Inhabited exomoon by artist Dan Durda

Imagine a terrestrial-type exomoon orbiting a Jovian-type planet within the habitable zone of a star. This exomoon has a thick, cloudy atmosphere that completely fills the sky, except for breaks in the clouds that occur about once every 400 years. When a break does occur, it is short-lived and reveals only a small area of the sky. Describe the civilization on this exomoon that has rarely seen beyond the clouds, including its culture and value system. Thought-experiment: Develop a short story using this theme and the accompanying data on the next slide

F5 star Mass ~2.8 x kg, luminosity ~ 3.0 x watts, and radius ~ 1.4 x 10 9 meters. Jovian planet Mass ~1.6 x kg, density ~1.2 grams/cm 3, radius ~ 6.9 x 10 7 meters, semi-major axis of planet’s orbit ~ 2.5 x meters, and orbital eccentricity ~ Terrestrial-type exomoon Mass ~ 8.4 x kg, albedo ~ 0.67, semi-major axis of exomoon’s orbit ~ 5.8 x 10 9 meters, orbital eccentricity ~ 0.00, radius = 7.27 x 10 6 meters, and rigidity of exomoon ~ 3 x Newtons/meter 2. The exomoon has land and oceans. F5 star Mass ~2.8 x kg, luminosity ~ 3.0 x watts, and radius ~ 1.4 x 10 9 meters. Jovian planet Mass ~1.6 x kg, density ~1.2 grams/cm 3, radius ~ 6.9 x 10 7 meters, semi-major axis of planet’s orbit ~ 2.5 x meters, and orbital eccentricity ~ Terrestrial-type exomoon Mass ~ 8.4 x kg, albedo ~ 0.67, semi-major axis of exomoon’s orbit ~ 5.8 x 10 9 meters, orbital eccentricity ~ 0.00, radius = 7.27 x 10 6 meters, and rigidity of exomoon ~ 3 x Newtons/meter 2. The exomoon has land and oceans.

Sagan C., et al. (1993) A search for life on Earth from the Galileo spacecraft. Nature, 365, “In its December 1990 fly-by of Earth, the Galileo spacecraft found evidence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium; together, these are strongly suggestive of life on Earth.”

Sagan C., et al. (1993) A search for life on Earth from the Galileo spacecraft. Nature, 365,

Inhabited exomoon by artist Dan Durda

Kaltenegger L., et al. (2010) Deciphering spectral fingerprints of habitable exoplanets. Astrobiology, 10(1),

Earth’s spectral signatures Visible Near infrared

Kaltenegger L., et al. (2010) Deciphering spectral fingerprints of habitable exoplanets. Astrobiology, 10(1), Earth’s infrared spectrum (black line) at 6-20 µm Infrared

Kaltenegger L., et al. (2010) Deciphering spectral fingerprints of habitable exoplanets. Astrobiology, 10(1), Comparisons of thermal infrared emissions as an indicator of oceans and/or thick atmosphere (right) during 1 orbital phase (left)

Kaltenegger L., et al. (2010) Deciphering spectral fingerprints of habitable exoplanets. Astrobiology, 10(1),

Oxygen cycle on Earth

Changes in the Earth’s atmospheric (O 2 /N 2 ) ratio during

Kaltenegger L., et al. (2010) Deciphering spectral fingerprints of habitable exoplanets. Astrobiology, 10(1), Hypothesized changes in Earth’s visible and infrared spectra through its geological history

Kaltenegger L. (2010) Characterizing habitable exomoons. Astrophysical Journal Letters, 712, L125-L130. Contrast ratio of absorption features by an Earth-like atmosphere during transit of an exomoon for M9, M5, and solar-type stars

Kaltenegger L. (2010) Characterizing habitable exomoons. Astrophysical Journal Letters, 712, L125-L130. Parameters associated with transits of Jupiter-sized exoplanets orbiting in the Earth-equivalent habitable zone of M0-M9 stars

Kaltenegger L. (2010) Characterizing habitable exomoons. Astrophysical Journal Letters, 712, L125-L130. Maximum orbital separation of an Earth-like exomoon (in prograde and retrograde orbits) from its Jovian host-planet (in stellar radii) for 1M J and 13M J

Kaltenegger L. (2010) Characterizing habitable exomoons. Astrophysical Journal Letters, 712, L125-L130. “… habitable exomoons around M stars would be tidally locked to their planet, not to their host star, removing the problem of a potential freeze out of the atmosphere on the dark side of an Earth-like exomoon,…”

Kaltenegger L. (2010) Characterizing habitable exomoons. Astrophysical Journal Letters, 712, L125-L130. R H = Hill radius = maximum stable distance of a satellite from its host-planet M p = mass of host-planet M star = mass of star e p = eccentricity of planet’s orbit e Sat = eccentricity of exomoon’s orbit a eR = critical semi-major axis of satellite with retrograde orbit a eP = critical semi-major axis of satellite with prograde orbit R H = Hill radius = maximum stable distance of a satellite from its host-planet M p = mass of host-planet M star = mass of star e p = eccentricity of planet’s orbit e Sat = eccentricity of exomoon’s orbit a eR = critical semi-major axis of satellite with retrograde orbit a eP = critical semi-major axis of satellite with prograde orbit