The thread for space cadets!

[red_elk]

Interestingly, meteor and comet impacts have a limited range of impact speed with Earth.
They will hit between 11km/s and 71km/s

This seems to be the 3-rd cosmic velocity +- Earth's orbital speed.
Meteoroids can have speed outside of this range, it's just uncommon.

 

[hobbsyoyo]

After all I'm just a guy who plays video games and you're an actual rocket scientist

Please don't say that sort of thing because:

Sorry, but that statement is so bad that it is not even wrong.

I shouldn't be taken as an end all authority and I don't like being on that pedestal because I am frequently wrong.

500 mph refers to the speed compared to the air, the aircraft are moving in.

In aviation they measure and use both air speed and ground speed.

isn't that pretty good evidence the Oort Cloud doesn't exist?

If a star passes thru it every 100k we should see craters and extinctions every 100k or so, right?

Course that doesn't mean the Earth gets pummeled each time, but still...

Not necessarily. Jupiter (and to a lesser extent the other gas giants) are fantastic at intercepting wayward asteroids and comets.

Something moving at 1000km/s could also hit Earth while pass through the solar system as a bullet. But It would be extremely improbable, like a random bullet hitting a fly in a cathedral. Maybe in some eons when Andromeda and the Milky Way collide.

I have read that when our galaxies collide there will only be on the order of like 5 stellar collisions. There is so much space between stars in our galaxies (and all galaxies) that while passing stars will interact gravitationally (and weakly at that), they will not collide.

 

[warpus]

It's fine, I'm your KSP protege, it will be hard for me to pretend you might not know space stuff. But I will try!

 

[uppi]

In aviation they measure and use both air speed and ground speed.

I was thinking about including ground speed in my post, but then I thought it is just another speed relative to something else. It is only significant, because the "something else" is where the people in the aircraft want to go. But yeah, it is another example why the question "What is the speed of an object" always needs a reference to compare to. We just skip that specification in most of our daily life, because there the ground is usually a very good reference. After all, "I was hurling around the sun at 30 km/s" is not going to help you much when a traffic cop asks you how fast you were going.

 

[Thorgalaeg]

In fact in aviatavion they use indicated airspeed which is not air speed but the air pressure measured in the pitot tube and presented over a speed scale, so it depends on static and dynsmic pressure and it aproximates to real air speed at sea level and standard atmospheric conditions but at usual altitudes it reads much lower airspeed than the real one.

 

[Berzerker]

damn you guys are smart, I feel like I'm watching a debate among multiple Sheldons

 

[Thorgalaeg]

Nah, i am rather dumb. It is only i lost many years playing Flight Simulator. Didnt know X-Plane was so much better...

 

[Berzerker]

in the land of the brain dead the half wit is king

 

[hobbsyoyo]

isn't that pretty good evidence the Oort Cloud doesn't exist?

If a star passes thru it every 100k we should see craters and extinctions every 100k or so, right?

Course that doesn't mean the Earth gets pummeled each time, but still...

Something moving at 1000km/s could also hit Earth while pass through the solar system as a bullet. But It would be extremely improbable, like a random bullet hitting a fly in a cathedral. Maybe in some eons when Andromeda and the Milky Way collide.

In fact in aviatavion they use indicated airspeed which is not air speed but the air pressure measured in the pitot tube and presented over a speed scale, so it depends on static and dynsmic pressure and it aproximates to real air speed at sea level and standard atmospheric conditions but at usual altitudes it reads much lower airspeed than the real one.

GPS gives ground speed as well. We aren't solely reliable on pitot tubes though I remember an air France flight out of Brazil crashing due to a fault airspees reading due to a clogged pitot...

 

[Thorgalaeg]

Yes, ice clogged pitots are a very common failure that can lead to an accident. Pitot tubes have heating systems to avoid that since indicated air speed is the absolute most important data for piloting a plane. however IAS is not used for navigation anymore because it is extremely difficult to get reliable ground speed values from it with so many variables. It was in the early years of aviation along magnetic compass, stars, sea waves direction, road signals and anything at hand and of course pilots got lost most of the time.

Then, in the 20s or 30s, all countries started building a huge network of ground radio stations to make radio navigation possible worldwide, which continues being used today as the default way to know position and ground speed, with GPS (which is nothing but a more advanced radio station network after all) slowly getting more and more relevance in the last decades.

 

[Cutlass]

 

[Broken_Erika]

Seems like a sensible precaution....
International Space Station Tented To Spray For Xenomorphs

 

[warpus]

Would it make sense that most solar systems in our galaxy would lie on planes that are parallel to each other? i.e. there wouldn't be many solar systems in the milky way perpendicular to us.. would there?

 

[Cutlass]

Would it make sense that most solar systems in our galaxy would lie on planes that are parallel to each other? i.e. there wouldn't be many solar systems in the milky way perpendicular to us.. would there?

All sorts of angles. Most bodies in a solar system are orbiting in a plain on the rotation of the star. But there's no reason that the up and down of any two stars would be the same.

 

[hobbsyoyo]

Would it make sense that most solar systems in our galaxy would lie on planes that are parallel to each other? i.e. there wouldn't be many solar systems in the milky way perpendicular to us.. would there?

All sorts of angles. Most bodies in a solar system are orbiting in a plain on the rotation of the star. But there's no reason that the up and down of any two stars would be the same.

I would think that the ecliptic planes of most other solar systems would be lined up roughly with the ecliptic plane of the galaxy the same way the planets in our solar system are lined up with the Sun's. There would be a ton of jostling over time so by no means would this be an absolute law but I think this is they way they would tend to line up on average. But that's purely a guess on my part.

 

[warpus]

Do you guys think we have any idea what the % might be of solar systems that are parallel to ours vs ones that are more perpendicular, and everything in between? I wonder if it's really unlikely for that to happen, if it happens every million solar systems, or every billion, or trillion, etc. Assuming we are talking about any sort of spiral galaxy that is not especially unusual

 

[hobbsyoyo]

Yes I am sure the number is out there but I could not find it in 5 minutes of searching. I do know that astronomers know that only 10% or so of stars are aligned such that we can use the transit detection method for exoplanets. This in turn implies they know the general orientation of most stars around us which can be extrapolated out for the whole galaxy. Unfortunately I could not find the exact number you were asking for.

 

[warpus]

Oh yeah, that does make sense wrt exoplanet detection, I never thought of that. Thanks for checking!

 

[Bootstoots]

It looks like the ecliptic is tilted 63 degrees from the galactic plane. Some Googling brought this answer from a Cornell astronomer saying that planetary systems in the galaxy are aligned randomly, and the galaxy's structure has no impact on their orbital planes. Maybe the 10% number is just the fraction of all planetary systems we'd expect to be aligned close enough to ours to have transiting planets, assuming a random distribution?

 

[hobbsyoyo]

That makes sense. Thanks!