Astronomy Bucket List, Reigniting A Dead Star, Types of Black Holes | Q&A 237

[@mihan2d]

Ok I got to ask, why did you retract the interview on the antimatter propulsion? Was it because of the blunder, about where do you get the energy to make antimatter?

[@frasercain]

Yeah, I had enough people tell me that the math didn't make sense, violating the laws of physics, that I pulled the video so I can investigate it further.

[@mihan2d]

@@frasercain Ooooh I smell behind the scenes drama 😉😉 But seriously man I appreciate your scientific integrity. That said, the video sadly went down along with a question I asked (there was even a small discussion), about what is the official scientific term for the point when the colony on Mars for the first time becomes so resource independent that they are able to continue to survive and grow indefinitely even if Earth goes poof, do you happen to know? I heard the term multiplanetary but it doesn't really convey that point of redundancy so to speak. Also would be nice to one day see a long video looking in detail into the technology and economics of making Mars colony fully tech and resource independent.

[@frasercain]

I think independent is a good word for it.

[@IDavidson55]

Thanks for that. I had watched the first few minutes and then had to do an errand. When I came back there was no trace of it. 🙂 @@frasercain

[@mihan2d]

​@@frasercainBut how do you refer to that singular point when the species becomes redundant, as in it can no longer go extinct if life on one planet is extinguished? I assume there is no established term then, you just gotta get creative and say something like point of redundancy?

[@apachetrout1223]

The addendum on having a conversation with your content supporters is spot on. The 15 minute conservation was greatly enjoyable and left me feeling honored to fund your work.

[@karlharvymarx2650]

I finally crossed off taking a picture of the Andromeda galaxy from my bucket list Monday. I would guess most viewers here would laugh at me for picking something so easy. Still, I'm essentially in a temperate rain forest, so lots of trees and clouds blocking the sky, My equipment is a raspberry pi camera, wifi, a 3d printed adaptor for Canon lenses, and an arduino to adjust the lens. I used Stellarium to make an informed guess about where to point it before sunset and hope it will eventually drift past. I think it took me 5 years to capture the bloody thing. It is probably the ugliest photo ever of a galaxy but I'm still damn proud of it.

[@darkonc2]

Did you post the picture publicly somewhere?

[@theoptimisticskeptic]

That's awesome, my Dad recently just did that from Upstate NY. Just think, you accomplished something it took humanity 100's if not 1000's of years to accomplish!

[@karlharvymarx2650]

@@darkonc2I was going to post it to YT for you but apparently that feature disappeared when I wasn't looking. Maybe after I add tracking motors I'll attempt a video.

[@karlharvymarx2650]

@@theoptimisticskeptic Thanks, that is a heck of a nice way to think about it.

[@KnittedFox]

I found the Universe Today podcast around 2004 and fell back in love with Astronomy because of it. So when I became a patron a year ago and got a chance to chat with Fraser I was ecstatic! He sat aside a good chunk of time to chat with me, and it was fantastic! It meant a lot to me to be able to tell him how much his work means to me, and has inspired me. Thanks again Fraser!!

[@davidallen306]

Just wanted to say that you, your channel and all those who make it possible are greatly appreciated!. Thanks for all the hard work!

[@theoptimisticskeptic]

Having lived right near Cape Canaveral, we used to sit by our pool and watch the rocket launches. Our trees blocked the first few seconds of lift off but once they were about 3 or 4 seconds up, we could see them perfectly! Especially at night! It was a dream come true for me, a New Yorker. But I'd also recommend: Viewing a comet and viewing Jupiter & Saturn with your own eyes as well. I was lucky enough to see Haley's and the Halle-Boppe comets, missed the most recent green one, like a dummy!

[@SuliXbr]

the way you described how most would see asteroid mining is not at all how I see it. I see asteroid mining as a way to build more stuff in space, if enventually it becomes cost effective to bring it back to the earth so be it, but the main goal is to build structures in space.

[@christopherwilkening7843]

agreed, like he said "asteroid mining will never ever never happen! but some day, maybe soon, we will do asteroid mining to use the materials directly in space to build things that will stay in space." ok but that is asteroid mining, unless I am missing something?

[@noelstarchild]

I was surprised that asteroids were basically gravel loosely bonded by gravity, but as I thought about it, it was fairly obvious really. Gravity is so weak that you need alot of matter for it to start becoming spherical. ..simple but important revelations , so thank you Mr Cain. Valarian

[@olorin4317]

Cheleb I’m from Orlando and seeing rockets is a little like how you see aurora often where you live. It is funny how astounding things can almost become routine. One tip is that I would definitely recommend seeing the biggest rocket possible.

[@realzachfluke1]

I saw the SLS launch from Orlando, and I will never forget it. The way it lit up the night sky, even from here, was jaw-dropping.

[@surferdude4487]

Starship 2 should be launching between Nov 13 and Nov 30. That's the biggest rocket anyone is likely to see for a while.

[@MelindaGreen]

Don't worry about ruining science fiction Christmas. In fact thank you for speaking up about hard realities. Whenever you find yourself disillusioned, it's best to ask yourself how you became illusioned in the first place.

[@Dr.Wael.Alrifai]

Thank you, Fraser! There is nothing I enjoy more than watching you ruining sci-fi Christmas! I love you for the science you report. There are other places if one is looking for fantasies :-)

[@NovaDeb]

😊

[@BabyMakR]

a year or so ago, I found a series where they would get an expert in a field and they would explain their field to school kids of 3 different levels. Primary, middle and secondary. I'd love an episode, or even a series probably where you or an expert you could get to do it would do this.

[@adamredwine774]

Ice cube keeps two over-winter staff who spend winter in Antarctica. It sounds like a fantastic experience. Also, there's another neutrino detector under construction in the Mediterranean.

[@nastropc]

Dr. Dre keeps four staff who spend summer in the Sahara.

[@Reyajh]

Ohh, you hit 400k Sub's!!! Congratulations!!! 🎉✨🎇🎊

[@byalexy93]

I’m in a local aurora Facebook group so that is what I would recommend for updates on when they happen!

[@NullCreativityMusic]

Another great show. Congrats with the 400k!

[@wavemaker54]

He deserves at least 5 times as many subscribers, there’s no annoying advertising every 3 minutes, and no BS. Up to date and accurate as always. Tell your friends and families, even total strangers, who isn’t interested in space, astronomy, and astrophysics?

[@WilliamHostman]

For really good aurorae, visit Fairbanks, AK, in mid-winter. You'll suffer for it (temps hit the -20°F range regularly)... but the reds, blues, and oranges in it are absolutely worth it... occasionally. Farbanks denizens tend to become inured by over-exposure. If you're eligible for hops on USAF MAC flights, Eilson AFB is in the greater Fairbanks area....Nome and Barrow have better, but are much harder to get to. (lower light pollution.)

[@ayushagrawal3346]

@frasercain The one video that absolutely opened up a different world of astronomy for me was the star party with you and trevor jones a couple of years back. When do you think you could do something like that again? Also, it would be really cool if you could get someone from the southern hemisphere along with you two

[@frasercain]

I really want to again. It's on my medium-term list. I'm going to get a new telescope setup and get Trevor's advice. :-)

[@michaelgian2649]

Belos gets my vote this week. The use of our present technologies as explainers brings it home.

[@abastein2000]

Congrats on 400k subs! 🍺🍺🍻

[@cykkm]

Rocket launches (35:00): SpaceX also have enough launches scheduled from Vandenberg AFB in SoCal, just south of Santa Barbara. It's a military base, and there is no public viewing area, but you can still see them from public roads. There's a lot of info on the 'Net on viewing locations. Make sure to have enough water and sun protection with you.

[@hoplitnet]

QUESTION: if humanity evolved on an earth-sized moon orbiting a very large gas giant, would it be easier to launch rockets if they were pointing directly at the gas giant using it's gravity as an assist?

[@chadr2604]

I have only seen aurora once in Barrow AK. Going that far north completely screws up my internal clock almost beyond repair and I actually felt dizzy. Basically being close to earths rotation axis and looking at stars I could perceive earths rotation over several minutes. I had to go back in the hotel and lay down. It was very different than being near the tropics.

[@aaronpettigrew9674]

Risa: Asteroid mining made me think of another question about it: wouldn't the first and most practical use of the concept be to smelt them into materials, and eventually forms that could be used to make larger and more functional space stations, and perhaps even science vessels that could further be used for better exploration of the rest of the solar system? Even if it were to only start out as frame and support pieces, allowing us to only need to send up lighter and more intricate supplies, which can only be manufactured here on earth for now. Culminating into it being more of an engineering plan rather than being driven by profit. I could probably write up a more detailed idea for such a concept if you'd be interested.

[@sentientdesign295]

that was great, resonated with me a lot, what you said. 🌙

[@fsmoura]

Attack ships on fire off the shoulder of Orion... And C-beams glitter in the dark near the Tannhäuser Gate, of course.

[@RichUniverse_]

Thanks for posting my question ❤ I changed my logo - It’s Rich Universe.

[@aureaphilos]

"I know that I'm ruining Sci-Fi Christmas" OMG that was such an hysterical line, Frasier!!!🤣🤣🤣. But I agree with your points; until we are a manufacturing in space, the costs of getting to another body, extracting metals, and then returning them to the bottom of our gravity well is just too impractical. 2001 A Space Odyssey set us up for such potential yet such disappointment.

[@Infiric2]

Love your content!! ❤

[@bbbl67]

9:51 I think the secret to profitable asteroid mining is to couple it up with space manufacturing too, where you take space factories upto asteroids and build stuff up there which stay up there. For example making space ships in space factories. The space ships can then bring pre-manufactured goods from the asteroids to Earth. Such as the spaceships themselves. Then the cost of transporting things in space will plummet astronomically.

[@aalhard]

Of course, 38:00 Look for PFAS , forever chemicals are the calling card and perhaps also, The Great Filter.😮

[@kengill9367]

Thank you love your show 🎉

[@krakhedd]

I feel a little bit like it's 1987 again and I'm in 2nd grade hearing about the imminent end of oil (20-30 years tops, we were told) when I say this: There will come a time when our economically accessible minerals run out, and asteroids may well be our only option for new deposits which are economically accessible. Especially with a Moon base and space elevators, I could see not only industrial but consumer purposes for either mining in situ, or taking a long-game approach, decades, and sending a mission to bring an asteroid near Earth for mining

[@vincentclark5739]

Bro, only 10 million of the 40 quintillion black holes are in our galaxy?! I can never wrap my head around the size of the observable universe

[@MrRoddyRod]

Hi Fraser! Awesome work. As an add-on note to your asteroide mining is not feasible. What people usually forget is that the asteroid is only worth a "quintillion dollars in precious metals" because these metals are rare. If you have a ready-steady, near infinite supply of them, They're not worth a quintillion dollars anymore. People on earth don't each consume a metric tone of platinum, gold and iridium... All of a sudden, you've destroyed the supposed value of your own product with an unrestricted supply, yet a restricted demand. No wonder these companies go bankrupt even before the takeoff. Who would invest in that?

[@stevens-universe]

I've got a quick space question, but I don't know if you've ever answered it before. Mars has Olympus Mons, and some of the moons of the gas giants have cliffs up to 20km, but Earth only has Everest. How relatively smooth would a super Earth type exoplanet and/or is there a limit to how high a mountain could get given the higher gravity?

[@johnfruh]

Fraser, back in Feb, you explained that we knew about spinning black holes because of frame dragging. My question has to do with frame dragging. So, here goes... Can frame dragging also happen directly into a black hole? If so, and space falls into a black hole (e.g. like the flowing river model of spacetime going over a waterfall/event horizon), how is the spacetime lost to the black hole replenished?

[@nerufer]

[Cait] Hello Frasier, my question: is it feasable for an advanced civilisation to redirect asteroids to, for example, give spin to a tidally locked planet / moon? What kind of speed/mass are we talking about? Also, on this note, what was the impact of previous large asteroid collisions on earth when it comes to rotation speed and maybe even orbital distance to the sun? Like for example the asteroid that killed the dino's. Thanks!

[@mikh9202]

A meteor sounds like the screeching roar of a fighter jet, with crackling and popping as bits come off it. I had a close encounter with one in 86.

[@supersaiyanfife]

Couldn't agree more about total solar eclipse. The moment it goes dark it is so eerie; you almost feel like you're in 2001: A Space Odyssey or something. I am hoping to make the 2024 one, but not looking great sadly. Glad I got in the 2017 one.

[@peterclarke3020]

Risa - Yes, the only material ‘worth’ bringing back to Earth, will be ‘scientific samples’. But even much of that could be performed remotely. So such ‘remote samples’ would be mainly for vanity purposes - like I can imagine them in museums. Although they would be more likely inside labs somewhere. In-situ use is definitely the way it would go.

[@CaptainAhorn]

Regarding the issue of “adding hydrogen to a star”, the main issue is convection. White dwarfs are believed to be fully convective, meaning they circulate all their hydrogen through the core areas and eventually burn nearly all of it. This is part of why they’s so long-lived. A star like the Sun is not fully convective, and a significant chunk of usable hydrogen never reaches the core where it could be fused into helium. This extra hydrogen ends up being mostly expelled during the red giant phase of stellar evolution. So adding hydrogen to the sun wouldn’t work. If anything could work, it would be either removing mass from the sun so that fusion slows down and the sun’s life is extended (i.e. turning a G-type star into a much longer-lived but smaller K-type star) OR finding a way to stir more of the hydrogen to the core in a controlled manner. Regarding an M-type red dwarf, it seems possible to extend its life by adding mass at a controlled rate that equalled its rate of expenditure. If you add too much you will simply increase its mass, increase its hydrogen consumption rate, and decrease its lifespan. However, this might be desirable if increasing the mass and increasing the luminosity (while decreasing the lifespan) makes an otherwise frozen star system habitable.

[@drwaynebuck]

A question about rocky asteroids that has always puzzled me: what kind of rock are they made of? Igneous, metamorphic or sedimentary? I can't see how gas, dust or even small grains of material could come together in the small volume of a typical asteroid to produce volcanoes (igneous), enough pressure and heat (metamorphic) or water/wind movement (sedimentary). Maybe "rock" when it comes to asteroids is just a misnomer? Thanks for all the great content!

[@duncanbeggs4088]

The JWST data on the Trappist-1c atmosphere just ruled out a thick CO2 atmosphere. It does not have the spectral sensitivity to detect a thinner atmosphere nor a thicker one with nitrogen, abiotic oxygen and several other gasses that are thought to be common around Red Dwarf planets.

[@NIL0S]

About asteroid mining... What if financial cost was not an object? What if we just want the resources for some megaproject? Monetary cost must be only considered if taking for granted that the current economic system will last forever. I highly doubt that will be the case.

[@SlyG67]

Thank-you soo much for your videos, great fun and soo interesting.

[@Yonko_W]

In my high school physics class, i learned that there is a Gravitational constant, and that it is everywhere. Now my question is how do we know if the constant is Gravitational waves or not. If not, then whats is it?

[@EinsteinsHair]

A constant is just a number, not a thing. There is a constant, about 2.2, to switch between pounds and kilograms. Multiply it times kilograms or divide it into pounds. Newton's Gravitational constant is the same everywhere and, using the right equations, can be used to convert to force or acceleration if you know mass and distance. Hope this answers the question.

[@NovaDeb]

" Ruined Sci-Fi Christmas." LOL 😂

[@kadourimdou43]

34:07 vote for Cheleb that is a good list. Q. Red Dwarfs have high energy flares, and would require a planet to be nearer. More massive Stars only last a few million years, so not enough time for complex life. So what is the mass range for a star that is best for complex or intelligent life. For example would 70% solar mass to say 20% more massive be ok. Do we know?

[@blogsfred3187]

Question: does black hole frame dragging slow rotation?

[@MelindaGreen]

If you get close to merging black holes spinning in the right frequency range but not so close for it to be a danger, there is a region where you will literally hear the gravitational waves coming through empty space as they gently push and pull on your eardrums.

[@takanara7]

That's an interesting question. It's also a question of whether or not the gravitational waves would cause regular acoustic waves in the air, and also if they would be directly detectable by your eardrums or w/e.

[@ashleyobrien4937]

Okay, how about this- we send a manned mission to Psyche and they set up a mass driver, solar or nuclear powered or both, the mass driver takes material from the asteroid and flings it into space, with the goal being to change the orbit of the asteroid, we bring the asteroid to us, maybe even get it to orbit the earth at say 50,000 kilometers. The amount of material required to do this will only be a miniscule amount of it's total mass.

[@jjchouinard2327]

Hey Fraser! What would be the minimum mass/distance of moon to a planet that would create enough tidal forces on the planet to maintain a liquid core and therefore a magnetic field? (Mars: asking for a friend.)

[@johnmann6866]

There's always someone who thinks that the amount of metals in an asteroid translate into untold riches for humanity. If you flood the market with gold, we'd use it to line our bathrooms and switch to iridium as the go-to precious metal.

[@Zane1414]

We have the Sudbury Neutrino Observatory located in Sudbury Ontario Canada. It was located in a mine around 2100m underground and used heavy water to detect neutrinos passing through. It shut down 2006 and not sure why.

[@eneslem]

Hey Fraser! Sorry if this question has already been answered. I have been wondering about this for a while. If you took a bowling ball and a golf ball to the ISS and put them in a vacuum, could you get them to orbit? What would this look like? How fast would the orbit be?

[@dondaniels127]

Frailer, as an airline pilot I had a rather unique experience of flying UNDER the northern lights while on the polar routes from Chicago or Washington DC to China. It was very much like flying under Virga, very beautiful but probably getting nuked at the time. Wish cameras were better back then, my current Samsung S-23 Ultra takes good hi-res night astronomy photos, my flip phone at the time was not up to the task.

[@bbbenj]

Thanks a lot 😊

[@oznerriznick2474]

Excellent discussion! Why would you bring resources back from asteroids? Send a swarm of autonomous ai agent entities capable of analysis, extraction, processing, manufacture and building structures in place to accommodate future visits from biological lifeforms. Imagine how much they could tell us long before we set foot on them.

[@triskeliand]

Set up a neutrino observatory on one of our distant icy moons/sub/planets

[@joeblackman100]

“A light-year of lead”, would that immediately collapse into a black hole? If so how big?

[@frasercain]

No, you need a collapsing star to do that. But I have no idea what you'd get.

[@joeblackman100]

Hmmmm 🤔 Maybe it would just sink to the centre of the galaxy and fall into the black hole, that would be interesting

[@ZionistWorldOrder]

what pleasant respite it is from all the death and suffering to dream away about the future here for some minutes

[@mrln247]

On starting/prolonging stars one of the other podcasts either Event Horizon or Cool Words, covered aome astro engineering for uplifting mass from a star to prolong it's life and engineer a steady brightness it might have been uplifting Helium as pretty sure it was the daughter (to borrow the fission term) products that you want to remove

[@ferenclucas2842]

Question I missed asking before: if the 4th dimension is theorized as being what we experience as linear time then would a being living in the fourth dimension experience time like we do in the fifth dimension and so on? Could the 1+ dimension always be a phenomenon like time for us?

[@garetclaborn]

hmmm I wouldn't say that they "would" so much as they "could". There are different theories of how time could be similar to (or the same as) spatial dimension, even some theories that suggest we have fewer spatial dimensions than we think. We don't really know from experiment. It is really more that what we experience in time can be modeled as a 4th dimension, rather than being the 4th dimension. Meaning we can represent it that way, but that's not the only possible representation. Still, in the right theory yes a 4 dimensional being could experience 5th dimensional time.

[@SeanBZA]

Seen a few eclipses, and watched them with a welding helmet, though I did have to use a range of 3 of varying density, as the denser ones were less useful as totality approached, but the view was great, even without a telescope or binoculars.

[@ivorcogdell8483]

Hi Fraser, A question. Why are Martian landers not designed with rotating solar panels, so that they can self clean the dust that gets on them or have them on all vertical surfaces? I realise weight is a factor so add gearing to the axle of rotation. Thanks for a great podcast.

[@douglaswilkinson5700]

The regolith adheres to the solar panels by static electricity. Turning them vertically would not cause it to fall off.

[@Michel613]

Andoria was the best for me.

[@jarirepo1172]

Here's a question: What would be good starting equipment to look at our planets, the moon etc? My sons birthday is soon and he seems interested in space and everything in it and I too would love to get to (literally) look some of it myself. Probably nothing too expensive or technical at first I guess but what would you get?

[@cjnthn]

never heard of the ice cube observatory

[@hansleeuw2840]

Should not more observatories also optical be built on both the North and South pole purely from the perspective of directions in the Universe / Galaxy that we now look at through a lot of (warm) atmosphere?

[@NathanaelNewton]

I follow website from a hm radio operator in Cornwall, Ontario called solarham for space wather news and technical details. I don't think he has an app that gives notifications, but I used to have Twitter notifications for him before that went south..

[@daverobert7927]

Love your work. Thankyou From Aussie "42" Dave

[@ewmegoolies]

Wow 40 quintillion black holes in the observable universe! If each black hole produces a universe inside of itself that's just incredible. I mean it would be really cool if universes existed inside black holes.

[@MakeAMark]

I understand the Planetary Nebula leave behind white dwarf stars, which you point out are the exposed core of the dying star. As an astrophotographer, Planetary Nebula are a favorite targets to shoot. Since Type 1A supernova events require a white dwarf and a companion feeding it hydrogen, are you aware of any visible (photographically) planetary nebula which are also supernova remnants?

[@cykkm]

Kinds of black holes (18:00) from the theoretical POV. There are a couple of theorems about _theoretical_ black holes-GR is maths-heavy-which we probably should assume hold true in the physical world, since GR haven't failed us in any observation yet. One proves that the only 3 possible observables of a _stationary_ (not evolving it time) black hole are its: 1) mass; 2) angular momentum, i.e. amount of rotation and 3) electric charge. No one believes that charged BHs exist: charges attract and repel very strongly, and there's enough free-floating charges in space that a charged BH would quickly attract enough of the opposite charges to equilibrate to net zero charge. A possible exception would be a non-stellar BH (like a primordial one from the Big Bang, which are unobserved, but theoretically plausible) that ended up in a deep void with practically no gas, but there is no mechanism that could leave them charged. Neither can stellar collapse, obviously-stars are electrically neutral. Astronomical BH are indeed _not_ evolving in time for the purpose of this theorem: accretion of an Earth mass a second by a BH is still too slow an evolution, and can be ignored. The time scale at which BH may not be considered stationary is on the order of 10 milliseconds for a 100 Msun BH. This takes us to the ringdown of a BH after a merger of two BHs. It cannot be approximated by a stationary solution. The ringdown is the process that stabilises a BH: the traveling wave component on the surface of the BH radiates enormous energy as gravitational waves (radial component, i.e. symmetric pulsation, doesn't radiate GW, but the whole wave decays eventually, in 20ms or so). The theorem on ringdown proves that the ringing post-merger BH may only converge to either Schwarzschild or Kerr stationary solution, the former describing a non-rotating, latter a rotating uncharged BH. Non-rotating BH must be a rarity. So I'd say there are only two “types” of physical BH, as we understand and observe, both electrically uncharged: 1) stationary, characterised by only mass and spin (two BHs of the same mass and spin are entirely identical) and 2) perturbed and ringing during, and ringing down after a merger, which exist for a short time, on the order of tens of milliseconds, which quickly shed the excitation energy by emitting GW and turn into type (1). They are still very important, despite short lifetime, as this is the one which produces the GW that we measure with LIGO and friends.

[@frasercain]

Do you think the ring down phase can tell us anything about the interior of the event horizon?

[@cykkm]

​@@frasercain I don't think they do. These are, after all, solutions to the same fully classical GR EFE-and all LIGO models are based on them, we don't "see" more in GW than the best fit of raw data to the theoretical model. It's an extremely weak signal; it is real magic that we can detect it at all. But in the end, the waveform is discarded if it deviates from the model too much. AFAIK, there was not even a suspected systematic deviation from theory, people are looking at the marginally discarded data indeed, and the residuals are just random. And according to GR, there is no matter inside, except for the central singularity. Rotating, and especially merging and ringing BH are more geometrically interesting that the plain old Schwarzschild solution (the Kerr singularity is ring-shaped, for one, but still has a non-physical zero volume), but it's still geometry of empty space.

[@simfromzim]

on Vendikar, isn't the correct answer "we don't know"? If we don't have any information about the state of matter inside a black hole, how could we possibly know if they are all the same?

[@michaeltumey7756]

I've seen aurora's in Illinois, though it's rare. I lived in Alaska for 5.5 years and one night in Fairbanks, I saw the most incredible auroras in my life. I saw a spoked wheel (without the outer circle wheel) rotating in the sky...

[@theoptimisticskeptic]

I've seem them once, in upsate NY in the Finger Lakes region. It was a rare event, but it was almost no colors at all just shades of grey and white. We were told that was because of how far south we were. This was around 1989-90, I'd guess. Of course it was also at a Rainbow Gathering and it was also the last time I ever dropped acid but the Aurora was actually real, at first we thought it was fireworks, then the acid. But then other people who were not on acid started seeing it too. So we knew it was real. So the one time I've seen them I was also tripping, it was pretty awesome! (edited to try to get the dates correct)

[@JMHGlass]

Speaking of harvesting asteroids ... What about when manufacturing has moved into space? Like to build habitats or ships, and there just happens to be a huge asteroid thats 90% iron. Wouldnt it be cheaper to harvest that opposed to bringing it up from earth?

[@HPA97]

[Vulcan] Would it be possible to align mirrors in some dyson sphere manner that we could heat up some of the planets/moons further out in the solar system, I.e. heat up Titan, Europa, etc...?

[@mister_r447]

For asteroid mining, Kurzgesagt made a video and they included the possibility of redirecting an asteroids orbit towards earth's orbit where it would be mined. Wouldn't that be cheaper?

[@BabyMakR]

If there was a star in close orbit to a black hole, how would the star be aged? Being close to a black hole, would time dilation impact our estimate of the age of that star?

[@MistSoalar]

Cheleb. Only one left for me! Will travel to Buffalo, NY for total eclipse.

[@geoswan4984]

At around 25 and a half minutes, when answering questions about the speed of gravity, Fraser asserts that the gravity waves from the clap when two Neutron Stars collided, the gravity waves arrived slightly before the light waves... But even the light waves wouldn't have arrived simultaneously, right? The full name of the speed of light is "the speed of light in a vacuum". Isn't the fundamental explanation for refraction that light at low frequencies slows down more when travelling through a dense medium than high frequencie do? Outer space is so close to a real vacuum that, at non-astronomical distances, all light seems to travel at the same speed. But, at the right level of precision, wouldn't we be able to detect a smear across the spectrum? So, would the density of the medium slow down gravitons? Would it slow down Neutrinos? In some comment, recently, I questioned whether Neutrinos, from an object traveling at a high speed, relative to us, would show the kind of lower energy we see from red-shifted light. Another respondent told me neutrinos would not show a loss of energy just because their source was retreating from us. But that just doesn't sound right to me. It seems to me the intensity of gravity waves would be related to the relativistic speed of their source, just like light.

[@dustman96]

What kind of information can you get from gravitation wave observations? Do gravitational waves "redshift"?

[@JamesCairney]

I appreciate the creation of this content. Thought I should say, and that, know? Risa, the answer and the planet There is another way to look at this question. Why would people not drill a kilometre down through the earths crust in order to reach a nice rich ancient sea salt deposit when they could just boil some sea water to extract exactly the amount of salt that they need? Is it not the same as mining in space? Why go to the expense when there is no need.

[@disinclinedto-state9485]

Hi, Fraser and team. Neutrinos are so difficult to detect... How did we ever know to look for them?

[@frasercain]

They were predicted when people did the math of hydrogen fusion. There should be leftover particles.

[@unclvinny]

Hey Fraser & friends. After Theia hit the Earth, about how long would it have taken for the Earth and Moon to become spherical?

[@Zurround]

On the topic of "reigniting a dying star" there is a science fiction movie filmed back in the early 2000s called SUNSHINE about exactly that. It was an awful movie. Season 3 (I think, took place after the destruction of the comet empire) of the anime TV series STAR BLAZERS dealt with the Gamelons, who went from being villains to allies, helping reignite Earth's dying sun

[@bertrand1289]

What about non rotating black hole or electrically charged black hole?

[@akers189]

Hey Fraser. If a planet the size of Jupiter was traveling at the speed of light and had a straight on collision with a micro blackhole or one the size of a car, what would happen? Thanks, Jason

[@seansarmast3355]

Hey Frasier…you talked about how gas giants if they get big enough become brown dwarfs etc but what is the lower limit for a gaseous planet? I.e. how small can they get before they’re not planetable? Thanks!

[@illogique7883]

question: does the sun and sagittarius a* have lagrange point?

[@thorstenkrug144]

UNLESS you siphpon of hydrogyn and remove it and lower the core pressure you can not enhance the Stars life. It will get cooler but live länger. You may even need to adjust the planets Orbit via Gravitation orbiting them to move them. Thats so though i think.

[@kengill9367]

I think one of your shows got pulled or is missing the one on a antimatter drive?

[@jeffmathers355]

Hey Fraser another question just popped into my head! Do astronomers have a good idea about how much total mass is in the Kuiper Belt and Ort Cloud? Is there a New Horizons 2 being planned to learn more? Thanks!

[@HughPryor]

What's the best resolution we're going to get for neutrino photographs or 'neutrinographs'??

[@JD-mm4ub]

Hi Fraser, My question is, why are Aurora’s mostly green? And what causes the other colors? Thank you ever so much! JD

[@terminusest5902]

What impact may Gereration 4 fission reactors have on space exploration.

[@Shaden0040]

Coyld darkmatter be drom photons and neuyrinos having miniscu;e mass greater than zweo?

[@jamesfowley4114]

Cheleb I saw a ring eclipse, about 90-95%. It was a really thin ring. A few stars were visible, but it wasn't like a sunset darkness. I saw a really good aurora when I was a kid. Northern Wisconsin, and I'll try to see one again, but the wonder of seeing one at seven years old or so will be hard to match.

[@EinsteinsHair]

There will be a total eclipse crossing part of the US in April 2024. Learned about it when looking up the recent annular eclipse. A NASA web page had a map of the tracks. There was a region outside San Antonio, Texas which would be near the center of both tracks, if weather permitted viewing.