975: Occulting Telescope

Explain xkcd: It's 'cause you're dumb.
Jump to: navigation, search
Occulting Telescope
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.
Title text: 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.


Cueball takes the useful practice of 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 extrasolar planets, might be more easily detected and examined. This refers to a proposed starshade mission, envisioned for space telescopes like the 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 Type II Kardashev civilization and a Dyson sphere.

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

A Type II Kardashev civilization is a theoretical civilization that has advanced to the point where it has harnessed all 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, and the idea of the vastness of space being frightening was revisited in 2596: Galaxies.


[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): He has a point...

comment.png add a comment! ⋅ comment.png add a topic (use sparingly)! ⋅ Icons-mini-action refresh blue.gif refresh comments!


A personal lesson I've learned long ago that I would like to share with Mr. XKCD and others: Don't worry about things you don't have direct control over, try to help people that do have control better understand the challenge they are facing and you will feel great with every accomplishment (similar to remembering to bring that reusable bag of yours to the store). If you don't know anyone with control, but feel you have a lesson to teach about the universe around us, put it in fiction form for future generations to learn from, and we will reward you with riches for it. - e-inspired 15:51, 27 February 2013 (UTC)

Wouldn't the disk covering the star reflect sunlight so the observer would end up with an EVEN BIGGER SPOT in the sky where the star used to be? (talk) (please sign your comments with ~~~~)

I assume you're talking about light from our Sun and not light from the observed star. Of course the disc would be made of dark non-reflecting material, the opposite of a mirror. But even if it would be a mirror it reflects only in one direction. Put a (reflecting) coin in your hand far away as possible and aim to every point around you, even when you intent to see the reflection of the Sun by having it just behind you it's not easy to see it. And turn only a tick to the left you see nothing. BTW: Please sign your comments. --Dgbrt (talk) 19:17, 20 September 2018 (UTC)

I don't think that sending all the energy back of a star to ONE planet would be advisable... mostly due to the scale of energy likely destroying said planet(or if not making it uninhabitable(unless they are horribly inefficient)) or (using our system(the solar system(our original solar system(the one with the planet Earth)))) all of the planets in our solar system, although it could be used to increase the amount of energy received by those planets 19:13, 24 September 2018 (UTC) 20:14 , 24 September 2018