@putrevomitory: This video should explain most of your questions.

Hmm, it's a day old. Possibly right after the EHT image. I'm amped.

Let's see if Israel can put a lander on the Moon for about the price of Gareth Bale or Gonzalo Higuain.

The stream keeps failing but it's AMAZING, they're showing all the data controllers see basically, altitude, inclination, speed horizontal, speed vertial, which engines are firing, it's amazing to watch.

shiittttttttttttttttttttttttttttttttttttttt they didn't make it

Didn't work, but they got so close. Everything worked perfectly until shortly before the end.

It's intense how light gets warped at the Schwartzchild radius. If it were rather a sphere and not an accretion disk, the view to an observer would be very insane, if the shadow would even be visible at all.

https://www.space.com/near-earth-astero ... flyby.html
So this happened, and it seems a Kamchatka scale-size tragedy is always looming. Interestingly enough, it was in a distance not far from where satellites orbit. So if the asteroid's speed was almost a fraction of the one it whizzed with, it might have clocked into orbit. I could be wrong but it falling into earth then missing (given the assumed fraction of its actual speed) due to earth revolving should lead to clocking to orbit - i.e. give it the speed close to that of the moon and it might have synced into orbit around the planet. What a way for space junk to pile up and accumulate had it been so.

I'm a bit late to post, but three weeks ago, a heavy metal core of a dead planet survived the destruction of a star death and can still be found "rocketing around" a dead star. Quite an amazing survival. Earth could end up dying similarly... although whether our remains would continue to orbit the sun, I don't know. That heavy metal core is really fucking metal!

https://www.livescience.com/65159-dead- ... metal.html

Gotta love the ring of "That's metal". But isn't 1AU a little too close for the Earth not to be engulfed and ripped apart completely by a red giant?

NASA will send their Psyche probe soon to a suspected heavy metal core to get a close look.

A one solar mass star (i.e. the sun) on the red giant branch (RGB) suffers a mass loss of 10^-8 solar masses a year, then on the asymptotic giant branch (AGB) will lose 10^-4 solar masses a year. In other words, the mass loss of the sun by winds will be enough to enlarge the radius of Earth's orbit and it may be enough to avoid touching the sun entirely. Fusion in RGB and AGB stars is remarkably violent and unstable as core and shell fusions will start and stop and continue at different rates to one another, which will all affect the properties of the sun and it's mass loss. Something else that has to be considered is that the outermost layers of AGB stars are so tenuous that it's difficult to say when the star properly ends, and the roche limit will also be moving with the changing mass. To complicate it more, AGB stars usually are not symmetrical in shape, and the sun may become a Mira-type variable in which radius changes over a set period of time due to conditions in the outer layers.

It is a complete toss up at this point if the Earth will survive, but it doesn't much matter for the sake of life as the Earth is thought to become completely sterile due to increasing luminosity of the sun in 1-2 Gyr anyway.

1. The 100,000 ly dimension is outdated as far as I know. Most estimates these days say the diameter is 150,000-200,000 ly (46-61 kpc). And it should be remembered that is only the diameter of a flat area. The area of a cross-section of the disc of the milky way would be 1.767x10^10-3.142x10^10 ly accordingly. And the disc of the Milky Way isn't totally flat anyway, on average it is around 1000 ly (0.3 kpc) thick. The volume of the average dimension of the disc of the Milky Way is then 1.767x10^13-3.142x10^13 ly.

This doesn't even take into account the enormous tenuous halo surrounding the disc which is full of metal-poor stars that orbit in all sorts of directions (Barnard's Star is thought to be one of these halo stars passing perpendicular to the disc) and the 150 or so known (probably much more) globular clusters which contain 10^4-10^6 stars on their own.

The average distance between stars in the Milky Way is ~5 light years. There are extraordinarily dense regions such as globular clusters, young open clusters, the galactic centre, and regions that are very empty such as the edges of the disc and the halo, and places in the middle, such as where we are. It is absolutely apparent why there are so many stars when the actual dimensions of the milky way are comprehended. It's such an enormous space that stars can be incredibly distant from one another and still total into the billions to trillions.

2. Galaxies do not have a concrete or defined edge to them. They simply become less and less dense with material until the intergalactic medium is reached. The best way to think about where a galaxy "ends" is where material doesn't appear to be "bound" to the system, but this is obviously fuzzy too, and galaxies are interacting with each other all the time. The edges of a system bound to a galaxy will go inside of another galaxy, an example are the Magellanic clouds. There are stars that have been found up to 900,000 light years away that are thought to be part of the milky way system, while being farther than the Magellanic clouds.

3. Planets/moons can exist as long as they don't experience any forces that wouldn't allow them to stay composite. Everything is going to decay eventually and fall into black holes so planets/moons won't exist forever but they certainly can exist longer than any star. These proposed rates of decay depend on all sorts of open fields of research such as if protons can decay or not and that's as far as I will say for it.

Planets, like stars and nebula, are formed by gravitational accretion, therefore it is formed and kept in its orbit by the sun for which it revolves around. If anything happened to that sun, the planets controlled by it would dissipate or be ejected into interstellar space.

Yeah, but unless they are subject to a supernova or some other catastrophic event they'll still stay composite even if ejected or released from a system. They'll survive longer than a star on the basis that planets simply aren't massive enough to collapse in on themselves. The reality is a bit more complicated than that; gas planets do shrink as their interior loses energy from internal radiation but it will stop as it reaches thermal equilibrium.

^ But for rocky planets, it is something closer to eternity before complete decay, given that they are small mass like the moon or less so their gravity will not support an atmosphere, which in turn anulls any form of erosion bar that of micrometeors (i.e. like on the moon). Even for massive rock planets that have the gravity to support an atmosphere, wind erosion (and other hypothetical forms of erosion, as per the planet's bio-system) would be the last of its worries in disintegration, so they might outlast stars.

A famous scientist announced an amazing discovery yesterday that the Moon is actually a part of Mars.

The stable genius was going by the Arecibo response, which quite frankly had our earlier solar system with four inner planets locked in a "quadipolar" position. Now, his not pseudoscience took off from there.
The low down: The government cuts back on aero-space research funding.

What are your guys thoughts on the Great Attractor? It is in the zone of avoidance, so we will never actually know what it is that is pulling entire galaxies with it's massive gravitational pull. As much fun as it is to imagine fantastic theories, what can it possibly be? I am leaning towards a massive cluster of galaxies, but who knows. Very interesting mystery.

It's nothing, just the center of gravity of everything around it.

The space junk harpoon was recently tested in debris recovery for general space decluttering. Impressive efforts, albeit the net used for overhauling debris will really miss out on the equally hazardous micro-junk. As the space race intensifies and private companies rushing in to put up their own satellites on LEO, the problem of junk will only intensify, even as it is being said that collisions are still far off. SpaceX is promising to track all its satellites, so in case of collisions, alleviation measures can be put into place. One thing though is just missing. They can't accommodate for fleeting meteors that have the off chance of tearing through a satellite, the more up there they are. More work for future space junk harpoons.

All the space junk initiatives so far are about de-orbiting so far, and I don't like that. That stuff is so expensive to get up there, I hope eventually there's be some space junk removal initiative that collaborates with a company like Made in Space and build a space scrapyard or something and use the junk to build new stuff in space.

Looked that up, and honestly the future has a lot in the offing. The current close option would be Kleos Space though for a different scenario. Their threat assessment possibilities would perhaps root out unprecedented meteoroids that could trigger or contribute to the Kessler Syndrome. 3D printing with space debris as feedstock seems a crafty, nay, the best method for Made in Space. Gotta cull and nip a runaway Kessler Syndrome at the bud.

Simply put, why shoot stuff up there if we already have stuff up there?

I don't know when the eschatological beliefs that the world would end on late 2012 started cropping up, but in the middle of that year, a Carrington Event class mass coronal ejection missed the planet by mere days. If this was the trigger that would have unchained these beliefs, it would still be disproved as a natural occurrence of solar origins, as was the previous one, though it would have made for interesting supernatural theories and wacky theories too. It is now predicted that by 2022 there will be a 12% chance of such a scale event, and here we are, two and a half more years to go. It seems we are close to a catastrophe that will push the planet back to the beginings of the space age — what with the ensuing losses that will stunt normal life for a few years?

While LEO littering is an unintentional way of closing off space faring and observations, on a second Kardashev scale, it seems like a Dyson sphere is an intentional way of cutting out interstellar travel. The better execution in the form of a Dyson ring would be close to an economically underutilized structure. I don't think with the strong will to explore beyond the solar system it would allow for a fully encompassing sphere. Or the megacorps will have to decide on either of these options, seeing that space is slowly becoming a commercial arm.

I don't think a Dyson sphere is in any way viable anyway. Remember that the Dyson sphere was conceptualised at a time when we didn't yet know that most things that come from the sun are lethal as fuck.

And I'm yet to see anyone refute the lethality of the sun's emissions in the context of the Dyson sphere (At least an article in the go-to journals?). The lethality would have been a good enough reason for the Dyson swarm theory to be discredited as one of the ways of harnessing the sun's energy, given that the ability to channel the sun's energy/emissions is a cornerstone of the 2nd Kardashev level.

Seriously, it's been 50 fucking years since we landed on the moon. It's amazing how we've failed to actually push our exploration, science, technology, and society forward since then. We should've been on Mars by now. Every science fiction film from 20 years around the moon landing promised that.

Every year our daily technology leaps ever further forward without us advancing into the universe is another point to how amazing it was that we landed on the moon with such minimal computing heft.

(I realize this meme is posted a few days off.)

I would love to see a human being on Mars in the next ten years but I think it's a bit unrealistic.
From 2050 and above, much more realistic.

At this rate, our civilization won't survive past 2050.

I expected we'd be on Mars by this point.