Blue Ghost lander captures sunset shots on moon before falling silent
40 comments
·March 19, 2025crazygringo
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.
lolc
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.
crazygringo
> 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.
daemonologist
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...
lolc
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.
dragonwriter
> 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.
zokier
> 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.
crazygringo
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.
vachina
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.
tialaramex
> 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.
piker
Is the Earth bright like that due to the moonlight reflecting back?
JumpCrisscross
Sun on the horizon, Earth above it. (See caption.)
croisillon
Eu só queria te contar
Que eu fui lá fora e vi dois sóis num dia
E a vida que ardia sem explicação
gus_massa
[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.]
celeritascelery
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.
timhh
It is possible to survive the lunar night. See
Tempest1981
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
looperhacks
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.
celeritascelery
Is it the actual silicon that can’t handle it, or is contraction in joints and connections that breaks?
kristianp
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.
atkailash
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
DarmokJalad1701
> 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...
amenghra
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.
alwa
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…
babyent
o7 buddy
Damn I honestly feel for the lander even though it’s just a machine lol
Here's the other photos of Earth eclipses seen from the moon,
https://fosstodon.org/@AkaSci/114163135356046535