orrery

[carmalee]

Hi - I'm new to this particular thread but would appreciate some advice. I'm soon to be unable to drive for a while due to an op and want to use the time doing things I've never done before. One criteria is that the places I want to visit have to be accessible by public transport. I have always really wanted to see a working orrery. I live on the East Sussex/Kent border (obviously good access to London) anyone know of a model in my area? There is a possibility I can get 'a driver' if it is very local but I will be able to travel. Thank you

[Buenchico]

Some locations here (under 'Where can I see some orreries?')
http://www.easytorecall.co.uk/orrery.htm

. . . with a lovely graphic here:
http://www.easytoreca...orrery_simulation.htm
(Press F11 to see it full screen).

Chris

[carmalee]

Buenchico - thanks a million, I got the first link by googling in exactly what you did and found it useful. But the second link ......just brilliant - what can I say? As soon as I opened it I knew what I was going to be doing tonight - watching this! Thank you thank you thank you - Brilliant

[carmalee]

chris -Bear with me - I'm thick! and I can't believe I've never cottoned on before! Please tell me I'm right by finally clicking that the moon goes around the earth every 24 hours whilst the earth goes around the sun every 365 days. Seeing that 2nd link you gave me seems to have cleared things up - please tell me I've at last understood it!

[Buenchico]

Part of the course I studied in Physics (for my teacher training) dealt with the rudiments of astronomy but, if I'm honest, I still struggle with some of the concepts!

Even so, there seems to be an error in what you've written:
It takes the Earth roughly 365¼ days to revolve around the Sun. (That awkward quarter of a day is why we need a leap year every 4 years, to get the calendars back to where they should be)

While that's going on, it takes the Moon one lunar month (about 27.3 days) to orbit the Earth (which is why we get a full moon roughly every 4 weeks)

But the Earth is also revolving once every 24 hours (which is why the Sun comes up, and later sets, on a daily basis)

Any clearer now?

Chris

[carmalee]

Ah yes - see my error - I had the moon whizzing around the earth at a great rate of knots didn't I. I can't tell you how grateful I am for the time you've taken to explain things. Just kept on looking at that image of the planets moving about last night - I can see this is going to be a whole new interest for me. Stay well C

[New Judge]

And just to complicate matters a little further beyond Chris’s’ excellent explanation:

As the moon progresses in its 28 day orbit around the earth the earth is revolving on its axis once a day (every 24 hours - I have rounded both these figures). The earth revolves about its axis in the same direction as moon orbits the earth. This means that the moon appears to progress across the sky as the lunar month progresses. That is, it appears at the same point in the sky about 50 minutes (24hrs divided by 28) later each day. It also explains why “high tide” (of which there are two a day) moves forward by about 50 minutes a day.

Simples !!!

[carmalee]

The more I learn about this the more I want to learn. Thanks New Judge