I squinted at that awhile, but the best alternative phrasing I could come up with was 'Based on "What If?" by and narrated by Randall Munroe'. Instead of despairing over the wording, I too will accept the headcanon that these video is narrated by the book. A shame; I was hoping to get Mr Munroe's voice reveal one of these days.
It does, but not for the reasons you think! It turns out if you point the telescope at Earth, nothing bad happens... until an alien telescope can now see through the reversed eye-piece of the hubble telescope, allowing them to resolve the dangerous human civilization below - rather than only being able to see our atmosphere as they initially expected. Correctly identifying us as a threat, they launch their deadliest weapons at us at some fraction of the speed of light - which will show up centuries in the future - destroying us without warning!
I've been reading xkcd since middle school and I love the webcomic so much. I read each new comic on the day it's released, and have read every comic multiple times. It's a big part of what inspired me to become a physics major. It's great to see it on a new platform.
I have, along with the what if Blog/Blag. Honestly I think Thing Explainer might be my favorite because I felt like a really learned a lot about stuff I had no clue about before.
One of the US reconnaissance satellites referred to at the end of this video is known as the KH-11. It's essentially a HST that is designed for staring at the Earth. The US has launched over a dozen of these things in orbit. Makes the HST seem positively quaint by comparison: en.wikipedia.org/wiki/KH-11_KENNEN
Fun fact: The Nancy Grace Roman Space Telescope (formerly WFIRST) is built with a leftover mirror of those Key Hole spy satellites. The NRO had a spare mirror lying around but moved on to better telescopes, so they gifted it to NASA.
In 2012, NRO gave two of these to NASA (with the electronics removed) so NASA could build more telescopes. One of them is nearing launch as the WFIRST mission next year. (The other remains in storage.)
Even the little bit which has been released about these satellites is mind blowing. Also, the "11" is the revision number. There were something like 20 KH-11s sent into orbit. IIRC there were on the order of 150 film-based spy satellites sent into orbit. And in an unrelated note, Trump's release of a classified satellite photo revealed that the current generation are operating at the optical limit.
@@brianorca If I remember correctly, the HST also started off as a 'gift' from the NRO (or whatever its predecessor was). Makes a lot of sense. In addition to just being nerds who think astronomy is cool too, the NRO gains from the more innovative technological developments a broader open community tends to come up with. It also allows supporting industry to build factories and such in the open for the scientific project, but make stuff for the NRO in secret using those facilities/capabilities.
3:21 I am so proud that I can watch this promotion, and then look up from my phone to see them all in a neat bookshelf. How good it feels to be ahead of the curve ❤
Wow! An official video series adaptation of xkcd stuff?! Thank you so much, Randall and Team! I hope this medium brings your content and ideas to more and more people. As it absolutely should!! Congrats on this new project and all the best to the Team for this endeavour.
Xkcd's What If blog was always my favorite thing that Mr. Munroe had ever put out, and I always wished there were more of it. Seeing this pop up on my homepage has me absolutely ecstatic!
3:14 I'd love a follow-up about how ground-imaging satellites, whether government or commercial, actually achieve their increasingly jawdropping levels of image quality.
I work as an GNC engineer at the company that takes the satellite images for google maps (among other things) - it's a lot of work by a lot of people to get those nice clean surface images!
@@MusicalMethuselah Ground imaging satellite are typically around 500-600km above the Earth's surface, not the 35 THOUSAND km above the earth's surface that geosynchronous orbit would be. The best way to take a detailed image is to stay relatively close to the thing you're imaging, not move 10's of thousands of kilometers further away. Also, geosynchronous orbits literally don't move with respect to the earth's surface, which makes it a pretty useless place to image any part of the earth from.
From what I heard from one of the engineers on the gambit 3 project (1960s and 70s), they were reading numbers off of russian ICBMs (allegedly. The exact resolution is still classified, along with the program's cost.)
Just finished my degree on the stuff (tho google man may know more than me). What is commonly used is a method known as push broom scanning where a single line of pixels (known as a linear array) scans the surface using this motion (edit: the orbital motion), building up a 2D image. To reduce calibration issues and (I think) motion blur, multiple of these arrays are used and averaged in a process known as Time delay integration (TDI). Hope this helps :))
Story time. I worked at NASA Goddard when HST arrived on orbit. HST was designed by Marshall SFC whose specialty was manned space systems, and NOT unmanned satellites. It showed. In every system on HST it showed. Lost in the din of thousands of GSFC engineers all lamenting “but why?”, because of the nature of HSTs capabilities and technology, the NRO involved itself in key elements of HST reviews. If there was too much leakage from the vendors making key components of the KH- family of assets into HST, our adversaries could deduce the capability of the keyhole sats. The answer to “but why?” Was frequently because of the firewall between people who REALLY knew how to make extremely complex and capable telescopes looking down, and the team trying to make the same thing, looking the other way.
@@camdensullivan5713 uhh, what "grandiose terminology" ? You mean the small number of abbreviations he uses, mainly HST=Hubble Space Telescope ? (NRO = National Reconnaissance Office, the folks operating spy sats, and SFC is probably Space Flight Center)
I love xkcd so much! I have how to and what if and I’ve been a dedicated follower of the webcomic forever. Thank you for putting work on this platform!
"Hubble is the best visible light telescope we have." It was made from spare parts from a fleet of satellites that already point at the earth 24/7 and get regular hardware updates since they were put in service. Hubble is the best visible light telescope we have........ Pointed at space. The best one we have period is pointed at either Russia or China.
I'd love to see a narrated/animated version of the debut What If.... the relativistic baseball. I've been an xkcd fan forever, so great to see a video version of What If appearing!
The audiobook exists and theoretically they could use that for the soundtrack, although they would have to work it out with Wil Wheaton's people (he's the narrator of the audiobook).
How did I not find this Channel sooner? I got one of this guy's book a while ago (How To: Absurd Scientific Advice for Common Real-World Problems) and absolutely loved it
I'm so excited! Every year during standardized testing, I bring books for kids who don't have one. And every year, students end up fighting over What If and How-To. I can't wait to share your videos with my students!
Randall Munro you are a unique person, I have read your books, and realized that no one has ever explained more complicated things to me in simple language with humor, so there are also MINI COMICS there!!! I am your big fan, greetings from Kazakhstan🎉🎉🎉
So excited that What If is getting videos now! I've read both books and most of the questions on the website, so I'm very excited to see some new stuff! I instantly came here and subscribed when I saw the MinutePhysics video.
I go to XKCD's What If site many times a week even though there are rarely updates. It's an entertaining read if I need to kill time at work without having to go to social media sites. Super excited to see there's a TH-cam channel now!
The equation used to determine max (angular) resolution is theta = 1.2×lambda ÷ d where lambda is the wavelength of observed light, d is the diameter of the light collecting area, and theta is in radians (the 1.2 comes from the Bessel function). Beyond this point, magnification only yields a blurry image. Assuming green light (which is in the middle of the visible spectrum, lambda = 550 nm) and the diameter of hubble's mirror is 2.4 meters, the max angular resolution is 2.75×10^-7 radians (0.00001576 degrees). At its orbiting altitude of 535 km, it can see objects as small as 14.713 cm (5.793 inches) on the ground. Since the keyhole spy satellites mentioned at the end of the video have very similar mirror diameters, we can say their resolution is similar. Rumors say that the best spy satellite resolution today is around 1 cm² per pixel Unrelated, but the demonstration at 0:37 was really clever!
5 inches seems a very large resolution compared to the example image in the video. Can you explain this? Do you believe the example image to be overly optimistic?
@@baffo32ios I probably should've used more significant figures for the Bessel coefficient (1.220). This would result in 8.57 cm (3.37 in). He might also have used the smallest wavelength of visible light for a max visible angular resolution. I can't think of any other reasons
Randall, if you’re reading the comments, I want you to know the second What If? book was the funniest nonfiction book I’ve ever read. That is, if you can consider it nonfiction. Some of those questions are kinda outlandish. I’m so glad there’s finally a video series to supplement it.
Awesome video! Anyone interested in the satellites mentioned at the end should check out the “secret” KH-11. They used to be launched on the shuttle too. There’s a few pictures out there believed to have came from them.
Many of the early high-resolution satellite images have been declassified and released to the public. I am not sure if the KH-11 images have been released yet.
You’re trying to over generalize something I was already fairly nuanced with. You are correct, sure, just as long as we’re stressing declassified and not the released to the public part. Anyone can just look into believed KH-11 photos. A good place to start is USA-224, maybe Samuel Loring Morison, and decide for yourself from there what you choose to believe. I don’t know why you needed to comment that.
I'm so glad you did the sound effects of the desk whizzing past Hubble, that was amazing! Your books are awesome and I just got two new people excited about them!
Thank you, Randall! I still haven't managed fo get through all of Thing Explainer to move onto What If? Vol. 1 due to life circumstances, so having some of them as videos is a big help. I was a huge fan of them on the main site and still really want to get the books!
man, I was like 14 when I got the first What if book for Christmas, and now 9 years later im getting nostalgia bumps on TH-cam. xkcd was my childhood...
I've been a huge fan of "What if?" ever since it launched so many years ago, and I was sad when it was put on hiatus. I'm hoping this TH-cam channel pans out!
There's a fun bit in the book "The Cuckoo's Egg" by Cliff Stoll, where he's chatting with a CIA agent, and the agent asks him to estimate how good the Hubble's resolution would be if it were pointed at the Earth. Based purely on the wavelength of visible light, Cliff does a bit of napkin math and gets an answer pretty close to the one in this video: good enough to see a person, but not good enough to make out their face. The CIA agent just smiles knowingly.
I'm very happy to have been alerted to the existence of this channel with only its second video published! I'm looking forward to more educational and entertaining content!
I've read every comic, every what if? entry in both books and the blog, every entry in how to, and most of Thing Explainer. I'm excited to see if there's going to be original questions answered on this one or maybe a 163rd blog entry!
Likely, you could clear up that picture with the right priors. I have seen some incredible results with much worse images using L1 regularization strategies. Dr. John Murray Bruce’s at my university (USF) does what is called computational periscopy, which uses diffuse reflections off of a wall to reconstruct images from a monitor. It’s incredible. A Nature paper too. Happy to see you come to TH-cam, Randall! This is exciting! I’ve been following XKCD since year 1 or so.
I have been reading your books, and what if? has been my favorite book of all time. Great first video! Can’t wait for more scientifically accurate absurdity!
They even did it before Hubble was launched. They hinted at NASA, that they should enlarge the lens size, since they know for reasons, that there is a manufacturer, who can produce them and has the exact tools for it. But I don't think earth facing satellites rotate as a whole, as suggested in the video. You could simply move the sensor or some optics, with much greater speed, effort and less energy.
Earth observation satellites do rotate to remain in the same position relative to the surface of the earth (cameras mostly facing down for electro-optical sensors). However, they use their motion relative to the ground to take a complete image because they have linear CCD sensors, while Hubble has a two dimensional CCD array to create images which is why it needs to remain as still as possible relative to its imaging target.
@@kaitlyn__L except here the whole scanner (aka the satellite) is moving over the scanned landscape. No moving part in push broom scanners. Older Landsat satellites had moving parts (whisk broom scanners) that were more prone to failures.
There are also earth-observation satellites with full 2D CCD imagers - I'd actually imagine those are almost more common these days. I work with one such satellite, and we do indeed roll the entire cubesat to track the earth from ~500km up. I'd be tempted to say those are more common these days than push broom or whisk broom, at least for new launches. The biggest challenge actually seems to be stabilising the satellite on that slew track, having whipped it around from a different target, so the motion is entirely smooth. Watching the raw frames as a video, you sometimes feel a little bit sea-sick.
@@danielevans1680 not sure about cubesats, as there are so many it's hard to keep track, but all the big birds designed for electro optical earth observation are push broom scanners. Even the slew of Chinese ones launched in the last decade or so, for which much less info is available, seem to use that technology for now. More generally, for a satellite in an orbit suited to its observation objectives, I don't quite see the benefit of a sensor array vs. a CCD line. The only one would be the need for higher stability during the entirety of the capture window which for big satellites is a more manageable problem than for small ones. Line sensors simplify the optics tremendously particularly for multispectral sensors.
Aerospace engineer here: Sorry but Hubble doesn't use gyroscopes for its orientation it uses reaction wheels and yes there's a significant difference. In my final year when we had to do 2 high level aerospace options one of mine was spacecraft dynamics. Most of my class took finite element methods and orbital mechanics. 4 or 5 of us (out of 40) took space craft dynamics instead of orbital and regretted it about 5 minutes into the first lecture when we realised how hard the maths was. While orbital mechanics (which isn't much easier) is about orbits and moving between them space craft dynamics is about orientating and pointing free bodies in space which sounds easy but gets into some nightmare maths. Because there's nothing to push back against when you move an antenna or point a camera the rest of the space craft moves in the opposite direction about the center of gravity. Its not so bad on things like the Voyager probes because of how they built them, but for things like Hubble and the ISS its gets into some weird math because things like gyros and reaction wheels cause things to rotate in odd ways because of precession. I did that class in 1987 during the time of Ronald Regan's Star Wars program. There were around 8-9 postgrads doing the higher level version of the class where they had to do a term paper as well. They were all sponsored by DARPA and a couple of them did some real interesting things the like of which very few people are aware of. Simply thing. let me say that making things like Hubble and James Webb work requires some extraordinary high level math skills. I still have nightmares from that class it was so hard.
I worked on a satellite and was on the team designing our own reaction wheels. It would save us a lot of money if we were able to build our own instead of purchasing it from commercial means. Just the act of balancing those god-forsaken wheels gives me a headache.
I don’t know why I’ve never looked for a "What If?" channel - I love the books - but I’m now a subscriber here! This video is very cool, as I was a professional photographer for about 20 years and I know all about shutter speed vs movement vs resolution. Studying photojournalism in college, we had to learn how to track objects while dragging the shutter in low-light situations in order to get a relatively non-blurred photo of a moving object. I spent hours on the fourth floor of the building where I worked, hanging out a window after sunset and trying to get good photos of passing cars on the street almost directly below. It’s very, very hard to do, even when you’re holding the camera. I can imagine the difficulty in trying to do that remotely on a telescope with limited speed for movement…
It looks like this "What If?" channel was only created recently - this video is the first one that's been uploaded here (although judging from the related videos it looks like XKCD has sometimes guess starred on minutephysics in the past).
@@gordontaylor2815 I see that now! The TH-cam algorithm obviously worked well in this case, suggesting a channel that I would definitely love right when that channel first started. Although I have to admit that I’m a little sad that they don’t have dozens or hundreds of older videos that I can binge-watch… That’s always the best part of finding something new here. Oh well, at least I’m subscribed so I won’t miss anything.
being a photographer for 20 years, i've been one for 45 there was no reason for you to mention how long or that you were allegedly a pro, anyone reading a book on beginner photography would understand the shutter speed motion resolution after about half an hour of reading
Shows what you all know. The desk is moving at a speed so fast, Hubble can't keep up and we're lead to believe that the telescope is what's moving faster. Joking aside, this was a nice video.
Those "Hubbles" that are aimed at earth are called "KH-11"s. There have been many of those. And they can rotate with their orbit of earth, no motion blur problems.
At 0:20 you said that Hubble points at the Earth pretty regularly to calibrate its instruments. Then you spent the rest of the video explaining why Hubble can't take clear pictures of the surface of the Earth. What is it calibrating? Its fuzz factor?
Thanks for a video that actually answers the title in 2 minutes instead of 30 minutes. I'm so done with explanations videos. And i'm subscribing instantly to you.
I'm so glad I found this! I don't know if you're just animating questions you've already gotten on the blog or if you're gonna take new questions, but I've got one for you: what would the the climatic effects of a ring system around Earth? Would the planet still be habitable?
I've been reading xkcd ever since I happened to pick up What If? in my school library when I was 11, and these videos are absolutely awesome! Will definitely be religiously watching every single one :)
Well, the KH-11 satellite used by the NSA is rumored to be the Hubble pointed at earth. Incidentally one of the first missions to the Hubble was to replace the mirror - my hunch is a HK-11 mirror was installed in Hubble by mistake.
I've been missing reading "What If" on the site. I miss the sketches and footnotes, but I really like how well done the video is. Looks like I have a new channel to watch.
"Narrated by and based on "What if?" by Randall Munroe"
I can't believe they managed to get the actual book to narrate the video!
that book has an excellent voice.
What if "What if ?" could talk ?
I squinted at that awhile, but the best alternative phrasing I could come up with was 'Based on "What If?" by and narrated by Randall Munroe'. Instead of despairing over the wording, I too will accept the headcanon that these video is narrated by the book. A shame; I was hoping to get Mr Munroe's voice reveal one of these days.
Next thing you know, they'll get some employees to wash hands for you!
@@Dusterisp Narrated by Randall Munroe, based on "What If" by Randall Munroe
This Randall guy has potential, nice to see up and coming creators.
Nice to see you as well! Haven’t watched your newest video yet but I plan to
Randall isn't up and coming lol
@@shiftoff9936woooosh
woosh@@shiftoff9936
@@shiftoff9936 you should be nice to small creators. "randall xkcd" only has one video out
So glad you're on TH-cam! Can't wait to watch every video.
Of course Cleo is an xkcd fan!! Makes me love her work even more
hubble
1.7K likes, 3 replies.
Next FAQ: James web telescope over earth
@@bierymolina4379 not possible, JWST cannot be turned sunwards or else its cameras would burn
So...this doesn't kill everyone? Theres a first.
Assuming the reasons for looking at earth aren't nefarious, yes :D
he said the tech is used by the US military, sooo....
It's amazing how we love potentially catastrophic technologies
It does, but not for the reasons you think! It turns out if you point the telescope at Earth, nothing bad happens... until an alien telescope can now see through the reversed eye-piece of the hubble telescope, allowing them to resolve the dangerous human civilization below - rather than only being able to see our atmosphere as they initially expected. Correctly identifying us as a threat, they launch their deadliest weapons at us at some fraction of the speed of light - which will show up centuries in the future - destroying us without warning!
for some reason, simply because it's xkcd, I expected Hubble to explode from the speed of tracking the Earth or something LOL
I've been reading xkcd since middle school and I love the webcomic so much. I read each new comic on the day it's released, and have read every comic multiple times. It's a big part of what inspired me to become a physics major. It's great to see it on a new platform.
You should read his 4 books if you haven’t yet
I have, along with the what if Blog/Blag. Honestly I think Thing Explainer might be my favorite because I felt like a really learned a lot about stuff I had no clue about before.
Same🔥, love the comics
I went through serious "What If?" withdrawals when he wasn't updating the web page. So happy to see this channel!
i remember feeling slick for reading articles about easter eggs on the xkcd website and finding them, it’s super fun with such a huge backlog
Absolutely fantastic
holy shit its my fav youtube channel in the wild
@@charlestheriault3870 Thanks, I appreciate it. Not often I hear people say that about me.
One of the US reconnaissance satellites referred to at the end of this video is known as the KH-11. It's essentially a HST that is designed for staring at the Earth. The US has launched over a dozen of these things in orbit. Makes the HST seem positively quaint by comparison:
en.wikipedia.org/wiki/KH-11_KENNEN
thank you-i thought this was going to be the subject of entire video when i clicked
Fun fact: The Nancy Grace Roman Space Telescope (formerly WFIRST) is built with a leftover mirror of those Key Hole spy satellites. The NRO had a spare mirror lying around but moved on to better telescopes, so they gifted it to NASA.
In 2012, NRO gave two of these to NASA (with the electronics removed) so NASA could build more telescopes. One of them is nearing launch as the WFIRST mission next year. (The other remains in storage.)
Even the little bit which has been released about these satellites is mind blowing. Also, the "11" is the revision number. There were something like 20 KH-11s sent into orbit. IIRC there were on the order of 150 film-based spy satellites sent into orbit. And in an unrelated note, Trump's release of a classified satellite photo revealed that the current generation are operating at the optical limit.
@@brianorca If I remember correctly, the HST also started off as a 'gift' from the NRO (or whatever its predecessor was).
Makes a lot of sense. In addition to just being nerds who think astronomy is cool too, the NRO gains from the more innovative technological developments a broader open community tends to come up with. It also allows supporting industry to build factories and such in the open for the scientific project, but make stuff for the NRO in secret using those facilities/capabilities.
3:21 I am so proud that I can watch this promotion, and then look up from my phone to see them all in a neat bookshelf. How good it feels to be ahead of the curve ❤
Wow! An official video series adaptation of xkcd stuff?! Thank you so much, Randall and Team! I hope this medium brings your content and ideas to more and more people. As it absolutely should!! Congrats on this new project and all the best to the Team for this endeavour.
Xkcd's What If blog was always my favorite thing that Mr. Munroe had ever put out, and I always wished there were more of it. Seeing this pop up on my homepage has me absolutely ecstatic!
3:14 I'd love a follow-up about how ground-imaging satellites, whether government or commercial, actually achieve their increasingly jawdropping levels of image quality.
I work as an GNC engineer at the company that takes the satellite images for google maps (among other things) - it's a lot of work by a lot of people to get those nice clean surface images!
Gotta be geosynchronous orbits, right? I don't actually know but that's my guess haha
@@MusicalMethuselah Ground imaging satellite are typically around 500-600km above the Earth's surface, not the 35 THOUSAND km above the earth's surface that geosynchronous orbit would be. The best way to take a detailed image is to stay relatively close to the thing you're imaging, not move 10's of thousands of kilometers further away. Also, geosynchronous orbits literally don't move with respect to the earth's surface, which makes it a pretty useless place to image any part of the earth from.
From what I heard from one of the engineers on the gambit 3 project (1960s and 70s), they were reading numbers off of russian ICBMs (allegedly. The exact resolution is still classified, along with the program's cost.)
Just finished my degree on the stuff (tho google man may know more than me). What is commonly used is a method known as push broom scanning where a single line of pixels (known as a linear array) scans the surface using this motion (edit: the orbital motion), building up a 2D image. To reduce calibration issues and (I think) motion blur, multiple of these arrays are used and averaged in a process known as Time delay integration (TDI). Hope this helps :))
I miss when the What If? page had regular updates, but excited to see where this channel goes!
It's so cool to see a video version of this! Thanks, Randall!
Story time. I worked at NASA Goddard when HST arrived on orbit. HST was designed by Marshall SFC whose specialty was manned space systems, and NOT unmanned satellites. It showed. In every system on HST it showed. Lost in the din of thousands of GSFC engineers all lamenting “but why?”, because of the nature of HSTs capabilities and technology, the NRO involved itself in key elements of HST reviews. If there was too much leakage from the vendors making key components of the KH- family of assets into HST, our adversaries could deduce the capability of the keyhole sats. The answer to “but why?” Was frequently because of the firewall between people who REALLY knew how to make extremely complex and capable telescopes looking down, and the team trying to make the same thing, looking the other way.
You've gotta be an engineer with that many acronyms!
@@camdensullivan5713 uhh, what "grandiose terminology" ? You mean the small number of abbreviations he uses, mainly HST=Hubble Space Telescope ? (NRO = National Reconnaissance Office, the folks operating spy sats, and SFC is probably Space Flight Center)
This is all a lie because you can’t put a satellite past the firmament
@@camdensullivan5713 simple is better
@@camdensullivan5713he’s terrible at communicating, not a liar
I love xkcd so much! I have how to and what if and I’ve been a dedicated follower of the webcomic forever. Thank you for putting work on this platform!
"Hubble is the best visible light telescope we have."
It was made from spare parts from a fleet of satellites that already point at the earth 24/7 and get regular hardware updates since they were put in service.
Hubble is the best visible light telescope we have........ Pointed at space. The best one we have period is pointed at either Russia or China.
Just here from Minute Physics!
Hah that's funny, I'm here from Minute Earth!
@@J75Pootlemin. Earth too
Same!!
I'm here from ur mums place. Last night
@@iFreshCrispy necrophile?
It's great to see you here on TH-cam! Some of my favorite books I've read (and of course my favorite webcomic)!
I'd love to see a narrated/animated version of the debut What If.... the relativistic baseball. I've been an xkcd fan forever, so great to see a video version of What If appearing!
I agree. Hopefully this will be one of next vids.
The audiobook exists and theoretically they could use that for the soundtrack, although they would have to work it out with Wil Wheaton's people (he's the narrator of the audiobook).
So... guess from which exact video I got here 🙂
I’ve been reading XKCD for over 15 years. Glad to have it as TH-cam channel!
How did I not find this Channel sooner? I got one of this guy's book a while ago (How To: Absurd Scientific Advice for Common Real-World Problems) and absolutely loved it
I'm so excited! Every year during standardized testing, I bring books for kids who don't have one.
And every year, students end up fighting over What If and How-To.
I can't wait to share your videos with my students!
Randal welcome to TH-cam!! I'm so excited you're doing these!!!
Randall Munro you are a unique person, I have read your books, and realized that no one has ever explained more complicated things to me in simple language with humor, so there are also MINI COMICS there!!! I am your big fan, greetings from Kazakhstan🎉🎉🎉
So excited to see Randall Munroe post content on youtube! My parents gave me "What If" as a birthday gift when i was younger and loved it so much!
So excited that What If is getting videos now! I've read both books and most of the questions on the website, so I'm very excited to see some new stuff! I instantly came here and subscribed when I saw the MinutePhysics video.
I'm so Excited for this Channel! I've been using XKCD comics and books for my classroom for years now and this will engage on a whole new level!
I go to XKCD's What If site many times a week even though there are rarely updates. It's an entertaining read if I need to kill time at work without having to go to social media sites. Super excited to see there's a TH-cam channel now!
Best video on where Spy Satellites are at. Which is what Hubble effectively was in the 1980s. They're way better now.
I love xkcd to death and am glad that I can now also watch you on youtube. Also shoutout to minutephysics for bringing me here.
The equation used to determine max (angular) resolution is theta = 1.2×lambda ÷ d where lambda is the wavelength of observed light, d is the diameter of the light collecting area, and theta is in radians (the 1.2 comes from the Bessel function). Beyond this point, magnification only yields a blurry image.
Assuming green light (which is in the middle of the visible spectrum, lambda = 550 nm) and the diameter of hubble's mirror is 2.4 meters, the max angular resolution is 2.75×10^-7 radians (0.00001576 degrees). At its orbiting altitude of 535 km, it can see objects as small as 14.713 cm (5.793 inches) on the ground. Since the keyhole spy satellites mentioned at the end of the video have very similar mirror diameters, we can say their resolution is similar. Rumors say that the best spy satellite resolution today is around 1 cm² per pixel
Unrelated, but the demonstration at 0:37 was really clever!
5 inches seems a very large resolution compared to the example image in the video. Can you explain this? Do you believe the example image to be overly optimistic?
@@baffo32ios I probably should've used more significant figures for the Bessel coefficient (1.220). This would result in 8.57 cm (3.37 in). He might also have used the smallest wavelength of visible light for a max visible angular resolution. I can't think of any other reasons
Randall, if you’re reading the comments, I want you to know the second What If? book was the funniest nonfiction book I’ve ever read. That is, if you can consider it nonfiction. Some of those questions are kinda outlandish. I’m so glad there’s finally a video series to supplement it.
Wait, is What if nonfiction?
I guess it would go in the boba fett category. (Only real fans get the joke)
@@rocketman2tm technically yes
A Randall Munroe channel with mini videos of absurd questions? It is not even my birthday! Never read the comics, but loved his books.
Finished book 1 a while back. Started book 2 yesterday ! What an absolute treat
Is this the first comment?
@@BFAYW yes
wow you're very easily pleased aren't you, excited like a wee puppy
This is easily the best video on the channel to date.
Awesome video! Anyone interested in the satellites mentioned at the end should check out the “secret” KH-11. They used to be launched on the shuttle too. There’s a few pictures out there believed to have came from them.
Many of the early high-resolution satellite images have been declassified and released to the public. I am not sure if the KH-11 images have been released yet.
trump showed one when he was president because he doesn't care about secrets.@@ericfielding2540
You’re trying to over generalize something I was already fairly nuanced with. You are correct, sure, just as long as we’re stressing declassified and not the released to the public part. Anyone can just look into believed KH-11 photos. A good place to start is USA-224, maybe Samuel Loring Morison, and decide for yourself from there what you choose to believe. I don’t know why you needed to comment that.
The 45th President happened to have tweeted it out relatively early in recently. (A photo of a failed Iranian space launch)
So now we know.
The Hubble telescope is literally a keyhole spy satellite that’s been downgraded.
I'm so glad you did the sound effects of the desk whizzing past Hubble, that was amazing! Your books are awesome and I just got two new people excited about them!
Thank you, Randall! I still haven't managed fo get through all of Thing Explainer to move onto What If? Vol. 1 due to life circumstances, so having some of them as videos is a big help. I was a huge fan of them on the main site and still really want to get the books!
2:26 this is where the alt text of the image would suggest some unit like second (of angle) per second (of time).
man, I was like 14 when I got the first What if book for Christmas, and now 9 years later im getting nostalgia bumps on TH-cam. xkcd was my childhood...
so glad an xkcd channel popped up now, here from minute physics ❤
It's nice to hear Randall's actual voice on TH-cam, I was always hoping for animated videos of "what if" on TH-cam.
I've been a huge fan of "What if?" ever since it launched so many years ago, and I was sad when it was put on hiatus. I'm hoping this TH-cam channel pans out!
With the state of the world these days, seeing xkcd making videos on TH-cam seems like the best news I've heard in ages.
honestly this is exactly how i imagined you'd sound like
Thanks Randall et al! What a fantastic addition to youtube this channel will be
There's a fun bit in the book "The Cuckoo's Egg" by Cliff Stoll, where he's chatting with a CIA agent, and the agent asks him to estimate how good the Hubble's resolution would be if it were pointed at the Earth. Based purely on the wavelength of visible light, Cliff does a bit of napkin math and gets an answer pretty close to the one in this video: good enough to see a person, but not good enough to make out their face. The CIA agent just smiles knowingly.
This is the best thing to happen to youtube, been reading what if again, its nice to have the fun visuals with a narration. Great work mr Munroe!
I'm very happy to have been alerted to the existence of this channel with only its second video published! I'm looking forward to more educational and entertaining content!
XKCD is phenomenal! I got the book years ago, and it was one of my nicest reads. Glad to see it in youtube content form!
I've read every comic, every what if? entry in both books and the blog, every entry in how to, and most of Thing Explainer. I'm excited to see if there's going to be original questions answered on this one or maybe a 163rd blog entry!
These videos are my new favorite thing.
Likely, you could clear up that picture with the right priors. I have seen some incredible results with much worse images using L1 regularization strategies. Dr. John Murray Bruce’s at my university (USF) does what is called computational periscopy, which uses diffuse reflections off of a wall to reconstruct images from a monitor. It’s incredible. A Nature paper too.
Happy to see you come to TH-cam, Randall! This is exciting! I’ve been following XKCD since year 1 or so.
I have been reading your books, and what if? has been my favorite book of all time.
Great first video! Can’t wait for more scientifically accurate absurdity!
They even did it before Hubble was launched. They hinted at NASA, that they should enlarge the lens size, since they know for reasons, that there is a manufacturer, who can produce them and has the exact tools for it.
But I don't think earth facing satellites rotate as a whole, as suggested in the video. You could simply move the sensor or some optics, with much greater speed, effort and less energy.
Earth observation satellites do rotate to remain in the same position relative to the surface of the earth (cameras mostly facing down for electro-optical sensors). However, they use their motion relative to the ground to take a complete image because they have linear CCD sensors, while Hubble has a two dimensional CCD array to create images which is why it needs to remain as still as possible relative to its imaging target.
@@gcrilouxah, so they’re one of those rolling tabletop scanners (that always got misaligned with the receipt halfway down) ;)
@@kaitlyn__L except here the whole scanner (aka the satellite) is moving over the scanned landscape. No moving part in push broom scanners. Older Landsat satellites had moving parts (whisk broom scanners) that were more prone to failures.
There are also earth-observation satellites with full 2D CCD imagers - I'd actually imagine those are almost more common these days. I work with one such satellite, and we do indeed roll the entire cubesat to track the earth from ~500km up. I'd be tempted to say those are more common these days than push broom or whisk broom, at least for new launches.
The biggest challenge actually seems to be stabilising the satellite on that slew track, having whipped it around from a different target, so the motion is entirely smooth. Watching the raw frames as a video, you sometimes feel a little bit sea-sick.
@@danielevans1680 not sure about cubesats, as there are so many it's hard to keep track, but all the big birds designed for electro optical earth observation are push broom scanners. Even the slew of Chinese ones launched in the last decade or so, for which much less info is available, seem to use that technology for now.
More generally, for a satellite in an orbit suited to its observation objectives, I don't quite see the benefit of a sensor array vs. a CCD line. The only one would be the need for higher stability during the entirety of the capture window which for big satellites is a more manageable problem than for small ones. Line sensors simplify the optics tremendously particularly for multispectral sensors.
I wonder if this guy will ever write a book. He could call something like "What If." I'll bet that book would be both funny and informative.
Aerospace engineer here: Sorry but Hubble doesn't use gyroscopes for its orientation it uses reaction wheels and yes there's a significant difference.
In my final year when we had to do 2 high level aerospace options one of mine was spacecraft dynamics. Most of my class took finite element methods and orbital mechanics. 4 or 5 of us (out of 40) took space craft dynamics instead of orbital and regretted it about 5 minutes into the first lecture when we realised how hard the maths was. While orbital mechanics (which isn't much easier) is about orbits and moving between them space craft dynamics is about orientating and pointing free bodies in space which sounds easy but gets into some nightmare maths. Because there's nothing to push back against when you move an antenna or point a camera the rest of the space craft moves in the opposite direction about the center of gravity.
Its not so bad on things like the Voyager probes because of how they built them, but for things like Hubble and the ISS its gets into some weird math because things like gyros and reaction wheels cause things to rotate in odd ways because of precession.
I did that class in 1987 during the time of Ronald Regan's Star Wars program. There were around 8-9 postgrads doing the higher level version of the class where they had to do a term paper as well. They were all sponsored by DARPA and a couple of them did some real interesting things the like of which very few people are aware of.
Simply thing. let me say that making things like Hubble and James Webb work requires some extraordinary high level math skills. I still have nightmares from that class it was so hard.
I worked on a satellite and was on the team designing our own reaction wheels. It would save us a lot of money if we were able to build our own instead of purchasing it from commercial means.
Just the act of balancing those god-forsaken wheels gives me a headache.
This is the first video of yours that I've watched and it will NOT be the last. Very well done, thank you.
I don’t know why I’ve never looked for a "What If?" channel - I love the books - but I’m now a subscriber here! This video is very cool, as I was a professional photographer for about 20 years and I know all about shutter speed vs movement vs resolution. Studying photojournalism in college, we had to learn how to track objects while dragging the shutter in low-light situations in order to get a relatively non-blurred photo of a moving object. I spent hours on the fourth floor of the building where I worked, hanging out a window after sunset and trying to get good photos of passing cars on the street almost directly below. It’s very, very hard to do, even when you’re holding the camera. I can imagine the difficulty in trying to do that remotely on a telescope with limited speed for movement…
It looks like this "What If?" channel was only created recently - this video is the first one that's been uploaded here (although judging from the related videos it looks like XKCD has sometimes guess starred on minutephysics in the past).
@@gordontaylor2815 I see that now! The TH-cam algorithm obviously worked well in this case, suggesting a channel that I would definitely love right when that channel first started. Although I have to admit that I’m a little sad that they don’t have dozens or hundreds of older videos that I can binge-watch… That’s always the best part of finding something new here. Oh well, at least I’m subscribed so I won’t miss anything.
being a photographer for 20 years, i've been one for 45 there was no reason for you to mention how long or that you were allegedly a pro, anyone reading a book on beginner photography would understand the shutter speed motion resolution after about half an hour of reading
Shows what you all know. The desk is moving at a speed so fast, Hubble can't keep up and we're lead to believe that the telescope is what's moving faster.
Joking aside, this was a nice video.
You made a mistake: the desk would not be Gaussian, but radially blurred.
Discovering that XKCD have its own youtube channel is a historical landmark for me
Those "Hubbles" that are aimed at earth are called "KH-11"s. There have been many of those. And they can rotate with their orbit of earth, no motion blur problems.
Was going to add this comment myself. The NSA/NRO recently-ish donated a few of their new old stock keyholes in case NASA wants to build a Hubble #2.
Finally we have xkcd in video format!!!!!
At 0:20 you said that Hubble points at the Earth pretty regularly to calibrate its instruments. Then you spent the rest of the video explaining why Hubble can't take clear pictures of the surface of the Earth. What is it calibrating? Its fuzz factor?
Probably a base brightness level. So when it looks at things in the sky it can say "oh, that's 0.00000000000000000071% as bright as Earth!"
Thanks for a video that actually answers the title in 2 minutes instead of 30 minutes. I'm so done with explanations videos. And i'm subscribing instantly to you.
What if we pointed Hubble at the earth?
Would we discover intelligent life?
Damn I was so hyped when I found this channel I ate through all the content in literally 10 minutes
Me and my friends have created a cult where we worship Randall. Don’t ask.
This is the greatest channel ever created.
Your first video is supposed to be bad not amazing
I'm so happy to see you venturing into TH-cam after years of reading your comics - you have a great voice for this!
Prime conspiracy fuel
This is the closest we'll ever get to an XKCD animated series, but anything Randall touches is educational gold, so it's obvious I'll take it.
I'm so glad I found this! I don't know if you're just animating questions you've already gotten on the blog or if you're gonna take new questions, but I've got one for you: what would the the climatic effects of a ring system around Earth? Would the planet still be habitable?
OMG! Welcome to TH-cam, xkcd!
AS AN AVID RANDALL ENJOYER I NEVER KNEW HOW MUCH I NEEDED THIS CHANNEL
Omfg! Is this the legendary XKCD??? AWESOME!!
I saw this and thought, my god, how have I missed this channel and then I realised it’s only 8 days old and the algorithm works godammit
After reading the site since almost the first year and having bought all the books ... now video! Hurrah.
There have been so many situations where I share an XKCD because it applies so well.
Awesome! It's so cool that you are on here as well now! I've been a fan since I was young and can ever stop laughing when I read your answers.
I've been reading xkcd ever since I happened to pick up What If? in my school library when I was 11, and these videos are absolutely awesome! Will definitely be religiously watching every single one :)
Hey that’s my dad’s photo at 2:00 :)
Thank you for the video, I enjoyed it!
Cool, the TH-cam algorithm is actually good ! It recommended me this channel on its first video ! I love xkcd.
I read the title and kept scrolling for another minute until I went "damn it, what would happen?" And scrolled back to watch this.
Best of luck to you. Can't wait to see this channel grow
Well, the KH-11 satellite used by the NSA is rumored to be the Hubble pointed at earth. Incidentally one of the first missions to the Hubble was to replace the mirror - my hunch is a HK-11 mirror was installed in Hubble by mistake.
what if in video form, i never thought i'd see this day
So excited that you're making videos!
I'll follow you anywhere Randall my captain. The Thing Explainer is my kids favourite book, they love when I let them look at it every 6 months.
Ngl, xkcd feels better than the actual what if channel.
Wonderful to have you on youtube so I have a constant reminder to check out your latest work.
I've been missing reading "What If" on the site. I miss the sketches and footnotes, but I really like how well done the video is. Looks like I have a new channel to watch.
Pick up the book, it’s great!
I'm gonna say it again, i didn't expect the book i got 2 years ago was on TH-cam and it's awesome
YES! I have both of the books and love xkcd soooo much
Great to see xkcd on here WOOOOO
Just found this! Nice to hear Randall’s voice after years reading XKCD. Subscribed.
Super excited to see more What Ifs in this new format!