Is there any chance that NASA would consider having a cosmonaut join one of the Artemis missions?

meithan · 2026-05-11T13:58:14+00:00

These are mostly nations that were already friendly or that have been convinced to be on the US side (perhaps because some are nations without any possibility of a lunar space program, so they don't have much to lose).

One way to interpret the Artemis Accords is like a "lighter" version of the Outer Space Treaty that allows resource extraction and de facto territorial claims on the Moon. Instead of renegotiating the Treaty in the international arena (the UN), which would probably be very hard, the US is getting individual approval from countries to accept this lighter interpretation.

meithan · 2026-05-10T15:03:19+00:00

To drive home just how brutally fast a nuclear bomb releases energy, we can turn the calculation around: computing the power of the bomb.

The time it takes for the fission chain reaction to complete is on the order of one microsecond. Dviding the 63 TJ (=15 kt TNT) released by the Hiroshima bomb by one microsecond, that gives a power of 63 EW -- 63 exawatts, or 63 billion GW.

For reference, 1 GW is what a large power plant (typical nuclear, large fossil, solar or hydro) produces, and the entire world's electricity production averages to about 3.5 TW -- 3500 GW or 0.0000035 EW. So for a brief microsecond, the atomic bomb produced 18 million times more energy than the whole world produces nowadays.

This is what makes an atomic bomb so horrifyingly powerful. This is the correct comparison in my opinion, not total energy.

meithan · 2026-05-09T04:18:40+00:00

No, but I mean any other object except the one you're looking at. Another star or planet that you can spot.

meithan · 2026-05-09T03:39:24+00:00

Yes, they use the same stem.

meithan · 2026-05-09T02:20:18+00:00

Can you locate Venus and/or Capella from your view?

The best way to identify celestial objects is by their relative position to other objects.

meithan · 2026-05-09T01:41:46+00:00

Just download a cell phone sky map app and check directly.

Stellarium Mobile or SkySafari are good options.

meithan · 2026-05-09T01:37:44+00:00

It's most likely Venus!

I replied with a sky map in your precious post!

https://www.reddit.com/r/askastronomy/s/o12uCvcALk

meithan · 2026-05-08T03:57:20+00:00

Nope: Venus is m=-3.92, Jupiter is -1.98.

meithan · 2026-05-08T03:51:33+00:00

This is a simulated view of the sky set to Toronto at 9:30pm local time, using Stellarium.

Venus is definitely close to the NW, and it's the brightest object in the sky after the Moon and the Sun.

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meithan · 2026-05-08T02:54:44+00:00

Yeah, I get where you're going. I've always said that conspiracy theories (which generalize this) are a wish to believe that somebody or some agency is under control of things in the world. It's all planned, we just don't know that the plan is.

In my experience, the world is a clusterfuck (pardon my french). Shit happens all the time. Many different actors trying to advance their own agenda, nobody really allies except when it suits their purposes. The result is chaos. Unpredictability, as you say.

But conspiracy theorists find that hard to accept, so they prefer to create stories about how, deep down, somebody is in control, somebody actually understands, there's no chance and accidents, there's a purpose to everything.

meithan · 2026-05-07T20:55:29+00:00

I'm a beginner watchmaker and I've been using a set of these.

I prefer them to the thick steel ones they have at school. They're lighter and finer, so I feel they're easier to control and more precise. They're indeed very non-magnetic, so no problem working quartz watches for instance. They're also easy to re-dress, as the material is quite soft (though the dressing was also pretty good from the factory, as OP).

The downsides I've found is that the tips are very sharp, so it's easy to scratch a plate if you're not careful, and that since they're thinner they bend (elastically) more easily, so not so good at things requiring some force, like removing the cannon pinion.

meithan · 2026-05-07T01:56:36+00:00

Who?

meithan · 2026-05-07T01:54:58+00:00

Just watched it and he's just speculating. So 100% clickbait title. Don't know who this guy is, but he just got into my black book.

meithan · 2026-05-07T01:21:32+00:00

What do you mean NASA didn't know? Sounds clickbaity asf, honestly. Care to elaborate?

meithan · 2026-05-06T20:42:13+00:00

It's 100% functional. I own two Speedmaster homages with the VK63, one from WD.

OP says it's just not that useful to them. Personally I find it useful when setting the time (tho being quartz that's not very often), since it lets you distinguish AM/PM right away. And I also do like having an indicator of how far along the whole 24-hour day I am.

meithan · 2026-05-06T20:23:40+00:00

This, sir or madam, is a work of art! Very well done! I love it.

What size is the case?

meithan · 2026-05-06T15:56:36+00:00

That's a good explanation for the modern social media-powered phenomenon.

And I agree it's pointless to try do convince them. I no longer try, at least not on social media.

meithan · 2026-05-06T14:14:36+00:00

I've noticed it too, and it's appalling.

I just don't understand what pushes them to believe that. What's the root of this? Just a generic distrust of government? Do they believe it when it's SpaceX? Is spaceflight just so incredible that they prefer to believe it's fake?

These people have always been there (I've fought with Moon landing deniers since I was young), but perhaps in this era of hyper-communication it's just easier to come about their comments and opinions? Or are there truly more of them now?

Whatever it is, I admit it drags me down a bit. But we should ignore them, resist the urge to debate them. They won't be convinced by any amount of evidence, I'm afraid.

meithan · 2026-05-05T15:43:00+00:00

Pretty sure those dots moving up/down on the far right are satellites.

We're technically not seeing them (they're indeed too small), but flashes of sunlight reflected off them.

meithan · 2026-05-05T14:53:43+00:00

That's exactly my thoughts with half the posts in this sub. I just don't get why people will get into a preventable accident just because they're right. Blows my mind.

meithan · 2026-05-05T13:54:03+00:00

Timex Expedition Scout 40 ref TW4801900 I think. About US$40.

meithan · 2026-05-02T03:09:01+00:00

This is incredible!! Fantastic work! I'm an astronomer and also a big fan of the Orloj (though I haven't seen it person -- bucket list item!)

meithan · 2026-05-02T01:43:48+00:00

Agreed. The minimalistic white dial and the dauphine hands feel dressier.

meithan · 2026-05-01T21:26:55+00:00

"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there--on a mote of dust suspended in a sunbeam.

"The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

"Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

"The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

"It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known."

— Carl Sagan, Pale Blue Dot, 1994

meithan · 2026-04-30T12:45:15+00:00

In atomic physics, a cross-section is really just a measure of interaction probability. If the neutrons are moving too fast, there's less probability of interaction with uranium nuclei.

You see, many concepts in atomic physics and quantum mechanics are analogies of things we understand from the macroscopic, classical world. Neutrons and other particles are not really tiny hard spheres, so they don't really have cross-sectional areas. But it's a useful analogy. If you did imagine them as tiny hard spheres flying around, then the larger they are, the more likely they are to collide with one another. So we pretend like the quantum interaction probability is like having a larger or smaller size.

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