Weirdest space fact that you know

[sir rocket]

Title

[KSK]

It makes perfect sense when you get the full explanation but it blew my mind when I first heard about it.

There's water ice on Mercury.

[sir rocket]

I agree

[Scotius]

As far as we know, compared to the rest of our Galaxy, Solar System is in fact a highly atypical one

[Superfluous J]

That Relativity is actually how the Universe works. It'd be so simple if it was just that light moved different speeds but no, instead time works differently based on how fast you're moving and accelerating.

Edited November 15, 2020 by Superfluous J

[kerbiloid]

All our galaxies are belong to it.
https://en.wikipedia.org/wiki/Great_Attractor

We've been flushed.

[sir rocket]

Out of likes so

[cubinator]

There is a planet with life on it.

[magnemoe]

We can not predict the orbit of halley's comet and other comets like it more than an couple of orbits into the future. 

It makes sense then you think about it, Pe is very high and low energy so tiny changes close to the sun has high impact on Pe who affect the orbital period who obvious has serious impact on next orbit. 
 

[Nuke]

7 hours ago, kerbiloid said:

All our galaxies are belong to it.
https://en.wikipedia.org/wiki/Great_Attractor

We've been flushed.

its like a bunch of super massive black holes all decided to have a party. and they ate too much of my bean dip.

Edited November 15, 2020 by Nuke

[NFUN]

An obvious answer, but it's so beautiful in its simplicity I have to choose it: HEXAGON on SATURN

[Bill Phil]

There's stuff out there that we just haven't seen yet. 

And to me, one of the weirdest things is the Bootes Void.

https://en.wikipedia.org/wiki/Boötes_void

It's not strictly empty, but it's a huge region that's relatively devoid in galaxies. Almost like a supercluster or two got deleted or something.

[razark]

Space is big.
Really big. You just won't believe how vastly, hugely, mind-boggling big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space. Listen; when you're thinking big, think bigger than the biggest thing ever and then some. Much bigger than that in fact, really amazingly immense, a totally stunning size, real 'wow, that's big', time. It's just so big that by comparison, bigness itself looks really titchy. Gigantic multiplied by colossal multiplied by staggeringly huge is the sort of concept we're trying to get across here.

[AHHans]

19 minutes ago, razark said:

Space is big.
Really big. You just won't believe how vastly, hugely, mind-boggling big it is.

Nope! It's bigger than that!

Edited November 16, 2020 by AHHans

[kerbiloid]

Not that big if use a logarithmic scale, we can see it all from here.

P.S.
Animal perception is based on logarithmic scale.

Edited November 16, 2020 by kerbiloid

[Codraroll]

The planet Tellus has trillions of inhabitants in pretty much all colours of the rainbow. 

Edited November 16, 2020 by Codraroll

[Hannu2]

On 11/15/2020 at 10:29 AM, KSK said:

It makes perfect sense when you get the full explanation but it blew my mind when I first heard about it.

There's water ice on Mercury.

I agree. Exotic physical things, like black hole mergers which release in few milliseconds orders of magnitude more energy than Sun will ever produce as gravitatonal waves, exotic phase of matter in neutron stars or strong relativistic effects near giant black holes may be more strange, but my intuition expects nothing in such extreme conditions I do not have any experience. But ice in vacuum on sun roasted Mercury is very counterintuitive thing.

[sevenperforce]

The very first rocket designed for a moon mission would have used a heat shield for ascent but not for re-entry.

It would not have gone well.

[kerbiloid]

Trying to understand, where were they going to get that parachute from...

Spoiler

Single canopy, attached to the bottom.

Edited November 16, 2020 by kerbiloid

[starcaptain]

The small rockets used to push the vehicle forward during staging, to ensure the fuel in the next stage gathers near the bottom, are called Ullage Motors. Ullage is a term that comes from winemaking; it is the name for the air bubble volume in a barrel or bottle that is not filled with wine. Ullage motors ensure the ullage is away from the fuel intake pipes.

Most players game the system when it comes to this function: since KSP does not simulate fuel volume physics inside parts, ullage is not necessary. However, sometimes motors are required to ensure jettisoned stages are clear of the rest of the vehicle. So rockets positioned like ullage motors typically push the spent stage away, instead of the next stage forwards.

Edited November 16, 2020 by starcaptain

[Vanamonde]

So you're in orbit. You want to go to a higher orbit? You speed up to get there but when you arrive you're going slower than when you started out. Want to go to a lower orbit? You slow down, but when you arrive you're going faster than when you started. 

[Spacescifi]

1 hour ago, Vanamonde said:

So you're in orbit. You want to go to a higher orbit? You speed up to get there but when you arrive you're going slower than when you started out. Want to go to a lower orbit? You slow down, but when you arrive you're going faster than when you started. 

 

Relatively speaking.

For example, if we had1g constant acceleration spacecraft flying from orbital velocity onwards at 1g for 20 min and then stalled acceleration, it's top speed will be I am betting higher than orbiting craft, but it will no longer be in a stable orbit eitherand likely will fly off into deep space unless it retroburn to slow for orbit again.

Orbit is only faster in that one can go in a circle faster, yet at higher orbits it takes much longer to fly in a circle. Go too fast and you shoot off like a rock from slingshot in a straight line.

Orbiting is not unlike how a fast plane makes a wide circle and a slow one makes a tight one.

Edited November 17, 2020 by Spacescifi

[Spica]

Even better, if you are lagging behind another vessel in your orbit and you want to catch up with it, you need to slow down. The reverse is true as well. If you are leading another vessel and want to "slow down" to rendezvous with it, you need to speed up.

Admittedly any KSP player figures this out after his/her first attempt at orbital rendezvous, but that doesn't change how wrong it feels at first. In fact, this is the very topic that Buzz Aldrin wrote his thesis about.

[Superfluous J]

6 hours ago, Vanamonde said:

So you're in orbit. You want to go to a higher orbit? You speed up to get there but when you arrive you're going slower than when you started out. Want to go to a lower orbit? You slow down, but when you arrive you're going faster than when you started. 

In the (very good) Niven book series that starts with The Integral Trees, the people live in a huge gas ring around a star. It's a large enough volume of gas that the people who live there travel from clump of matter to clump of matter via learned orbital mechanics. They even state a mantra, similar to "red sky at morning..." that reads, at least to the best of my memory,

"East takes you In, In takes you West, West takes you Out, Out takes you East."

"East" and "West" are their words for retrograde and prograde. I may have them backward, as they were arbitrary. But I always loved that mantra.

[kerbiloid]

Low-orbit period = 2 * pi * R^3/2 / (G * M)^1/2 = 2 * pi * R^3/2 / (G * (4/3) * pi * R³ * density )^1/2 = 2 * pi^1/2 / (G * (4/3) * density )^1/2 = 2 * pi^1/2 / (G * 4/3)^1/2 / density^1/2 ~= 375900 / density^1/2 , s.
where density, kg/m3

Say, for the Earth (density ~= 5500 kg/m³) it's ~5068 s = 1.4 h.

But this means that the low-orbit period of a uniform body depends only on its density, and on nothing more.

As the typical celestial body densities are ~1000 (ice)...8000 (iron), for planets, moons, and stars,
so you low-orbit turn around any celestial body (except neutron stars, etc)
takes from 1.2 (pure iron) to 3.3 (pure ice or Saturn) hours, no matter if it's an icy moon or a star.

The rocky bodies are in between, 1.5 +/- 0.2 hours.

This stability looks weird for me.

***

A neutron star (density ~10¹⁸) : ~0.1..0.3 ms

***

Also this allows to describe any celestial body as an oscillator with stable frequency (depending on density).

So, for moons, stars, planets the frequency is 1/(1.2 * 3 600) .. 1 / (3.3 * 3 600) = 0.08..0.23 mHz

For the Earth - 0.2 mHz.

Raising your ship orbital oscillation frequency sqrt(2) times, you escape the planetary orbit.
But before that you actually get your orbital frequency decrased down to ~0, reaching high elliptic orbit.

So, like you break the oscillator by trespassing a critical limit of frequency, and it stops oscillating at all.

***

Probably this could be used in sense of harmonics, resonant frequencies, and other wave physics things.