explain xkcd - User contributions [en]

975: Occulting Telescope

2021-12-24T00:45:21Z

Tlynnec: /* Yes, I'm late to the discussion, but this appears to be such a clear Nightfall reference that I'm amazed its not here already */

{{comic
| number = 975
| date = November 09, 2011
| title = Occulting Telescope
| image = occulting_telescope.png
| titletext = Type II Kardashev civilizations eventually completely enclose their planetary system in a Dyson sphere because space is way too big to look at all the time.
}}

==Explanation==
[[Cueball]] takes the useful practice of {{w|occulting}} stars beyond its intended purpose. Occulting is used in astronomy to block the light from a star under observation so that adjacent dim objects, such as any surrounding {{w|Exoplanet|extrasolar planets}}, might be more easily detected and examined. This refers to a proposed {{w|New Worlds Mission|starshade mission}}, envisioned for space telescopes like the {{w|James Webb Space Telescope}}, in which a large occulter would fly in formation with that telescope.

Instead of blocking the light of a single star for the purposes of observation, Cueball proposes blocking the light from all stars, for the purpose of making him feel comfortable with the night sky. Cueball feels, some might say irrationally, that "there are too many stars", and "it's been freaking me out". This may be a reference to Isaac Asimov's "Nightfall" which explores in depth the psychological implications by which stars make some people feel small and insignificant because they demonstrate just how vast is the universe.

The title text refers to both a {{w|Kardashev scale|Type II Kardashev civilization}} and a {{w|Dyson sphere}}.

A Dyson sphere is a theoretical construction consisting of a network of satellites that orbit and completely surround a star. The purpose to capture and transmit all of the available solar energy back to a planet.

A Type II Kardashev civilization is a theoretical civilization that has advanced to the point where it has harnessed the energy radiated by its own star (for example, the stage of successful construction of a Dyson sphere).

For comparison purposes:
*A Type I Kardashev civilization is one that has harnessed the energy of their entire planet.
*A Type III Kardashev civilization is one that has harnessed the energy of their entire galaxy.
*We are currently less than I.

The title text reveals that Type II Kardashev civilizations construct Dyson spheres not for the purposes of capturing all solar energy, but merely to block the view of all that hideous space. This may allude to Douglas Adam's Hitchhiker's Guide to the Galaxy novel series, where a planet called Krikkit is completely obscured by a dust layer. Upon building a spacecraft to explore what lies behind that dust cover, they decide to destroy all living beings in the rest of the universe. See http://hitchhikers.wikia.com/wiki/Krikkit.

The concept of an occulting space telescope was visited again in [[1730: Starshade]].

==Transcript==
:[Cueball is presenting his new telescope in front of a white board, pointing to the diagram of said telescope with a pointer. He is standing on a raised podium facing a crowd off-panel]
:Cueball: The occulting observatory consists of two parts—the telescope and the discs.

:[A frame-less panel with a black center with white drawings that shows the diagram from the white board in the first panel. It shows a satellite with solar panels above and below the main body which has a front end that looks wider like a telescope. The satellite is labeled with a small arrow pointing at the front end. 11 light waves are indicated as coming towards it from the right, and below these they are labeled. Three of the waves is blocked in the middle by a small vertical line which is also labeled with a small arrow. Above and below the diagram outside the black area Cueball is narrating.]
:Cueball (narrating): When the telescope sees a star, a disc is carefully steered to block its light.
:Label: Telescope
:Label: Light from star
:Label: Disc
:Cueball (narrating): This procedure is repeated until all stars are covered.

:[Back to Cueball on the podium who now looks down on the audience from where a question emanates at the top of the left frame.]
:Person #1 (off screen): Wait, ''all?'' Why?
:Cueball: I'll feel better.

:[Close-up on Cueball. as two different persons talks to him, from the lower left frame.]
:Person #2 (off-screen): I thought the point was to image extrasolar planets.
:Cueball: The point is that there are ''too many stars.''
:Cueball: It's been freaking me out.
:Person #2 (off-screen): What?
:Person #3 (off screen): <small>He has a point...</small>

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Astronomy]]
[[Category:Space]]
[[Category:Exoplanets]]
[[Category:Public speaking]]
[[Category:Telescopes]]

Talk:1730: Starshade

2021-12-24T00:29:11Z

Tlynnec:

I would like to note that in the last frame the microphone booms on the headsets are on the right side, rather than on the left, which would have been more common. [http://ux.stackexchange.com/questions/60749/why-most-of-the-microphones-are-placed-on-the-left-of-headsets-headphones Stackexchange discussion] {{unsigned ip|173.245.48.83}}
:Wauw that is not important here ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:24, 7 September 2016 (UTC)

Does "kickstart" refer to {{w|Kickstarter}}? --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 14:15, 7 September 2016 (UTC)
: Pretty clearly, but it might be good to make that explicit, and point out that either there is no such [https://www.kickstarter.com/signup?context=new_project&then=%2Fprojects%2Fnew%3Futf8%3D%25E2%259C%2593%26project%255Bcategory_id%255D%3D16%26project%255Bname%255D%3DWebb%2BStarshade%26project%255Bcountry%255D%3DUS%26commit%3DSave%2Band%2Bcontinue Kickstarter] project yet, or (less likely) link to the project.
: —[[User:FlashSheridan|FlashSheridan]] ([[User talk:FlashSheridan|talk]]) 14:59, 7 September 2016 (UTC)
::Have mentioned this in the explanation. Not sure it is a reference to that. She does not call is kickstarter... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

May be related to 975: Occulting Telescope (https://xkcd.com/975/).
[[Special:Contributions/108.162.245.120|108.162.245.120]] 17:08, 7 September 2016 (UTC)
:Definitely worth referring too. Thanks and done. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

The reaction in the last panel seems rather extreme. I wonder if perhaps this was a custom starshade resembling the final image at the bottom of this page: https://what-if.xkcd.com/136/ [[Special:Contributions/108.162.216.67|108.162.216.67]]siliconwolf

The James Webb Telescope already has measures to shade the stars!
[http://www.jwst.nasa.gov/nircam.html http://www.jwst.nasa.gov/nircam.html]: "NIRCam is equipped with coronagraphs, instruments that allow astronomers to take pictures of very faint objects around a central bright object, like stellar systems. NIRCam's coronagraphs work by blocking a brighter object's light, making it possible to view the dimmer object nearby - just like shielding the sun from your eyes with an upraised hand can allow you to focus on the view in front of you. With the coronagraphs, astronomers hope to determine the characteristics of planets orbiting nearby stars." - Sebastian --[[Special:Contributions/162.158.83.168|162.158.83.168]] 18:26, 7 September 2016 (UTC)
:From a [https://exoplanets.nasa.gov/exep/about/probe-scale-stdt/Exo-C_InterimReport.pdf NASA report]: "JWST/Near Infrared Camera (NIRCam) coronagraphy should be capable of detecting companions at contrasts of 10−6 at separations beyond 1.5 arcsec, capturing objects like our own Jupiter in 4.5 μm thermal emission if they are orbiting the nearest M stars. The uncertain luminosity evolution of young giant planets clouds the picture somewhat (Marley et al. 2007), but it appears that the some of the more massive planets orbiting nearby (d < 20 pc), young (age < 1 Gyr), low-mass (M < 1.0 Msun) stars could be in view by 2024." - it talks about detecting, not imaging, objects like Jupter. - Sebastian --[[Special:Contributions/162.158.83.168|162.158.83.168]] 18:57, 7 September 2016 (UTC)
::Included in the explanation. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

Perhaps it should be mentioned in the article that the James Webb is a near infrared and middle infrared telescope (+ orange visible light). For good infrared images one needs high mountains or space. Nasa has an article why infrared is good for examining (the spectra of) exoplanets: [http://asd.gsfc.nasa.gov/blueshift/index.php/2013/10/24/maggies-blog-why-infrared-exoplanet-edition/ http://asd.gsfc.nasa.gov/blueshift/index.php/2013/10/24/maggies-blog-why-infrared-exoplanet-edition/] - Sebastian --[[Special:Contributions/162.158.83.168|162.158.83.168]] 18:33, 7 September 2016 (UTC)
:Included in the explanation. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

I made it so it's not incomplete anymore. Also, the comic isn't random, because it's 2016 and it's scheduled to launch in less than two years (because 2016 is almost over). I also added a citation to the Wikipedia article for the James Webb Telescope with links to the "budget issues" revealed in the comic. I hope this clears up a few things. :) -- [[User:JayRulesXKCD|JayRulesXKCD]] ([[User talk:JayRulesXKCD|talk]]) 7:41, 9 September 2016 (EDT)

This comic makes sense in context of 2016 launch date. As of 2021, JWST still has not launched. See [https://www.explainxkcd.com/wiki/index.php/2014:_JWST_Delays[https://www.explainxkcd.com/wiki/index.php/2014:_JWST_Delays]] and [https://www.explainxkcd.com/wiki/index.php/2550:_Webb[https://www.explainxkcd.com/wiki/index.php/2550:_Webb]] for further Cueball commentary on the subject. --[[User:Tlynnec|Tlynnec]] ([[User talk:Tlynnec|talk]]) 00:29, 24 December 2021 (UTC)

"Ponytail may be referring to the crowdfunding site Kickstarter, but it does not seem like there is any project (yet) for a Starshade for Webb (or for New Worlds Mission, see title text explanation)." I am absolutely flabbergasted that there is even a hint of a doubt expressed here, in the article, or in this discussion. This is 100%, without a doubt, unequivocably, unquestionably a reference to Kickstarter. "Kickstarter" and "Kickstart" are words that simply do not exist in the English language outside of the world of Kickstarter. The closest is where they clearly got their name, the kick starting of a motorcycle (which to the best of my knowledge is two words, or at least hyphenated). With the rising popularity of Kickstarter, people have coined the verb "Kickstart", meaning to start a Kickstarter campaign to fund the verb's object, which is how Ponytail is using it here. As for there not being such a Kickstarter project, OF COURSE THERE ISN'T! This is a comic! It's a joke! And Ponytail isn't a real person who can start one! Non-existant concepts have appeared throughout the history of XKCD! For example, the comic where Black Hat breaks into an Internet Troll's house to tell him off for being disgusting to nerd girls on the internet, he's followed by a girl with a weapon he names an EMP cannon. I seriously doubt such a portable weapon exists, yet there it is in the comic. Or the Rule 34 comic, where they started a WetRiffs website. Nobody started that, it didn't exist until Randall did afterwards for giggles because of his comic.

Doubt on this point is inappropriate, dilutes this site's credibility, and it should be removed. - NiceGuy1 [[Special:Contributions/108.162.218.172|108.162.218.172]] 06:01, 11 September 2016 (UTC) I finally signed up! This comment is mine. (Wow, I'm surprised that idiotic line is still in the explanation, that nobody ever fixed it. I'm all about caution in making statements, but this is ridiculous) [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 10:39, 9 June 2017 (UTC)

Talk:1730: Starshade

2021-12-24T00:28:15Z

Tlynnec:

I would like to note that in the last frame the microphone booms on the headsets are on the right side, rather than on the left, which would have been more common. [http://ux.stackexchange.com/questions/60749/why-most-of-the-microphones-are-placed-on-the-left-of-headsets-headphones Stackexchange discussion] {{unsigned ip|173.245.48.83}}
:Wauw that is not important here ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:24, 7 September 2016 (UTC)

Does "kickstart" refer to {{w|Kickstarter}}? --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 14:15, 7 September 2016 (UTC)
: Pretty clearly, but it might be good to make that explicit, and point out that either there is no such [https://www.kickstarter.com/signup?context=new_project&then=%2Fprojects%2Fnew%3Futf8%3D%25E2%259C%2593%26project%255Bcategory_id%255D%3D16%26project%255Bname%255D%3DWebb%2BStarshade%26project%255Bcountry%255D%3DUS%26commit%3DSave%2Band%2Bcontinue Kickstarter] project yet, or (less likely) link to the project.
: —[[User:FlashSheridan|FlashSheridan]] ([[User talk:FlashSheridan|talk]]) 14:59, 7 September 2016 (UTC)
::Have mentioned this in the explanation. Not sure it is a reference to that. She does not call is kickstarter... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

May be related to 975: Occulting Telescope (https://xkcd.com/975/).
[[Special:Contributions/108.162.245.120|108.162.245.120]] 17:08, 7 September 2016 (UTC)
:Definitely worth referring too. Thanks and done. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

The reaction in the last panel seems rather extreme. I wonder if perhaps this was a custom starshade resembling the final image at the bottom of this page: https://what-if.xkcd.com/136/ [[Special:Contributions/108.162.216.67|108.162.216.67]]siliconwolf

The James Webb Telescope already has measures to shade the stars!
[http://www.jwst.nasa.gov/nircam.html http://www.jwst.nasa.gov/nircam.html]: "NIRCam is equipped with coronagraphs, instruments that allow astronomers to take pictures of very faint objects around a central bright object, like stellar systems. NIRCam's coronagraphs work by blocking a brighter object's light, making it possible to view the dimmer object nearby - just like shielding the sun from your eyes with an upraised hand can allow you to focus on the view in front of you. With the coronagraphs, astronomers hope to determine the characteristics of planets orbiting nearby stars." - Sebastian --[[Special:Contributions/162.158.83.168|162.158.83.168]] 18:26, 7 September 2016 (UTC)
:From a [https://exoplanets.nasa.gov/exep/about/probe-scale-stdt/Exo-C_InterimReport.pdf NASA report]: "JWST/Near Infrared Camera (NIRCam) coronagraphy should be capable of detecting companions at contrasts of 10−6 at separations beyond 1.5 arcsec, capturing objects like our own Jupiter in 4.5 μm thermal emission if they are orbiting the nearest M stars. The uncertain luminosity evolution of young giant planets clouds the picture somewhat (Marley et al. 2007), but it appears that the some of the more massive planets orbiting nearby (d < 20 pc), young (age < 1 Gyr), low-mass (M < 1.0 Msun) stars could be in view by 2024." - it talks about detecting, not imaging, objects like Jupter. - Sebastian --[[Special:Contributions/162.158.83.168|162.158.83.168]] 18:57, 7 September 2016 (UTC)
::Included in the explanation. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

Perhaps it should be mentioned in the article that the James Webb is a near infrared and middle infrared telescope (+ orange visible light). For good infrared images one needs high mountains or space. Nasa has an article why infrared is good for examining (the spectra of) exoplanets: [http://asd.gsfc.nasa.gov/blueshift/index.php/2013/10/24/maggies-blog-why-infrared-exoplanet-edition/ http://asd.gsfc.nasa.gov/blueshift/index.php/2013/10/24/maggies-blog-why-infrared-exoplanet-edition/] - Sebastian --[[Special:Contributions/162.158.83.168|162.158.83.168]] 18:33, 7 September 2016 (UTC)
:Included in the explanation. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 19:53, 7 September 2016 (UTC)

I made it so it's not incomplete anymore. Also, the comic isn't random, because it's 2016 and it's scheduled to launch in less than two years (because 2016 is almost over). I also added a citation to the Wikipedia article for the James Webb Telescope with links to the "budget issues" revealed in the comic. I hope this clears up a few things. :) -- [[User:JayRulesXKCD|JayRulesXKCD]] ([[User talk:JayRulesXKCD|talk]]) 7:41, 9 September 2016 (EDT)

This comic makes sense in context of 2016 launch date. As of 2021, JWST still has not launched. See [https://www.explainxkcd.com/wiki/index.php/2014:_JWST_Delays[https://www.explainxkcd.com/wiki/index.php/2014:_JWST_Delays]] and [https://www.explainxkcd.com/wiki/index.php/2550:_Webb[https://www.explainxkcd.com/wiki/index.php/2550:_Webb]] for further Cueball commentary on the subject.

"Ponytail may be referring to the crowdfunding site Kickstarter, but it does not seem like there is any project (yet) for a Starshade for Webb (or for New Worlds Mission, see title text explanation)." I am absolutely flabbergasted that there is even a hint of a doubt expressed here, in the article, or in this discussion. This is 100%, without a doubt, unequivocably, unquestionably a reference to Kickstarter. "Kickstarter" and "Kickstart" are words that simply do not exist in the English language outside of the world of Kickstarter. The closest is where they clearly got their name, the kick starting of a motorcycle (which to the best of my knowledge is two words, or at least hyphenated). With the rising popularity of Kickstarter, people have coined the verb "Kickstart", meaning to start a Kickstarter campaign to fund the verb's object, which is how Ponytail is using it here. As for there not being such a Kickstarter project, OF COURSE THERE ISN'T! This is a comic! It's a joke! And Ponytail isn't a real person who can start one! Non-existant concepts have appeared throughout the history of XKCD! For example, the comic where Black Hat breaks into an Internet Troll's house to tell him off for being disgusting to nerd girls on the internet, he's followed by a girl with a weapon he names an EMP cannon. I seriously doubt such a portable weapon exists, yet there it is in the comic. Or the Rule 34 comic, where they started a WetRiffs website. Nobody started that, it didn't exist until Randall did afterwards for giggles because of his comic.

Doubt on this point is inappropriate, dilutes this site's credibility, and it should be removed. - NiceGuy1 [[Special:Contributions/108.162.218.172|108.162.218.172]] 06:01, 11 September 2016 (UTC) I finally signed up! This comment is mine. (Wow, I'm surprised that idiotic line is still in the explanation, that nobody ever fixed it. I'm all about caution in making statements, but this is ridiculous) [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 10:39, 9 June 2017 (UTC)