CHALLENGE for proof of a local Sun (and possibly a Flat Earth) 

Difficulty: Medium
Cost: $$ (Gear cost < USD 500)

NOTE: There is a simple starter variant of this challenge, very easy and with no gear cost. See below.

1. Produce a photograph of the solar disk from anywhere in the world and demonstrate an angular diameter outside the 31-32 arcminutes range.
   You must provide hard evidence of the measured angle. See conditions and recommendations below. 

2. If you have time: Take several pictures, and try to prove a changing size of the solar disk. 

3. If you have even more time and ability to travel: Take photos from different locations. 

If you succeed in this, you may have proven a so-called “local sun”, one of the fundamental parts of Flat Earth Theory.

Any such findings should be reported to your local university or the International Astronomical Union. 

Good Luck! 

A simple starter version of the experiment

Before you start this challenge you can start with a very simple experiment. Go outdoors on a sunny day, with clear skies or the sun hidden behind just a thin cloud layer. Wear a pair of really strong sunglasses, or even better glasses made of eclipse protection material. Welding glasses can be used too. Now straighten out your arm in the direction of the sun. Compare the width of the solar disk with the width of the tip of your little finger. What can you see?

If the width of the Sun is always (for repeated observations) about half the width of the tip of your little finger you have a strong indication of a non-local Sun.
If the width is greater or smaller than about the half the width of the tip of your little finger, or if it seems to change between different measurements you have an indication of a local Sun.
Even though this measurement is quite "un-scientific" it can be good as a preparation for the experiment below. You may also stop here, and use the knowledge from just your little finger. 

Now over to the real experiment....

These conditions apply

• Digital camera for still photos. 

• The digital camera should produce RAW files with EXIF data

  • RAW files are difficult to manipulate or forge. The EXIF data will contain information about the camera, lens, focal length used (“zoom level”), time of day, and (in some cases) even your geographical location. This information must be presented to anyone reviewing your experiment. 

  • You can also use a cell phone if it is capable of producing RAW files with EXIF data. Most modern cell phones have this capability, but in some cases, you need to use special photo apps for this.  

• Known optics with known field of view (FOV)

• Solar disk size easily calculated using pixel count

• Protect your eyes using a solar filter or similar. 

  • Looking into the sun with larger lenses without proper filter protection can cause retina burns and permanent loss of vision. 

  • Failure to use a proper solar filter can also damage your gear. But your eyes are much more valuable.. 

How to calculate the sun disk angular size

• Measure the width of the disk in pixels in your image.

• Take note of the horizontal and vertical size of your sensor (in pixels)

• Take note of the field of view of your lens (in degrees)

• Use the formula below

You can also download this excel sheet and insert your numbers (contains a more exact calculation of FOV).

Recommendations

• VERY IMPORTANT: Use a solar filter, strong welding glass, or similar in front of your lens.

  • The filter factor should be at least 100000. 

  • This will reduce the risk of your eyes getting hurt.

  • This will show the actual disk better, and reduce flare. 

    • I used a Baader filter, mounted in a ring fitting my lens. You can find information here. 

  • At sunset or sunrise, you may skip a strong solar filter but be careful to reduce exposure to really show the solar disk.
    Also be careful with your eyes at all times. 

• You don’t need a very long focal length lens, a Nikon P900, a telescope, etc. Just a camera capable of producing raw files and a lens, and the lens can even be a normal or wide-angle lens. You can use a cell phone too! 

  • I used a 15-year-old DSLR (Nikon D700). Lenses have been 35 and 105 mm. For some shots, I used a long telephoto lens (500mm) 

    • But the short lens (35 mm) produces enough pixel width of the sun disk to be useful. 

• Make sure you set the focus on infinity.

  • A hard-stop manual focus lens is the best option. Just turn the focus ring to the mechanical stop at infinity. 

  • If the lens is autofocus, it is advisable to disable the autofocus and stick to manual focus. 

    • If you use a cell phone, you may try a dedicated photo app allowing more control of focus. 

• A fixed focal length lens (prime) is the best option. 

  • If you use a variable focal length lens (zoom) or a cell phone, you need to carefully record exactly the field of view (FOV) to calculate the resolution (see formula above)

• Make sure your exposure time is short enough to reduce any motion blur. A tripod can be used if your hands are unsteady.

  • For a DSLR: a tripod is advised if the exposure time is longer than double the focal length. 

    • If your focal length is 100 mm, then you should use a tripod if the exposure time is longer than 1/200 s.  

• Manual exposure will probably be needed. Auto-exposure can get tricky since the subject is rather “odd”. 

• I used settings in the ballpark of  ISO 320, 1/400 s, and f/8 for my pictures taken with a solar filter (filter factor 100000).

  • This will get a white circular disk on a pitch-black background.

    •  If you expose correctly, you will as a bonus also be able to see sunspots and get a hint of light falloff at the rim of the solar disk (showing the sphericity of the Sun). 

• For sunset/sunrise, I used settings like ISO 320, 1/6400 s, and f/8, and no solar filter. (But be careful!) 

  • 1/6400 s is very fast. If your camera can't reach such a short exposure time, then use the shortest shutter speed available. 

• Take several pictures and adjust exposure if needed. 

• If using a cell phone: You may need a dedicated photo app to be able to control exposure better.

• For estimating the size of the solar disk you can use any photo editing software. 

  • You need to count the pixels from edge to edge of the image of the solar disk

    • I used Photoshop for this. It has a nifty “ruler” function which does the job. 

• For pictures taken close to sunset or sunrise (near the horizon) you may get vertical distortion due to atmospheric refraction. The sun will get “stretched” or “squeezed” or in some cases get a strange “pear-like” appearance. In those cases always use the horizontal extension of the solar disk for any calculations (It is normally not affected much by atmospheric refraction). 

• See this folder for an example of some pictures, including some documentation. 

This is a typical photo of the Sun where a solar filter has been used properly. Here we have also used a rather long focal length (500 mm), allowing us to see details (sunspots, faculae and limb darkening). But you don't need a long telephoto lens or a telescope!  The important thing: A pitch-black background which makes it easy to see the extension of the disk! 

Some simple theory

A Flat Earth cannot exist unless the Sun is local (nearby)

Otherwise, if the sun is very distant then solar elevation would be the same everywhere on Earth.

See the picture below.

We know that solar elevation is not the same for everyone on Earth at a given moment. It is easy to check up.

Just make a phone call to a friend on another continent and ask about the time of day. 

So the picture above cannot work. 

So this would need us to lower the Sun to a much lower altitude. Something like this:

We can see that a different (and changing) solar size is necessary for the Flat Earth Model to work out. 

To prove the Flat Earth Model, we must prove the sun to have a varying size!
This observation is necessary proof for the Flat Earth model. 

Professional astronomers have observed the Sun for centuries. The angular size has been established in the 31-32 arc minutes range. There is a slight yearly change due to the elliptic orbit of the Earth around the Sun. This is what conventional Astronomy teaches us anyway. But is this correct? The challenge will allow you to disprove this observation. A varying size should produce great differences: We would expect smaller than 10 arc minutes and greater than 60 arc minutes easily. Can you show this?