Brilliant Matthew, just brilliant.
I had only intended that non-Brits and those under 50’s on the Forum should tackle the relatively simple sum ie … 2 x £2 :11s :7d = £5: 3s :2d.
But you took on the main challenge, and succeeded. Well done.
Thanks for another year of puzzles @Don.
I had thought of an obscure question on our longest day about where would I need to be, to be closest to the sun. Until I realised this was solved many years ago. But I did read that it moves every year.
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Thank you for your kind words Mike.
My recollection is that the Earth’s elliptical path puts it closest to the Sun around about 4th January. And that, together with its tilt, must put somewhere between the Equator and the South Pole the closest the Earth ever gets to the sun …
… you might well qualify this coming Saturday 
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Ah, slightly different answer to mine. Maybe we do need this teaser?
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On the topic of celestal bodies, how many times does the earth rotate during one orbit of the sun?
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That’s a nice teaser Matthew, and very seasonal too
I recon that many people with a number in mind would say “365 days most years and 366 days every 4th year” …
A fair number would say 365.25 or 365.24 ie about 365 and a quarter.
But I wouldn’t say any of the above.
I would add an extra day for good luck !
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Or add an extra day for good physics.
About 10 years ago (or 3662.422 sidereal days), Mrs R conducted an experiment as part of an astronomy course by going out each night to record the time that a chosen bright star passed a known point. She found that it was about 4 minutes earlier each night.
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Hi Mike,
There is a risk that your teaser might be overlooked because we started responding to Matthew’s teaser.
Hopefully, this post will rectify things
Mike,
I’m going to opt for some high mountain place, on or just south of the Equator.
I know that the top of Everest isn’t the furthest place from the centre of the Earth. However, I seem to recall some volcano in South America might fit the bill.
But i’m going to be reduced to “Google” for a name.
And even then, i’m not sure if i’m in the right ball-park !!
Nice teaser.
Well Mike !!!
Looking for the name of a mountain, even one close to the 23rd Parallel South of the equator has thrown up a can of worms …
eg the following abstract from an interesting website (not necessarily accurate !) "…the question of which point on Earth will get closest to the Sun depends on the period of time on which it is considered. For each year, each century and any other arbitrary period of time, the answer will be different."
As I said, nice one !!
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I didn’t use Google, but I recall that the closest point to the Sun (perihelion) is in mid-winter for us in the northern hemisphere. I only remember it because it seems a bit ironic to be so cold at the closest point!
I didn’t use Google but instead used my astronomy app (Celestron Sky Portal) which gives stats on the sky at any time past or future. It suggested around 1pm to 2pm GMT on 4th January 2025 is the closest for 2025.
I had also concluded that the Tropic of Capricorn would be about the right place, since we are close to the December solstice and the sun would be directly overhead. Maybe a little north of the tropic since it’s 2 weeks from the solstice.
So my guess would be Namibia, if it needs to be on land, since it is on a broadly similar latitude to UK, perhaps a little too much east.
I had assumed that the height of any mountain would be of lesser importance than getting the timing correct. By the time any South American volcano was lined up (mid-day), the Earth would have started to move away from the Sun. Maybe my assumption is wrong though.
Great teaser!
Same here !
But I guess if you live in Australia or New Zealand, it’s really obvious.
Pedant’s question … Did you mean ‘longitude’ rather than ‘latitude’ ?
Yes, good spot. I was too distracted trying to remember which Tropic is which, so forgot to check my longitude vs latitude!
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Contrary to my earlier answer (where I went along with Don’s +1 turn to give about 366.25), I’m sticking my neck out with about 365.25.
The rationale for 366.25 is that each day the Earth has travelled a bit round the Sun (say about 1 degree for simplicity), so it has to turn an extra 1 degree to re-align with the Sun. This is how we perceive a day. Using a sidereal frame of reference (one aligned with the stars that for practical purposes are fixed), our 24 hour day is slightly longer than a 360 degree revolution.
An alternative argument is to consider that an orbiting object is travelling in a straight line in curved space. I know this is straying into relativity which can be a conceptual headache, made even harder by yesterday’s late night celebrations. With this frame of reference, the Earth is spinning by reference to its straight ahead trajectory, in which case the normal perception of a day is correct.
I should point out that my perceptions of relativity and other tricky physics do not fully align with the established expert consensus. Also, I’m not a Physicist. However, my answer is 365.25.
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Visualize a non-rotating satellite going around the sun. Each side gets a a direct exposure to the sun in the course of its year. I am going with 364.25 rotations to plus this “built-in” day to total 365.25 days.
Looks like we are going to have to give this a bit more thought !
Starting with “the earth moves around the Sun” which although a long way away (c. 93 million miles) is virtually nothing, compared to even the nearest Star. The Stars are effectively objects at infinity, the Sun most definitely isn’t - the Earth moves around it. And whilst moving around the Sun, the earth rotates about its own axis.
A fixed point on the Earth has to rotate on its axis a little bit further than 360 deg, on each rotation on its axis, in order to line up with the Sun. In doing so it will have lined up with the same distant Star, a short while before. (short while = approx 4 minutes or 1 degree)
A “Day” is therefore associated with an Earth rotation of 361 deg (approx)
The above process repeats about 360 times each year.
I’ll stop there for now. As I said above, “Looks like we are going to have to give this a bit more thought !”
It is important to know the rotational direction of the earth around the sun and the earth around its own rotational axis…
And every 100 years a leap year is missed, but every 400 years a leap year is again added…
Still just an approximation…
Mike asked where would be closest to the sun on our longest day of the year.
Guessing that Mike is in NZ given his pic that would mean closest point on earth to the sun on December 21st. The earth will be moving closer to the sun on this day and so the part of earth closest to the sun would be at 11:59:59 pm New Zealand time, at 23 degrees south. That lands us in Namibia…
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