(Untitled)

[beckyc]

It's Saturday night, and am I out having fun? Am I painting the town red? No. Not even beige.

I'm studying. Or I was. Alternatively, I might just be looking at web pages related to Planetary Science. Lego Orrery - how neat is that

Comments

[wellinghall]

I've seen a home-made lego orrery before; also a lego pinhole camera.

Which of the planets in our solar system, other than ours, is most likely to support life? And which satelite?

Give me some thoughts on Pluto's eccentric orbit.

In the three middle years of the 1960s, the UK album chart was topped by three acts, and one other soundtrack album. Which acts, and which soundtrack album?

[beckyc]

Which of the planets in our solar system, other than ours, is most likely to support life?

Mars is about the only possibility. Planetary satellites: Europa is thought to be a possibility, and perhaps Triton (I doubt it).

Pluto is nothing special: it has an orbit around 39.4 Au, which is actually common for small bodies called plutinos, because it's in orbital resonancec with Neptune.

I'm afraid I know little of the charts of the 1960s, but looking it up, it seems to have been the Sound of Music, Bob Dylon, the Rolling Stones and the Beatles.

[_nicolai_]

What's the composition and period of rotation of any bodies orbiting the former planet still known as Pluto? How would you establish these data?

[beckyc]

Interesting that you know that there are bodies (plural). I only found that out when I was taking this course - I had been in Peru when the announcement was made and assumed everyone bar me knew until it turned out nobody in the pub did.

There's Charon, Nix and Hydra. From their location, they are probably formed from a mixture of rocky and icy material. Composition can be approximately determined remotely by looking at reflectivity. More detailed information close up can be determined from gravitational measurements, but you would probably have to send a probe for that.

Periods of rotation I had to look up. Wikipedia claims unknown periods of rotation for Nix and Hydra. But orbital period of Hydra is 38.2 days, Nix 24.9 days, Charon 6.4 days. I'd have guessed that they might well be in synchronous orbit, but Pluto's very little, so I guess it's plausible be that they aren't.

[crazyscot]

Does planetary life as we know it arise from a single identifiable "Genesis" moment? Discuss. (20)

[beckyc]

An excellent and difficult question. Organic matter can be produced without the need for life, and can under certain circumstances reproduce itself. We don't even really know whether or not life began on the Earth - the panspermia theory has a certain amount of appeal to many.

We don't even know whether or not life has arisen on the Earth more than once, or if it were just descended from the most recent event.

[beckyc]

Crumbs! 12 is a bit young to know about trigonometry, so without that it's rather tough. And I'm afraid that I tend to give rather literal explanations of the definition. Well, other than wooly definitions along the lines of "Really, really big number that gets used in astronomy".

Give specific instances of stars that are a particular distance away? Use small angle approximations?

[kargicq]

You draw a diagram with a vastly exaggerated parallax angle, and explain about how you'd have to swing a telescope in different directions to track a star as the earth goes between different positions, possibly with analogies about looking at things from moving vehicles. Then you'd explain what an arc-second is, and suggest without proof that there's a particular distance where the angle is an arc-second?

[alexthai]

Interesting!