Corey S PowellMar 14, 2025

Here it is: The first clear image of an eclipse of the Sun by the Earth, taken from the surface of the Moon.

This is what last night's lunar eclipse looked like from the Blue Ghost lander's perspective on the Moon. Amazing!

https://www.flickr.com/photos/fireflyspace/54386246629/in/dateposted/ #space #science #art #tech

Blue Ghost Mission 1 - Solar Eclipse Diamond Ring Effect

Flickr
Show threadAlexandre Oliva
there's something very puzzling about this picture, that seems to call for some fact checking

I mean, it's a great coincidence to begin with that the moon and the sun have the same apparent sizes when seen from the earth in solar eclipses

but the earth is significantly bigger than the moon, and the moon is as far away from the earth as the earth is from the moon, so the apparent size of the earth as seen from the moon should be bigger than that of the moon as seen from the earth

but the earth seems slightly smaller than the sun in the picture, and it's not like the moon is closer to the sun than the earth is to justify this discrepancy by seeing an apparently bigger sun

ISTM that it's too much of a coincidence that the apparent size of the earth would be as close to that of the sun as seen from the moon, on top of the coincidence that the apparent sizes of the moon and of the sun are about the same when seen from the earth.

it's not absolutely impossible, but the moon orbit would have to be just weird enough to make for this coincidence just at the time of the eclipse that I'm having trouble believing that.

can anyone offer evidence that the compounded coincidence is indeed plausible, and that the picture isn't a fake? I could more easily believe it's a picture of an earlier solar eclipse seen from the earth, or some AIrstistic rendering of a solar eclipse as seen from the moon misgeneralized from pictures of solar eclipses taken from the earth

cc: @[email protected] @[email protected] @[email protected]
Mar 15, 2025 at 10:45amWeb
Show threadStephen SekulaMar 15, 2025

@lxo @coreyspowell

The Earth would cover the Sun completely during an eclipse viewed from the Moon. This is why a lunar eclipse lasts longer than a solar one, where the Moon covers the Sun as viewed from the Earth.

However, this picture can still be real. The sun's disk appears smaller than the disk of the Earth. Refraction of sunlight in the atmosphere would ring the entire Earth in light. This diamond ring effect is due to the Sun being to one side.

Pic is certainly plausible.

Show threadAlexandre OlivaMar 15, 2025
thank you professor!

now that you mention it, I can see that the "blotch of light" from behind earth's lower right quadrant, that I had mistaken for a distortion, does indeed draw a perfect arc that is indeed apparently smaller than the earth, in the proportion I would have expected. the refraction around the earth's atmosphere had indeed confused me, to the point of misidentifying the arc of the sun as that.

now, with the concern that it might be a fake entirely relieved (thanks @[email protected] too for the reassurance) I can go back to the awe and the appreciation of the beauty of the moment captured in the picture. wow!

CC: @[email protected]
Show threadStephen SekulaMar 15, 2025

@lxo @hydropsyche @coreyspowell

In the modern age, it’s good to be a little skeptical. But I admire that you did it, sought input, and even though it’s impossible to ever give 100% assurance, all of us gave it a think and now we can step back and look at these images and just go…

WOW.

Show threadElizabeth SudduthMar 15, 2025

@lxo @coreyspowell

It's from the official Firefly Aerospace Flickr account, which otherwise mostly shows pictures of stuff they send to space. I suppose it's possible they decided to add fake pictures of the eclipse, but that seems like a weird approach for a not particularly self-promotional company to do. Surely if they were in it for the clicks they would be doing this on Instagram, which is full of fakes, not on Flickr, which hardly anyone uses except actual photographers.

Show threadFaMar 15, 2025

@lxo @coreyspowell @steve @JorgeStolfi

Oi
O tamanho aparente de um objeto no céu depende do seu tamanho real e da sua distância do observador.

O Sol tem um diâmetro de cerca de 1,39 milhões de km, e a Lua tem 3.474 km.

A distância média do Sol à Terra é de cerca de 149,6 milhões de km. A Lua está a 384.400 km.

O Sol é cerca de 400 vezes maior em diâmetro do que a Lua. Mas está cerca de 400 vezes + distante da Terra do que a Lua. Isso faz com que ambos pareçam ter o mesmo tamanho no céu.

Show threadFaMar 15, 2025

@lxo @coreyspowell @steve @JorgeStolfi

Resumi um textinho do Deep Seek - :) -

Show threadAlexandre OlivaMar 15, 2025
isso só explica o sol e a lua terem o mesmo tamanho aparente, vistos da terra. não há novidade aí, embora já seja uma baita coincidência.

a coincidência composta com essa que me pegou de surpresa na foto foi que também o sol e a terra tinham o mesmo tamanho aparente, vistos da lua, pelo menos no momento do eclipse desta semana. parece-me que não era pra ser assim: penso que a terra deveria parecer maior
Show threadFaMar 16, 2025

Oi Alê,
de novo, o Deep Seek informa:
Há uma fórmula para calcular

Tamanho aparente =
2× arctan ⁡(Diametro do objeto / 2×Distancia)

tamanho aparente do Sol visto da Lua:
diâmetro do Sol - 1,39 milhões de km
distância média entre Sol e Lua - 149,6 milhões de km
tamanho aparente do Sol visto da Lua = cerca de 0,5 graus (ou 30 minutos de arco)

Show threadFaMar 16, 2025

Tamanho aparente da Terra vista da Lua:
diâmetro da Terra = 12.742 km
distância média entre Terra e Lua = 384.400 km
tamanho aparente da Terra vista da Lua = cerca de 1,9 graus (ou 114 minutos de arco)

Ou seja, quando vistos da Lua, a Terra parece quase 4 vezes maior do que o Sol.