Distance to the Sun

Hey, I just got a pretty cool idea, and it gives everyone another opportunity to do some observations.

The autumnal equinox is nearly upon us (18 days away), which gives us a very unique opportunity. For at least 24 hours on either side of the equinox the sun will be within a half-degree of the equator, which presents a unique (well, ish, it happens twice a year) opportunity for observations and calculations.

The equinox happens at 20:39 UTC on the 22nd of September. Between 20:40 UTC on the 21st and 20:40 UTC on the 23rd the sun will move only 46' southward. We can round this to 1° (60') for very conservative numbers.

But what are we measuring? The sun, of course!

There are a few records of various solar experiments done regarding the angle of the sun from cities directly north-south of each other and using this to calculate the altitude of the sun. We can do the same here, and the equinox provides very nice calculations!

What do you need to do? Well, here, I'll do a little write-up:

---

Distance to the Sun:

Materials:

• A straight object of known length (yardstick)
• A method of measuring length (tape measure)
• A piece of flat ground (flat enough will work for this)
• A way to find solar noon for your location
• Your latitude

Method:
At solar noon for your location on either the 21st, 22nd, or 23rd measure the angle of the sun. This can be done by measuring the length of the shadow of a vertical object. The angle of the sun is the arctangent of the height of the object divided by the length of the shadow:

Post the results (your latitude and the angle of the sun) here for all to see.

---

During those three days the sun will be within at most 30' (0.5°) of the equator, meaning your latitude will be within 30' (0.5°) of your distance from the point at which the sun would be at zenith. Because a degree of latitude is 1/90th of the distance from the north pole to the equator our results will be in terms of this.

If you wish to do the maths yourself to figure out the height you get for the sun you can (post them with the other infos). You can use one of the below equations:

Once again, the answers will be in terms of degrees of latitude, each one is 1/90th the distance from the north pole to the equator.

I'll be doing this one for sure! I'll insert my results into this post when I have them.

RESULTS:

My latitude: 30° South.

Using a 1m long stick, set vertical by use of a simple plumb bob, I measured a shadow 585mm long.
Allowing ±5mm for possible errors in measurement, this yields a sun angle between 30.11° and 30.54° to the vertical.

Now, assuming a flat earth, I made the following calculations:
Allowing ±0.5° for possible error in my latitude (obtained from a WAC), this then gives a sun height between 52.6/90 * D and 50.0/90 * D, where D is the distance from the equator to either geographic pole.
Assuming D to be ~6000 statute miles, this gives a sun altitude between 3507 miles and 3,333 miles.

CONCLUSION:

I'm allowing for a great deal more error than I believe existed in my measurements, and yet I'm more than 10% off the oft-cited FE figure of 3,000 miles. Has anyone else managed to do this experiment? I'd be very interested to compare results!

And how in the hell is this going to prove the distance to the sun?

And how in the hell is this going to prove the distance to the sun?

Please sceptimatic, return to your sandbox thread and leave this brainwashed bullcrap measures to indoctrinated people. Why do you ask for something you will discard anyway ?

Make sure the stick is upright, completely vertical

And how in the hell is this going to prove the distance to the sun?

On a flat earth you can use trigonometry

Quote from: sceptimatic on September 05, 2013, 03:51:32 AM

And how in the hell is this going to prove the distance to the sun?

On a flat earth you can use trigonometry

Let's see how you do it on your spinning globe.

Quote from: Cartesian on September 05, 2013, 05:21:37 AM

Quote from: sceptimatic on September 05, 2013, 03:51:32 AM

And how in the hell is this going to prove the distance to the sun?

On a flat earth you can use trigonometry

Let's see how you do it on your spinning globe.

As I said in another thread you must first embrace the RE model first

Quote from: sceptimatic on September 05, 2013, 06:31:30 AM

Quote from: Cartesian on September 05, 2013, 05:21:37 AM

Quote from: sceptimatic on September 05, 2013, 03:51:32 AM

And how in the hell is this going to prove the distance to the sun?

On a flat earth you can use trigonometry

Let's see how you do it on your spinning globe.

As I said in another thread you must first embrace the RE model first

So you don't have a clue how they measure the sun on your rotating globe. Ok, fair enough.

Quote from: Cartesian on September 05, 2013, 07:06:51 AM

Quote from: sceptimatic on September 05, 2013, 06:31:30 AM

Quote from: Cartesian on September 05, 2013, 05:21:37 AM

Quote from: sceptimatic on September 05, 2013, 03:51:32 AM

And how in the hell is this going to prove the distance to the sun?

On a flat earth you can use trigonometry

Let's see how you do it on your spinning globe.

As I said in another thread you must first embrace the RE model first

So you don't have a clue how they measure the sun on your rotating globe. Ok, fair enough.

No. YOU don't have a clue how to measure the sun's distance. Too much indoctrinated maths, so you will dismiss any kind of explanation.
Again, why are you asking ?

Quote from: sceptimatic on September 05, 2013, 07:15:39 AM

Quote from: Cartesian on September 05, 2013, 07:06:51 AM

Quote from: sceptimatic on September 05, 2013, 06:31:30 AM

Quote from: Cartesian on September 05, 2013, 05:21:37 AM

Quote from: sceptimatic on September 05, 2013, 03:51:32 AM

And how in the hell is this going to prove the distance to the sun?

On a flat earth you can use trigonometry

Let's see how you do it on your spinning globe.

As I said in another thread you must first embrace the RE model first

So you don't have a clue how they measure the sun on your rotating globe. Ok, fair enough.

No. YOU don't have a clue how to measure the sun's distance. Too much indoctrinated maths, so you will dismiss any kind of explanation.
Again, why are you asking ?

You seem a bit defensive here. If you don't know how they measure the sun on your rotating globe, it's fine, I just thought one of you might know, that's all.

There is a thread discussing about trigonometric parallax, go and have a look.

Scepti, this thread is about using measured observation to calculate the altitude of the sun over a flat Earth. This thread is not about a round Earth, or heliocentric, or anything like that. If you wish to discuss the Sun-Earth distance in a non-flat-earth model, please do so in another thread.

For the heliocentric distance, I'd recommend this thread: http://www.theflatearthsociety.org/forum/index.php/topic,59776.msg1535365.html#msg1535365

You should explain how to tell when solar noon is in my area. Something along the lines of "when the shadow cast is at it's shortest" with some sort of methodology surrounding it.

You should explain how to tell when solar noon is in my area. Something along the lines of "when the shadow cast is at it's shortest" with some sort of methodology surrounding it.

If you know your longitude, you can use UTC. If your longitude is Easterly, you subtract 4 minutes per degree from 1200hours (so for me, 150° x 4 minutes = 10 hours which puts local noon at 1200local - 10 hours = 0200UTC). If it is Westerly, you add 4 minutes per degree (so, New York's official longitude of ~74W would give you 4 hours 56 minutes, or 1656UTC for local noon).

Just for curiosity, who else is going to take these measurements? The more the merrier! Helpful hint for those who are: you can make a simple plumb bob out of any string or similar and a weight to make sure your yardstick is exactly vertical, this will help with the accuracy of your measurement.

I am interested to participate. It's midday Sunday so the timing is ideal for me. I know which lat/long I live but I will use a free GPS app on my mobile to calculate my exact position anyway. According to that site, where I live solar noon should be at around 12:56 on that date. But I think we must give an easier way on how to find out solar noon to everyone. Taking the measurement correct is really important for this to get the most accurate result as possible; the time must be solar noon, the yardstick must be upright, the pole must be at least a certain height from the base (if it is too low then the error will be higher), the base must be horizontal, etc.

Maybe there is a way to simplify this experiment such as measuring the shadow of a lamp pole at a particular time? But how can I measure the height of a lamp pole?

And finally my biggest worry is the weather. I hope it will be sunny that day

I am interested to participate. It's midday Sunday so the timing is ideal for me. I know which lat/long I live but I will use a free GPS app on my mobile to calculate my exact position anyway. According to that site, where I live solar noon should be at around 12:56 on that date. But I think we must give an easier way on how to find out solar noon to everyone. Taking the measurement correct is really important for this to get the most accurate result as possible; the time must be solar noon, the yardstick must be upright, the pole must be at least a certain height from the base (if it is too low then the error will be higher), the base must be horizontal, etc.

Maybe there is a way to simplify this experiment such as measuring the shadow of a lamp pole at a particular time? But how can I measure the height of a lamp pole?

And finally my biggest worry is the weather. I hope it will be sunny that day

Due to the obscurity of time zones, solar noon will be different everywhere. I think that longitude calculation might work, if and only if solar noon for London is at exactly 12:00 noon.

Accurate measurements are pretty critical. Just do the best you can, and if you feel you didn't do a good job of measuring add uncertainty to your data. For instance:

Latitude: 45.54° N
Length of stick: 914.4 mm
Length of shadow: 940 mm ± 5 mm
Angle of sun: 44.21° ± 0.15°

You should explain how to tell when solar noon is in my area. Something along the lines of "when the shadow cast is at it's shortest" with some sort of methodology surrounding it.

When the shadow points due north (assuming that you're in the northern hemiplane).

Quote from: EnigmaZV on September 06, 2013, 02:55:51 PM

You should explain how to tell when solar noon is in my area. Something along the lines of "when the shadow cast is at it's shortest" with some sort of methodology surrounding it.

When the shadow points due north (assuming that you're in the northern hemiplane).

Due polar north. Magnetic north, which is how I think most people would check for 'due north' is different. Here in Portland, a compass actually points over 15 degrees east of north. You can find your declination here: http://magnetic-declination.com/

Quote from: EnigmaZV on September 06, 2013, 02:55:51 PM

You should explain how to tell when solar noon is in my area. Something along the lines of "when the shadow cast is at it's shortest" with some sort of methodology surrounding it.

When the shadow points due north (assuming that you're in the northern hemiplane).

I am not sure if it right or wrong, but usually solar noon is also the middle time between sunrise and sunset. It's usually easier to find sunrise and sunset for a particular location than solar noon.

To find solar noon for your location you can use a tool like this: http://www.timeanddate.com/worldclock/astronomy.html?n=197&month=9&year=2013&obj=sun&afl=-11&day=1

Only a few days left until this opportunity to collect some meaningful data, so who's in?!

I bought a spirit level few days ago. I just hope that it's not cloudy or raining this Sunday.

Where I live, according to forecast it will be cloudy on Saturday/Sunday and sunny on Monday. Equinox is predicted to be September 22 2013 20:44 GMT so I guess I can still do this on Monday 23rd.

Just in case nobody checks back to my original post in this thread, where I have now inserted my results, I will duplicate them here:

RESULTS:

My latitude: 30° South.

Using a 1m long stick, set vertical by use of a simple plumb bob, I measured a shadow 585mm long.
Allowing ±5mm for possible errors in measurement, this yields a sun angle between 30.11° and 30.54° to the vertical.

Now, assuming a flat earth, I made the following calculations:
Allowing ±0.5° for possible error in my latitude (obtained from a WAC), this then gives a sun height between 52.6/90 * D and 50.0/90 * D, where D is the distance from the equator to either geographic pole.
Assuming D to be ~6000 statute miles, this gives a sun altitude between 3507 miles and 3,333 miles.

CONCLUSION:

I'm allowing for a great deal more error than I believe existed in my measurements, and yet I'm more than 10% off the oft-cited FE figure of 3,000 miles. Has anyone else managed to do this experiment? I'd be very interested to compare results!

There was no sun at all yesterday where I live so I couldn't do the measurement. This morning seems very cloudy as well, although the forecast said that it would be sunny later. I hope sun will appear before the solar noon.

Sorry it's been a dull day again. The sun only came out at about 4pm

That's about what the sky looks like here too. Been that way for the past week.

Did no-one else manage to do this over the weekend? I can understand those who suffered adverse conditions not doing it, but surely someone else had a bright, sunny day between the 21st, 22nd, and 23rd?!

That's about what the sky looks like here too. Been that way for the past week.

The white sky and no direct sun shine is probably due to chemtrail spraying.