Eratosthenes Experiment: Know anyone in Alaska and Florida?

[O2HeN2]

This June 21st, on the Summer solstice I'd like to run the Eratosthenes experiment in three different locations, the Southern US, Colorado and Alaska.

I need to connect with folks in, say, Miami and Anchorage (South Texas would work too) and have them do the following at ~1pm their local time on Friday, June 21st (though the 20th or the 22nd would probably work just fine):

• On a flat surface setup a vertical stick - a carpenter's level (see picture below) would be perfect because it'd be an exact length AND allow you to assure it's vertical easily.
• About 1pm (I'll give them the exact time when I know where they area and which day they're taking the measurement) I'll need them to measure the length of the shadow cast by the vertical object on the [must be] flat surface supporting the stick.
• Email me their exact latitude, the height of the stick and the length of the shadow.

Anyone got some good buddies in either of those areas that can help me? Please PM me if so and I'll give you my email and phone number to forward onto them.

Thanks!

O2

Level:

[Irving]

I've got friends in Florida and Huston. We have members that live in Alaska and have property in Florida.

[crashdown]

I’m down to help, but it’s rainy as hell this year, so might not be sunny enough for a shadow.
Send me your number and we can text out the details.

[OtterbatHellcat]

I'd like to see how this turns out. Kinda neat.

[GilpinGuy]

This will prove once and for all that the Earth is flat right? I mean come on...

[OtterbatHellcat]

I think it's cool to want to recreate the findings.

There are a lot of smart MoFo's in this community, but those dudes figured some shit out back then, and it's impressive.

[O2HeN2]

This will prove once and for all that the Earth is flat right? I mean come on...

No, which is why I want multiple locations. Only one location can be interpreted as figuring out the diameter of the earth or the [short] distance to the sun if the earth is flat.

You can't come to a flat earth conclusion with multiple latitudes.

O2

Ps. I should have some time this week to writeup the process. I'll publish it here in case anyone wants to give it a whirl on the 21st themselves.

[Walker2970]

Im in Florida

[O2HeN2]

For those of you that have PMed me, I'll be contacting you directly. A word document of my instructions can be found here (the link will download a word document).

Here's my best shot at copying the document here:

Eratosthenes Experiment
Calculating the diameter of the earth using the same method that Eratosthenes of Cyrene used in 240BC.

Notes:
We?ll be taking a small measurement and blowing it up to 40,000 kilometers in size, so the more accurately you can perform the experiment (perfectly vertical stick on a hard, level surface, exact location, time and measurements) the better!

The best day to perform this experiment is June 21st, but given the accuracy (or lack thereof), a couple days before or after should work just fine.

Your stick and shadow measurement can be metric or English units, it won?t matter for the final calculations.

Information/items you need to gather prior to your observation:
? Exact latitude and longitude of observer (suggested: suncalc.org).
? Perfectly vertical stick or building* of exact known height.
? Stick on hard, flat and level surface on which to cast a clear, crisp shadow.
? Measuring device (tape measure, yardstick, meter stick, whatever).
? Watch set to correct time (suggested: time.is).
? Find when local noon/solar culmination is on June 21st or on the day you?re taking measurements if a day or two before/after the 21st (suggested: suncalc.org).

Performing the experiment:
At the time of solar culmination on June 21st (or whatever day you?re taking your measurement) measure and record the length of the shadow cast by the stick. I?d perform the measurement several times to make sure you got a good number.

Crunching the numbers:
1. Determine your distance from the Tropic of Cancer (which the sun is directly over at solar culmination): ([your latitude in decimal degrees] - 23.5) x 111 = kilometers from Tropic of Cancer.
2. Determine angle between the Tropic of Cancer and your location: Divide the length of the shadow by the length of the stick and take the arctangent.
On Windows 10, open the calculator, in the top left menu set it to ?Scientific?, divide the shadow length by the stick height and then click ?tan-1?. Note the ?-1? on ?tan-1?!
3. The angle calculated in step 2 makes is just a part of the circle that makes up the circumference of the earth. Now figure out how many of those angles make up 360 degrees: Divide 360 by the angle from step 2.
4. Calculate the circumference of the earth: Multiply the distance from the Tropic of Cancer (step 1) by the number found in step 3. It should be about 40,000 kilometers.
* Note that a building will potentially give you a more accurate result, but there are some problems you should be aware of. You must know the exact height of the building and there must not be any overhangs at roofline (like eaves). The bottom of the building must meet the hard, level surface at right angles (no drainage slope), etc. Again, small errors in the shadow measurement will be multiplied by many times!

Using suncalc.org:
Type ?suncalc.org? into your favorite browser and then move the map to the location that you will perform your experiment. In the example below, I?m using John and John?s Ice Cream shop in downtown Colorado Springs (not where I?ll be taking my measurements, but the best Ice Cream I?ve ever had).



In the top red box, click on the date and change it to June 21, 2019 (or your date of observation, from two days before to two days after June 21st). In the bottom red box, note the culmination time. This is the time you?ll want to measure the length of the shadow from the bottom of the stick.

In the top blue box, click on the time and change it to the culmination time.

You can get your decimal latitude from in the information in the bottom blue box.

Note that this site gives you a length of shadow for a [default] 10-meter stick at the time you specify (which, if you followed the directions above, will be the culmination time). You can use this information to make sure the results you?re getting are in the ballpark. Don?t fudge though, use the actual shadow length measured!

If you have any questions or suggestions, or most importantly your results (include your latitude, stick height and shadow length), please email me at experiment@nankoweap.com.

Thank you!

[O2HeN2]

Mo' bettah; forget the Word document, I just converted it into a web page: Eratosthenes Experiment

O2