Editing 2828: Exoplanet Observation

{{comic
| number    = 2828
| date      = September 13, 2023
| title     = Exoplanet Observation
| image     = exoplanet_observation_2x.png
| imagesize = 295x272px
| noexpand  = true
| titletext = NASA prefers to say that their rovers are 'looking for signs of past life on Mars' and not 'ghost hunting.'
}}

==Explanation==

In this comic, Cueball states that observations of light that passed through the atmosphere of a distant planet indicate that there are ghosts on that planet, because some of the light was absorbed in a way that is unique to ghosts. This is analogous to how gases or suspended particles absorb certain wavelengths, allowing scientists to identify properties of distant objects using telescopes. The pun is that in this comic "spectral analysis" refers to both {{w|Spectroscopy|the analysis of the light spectrum}} and the analysis of specters (ghosts).

{{w|Spectroscopy|Spectral analysis}} is the study of the {{w|electromagnetic spectrum}} that results from the interaction between electromagnetic radiation (which includes visible light) and matter. In the study of {{w|exoplanet}}s and other distant objects in space, it refers to using the intensities of different frequencies of light (and other electromagnetic radiation) from stars which they occlude to infer data about their chemical composition. This is used to detect certain gases in the atmosphere, such as {{w|Oxygen#Allotropes|free oxygen}}, which might suggest generation by and for Earth-like life. On the day before this comic was published, {{w|NASA}} announced that spectral analysis of the exoplanet {{w|K2-18b}} showed abundance of {{w|methane}} and {{w|carbon dioxide}}, and shortage of {{w|ammonia}}, which are chemical footprints that support the hypothesis that it may have a life-supporting water ocean; and there was possible detection of {{w|dimethyl sulfide}}, which on {{w|Earth}} is only produced by life.[https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b] If confirmed, these would be very interesting findings, although it may turn out to be less remarkable on closer study (as {{w|Life on Venus#Phosphine|with Venus}} for example).

"Spectral" also has another meaning: relating to specters (ghosts). Hence "exoplanet spectral analysis" could be interpreted as the analysis of ghosts on planets outside the solar system instead of the analysis of the elements that might be present on the planet. "Specter" and "spectrum" have the same etymological root, deriving from Latin "spectrum" meaning "appearance", with a specter specifically referring to a visible shadow or ghost.

The title text refers to the search for past life on Mars. Just like the comic, it also humorously conflates the practice of searching for signs of past life such as specific molecules or fossils (which NASA does actively search for), versus the disreputable practice of searching for ghosts, with this conflation framing both as an equally scientific indication of past life. In a very loose sense, real signs such as gases or fossils could be considered "ghosts" of past life.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:: [Cueball is holding a stick and pointing at a slide with two ghosts and a planet]
:: Cueball: When the planet passed in front of its host star, some of the light was absorbed by ghosts, indicating that the planet is likely haunted.

:: [Caption below the panel]
:: Exoplanet Spectral Analysis

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Astronomy]]
[[Category:Exoplanets]]
[[Category:Aliens]]
[[Category:Puns]]