Sun to Earth scale for pictures: Is this right?

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Thefatkitty
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Sun to Earth scale for pictures: Is this right?

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Post by Thefatkitty »

Earlier today I took some shots of le Soleil, and got to thinking about how I've seen others on here scale the Earth to their Sun pictures.

I'm not even to sure what to search for on that, so I tried something. I don't know if this is right, so that's why I ask.

First I brought up my pics of the Sun. I then overlaid a grid on the pic, and measured with the select tool how many pixels it was across the exact center from one edge of the disc to the other. I had to check that a few times, as the result in pixels was the exact same as my year of birth, 1965. Odd that, but easy to remember :lol:

I did a search on converting pixels to inches, and came across this site, Ninjaunits.com. Neat. It needed the DPI of my monitor (obviously) which was 75. I then put in the pixels, and the result in inches was 26.2.

I then did a search on sun scaled diameter, and ended up on this site, Exploratorium.edu. Fun site, actually. You can put in the dimensions for making a scale solar system, so I put in 26.2 inches for the Sun, and in comparison the Earth was 0.2398 inches.

Back to Ninjaunits, where I was informed that 0.24 inches was 18 pixels. Ok, so I'm off by 0.0002 inches...

I then drew a circle in my image 18 pixels across, and colored it pale blue :lol:

So that's my question here; is my logic on this right or am I off base on this?

This is the image I ended up with, my "earth" is to the bottom right. I'd appreciate any and all advice :D
Sun_Earth_s.jpg
Thanks again and all the best,
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notFritzArgelander
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Re: Sun to Earth scale for pictures: Is this right?

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Post by notFritzArgelander »

Your logic is fine. But there is an easier way. The Sun's radius is about 109 times Earth's. So the number of pixels in the Sun diameter, 1965/109=18 the number of pixels in Earth's diameter.
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Re: Sun to Earth scale for pictures: Is this right?

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Post by MistrBadgr »

That is an excellent demo picture, showing the relative sizes and a sunspot that is about the same size as the Earth, even without the extra frills to the left of the dark dot! :)
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Thefatkitty
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Re: Sun to Earth scale for pictures: Is this right?

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Post by Thefatkitty »

notFritzArgelander wrote: Thu May 13, 2021 2:02 am Your logic is fine. But there is an easier way. The Sun's radius is about 109 times Earth's. So the number of pixels in the Sun diameter, 1965/109=18 the number of pixels in Earth's diameter.
Leave it to me to overthink this one... Whenever it comes to math I always seem to take the hard route to my answer. Could've saved myself a lot of typing too :lol:

Thanks for the verification nFA!

All the best,
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Re: Sun to Earth scale for pictures: Is this right?

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Post by AstroBee »

I've successfully used the "Solar Ruler" in the past.

https://thesolarexplorer.net/index.php/ ... olar-ruler

Look about half-way down this link for the "La Règle Solaire (pdf 88 Ko)" link.
https://sites.google.com/site/astroblue ... ico-utiles

You can convert the PDF into a PNG and bring it in as a layer over your image. Resize to fit, voila!

It's really great because it gives you an idea of the height of the prominences too.
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messier 111
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Re: Sun to Earth scale for pictures: Is this right?

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Post by messier 111 »

fine work , thx .
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