Editing 1371: Brightness

{{comic
| number    = 1371
| date      = May 21, 2014
| title     = Brightness
| image     = brightness.png
| titletext = Recently, some exoplanet astronomers have managed to use careful analysis of reflected light to discover Earth during the day.
}}

==Explanation==
Exoplanets are planets outside of our solar system, and exoplanet astronomers are astronomers who attempt to discover and study such planets. One method of discovering exoplanets is detecting fluctuations in a star's brightness over time.  Such fluctuations could be caused by a planet's orbit around the star, partially blocking the light that reaches an observer on Earth.  In the comic, the exoplanet astronomer is trying to observe the sun through the ground at night, observing that it has decreased in brightness compared to daytime (which it has by 100%). She then rightfully concludes that the star is orbited by at least one planet (the Earth), which is of course true.

The title text refers to another method of discovering exoplanets by detecting light reflected off of them from nearby stars.  Observing the light that reflects off of the Earth is in fact how we see everything around us, so one hardly needs to be an exoplanet astronomer to discover the Earth in this way.

This comic shows Megan using a common [http://en.wikipedia.org/wiki/Exoplanet exoplanet] discovery [http://en.wikipedia.org/wiki/Exoplanet#Indirect_methods technique] to discover a planet (Earth) around a nearby star (the Sun). When a planet passes between an observing astronomer and a star the planet will block some of the light coming from that star causing it to appear dimmer for some amount of time. When the Earth does this, we call it [http://en.wikipedia.org/wiki/Night Night]

The title text alludes to using more complicated techniques to look observe light reflected off of small, dark planets like the Earth. For example, detecting [http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Polarimetry polarized light] reflected from the planet's atmosphere. Since these require light from the star to reflect off of the planet, it's easier for us to image the Earth directly during daylight hours.

More details at: http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets

==Transcript==
:[Megan is standing on a black (night-time) background, staring at the ground.]
:Megan: Based on this decrease in the star's brightness, I believe it is orbited by at least one planet.

:Exoplanet Astronomers At Night

{{comic discussion}}
@@ Line 8: / Line 8: @@
 ==Explanation==
-{{w|Exoplanets}} are planets outside of our solar system, and exoplanet astronomers are astronomers who attempt to discover and study such planets.
+Exoplanets are planets outside of our solar system, and exoplanet astronomers are astronomers who attempt to discover and study such planets. One method of discovering exoplanets is detecting fluctuations in a star's brightness over time.  Such fluctuations could be caused by a planet's orbit around the star, partially blocking the light that reaches an observer on Earth.  In the comic, the exoplanet astronomer is trying to observe the sun through the ground at night, observing that it has decreased in brightness compared to daytime (which it has by 100%). She then rightfully concludes that the star is orbited by at least one planet (the Earth), which is of course true.
-[[Megan]] is using a common exoplanet {{w|Exoplanet#Indirect_methods|discovery technique}} to discover a planet around a nearby star. When a planet passes between an observing astronomer and a star, the planet will block some tiny part of the light coming from that star, causing it to appear dimmer for some amount of time. The {{w|Kepler (spacecraft)|Kepler telescope}} used this technique to find evidence for exoplanets.
+The title text refers to another method of discovering exoplanets by detecting light reflected off of them from nearby stars.  Observing the light that reflects off of the Earth is in fact how we see everything around us, so one hardly needs to be an exoplanet astronomer to discover the Earth in this way.
-But here Megan is standing on the surface of the Earth at night, looking at the ground, and therefore presumably looking in the direction of the sun. By observing that it is completely occluded at night, she correctly concludes that the Sun is orbited by at least one planet: the Earth. This is obviously an absurd usage of that method. Reasons include the fact that exoplanets are not big enough to block out all of their stars' light when seen from Earth,{{Citation needed}} making what Megan says a massive understatement, and that the period of the brightness oscillations would correspond to the length of a day, not a year as it would for exoplanets.
+This comic shows Megan using a common [http://en.wikipedia.org/wiki/Exoplanet exoplanet] discovery [http://en.wikipedia.org/wiki/Exoplanet#Indirect_methods technique] to discover a planet (Earth) around a nearby star (the Sun). When a planet passes between an observing astronomer and a star the planet will block some of the light coming from that star causing it to appear dimmer for some amount of time. When the Earth does this, we call it [http://en.wikipedia.org/wiki/Night Night]
-The title text alludes to using more complicated techniques to observe light reflected by small planets like the Earth, for example by detecting {{w|Methods of detecting exoplanets#Polarimetry|polarized light}} reflected from the planet's atmosphere. In some sense, observing the light that reflects off of the Earth during the day is in fact how we see everything around us. It also implies that astronomers, who because of their career choice are more likely to work at night, might be completely unaware of Earth's existence in the daytime and thus surprised to "discover" it from their nighttime work.
+The title text alludes to using more complicated techniques to look observe light reflected off of small, dark planets like the Earth. For example, detecting [http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Polarimetry polarized light] reflected from the planet's atmosphere. Since these require light from the star to reflect off of the planet, it's easier for us to image the Earth directly during daylight hours.
+More details at: http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets
 ==Transcript==
-:[This panel is white on black, instead of black on white. Megan is standing staring at the ground.]
+:[Megan is standing on a black (night-time) background, staring at the ground.]
 :Megan: Based on this decrease in the star's brightness, I believe it is orbited by at least one planet.
-:[Caption below the panel:]
+:Exoplanet Astronomers At Night
-:Exoplanet astronomers at night
-==Trivia==
-*The title text may also be a reference to [[1231: Habitable Zone]] where an astronomer is messed up by someone who puts a mirror in front of the telescope.
-*More details at: {{w|Methods of detecting exoplanets}}.
 {{comic discussion}}
-[[Category:Comics with inverted brightness]]
-[[Category:Comics featuring Megan]]
-[[Category:Astronomy]]
-[[Category:Exoplanets]]