The Official Space and Astronomy Thread v. Well, this is weird.

[wasteland]

Europa is very fascinating because of the water. But I'm pretty sure there is no life there.

I want to see a fucking nearby supernova!

That'd be the last thing you ever see

Nah, that won't be the case. Unless we stand in the line of the gamma ray burst (assuming there will be one). We had nearby (~1000ly) supernovas in 1054, 1106, 1572, 1604 and yet we are still here

[BlackInk]

What makes you say that? How do you explain the red coloring that emerges through all the crevasses? The Earth has lakes that are similar in color due to decaying organisms and lack of oxygen flow. There is extreme heat at its core that would be more than enough to provide organisms with an energy source.

I guess.. I just think there are astronomically low chances. I haven't really read much about Europa in a few years so maybe I should.

Nah, that won't be the case. Unless we stand in the line of the gamma ray burst (assuming there will be one). We had nearby (~1000ly) supernovas in 1054, 1106, 1572, 1604 and yet we are still here

Well yeah, if a 1000 lightyears is close by. But I guess it is when compared to the rest of... space x)

[Chino]

Europa is very fascinating because of the water. But I'm pretty sure there is no life there.

I want to see a fucking nearby supernova!

That'd be the last thing you ever see

Nah, that won't be the case. Unless we stand in the line of the gamma ray burst (assuming there will be one). We had nearby (~1000ly) supernovas in 1054, 1106, 1572, 1604 and yet we are still here

Our sun isn't large enough to go supernova. Sadly it will just engulf the Earth in its red giant phase

As weird as this sounds, I think it would be awesome to be on the planet when a cosmic event destroys Earth. Getting caught in the gamma ray burst from a near by star would be lame though. I'd rather be hear to watch the Andromeda inch it's way closer to the Milky Way!

[wasteland]

Getting a GRB in the face would indeed suck very very hard. Our death would be surely painful, and maybe not instantaneous. What I know is that the shower of gamma photons would ionize the entire ozone layer and IIRC even break the ozone bonds, depleting the layer and exposing us to high energy photons from the sun or from the cosmic rays vs. atmosphere collision. Which would kill us.

And if the GRB is long enough (that is more than a few seconds, I remember some lasting up to a couple of minutes) then it would likely reach sea level, triggering a mass extinction (there is a candidate GRB-triggered mass extinction somewhere in the past, I know).

Fortunately, there is no indication that a supernova within the danger radius will happen in the near future, and it seems that those farther have their axis positioned in a way that would prevent the gamma jets to hit the earth.


As for the Andromeda collision, it will hardly affect life or the gravitational dynamics of the solar system. The chances of the sun being expelled from the galaxy are slim, and the chances of collision or disruptive stellar interaction are practically zero. This picture is an artist's rendition of what we could see, if life were still possible at the time of the collision. I think it has already been posted, but nonetheless:

[Chino]

But while our solar system may not be hit or directly affected by Andromeda, isn't our solar system held together to some degree by the other celestial bodies in the Milky Way? Wouldn't our sun be ejected from it's current orbit (not the Milky Way itself) and bring the planets with it? While our orbits around the now rouge sun may stay the same, couldn't it put our entire solar system on a collision path with other stuff in the Milky Way? If the two galaxies were to merge (that might not happen), wouldn't that fuck everything up? I understand the the vast distances between stars is so great in makes it unlikely, but I can't help but think that the energy contained in two approaching galaxies wouldn't cause mass devastation upon their collision. I would imagine all solar systems would be in a shooting gallery of space debris for millions of years.

I'm not challenging you. I am genuinely curious and like to learn about as much of this stuff as I can.

[wasteland]

But while our solar system may not be hit or directly affected by Andromeda, isn't our solar system held together to some degree by the other celestial bodies in the Milky Way? Wouldn't our sun be ejected from it's current orbit (not the Milky Way itself) and bring the planets with it? While our orbits around the now rouge sun may stay the same, couldn't it put our entire solar system on a collision path with other stuff in the Milky Way? If the two galaxies were to merge (that might not happen), wouldn't that fuck everything up? I understand the the vast distances between stars is so great in makes it unlikely, but I can't help but think that the energy contained in two approaching galaxies wouldn't cause mass devastation upon their collision. I would imagine all solar systems would be in a shooting gallery of space debris for millions of years.

I'm not challenging you. I am genuinely curious and like to learn about as much of this stuff as I can.

The fact is that there would be no collisions, not even in the dense core of the galaxies. Just think of this: the inner solar system is a couple of light hours across. Let's say one light day, to be optimistic. The volume would then be proportional to this lenght cubed. Now we do know that there are 45 stars within a radius of 17 light years, which means that the free volume between two stars in our galactic neighborhood is about 5.3 billions of light days. This means that the ratio between the volume of our solar system and the average volume between stars is 1 on 5 billions! Now, since we know that the merging of the galaxies will involve a number of grazing collision before the eventual merging of the black holes, it's clear that our little place will interact with the outer regions of the Andromeda disk, which sport similar values of stellar density. This being said, the chances of impact are about the same of two flies (1 cm across) flying on a reasonably straight line in a room that's 20 meters across.

And by the way, I read now (after writing all that's above) the "I'm not challanging you". I didn't feel challanged at all, it's a huge pleasure for me to be able to speak of this with other people! And to be able to have the chance of doing such interesting calculations on the fly to give a rough reason of plausibility to the refined theories that have been or are being produced by astrophysics and whose results and implication we can accept but still wish to comprehend on a deeper level.

Oh, by the way: the only possible negative consequence of the gravitational perturbation of a passing star is a wave of comets being pushed towards the inner solar system. Which would be quite nasty, but in the end minimally concerning for a simple reason: by the time the Andromeda collision happens, the sun's power output, that is nothing but its luminosity, will have increased because of the increase of the core temperature due to the enhancement of the mean particle-to-hydrogen mass ratio (if you take hydrogen and add helium, which is what happens every second in our star, the mean mass of the particles in the core increases, as the mass of a helium nucleum is 4 times that of a hydrogen's). Basically the augmented luminosity will have made at least multicellular life impossible on the earth barring any human intervention, that would be "shipping" the earth to a wider orbit to keep the incoming light flux (the so called solar constant) within the tolerable range. You understand that displacing a whole planet (and the moon too, as doing without the moon would require further eingineering to stabilize the true pole wander) would require a much greater endeavour and technological level than preventing a swarm of oversized iceballs to hit out planet. And by the way, another star passing close enough to influence the *still theoretical* Oort Cloud (the main repository of comets) is an event that would likely have happened naturally another couple of times, or maybe more than a couple, before the galactic event begins.

ETA: I think I may have failed to address your main point: yes, there's a reasonably high (literature says 12%) probability that the sun will be ejected during one of the grazing encounters, and it is also said that it's almost a certainty that the sun will be swept farther from the nucleus of our galaxy (and stay there until the new galaxy is born). This would bear no ill consequences for our solar system. The gravitational force is what keeps our system together, and it decays with the square of distance. Twice as far, one fourth as intense. The effects of the change of inner structure of our galaxy would be dramatic in terms of galactic dynamics of our system, as I said, but I'm quite positive that they will hardly be noticble considering only the planetary dynamics within the system

So that being said, my post was definitely too longm, but I hope not uniteresting enough to earn a tl;dr. Let's keep this thread running, it's amazing!

[BlackInk]

Yeah, what I was going to say was that there would be very few or no collisions at all in a galaxy merge. But I think wasteland covered pretty much everything. And I'm way to lazy to write all that so that's good!

[Chino]

I feel so much smarter after reading that  . I think that would be one hell of a spectacle to the humans alive in that time (that is if we still exist).

[wasteland]

Well it would ideed be, but what you can see in the frames spans almost a billion years. No man, assuming we don't ascend to a state of apparent immortality which is something that I don't label as impossible, would ever be able to notice any change in a stunning but still scape of colliding strems of stars.

[BlackInk]

It would have been awesome though to see a galaxy in the sky that clearly, even if you don't notice any change in distance.

[wasteland]

I heard from an astronomer once that the show wouldn't be as impressive as those pics might suggest. I don't recall the explaination, it had to do with the flux per unity of emitting apparent angular surface, that is essentially how bright we see a sky body, remaining the same as the apparent size increase compensates exactly the flux increase due to the reduced distance. Essentially, we get more light, but that's smeared over a larger area.

Right now the Andromeda galaxy has a visual magnitude of about 3.5, meaning that it's easily visibile with unaided eye, but not in light polluted surroundings. It's going to be the same, and appear extremely dim due to the spread. So, I'm afraid, no breathtaking show unless you are blessed with very clear skies. And even then it won't get as bright as the current milky way until the very final stages 

[BlackInk]

Would that mean that we wouldn't be able to tell that the large bright thing in the night-sky was a galaxy? I just want to see that second or third image when walking outside a clear night and looking up:

[wasteland]

Well, you are not going to see it. After all, did you ever seen something comparable to the first, which is supposed to be an actual photograph? Getting colors visually with our eyes is very difficult, and surely not on such big scales.

[PuffyPat]

Just took my first exam in my Astronomy class. I'd say the over/under is a 75.

[wasteland]

Just took my first exam in my Astronomy class. I'd say the over/under is a 75.

Pardon?

[PuffyPat]

Just took my first exam in my Astronomy class. I'd say the over/under is a 75.

Pardon?

I'm using my terrible knowledge of betting to say that I think I got around a 75% on the exam.

[TioJorge]

I just need to say I keep reading this thread as "The Office Space and Astronomy Thread v. Well, this is weird" and it's really fuckin' with me.

Did you get the moon memo?

[Azyiu]

Just took my first exam in my Astronomy class. I'd say the over/under is a 75.

Pardon?

I'm using my terrible knowledge of betting to say that I think I got around a 75% on the exam.

**insert drum rolls here** 

[gmillerdrake]

Thought I'd share with this thread being that it's all astronomy lovers in here....my boys...especially my 5 year old, are/have been infatuated with anything space the past few months. I went and bought some real interesting and great introductory books concerning space, our solar system and the descriptions thereof.
  They aren't rudimentary by any means...they are perfect for a 5 and 6 year old. It's just neat teaching them this stuff...the fact that they already know our solar system and the order of the planets. I mean tonight, I was explaining how our solar system fits in our galaxy...and then how there are countless galaxies and so on. And you'd think that'd put most young kids to sleep but they were right there in it. And my 5 year old insists that he will be traveling to all the planets, so that's kind of cool.
  Anyway....just wanted to share that...carry on with mind blowing facts about the cosmos...

Oh which reminds me, one of the cool ways one of these books explains how big the Sun is to a child is to show them a marble...tell them that is Earth, walk 100 steps away from an adult. That is how far away the Earth is from the Sun and the Adult is the 'size' of the sun. Kind of interesting.

[Super Dude]

I would also settle for an underground cave mission on Mars.

Wasn't there something recently about a proposed TV drama of actual people trying to make a life on Mars, and they were looking for volunteers?

[Chino]

I'm listening to Cosmos in the library right now and just heard something that I never noticed before. In episode 12, Carl Sagan is explaining the Drake equation. He says something like "assuming every sun has an average of 10 planets like ours does"... We thought there were 10 planets 40 years ago?

[wasteland]

I'm listening to Cosmos in the library right now and just heard something that I never noticed before. In episode 12, Carl Sagan is explaining the Drake equation. He says something like "assuming every sun has an average of 10 planets like ours does"... We thought there were 10 planets 40 years ago?

I can answer this: when physicists make estimates, and more so when they estimate parameters of equations made of extremely little known parameters such as with Drake's, what really matters is the order of magnitude. At the times there were 9 planets known, I think, but 9=10 for all the purposes of evaluations. It's clear that our poor (maybe chronically so) knowledge of the other moltiplicative factors of Drake's equation will prevent us to get an accurate number, hence no need to be precise with what we know.

This kind of estimates are known as Fermi's problems, after the Italian physicist that excelled in them and made them famous and scientifically relevant. The most famous of those, which I was given on my first day of Univeristy, is: "How many piano tuners are there in Chicago?". Wikipedia provides the solution:

There are approximately 5,000,000 people living in Chicago.
1. On average, there are two persons in each household in Chicago.
2. Roughly one household in twenty has a piano that is tuned regularly.
3. Pianos that are tuned regularly are tuned on average about once per year.
4. It takes a piano tuner about two hours to tune a piano, including travel time.
5. Each piano tuner works eight hours in a day, five days in a week, and 50 weeks in a year.

From these assumptions, we can compute that the number of piano tunings in a single year in Chicago is
(5,000,000 persons in Chicago) / (2 persons/household) × (1 piano/20 households) × (1 piano tuning per piano per year) = 125,000 piano tunings per year in Chicago.
We can similarly calculate that the average piano tuner performs
(50 weeks/year)×(5 days/week)×(8 hours/day)/(2 hours to tune a piano) = 1000 piano tunings per year per piano tuner.
Dividing gives
(125,000 piano tunings per year in Chicago) / (1000 piano tunings per year per piano tuner) = 125 piano tuners in Chicago.

[BlackInk]

Well, you are not going to see it. After all, did you ever seen something comparable to the first, which is supposed to be an actual photograph? Getting colors visually with our eyes is very difficult, and surely not on such big scales.

Maybe not in that much detail. But I just thought since the disc of the milky way is clearly visable when looked at "horizontally", that a galaxy that close would at least be visable on a clear night since it's a pretty large source of light. Of course those extreme colors and details won't be there but it must be noticable.

[wasteland]

Well I'm sure you could see it. As for the colors, I'm skeptical. Look at the stars: Betelgeuze is one of the reddest stars know and still appears a faint orange. Our eyes are not really suited for perceiving colors from sources that dim.

Have you ever tried to look at the Orion Nebula? You can do it tonight, then come here and tell me if you can see any colors. I never could and I'm pretty sure it's not my eyes to be faulty

[MrBoom_shack-a-lack]

..and that leads me to the fact that i rarely see the stars where i live unless i drive outside the city which i rarely do sadly...well i do but not to look at the sky. Light pollution is a very low priority problem these days.

for keeping the thread alive!

[Chino]

I live out in the boonies on top of a pretty good sized mountain. I have next to no light pollution (relatively speaking) and have a great view of the stars. Whenever I come home at night, I stop in my driveway, look up, and do a couple of slow spins while taking it all in. I seriously have one of the best views in town. When most of CT lost power for a week in October of 2011, I never saw a sky so clear and bright. I was blown away. I stood outside in the freezing cold for about 20 minutes just looking up in awe.

[MrBoom_shack-a-lack]

Yea i had one of those jaw moment too a couple of years ago. I was on a trip with my class at the time in north of sweden in "nowhereland" and i remember one night when we were outside and looking up at the sky in awe because i had never in my life seen so many stars in the sky, i could even see very clearly the milky way arm stretching across the sky and that made a big impact on me, no photo could ever stun me as the real thing. After that i went into a deep fasination about astronomy and space which lasted pretty long until i touched the one area i seriously lacked in: Math! 

So yea that experience made a big impact on me and still do.

[Chino]

Dung Beetles use the Milky Way light to navigate.

https://newswatch.nationalgeographic.com/2013/01/24/dung-beetles-navigate-via-the-milky-way-an-animal-kingdom-first/

[wasteland]

From my place I can see up to magnitude 4, if I know where to look. I can see 6 pleiades out of 7 (but I think no one can see the seventh under normal conditions), but no milky way, by any chances. I've seen our galaxy a couple of times, though. Always stunning, especially under a lightouse on the westernmost promontory of an island

[MrBoom_shack-a-lack]

Dung Beetles use the Milky Way light to navigate.

https://newswatch.nationalgeographic.com/2013/01/24/dung-beetles-navigate-via-the-milky-way-an-animal-kingdom-first/

That is pretty damn cool.

He added that this discovery reveals another potential negative impact of light pollution, a global phenomenon that blocks out stars.

"If artificial light—from cities, houses, roadways, etc.—drowns out the visibility of the night sky, it could have the potential to impact effective orientation and navigation of dung beetles in the same way as an overcast sky," Whipple said.

It's sad when you think about all the people in the cities and other parts of the world that are impacted by light pollution and how most of them live their whole life completly disconnected to the sky above us even though that's the one big mystery we as humans have in common.

[Chino]

Blast Off! Musk's View from SpaceX Mission Control
https://www.bloomberg.com/video/blast-off-inside-spacex-s-mission-control-nwyyO5u0QO2EuU5ABszElA.html

Elon Musk is such a cool guy. My buddy is a software engineer for SpaceX. He gave me a private tour of the facility when I visited him last summer. The facility was closed for the day, but mission control was filled seeing as the dragon capsule had just made its first successful dock with the ISS two days earlier. I had the pleasure of being introduced to Elon. He's such a nice down to Earth guy. If I didn't know who he was and just happened to bump into him on the street, I'd never suspect he was a billionaire.

This has some gems in it.

www.shitelonsays.com

Some of my favorites:

"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact. "

" I went to Russia three times to negotiate purchasing an ICBM. "

"If one set a standard that you couldn't have loss of life, then there would be no transport. You wouldn't even be allowed to walk. "

" At the beginning of starting SpaceX I thought that the most likely outcome was failure. "

[BlobVanDam]

Guys, in my dream last night Neil Armstrong was still alive, and he went on a mission to the moon to raise interest in more moon missions. I was thinking that a guy his age wouldn't qualify to go to the moon, but that's apparently why he went. He was basically taunting the space program and saying it was now so easy that even an old man could do it safely these days.

[wasteland]

Funny fact: unlike many space/astronomy lovers, I never wanted to become an astronaut. Too dangerous, I was afraid of any of the 76483995 deadly incidents that ca happen (and happened) in space.

[Orbert]

Same here.  It's amazing to see the pictures and mind-boggling to think about what's out there, and on what scale.  But I'm fine sitting at home letting others do the exploring and take the risks.  If your car breaks down, you call for help, or start walking.  There are options.  Something goes wrong with your rocket ship, there's a meter keeping track of how much oxygen you have left.

[Chino]

Space X launch in three minutes.