Blue Ghost lander captures sunset shots on moon before falling silent
phys.org103 points by pseudolus a month ago
103 points by pseudolus a month ago
Here's the other photos of Earth eclipses seen from the moon,
I am curious what causes these landers to fail in the bitter cold of night? Is it the batteries? It seems like circuitry should be fine.
Commercial chips have min/max temperature specs, like -20°C to +70°C, or perhaps -40°C to +125°C. (Not sure what spacecraft use.)
Lunar temps can drop to -130°C to -250°C
The moon gets _really_ cold, way below spec for most electronics. That's why sensitive parts are sometimes in a heating component, but that also depends on the battery. And yes, cold batteries might not recover properly.
Is it the actual silicon that can’t handle it, or is contraction in joints and connections that breaks?
14 days is a long time to keep warm something warm. That's in the realm of a Radioactive decay heater. That might at least keep things warm enough that it can wake up the next day.
Meanwhile voyager is beyond the solar system. I don’t see why they didn’t use something that’s not solar so they aren’t just littering the moon
> Meanwhile voyager is beyond the solar system
Which is powered by Pu-238 - something which is in short supply nowadays, extremely expensive and pretty much inaccessible for a private company like Firefly who built the Blue Ghost lander.
> I don’t see why they didn’t use something that’s not solar
Cost. NASA paid Firefly $101.5M for the Blue-Ghost 1 contract [1]. Just the RTG used on the MSL Mars Lander cost $109M [2] (not counting the R&D costs).
> so they aren’t just littering the moon
Well, right now it is harming no one. They can only be seen by cameras orbiting the moon. If and when humanity starts living on the moon, these landers will go in museums and will no longer be "litter".
[1] https://spaceflightnow.com/2025/03/18/firefly-aerospaces-blu...
[2] https://en.wikipedia.org/wiki/Multi-mission_radioisotope_the...
For context, some moon rovers have radioisotope heaters,
https://en.wikipedia.org/wiki/Chang%27e_4#Chang'e_lander_and... ("Both the stationary lander and Yutu-2 rover are equipped with a radioisotope heater unit (RHU) in order to heat their subsystems during the long lunar nights")
https://en.wikipedia.org/wiki/Lunokhod_1#Rover_description ("During the lunar nights, the lid was closed, and a polonium-210 radioisotope heater unit kept the internal components at operating temperature")
The moon is huge compared to a single thing we can currently send there. Comparatively, we are “littering” our own atmosphere a ton more during liftoff.
I can’t help but suspect Starship’s recent run of spectacular explosions might frustrate efforts to launch more nuclear-powered craft like the Voyagers too soon…
It's a private flight. Probably made cheaply. The article said the lander planned to drill 10 feet but could only do 3.
Whole thing smells like shoddy craftsmanship.
Give it a go, see how far you get before we all call your work "shoddy".
I don't understand these photos at all. Why does it look like there are two suns in two of the photos -- one at the horizon and one above?
Is one of them lens flare or something? I don't think the top one could be an overexposed earth because we're obviously looking at the earth's dark side. And in the other photo (middle in the galley) it looks like a little bit of the earth is eclipsing the second sun.
They say there are sun, earth and Venus in the shot. So the second most bright thing must be the earth.
I assume the earth here is simply blown out from overexposure. With my digital camera I can overexpose a new moon if I set the exposure long enough. So I guess it works the other way too.
Edit: Actually it looks like the moon surface is already mostly in the shade with the hills illuminated from the back. There must be a hill behind the lander. So this light was reflected twice and is rather weak. On the left there are some higher hills still in direct sunlight, they are blown out. Meanwhile, light from earth is reflected twice, but at an acute angle.
> I assume the earth here is simply blown out from overexposure.
That was my first thought but I don't see how that's possible since we're looking at the dark side of the earth. It can't be overexposed when it's going to be much darker than the surface of the illuminated parts of the moon. At most, the earth would have a tiny sliver of light at the edge and we'd see a crescent shape.
I suspect that crescent shape is so relatively bright the bloom/lens flare is obscuring the details of its shape and making it just look like a blob. There's a little bit of "flatness" on top which would correspond to the darker inside of the crescent (think of what you'd get if you did a threshold and dilation, except it's probably happening entirely in-camera).
I also suspect the surface of the moon is not directly illuminated by sunlight, as you can see what appear to be brighter (higher elevation? more "westerly?") areas of the surface in the distance. It might be scatter from other terrain or the thin atmosphere. Hard to say without more information - on a world with almost no atmosphere and a "moon" the size of earth the usual visual instincts kind of go out the window.
There's another photo here which might be clearer: https://scx2.b-cdn.net/gfx/news/hires/2025/blue-ghost-lander...
I actually think the other photo you link does it make it clearer, in the opposite way.
That photo shows the top bright circle clearly partially obscured by another dark circle of the same size. The only explanation is it's a partial eclipse of the sun by the earth. Nothing else produces that shape. And indeed, other photos show a full eclipse and are labeled as such, so we know that the timing is right! The shape is clearly defined -- it's not bloom or lens flare. Which means that above the horizon we see both earth and sun. And in the hero image, we see the same thing, as you describe it "a little bit of flatness". But that shape can't be produced by blooming a crescent. It's answered by your linked photo -- it's the dark, black earth obscuring the edge of the sun.
Which leads to my original question -- what the heck is the brightness touching the horizon of the moon? It simply can't be the sun. Also, the way it dips below the horizon shows that if it is real, it actually has to be nearly entirely "bloom". But then the sun above should have way more bloom and it doesn't... which means it isn't a real object at all, not even a real reflection you'd see on the lunar surface.
So I did a little bit more digging and it turns out this is a common effect in camera lenses, duplicating the sun. It's not lens flare exactly, but it's the same idea. Examples here on earth:
https://www.reddit.com/r/Damnthatsinteresting/comments/15dj3...
https://www.reddit.com/r/atoptics/comments/1cqk6dv/took_sunr...
https://www.metabunk.org/threads/explained-two-suns-sanibel-...
So this isn't sunset. The sun is above the horizon, and the bright "sun" touching the horizon is a reflection of the sun in the camera's optics. It doesn't exist in reality.
The parts of the moon in direct sunlight are blown out too. Where we see the terrain's texture, it's illuminated from the back; with what must be light reflected from the moon's surface.
The dark side of Earth is illuminated by a full moon.
> The dark side of Earth is illuminated by a full moon.
Yes it is, but it's still going to be extremely dark. Think of how dark it is outside even when it's a full moon. You can see things, but it's still orders of magnitude less than daylight brightness.
And if the camera were exposed for minutes in order to not just capture that but overexpose it, we'd see stars everywhere. But we don't. So no. Earth is going to be black in this picture, period, except for a possible crescent.
It doesn't take very special cameras to capture a new moon. I have many pictures that look like this: https://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Lu...
For a photo like this I use an exposure of around one second.
I think we're agreeing -- you're using a shorter exposure that captures the dark part of the moon, but isn't long enough to capture stars.
If you want to capture stars, it needs to be longer. Looking it up says that 20 seconds is roughly the minimum. Which is also around what would overexpose the entire moon in your example. So that's what I'm saying -- the dark side of the earth doesn't seem like it could be overexposed because we can't see any stars.
You propose that the sun is above the horizon and that the bright light on the horizon is a reflection of sunlight. That seems off to me: With the sun in the sky, why would its reflection have the strongest diffraction spikes? Why would there be a blown out fringe along the horizon, and no blown out surface close to the craft?
I agree that I'd expect to see stars when the moonshine on earth is overexposed. Maybe it's just glare that makes the light from earth's crescent orb-shaped. In an image of a different camera where the sun is obscured[0], the earth crescent is well visible, and no moonshine on earth. Firefly's page on the mission has enough detail[1] to put your and my speculation to rest :-)
[0] https://fireflyspace.com/wp-content/uploads/2025/03/Blue-Gho...
[1] https://fireflyspace.com/news/blue-ghost-mission-1-live-upda...
> I don't think the top one could be an overexposed earth because we're obviously looking at the earth's dark side
It's Earth. Venus is also visible as small dot.
It can't be though. It's earth's dark side. It couldn't be bright like that -- it's not physically possible, right? At best it would be a sliver of a crescent.
Also, in the other photo, there's a dark circular object partially obscuring. That would have to be earth, no? Obscuring the sun, which means the object on the horizon is... lens flare even brighter than the sun, or something?
Do people here understand my confusion? I'm not convinced the captions are accurate, because they seem to contradict what's physically possible.
I know you’re feeling crazy right now, im too appalled at HNers inability to comprehend such simple logic and yet sound so confidently wrong at the same time.
How is it possible you’re looking at a light source, and still see the shadow of an object shining? Right? Unless there is another very bright light source behind, which in this case there isn’t.
Thank you for the validation! I was starting to think I was taking crazy pills.
I believe I have solved it, I described it in another comment:
https://news.ycombinator.com/item?id=43452888
tl;dr: The bright object above is the sun, not the earth. The bright "object" on the horizon is a "doubling" reflection of the sun in one of the camera's lenses. It doesn't exist in reality. This happens when photographing the sun on earth as well with certain lenses. The earth is black and totally invisible, except that it's a tiny partial eclipse covering up a tiny bit of the sun at the top (clearer in other photos), which is why it's a little "flat" at the top. The photo is not the precise moment of sunset. The caption is entirely wrong.
> the object on the horizon is... lens flare even brighter than the sun, or something?
This is a photo of sunset. The nature of sunset ought to be pretty easy to understand, from the point of view of the camera on a large object, the Sun seems to go behind the object and then it can't see the Sun any more, and we call this "setting". So no, the object on the horizon is the Sun, it's incredibly bright.
I expect the problem is like with that "3.6 Roentgen, not great, not terrible" meme, you're assuming that a device (the camera) is giving you correct information but it was maxed out instead. The Earth looks bright from the Moon, as the Moon does to us. So lets call that 100% bright. Now the Sun is several hundred thousand times brighter. That's um... oh, it's 100% bright again, because we've maxed out the device.
> The Earth looks bright from the Moon, as the Moon does to us. So lets call that 100% bright.
No it doesn't, because as I've stated twice, it's the dark side of the earth we're seeing, because the sun is behind it. It's more like 1% bright, as compared to the moon's visible illuminated surface.
Think how bright the dark part of a thin crescent moon is. That's how bright the earth is going to be in this picture. Close to black, except for maybe a sliver of a crescent similar in brightness to the moon's surface.
So again -- this photo makes no sense. Unless one of the two objects is just lens flare, or there's another kind of artifact.
Wide angle lens could explain it. We see the earth is not fully illuminated in one of the pictures. And the “curve” of the lunar surface is most likely from wide angle lens.
No, wide angle lens has nothing at all to do with exposure or illumination. That wouldn't explain anything.
You’re stuck on being certain we’re looking at the dark side. My point of wide angle lens is maybe we’re not looking at it in a crescent state after all, the angles just appear that way due to the lens. You can see the illumination state in the other photos.
I’m not sure what you’re proposing, that this is a fake image?
I'm not "stuck" on it being the dark side. Of course I'm certain it is, that's how the solar system works. It's how shade works. The sun isn't in between the earth and the moon, or else we wouldn't be here commenting on HN. ;)
I'm pretty sure I solved it, see: https://news.ycombinator.com/item?id=43452888
Not a fake image, but a totally incorrect caption.
No stars though.
You don't usually see stars during the day
Because of the atmosphere diffuses all the blue from the sunlight all over the place. I've seen people demonstrate that if you know where to point a telescope, it is just about possible to make out some of the brighter objects — though I can't remember if that was a star or a planet…
But in this case, the exposure is set at a level that even Venus isn't quite fully saturating the sensor.
Yup, it's less to do with atmosphere and more with exposure.
Shots of stars at night have exposures of a few seconds to get them to appear. Shots in the daytime are more like 1/60 sec.
On the moon, the sunlight bouncing around is still enough to outshine the stars
> Why does it look like there are two suns in two of the photos -- one at the horizon and one above?
I think that its a reflection (on what? internal to the camera optics, somehow?) In both cases, the second sun also seems to have a horizon occluding it, from the opposite direction.
Here you go: https://www.youtube.com/watch?v=IpA9DORDkeE.
> we're obviously looking at the earth's dark side
We are not. Why would we?
>> we're obviously looking at the earth's dark side
> We are not. Why would we?
Yes we are.
Because the earth is in between the sun (faraway) and the moon (where we are) and very close to the line between the sun and us (because they're close by in the image -- it's not like the sun is in front and the earth is 90° above us which would half-illuminate it, or 180° behind us which would entirely illuminate it).
If you turn on a lamp in a room, and hold an object between you and the lamp, obviously you're looking at the side of the object that is in shade. The illuminated side faces the lamp, which is opposite you.
The photo’s caption says:
“This image provided by NASA/Firefly Aerospace, Tuesday, March 18, 2025, shows the sun setting on the moon, with Earth and Venus in the distance.”
Because there are two Suns and we actually live on Tattooine and George Lucas was right all along and it’s Elon Musk and Lee Harvey Oswald what tried to keep the Truth from coming out but Birds Arent Real and the Area 58 chemtrails prove there’s your Face on Mars, sheeple!!1
Eu só queria te contar
Que eu fui lá fora e vi dois sóis num dia
E a vida que ardia sem explicação
[This is part of the lyric of a song https://www.musixmatch.com/es/letras/C%C3%A1ssia-Eller/O-Seg... This kind of comments are usually downvoted here.]
o7 buddy
Damn I honestly feel for the lander even though it’s just a machine lol
