The back of my house faces almost exactly due west and at this time of year is getting a lot of light in the afternoon. Over the last week I have taken to marking, at regular intervals, a corner of the square of sunlight which comes in through the roof light over the stairs. This tracks along one wall from about 1pm and then onto the back of the hallway before disappearing at about 8pm.

At the moment the daily horizontal lines are dropping lower on the wall by about an inch a day but I’m assuming the gaps will compress as we get closer to the solstice. Lines drawn through the same time every day e.g. 7pm end up pretty far off the vertical. I haven’t checked yet but I’m guessing the angle of this line from the vertical will equate to the tilt of the earth. What else can I deduce from these lines on the walls? Latitude? Curvature of the earth?? Would be cool to use lockdown to prove the earth is a sphere (I know it’s a sphere).

My wife is totally cool with this before anyone asks.

Sounds interesting , photos would be good 👍

OP You need to get back to work and stop living up to your forum name 🙂

Or are you showing that the sun is moving and we are stationary at the centre of the universe? We can’t be moving or we’d feel it, right?

If you go and look at one of those big sundials where you have to stand to cast the shadow, many were done for the millennium, the bit where you stand is on a large figure eight, and markings showing the place to stand for each month.
It’s using the same principle that you’re exploring on the wall. But won’t generate quite as much tutting.

Since the earth is flat and stationary what you have discovered is subsidence in your property.
Quite bad subsidence it would appear.

I remember my grandad pointing out to me where the sun would set on the summer/winter solstices, and the equinox too.
One of the advantages of living in the same house for 78 years i suppose.
If we were the centre of the universe, what could cause the sun to move up and down to give this effect, without that same force affecting our (flat) earth too?
(Not a serious question btw, i know we’re on the back of a giant porpoise or something)

Tom Hanks did a similar thing in his cave in Castaway didn’t he? He also had a ball as a best friend. Do you have a ball as a best friend?

I’m best friends with Both my balls . .

You could track the transit of the ISS across the sun and work out the distance from the earth to the sun (maybe)

(Credit. My mate in his back garden in Penzance)

I’m not too worried about the subsidence as I am expecting the house to bounce back again come the end of June.

Think I could deduce latitude from the horizontal lines if I knew the length of the day on the solstice. Need to think this through more.

Do you have a ball as a best friend?

His ball left him for a stamp collector to get more excitement in its life.

Its been posted on this site before, but I love this….

https://www.youtube.com/watch?v=1zJ9FnQXmJIMilky Way Static as Earth Rotates

Spoiler alert it’s 23.5 degrees.

What else can I deduce from these lines on the walls? 

That lockdown is affecting different people in different ways?

Since the earth is flat and stationary what you have discovered is subsidence in your property.
Quite bad subsidence it would appear.

Good one! You made I laugh!