The Astronomy Thread

Burns · May 21, 2023

Sanrith Descartes said:
I never thought of it like this before. So with FTL and a proper telescope, you could look back in our history and really see shit as it truly happened.

FTL travel is time traveling into the past. You don't need a telescope, you just fly around in circles at FTL and you will arrive before you departed. Wormholes have the same problem, as you can use them to time travel, just as you can use them to travel between two points in space.

Also, FTL is impossible according to relativity, so you might as well just play the time travel thought experiment.

Tripamang · May 21, 2023

Cybsled · May 21, 2023

Lambourne said:
It's not really feasible even disregarding the FTL issue because even from a distance of 5-20 lightyears the telescope you need to resolve anything human sized becomes so huge as to be essentially impossible to construct.

Also means aliens aren't watching you from afar (no guarantees as to from up close though...)

Does that apply to gravitational lensing telescopes, though? You essentially use the warped space surrounding a star to significantly boost your magnification abilities.

Burns said:
Also, FTL is impossible according to relativity, so you might as well just play the time travel thought experiment.

In terms of linear speed, yes. But in theory if you could warp space you could potentially travel faster than light in terms of how long it takes you to travel a light year of distance. You don't actually need to travel faster than light - you just need to be able to take a shortcut that cuts down on travel time.

Captain Suave · May 21, 2023

Cybsled said:
Does that apply to gravitational lensing telescopes, though? You essentially use the warped space surrounding a star to significantly boost your magnification abilities.

I won't bore you with the napkin math, but a telescope 20 light-years away would need to be 35 million miles across in order to resolve an object six feet long. It gets worse than that very fast if you want to see any detail at that scale or are farther away.

1987 · May 21, 2023

Sanrith Descartes said:
So this happened about 21 million years ago? That speed of light thing always numbs my mind. Its like we are forever looking into the past when we peer into space.

You're looking into the past at literally everything. Just not very long ago in most cases.

Lambourne · May 22, 2023

Cybsled said:
Does that apply to gravitational lensing telescopes, though? You essentially use the warped space surrounding a star to significantly boost your magnification abilities.

Similar issue, it's feasible to see surface detail for planets within a few lightyears but wanting to look further back than that the (gravitational) lens just isn't big enough, certainly not to see back tens of millions of lightyears to see dinosaurs.
The engineering challenges are also such that by the time it becomes feasible to construct, sending interstellar probes is probably well within reach too. The focal point for the sun is 5-600 AU out, Voyager 1 is our fastest and most distant object and even it won't reach that distance until the 2130s. Add the engineering required to bring it to a stop and also be able to move it laterally at incredible speeds to keep looking at a certain object and by that time you've invented everything you need to just send actual probes towards nearby stars.

Cybsled · May 22, 2023

Another alternative I have seen is you basically send out a string of probes to account for the issues with stopping or needing to adjust position in order to maintain focus. Downside is you need more probes and more material.

Kharzette · May 27, 2023

Interesting software bug. A routine was watching the rate of change of altitude to try to catch a radar sensor going faulty and it triggered when they flew over a cliff.

Edaw · May 28, 2023

Furry · May 28, 2023

Lambourne said:
It's not really feasible even disregarding the FTL issue because even from a distance of 5-20 lightyears the telescope you need to resolve anything human sized becomes so huge as to be essentially impossible to construct.

I’ll disagree there. Yes it’d need a massive scale, but through the magic of interforemetery, it doesn’t need to be one object. It would be quite the undertaking, but far from impossible.

Araxen · May 28, 2023

Edaw said:

That isn't the only picture. There were several taken. It's a shame how Venus has been blown off. We have a lot to learn from the planet. I feel more than Mars offers us.

Lambourne · May 29, 2023

Furry said:
I’ll disagree there. Yes it’d need a massive scale, but through the magic of interforemetery, it doesn’t need to be one object. It would be quite the undertaking, but far from impossible.

Issue with interferometry is that it you get better angular resolution but far worse sensitivity (because you're only detecting photons at a few smaller points instead of collecting them in a huge lens) and you're not looking at a star but at an incredibly faint object by comparison.

Video i linked last page goes into this as well, it's worth watching. The maker is an astronomer.

Furry · May 29, 2023

Lambourne said:
Issue with interferometry is that it you get better angular resolution but far worse sensitivity (because you're only detecting photons at a few smaller points instead of collecting them in a huge lens) and you're not looking at a star but at an incredibly faint object by comparison.

Video i linked last page goes into this as well, it's worth watching. The maker is an astronomer.

I have no doubts that it'd be an incredible great work worthy of thousands of years of dedication. But that doesn't meet the level of 'impossible'. It already has produced amazing images.

Edaw · May 29, 2023

Kajiimagi · May 29, 2023

Araxen said:
That isn't the only picture. There were several taken. It's a shame how Venus has been blown off. We have a lot to learn from the planet. I feel more than Mars offers us.

Think technology got them. Anything sent died pretty quickly. I seem to recall a few new missions for Venus but cannot remember who is doing it.

Cybsled · May 29, 2023

The next mission to Venus that actually goes onto the planet is more likely to be a flying thing than a surface thing. The surface is a very difficult technical challenge due to the extreme temperatures and pressures. The upper atmosphere is more Earth like in terms of temperature and outside of sulfuric acid cloud problems (which is a bit easier to solve for - I presume they would coat everything with Teflon or something similar since it is very adept at resisting acids), it is a much easier environment to work in for an extended period of time

Rajaah · May 29, 2023

MusicForFish said:

More incredible stuff from these guys. Except every time I see their latest tech, I imagine the Pentagon and the military deepstate are licking their chops to get ahold of said tech to find military uses for it.

Used to be military conflict drove technological achievement, now it's the military waiting for tech breakthroughs they can co-opt.

Aaron · Jun 14, 2023

Sanrith Descartes said:
So this happened about 21 million years ago? That speed of light thing always numbs my mind. Its like we are forever looking into the past when we peer into space.

It also means that a star could have gone nova close to us and we won't know it until it vaporizes us.

Araxen said:
That isn't the only picture. There were several taken. It's a shame how Venus has been blown off. We have a lot to learn from the planet. I feel more than Mars offers us.

I won't quite go so far as you, but we definitely should spend more time there.

Edaw said:

He's telling the truth. Most people, even space buffs, don't realise that the Chinese have a manned space station in orbit, and that for a period of about 10 years (from the end of the last Shuttle mission til Musk started his manned flights) there were only two nations on the planet that had a manned space program: Russia and China. American astronauts had to be shot up on Russian craft.

Burns · Jun 15, 2023

Rajaah said:
More incredible stuff from these guys. Except every time I see their latest tech, I imagine the Pentagon and the military deepstate are licking their chops to get ahold of said tech to find military uses for it.

Used to be military conflict drove technological achievement, now it's the military waiting for tech breakthroughs they can co-opt.

There are already far more efficient technologies to murder people with than some plasma beam with a 100 foot range. This will not be weaponized unless it's as a delivery method. In that regard, it's impossible to tell if it's any better than what they are already using for hypersonic missile engines (as that would be top secret tech). The starship has requirements that missiles just don't need, like the ability to land without blowing up.

Also, the Hungarians already made a Jet tank...to blow out fires:

Aaron · Jun 15, 2023

Gotta love crazy shit like that. I imagine it came about in a manner somewhat like this:

Engineer 1 hits blunt: "Duuudde... what if we, like, strapped a couple of jet engines to a tank?"
Engineer 2: "Far out man..."

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