Astronomy and Space

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Grumble
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Re: Astronomy and Space

Post by Grumble » Tue Jul 02, 2024 7:44 pm

Not strictly astronomy, but is there such a thing as a globe that illuminates half the surface to allow you to show how the seasons work? I’m imagining a tilted globe but with the light terminator being vertical, so that when you spin it, it simulates the day light at a particular time of year. You would have to be able to move the light around to change the time of year.
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Gfamily
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Re: Astronomy and Space

Post by Gfamily » Tue Jul 02, 2024 7:53 pm

Grumble wrote:
Tue Jul 02, 2024 7:44 pm
Not strictly astronomy, but is there such a thing as a globe that illuminates half the surface to allow you to show how the seasons work? I’m imagining a tilted globe but with the light terminator being vertical, so that when you spin it, it simulates the day light at a particular time of year. You would have to be able to move the light around to change the time of year.
If this is for teaching purposes, we used a globe bulb on a table lamp without a lampshade to stand for the Sun, and then gave a polystyrene ball on a stick (held at an angle towards one wall) to each person, that they could walk around the table lamp to show how the sunlight fell more on one hemisphere then the other.
My avatar was a scientific result that was later found to be 'mistaken' - I rarely claim to be 100% correct
ETA 5/8/20: I've been advised that the result was correct, it was the initial interpretation that needed to be withdrawn
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Grumble
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Re: Astronomy and Space

Post by Grumble » Tue Jul 02, 2024 7:58 pm

Gfamily wrote:
Tue Jul 02, 2024 7:53 pm
Grumble wrote:
Tue Jul 02, 2024 7:44 pm
Not strictly astronomy, but is there such a thing as a globe that illuminates half the surface to allow you to show how the seasons work? I’m imagining a tilted globe but with the light terminator being vertical, so that when you spin it, it simulates the day light at a particular time of year. You would have to be able to move the light around to change the time of year.
If this is for teaching purposes, we used a globe bulb on a table lamp without a lampshade to stand for the Sun, and then gave a polystyrene ball on a stick (held at an angle towards one wall) to each person, that they could walk around the table lamp to show how the sunlight fell more on one hemisphere then the other.
I know how to do that, it’s just in my house that I’m thinking. We have a light up globe, I just thought it would be cool to make it work differently. With modern LEDs I’m sure you could make it happen.
where once I used to scintillate
now I sin till ten past three

IvanV
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Re: Astronomy and Space

Post by IvanV » Tue Jul 02, 2024 9:24 pm

Grumble wrote:
Tue Jul 02, 2024 7:58 pm
Gfamily wrote:
Tue Jul 02, 2024 7:53 pm
Grumble wrote:
Tue Jul 02, 2024 7:44 pm
Not strictly astronomy, but is there such a thing as a globe that illuminates half the surface to allow you to show how the seasons work? I’m imagining a tilted globe but with the light terminator being vertical, so that when you spin it, it simulates the day light at a particular time of year. You would have to be able to move the light around to change the time of year.
If this is for teaching purposes, we used a globe bulb on a table lamp without a lampshade to stand for the Sun, and then gave a polystyrene ball on a stick (held at an angle towards one wall) to each person, that they could walk around the table lamp to show how the sunlight fell more on one hemisphere then the other.
I know how to do that, it’s just in my house that I’m thinking. We have a light up globe, I just thought it would be cool to make it work differently. With modern LEDs I’m sure you could make it happen.
You could actually buy one, a little while ago, but it has been discontinued. It was the Elenco Night & Day Globe. It seems to be not very easy, which is why this is the only model I have found, even in specialist globe retailers, and it has been discontinued. But you can look at this manual and perhaps gain some clues from the mechanism it depicts.

With a globe that is lit externally, you would need the light to be at some distance from the globe to present a sharp day/night terminator. The light could remain in a fixed location, but you'd have to generate the seasons by rotating the globe base so that the axis rotated relative to the light.

With a globe that lights up in the interior, what you'd really need would be an internal light-proof vertical partition, with a light on one side of it, to separate day and night. But as it would turn on a different axis from the external globe's axis, that would be bit tricky to arrange. Maybe there'd be some trick with something that looks a bit like the mechanism of a maritime self-levelling compass, but with pivots at an angle of 23 degrees rather than 90 degrees, you'd have in the interior to organise it. Or maybe you'd some kind of a channel around the antarctic circle, as some point of the antarctic circle would always be at the lowest point, that the axis would pierce through. Though if you can rotate something all the way around the antarctic circle, how does the globe avoid falling into two pieces. In fact, having a look at that Elenco globe manual, basically they don't have anything south of the antarctic circle. They rotate the upper part of the globe around the blank antarctic circle piece. There is a partition inside the globe with a bright light on one side of it. The partition rotates around a vertical axis that is fixed to one edge of this fixed antarctic circle part.

It strikes me that you could alternatively have an external hemisphere, which covers over the night side, to separate them. But it would need some kind of provision that the fixing for the globe's own axis could move through it, when the south pole was in antarctic summer, for example. So that would also be awkward, but again maybe something that looks a bit like a self-levelling compass would achieve it.

You could in principle stud the globe with lots of little LEDs, but you'd need a computer program to select them.

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Re: Astronomy and Space

Post by Grumble » Tue Jul 02, 2024 10:10 pm

IvanV wrote:
Tue Jul 02, 2024 9:24 pm
Grumble wrote:
Tue Jul 02, 2024 7:58 pm
Gfamily wrote:
Tue Jul 02, 2024 7:53 pm


If this is for teaching purposes, we used a globe bulb on a table lamp without a lampshade to stand for the Sun, and then gave a polystyrene ball on a stick (held at an angle towards one wall) to each person, that they could walk around the table lamp to show how the sunlight fell more on one hemisphere then the other.
I know how to do that, it’s just in my house that I’m thinking. We have a light up globe, I just thought it would be cool to make it work differently. With modern LEDs I’m sure you could make it happen.
You could actually buy one, a little while ago, but it has been discontinued. It was the Elenco Night & Day Globe. It seems to be not very easy, which is why this is the only model I have found, even in specialist globe retailers, and it has been discontinued. But you can look at this manual and perhaps gain some clues from the mechanism it depicts.

With a globe that is lit externally, you would need the light to be at some distance from the globe to present a sharp day/night terminator. The light could remain in a fixed location, but you'd have to generate the seasons by rotating the globe base so that the axis rotated relative to the light.

With a globe that lights up in the interior, what you'd really need would be an internal light-proof vertical partition, with a light on one side of it, to separate day and night. But as it would turn on a different axis from the external globe's axis, that would be bit tricky to arrange. Maybe there'd be some trick with something that looks a bit like the mechanism of a maritime self-levelling compass, but with pivots at an angle of 23 degrees rather than 90 degrees, you'd have in the interior to organise it. Or maybe you'd some kind of a channel around the antarctic circle, as some point of the antarctic circle would always be at the lowest point, that the axis would pierce through. Though if you can rotate something all the way around the antarctic circle, how does the globe avoid falling into two pieces. In fact, having a look at that Elenco globe manual, basically they don't have anything south of the antarctic circle. They rotate the upper part of the globe around the blank antarctic circle piece. There is a partition inside the globe with a bright light on one side of it. The partition rotates around a vertical axis that is fixed to one edge of this fixed antarctic circle part.

It strikes me that you could alternatively have an external hemisphere, which covers over the night side, to separate them. But it would need some kind of provision that the fixing for the globe's own axis could move through it, when the south pole was in antarctic summer, for example. So that would also be awkward, but again maybe something that looks a bit like a self-levelling compass would achieve it.

You could in principle stud the globe with lots of little LEDs, but you'd need a computer program to select them.
Thanks, that’s exactly the kind of thing. Yes, I realised having two different axes would be tricky, which is why I thought about using LEDs. If the internal surface was evenly covered in LEDs then it couldn’t be all that hard to write a program on a Raspberry Pi or similar to switch on the lights that simulate sunlight at a particular day and time. Or go one step further and make a globe shaped screen, then you could change the display to match Google Earth or whatever.
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Re: Astronomy and Space

Post by dyqik » Wed Jul 03, 2024 10:14 am

I'd do it with a sphere inside a sphere, magnetically constrained by a stand, and powered wirelessly. The inner sphere would be half black, half lit.

You could probably even make it float.

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Re: Astronomy and Space

Post by Gfamily » Wed Jul 17, 2024 5:05 pm

Here's a great talk by the Astronomer Royal for Scotland, talking about some of the issues with Cosmology and how cosmologists are really looking for the rest of the astronomy community to help them understand what's behind the problems.

The talk is one of the Plenary Talks for the National Astronomy Meeting (currently taking place in Hull); however, as Catherine Heymans is one of the many sufferers with Long Covid, she had to give it remotely; which means it can be shared to a wider audience.

https://media.ed.ac.uk/media/NAM+2024/1_9dmbfg5o
My avatar was a scientific result that was later found to be 'mistaken' - I rarely claim to be 100% correct
ETA 5/8/20: I've been advised that the result was correct, it was the initial interpretation that needed to be withdrawn
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Re: Astronomy and Space

Post by Brightonian » Thu Jul 18, 2024 7:23 pm

Selenological spelunking, anyone?
https://www.bbc.com/news/articles/ce784r9njz0o

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Re: Astronomy and Space

Post by dyqik » Thu Jul 18, 2024 7:53 pm

Brightonian wrote:
Thu Jul 18, 2024 7:23 pm
Selenological spelunking, anyone?
https://www.bbc.com/news/articles/ce784r9njz0o
It sounds safer than cave diving...

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Re: Astronomy and Space

Post by Boustrophedon » Sun Jul 21, 2024 6:13 pm

Grumble wrote:
Tue Jul 02, 2024 7:44 pm
Not strictly astronomy, but is there such a thing as a globe that illuminates half the surface to allow you to show how the seasons work? I’m imagining a tilted globe but with the light terminator being vertical, so that when you spin it, it simulates the day light at a particular time of year. You would have to be able to move the light around to change the time of year.
Not seen a 3D one but bizarrely there is a 2D map clock that shows a map of the world with day and night and the changes with the seasons. Needless to say, I want one.
https://www.geochron.com/

Image
Perit hic laetatio.

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Grumble
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Re: Astronomy and Space

Post by Grumble » Sun Jul 21, 2024 6:34 pm

Boustrophedon wrote:
Sun Jul 21, 2024 6:13 pm
Grumble wrote:
Tue Jul 02, 2024 7:44 pm
Not strictly astronomy, but is there such a thing as a globe that illuminates half the surface to allow you to show how the seasons work? I’m imagining a tilted globe but with the light terminator being vertical, so that when you spin it, it simulates the day light at a particular time of year. You would have to be able to move the light around to change the time of year.
Not seen a 3D one but bizarrely there is a 2D map clock that shows a map of the world with day and night and the changes with the seasons. Needless to say, I want one.
https://www.geochron.com/

Image
Why didn’t you link this before my birthday? Honestly. I’ll have to wait till Christmas now. $500 though, might need to save up for that one.
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Re: Astronomy and Space

Post by Boustrophedon » Sun Jul 21, 2024 8:43 pm

Grumble wrote:
Sun Jul 21, 2024 6:34 pm

Why didn’t you link this before my birthday? Honestly. I’ll have to wait till Christmas now. $500 though, might need to save up for that one.
The mechanical one is £3K
Perit hic laetatio.

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Grumble
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Re: Astronomy and Space

Post by Grumble » Sun Jul 21, 2024 8:58 pm

Boustrophedon wrote:
Sun Jul 21, 2024 8:43 pm
Grumble wrote:
Sun Jul 21, 2024 6:34 pm

Why didn’t you link this before my birthday? Honestly. I’ll have to wait till Christmas now. $500 though, might need to save up for that one.
The mechanical one is £3K
Yeah, no
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Re: Astronomy and Space

Post by dyqik » Sun Jul 21, 2024 9:05 pm

A 4K TV, a RPi and a screensaver would be cheaper.

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Re: Astronomy and Space

Post by Gfamily » Sun Jul 21, 2024 9:07 pm

Grumble wrote:
Sun Jul 21, 2024 8:58 pm
Boustrophedon wrote:
Sun Jul 21, 2024 8:43 pm
Grumble wrote:
Sun Jul 21, 2024 6:34 pm

Why didn’t you link this before my birthday? Honestly. I’ll have to wait till Christmas now. $500 though, might need to save up for that one.
The mechanical one is £3K
Yeah, no
I refrained from suggesting you could program a Raspberry Pi to display one on a cheap display.
But if you have a techy young relative, she may be appreciative of having a project - would look good on an application form*

*gfamdottir wrote her own IRC client in the downtime after Uni and I'm sure it helped her job search.
My avatar was a scientific result that was later found to be 'mistaken' - I rarely claim to be 100% correct
ETA 5/8/20: I've been advised that the result was correct, it was the initial interpretation that needed to be withdrawn
Meta? I'd say so!

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Re: Astronomy and Space

Post by Boustrophedon » Sun Jul 21, 2024 9:51 pm

Gfamily wrote:
Sun Jul 21, 2024 9:07 pm

I refrained from suggesting you could program a Raspberry Pi to display one on a cheap display.
The same could be said of any of my clocks, they could be replaced by a display, but that's really not the point. The mechanical Geochron has gears and levers and cam controlled bendy shades to cast the shadows, an electronic display is just not the same. I hate to come over all 'Clarkson talking about an Alfa Romeo' but it's got no soul.
Perit hic laetatio.

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Re: Astronomy and Space

Post by Gfamily » Sun Jul 21, 2024 10:11 pm

Boustrophedon wrote:
Sun Jul 21, 2024 9:51 pm
Gfamily wrote:
Sun Jul 21, 2024 9:07 pm

I refrained from suggesting you could program a Raspberry Pi to display one on a cheap display.
The same could be said of any of my clocks, they could be replaced by a display, but that's really not the point. The mechanical Geochron has gears and levers and cam controlled bendy shades to cast the shadows, an electronic display is just not the same. I hate to come over all 'Clarkson talking about an Alfa Romeo' but it's got no soul.
Huh, so Dyqik gets away with it, but my personal family history 'has no soul' - I can tell you, young man* - if I was less sozzled on a Sunday evening, I would be less offended

* modify adjective and noun as appropriate.

Oh, and Grumble thanks you for the kind offer and wonders when they can come round to pick it up
My avatar was a scientific result that was later found to be 'mistaken' - I rarely claim to be 100% correct
ETA 5/8/20: I've been advised that the result was correct, it was the initial interpretation that needed to be withdrawn
Meta? I'd say so!

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Re: Astronomy and Space

Post by Boustrophedon » Sun Jul 21, 2024 10:34 pm

Gfamily wrote:
Sun Jul 21, 2024 10:11 pm


Huh, so Dyqik gets away with it, but my personal family history 'has no soul' - I can tell you, young man* - if I was less sozzled on a Sunday evening, I would be less offended

* modify adjective and noun as appropriate.
My apologies for picking on you particularly, I could have included both quotes, I usually never pass up a chance for a dig at Dyqik.
Perit hic laetatio.

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