had largely cleared and we went outside again. Orion was just rising; we looked at the nebula, and at Betelguese, and the Pleiades. The night sky, still just as it was last winter.

The old gods

The astronomy season is starting again

We’re getting to the time of year now when it’s properly dark before a reasonable bedtime; as opposed to a couple of months ago, when it is still twilight in the deepest part of the night, which around here happens at about quarter past one in summer. August, by comparison, is the time of year when I can go outside at 10pm and see if the sky is clear enough to do a small bit of stargazing before bed. It’s too late to wake up The Child Who Likes Space, who nominally owns the telescope, but nevertheless, I rationalise, I can always tell him about it in the morning.

A while ago, I noticed that according to timeanddate.com’s planet apparent size calculator, Jupiter would have a relatively large disc right now. Right now, in fact, it’s receding from us, but it’s still a relatively chunky 49 arcseconds wide. Still a dot to the naked eye—the Moon is about 36 times bigger in apparent diameter if my rough mental calculations are correct—but big for a sky object, and with the best chance we would have of seeing features on it. Over the past few weeks I’ve noticed that Jupiter and Saturn together, although relatively low in the sky, are very definitely the brightest things in the south-eastern sky when I go to bed. So last night, as the sky was almost clear, I decided to get the telescope out.

Last spring I found it rather hard to get the telescope set up in the new garden, due to the street light that shines directly into it over the garden wall. Back then, though, the garden was a rocky, rubble-strewn wasteland, which didn’t help. Now it’s grassed, and at the moment I can tuck the camping table and the telescope into a relatively shady distant corner; from which both planets were shining bright in the sky. It was as easy as any astronomy I could think of: set up the telescope, point the finder on Jupiter, and as soon as I had focused, I had the planet and the four Galilean moons right in the centre of the eyepiece. All four of the moons were on the same side of the planet last night, Io just visible almost touching the planetary disc, the other three clear and sharp and separate spread out to the east of the planet. Jupiter itself was a fairly uniform cream colour, with a thin, darker, more reddish band visible near its equator. It seemed so sharp and clear, much more clear and bright than a photograph.

After Jupiter, I trained the spotter on Saturn, much smaller in the sky. At first it just seemed to be an oval blob, but I’d knocked the focus off slightly. Tweaking it showed the planet, orange in colour, and its rings. We don’t have anywhere near enough magnification to show the ring divisions, and the rings and the planet seemed to have a fully uniform colour. It’s strange to think that when Stegosaurs were alive and tramping the planet, Saturn probably didn’t have any rings at all. I couldn’t make out any of the planet’s moons, but I know they are much fainter than those of Jupiter, my eyes probably hadn’t had time to fully adapt to the dark, and I didn’t know where to be looking in any case. I wonder how different the history of science would have been, if Jupiter didn’t have four clear bright moons for Galileo to spot easily with his early telescopes.

Incidentally, due to geometry, it’s impossible for the planets orbiting outside Earth to have phases like the Moon does: their discs will always appear from our standpoint to be fully illuminated. This coming winter Venus will be the largest planet in the sky—it peaks at just under 63 arcseconds on January 8th—and it will be interesting to see if around then more than a thin crescent is visible. Assuming the skies are clear, of course.