N O T E S
1. “Planetary science” traditionally refers to the study of planets within our solar
system. This discipline formed before exoplanets were discovered, and it is increas-
ingly common for those trained in studying solar system planets to apply their meth-
ods to exoplanets.
2. Icarus was given a pair of wings made of feather and wax by his father, Dae-
dalus. Though Daedalus warned Icarus not to fly too high, he was swept up in the
joy of soaring through the sky and eventually flew too high and too close to the Sun.
The wax that bound the wings together melted, and Icarus met a watery death in the
3. For more on the history of planetary science in America, see Doel (1996),
Chamberlain and Cruikshank (1999), and Launius (2013).
4. Statistics generated using the Web of Science database, searching across Astro-
physical Journal, Astrophysical Journal Letters, and Astronomical Journal. The number of
articles reported is based on a search for “exoplanet” and “extrasolar planet” in topic.
5. Though, as I put forth in the previous section, “planet” is both cultural and
6. At the same time that Latour invites us to think of Earth as an actor, he also
suggests that we need not think beyond the Earth. See Olson and Messeri (2015) for a
critique of this position.
7. For more on “the planetary,” see Morgan (1984), Pratt (1992), Friedman (2010),
Masco (2010), Jazeel (2011).