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Diamond Rain on Neptune and Uranus
Diamonds, the strongest bulk material known to mankind, are coveted on Earth although they may not be very rare elsewhere in the solar system. Two of our celestial neighbors, Neptune and Uranus, may contain more bling than all the jewelry stores on Earth combined. It is theorized that diamonds fall like raindrops from the atmospheres of both planets, and may perhaps even pile up miles thick towards the planetary cores (Tyson 2000, Eggert et el 2010 & Sanders 1999).
Uranus and Neptune have similar geological compositions, each being made up of a three layer structure. Both planets contain a hydrogen-helium atmosphere, a water-methane-ammonia ice mantle, and a rocky or metallic (maybe diamond?) core. It is also theorized that both planets have churning methane oceans several thousand degrees Kelvin in temperature (Hirai et el 2009).
The scientist Marvin Ross first suggested that diamond formation could occur on Neptune and Uranus in 1981. Large amounts of methane is found on both planets (methane being an important constituent in the planets’ overall chemical constitutions). Under extreme temperature and pressure this methane can be converted into crystalline diamond form as well as other complex organic matter compounds (Kerr 1999). Shock compression studies performed by Hirai et el recorded the transition of methane into diamond at 19 GPa and between 2200 and 3000 degrees Kelvin. The conversion of methane into diamond is primarily dependent on temperature, but the ambient pressure of the atmosphere is also important to consider (2009).
In addition to being awesome, diamond rain could also account for the excess heat radiated from Neptune (in addition to heat from the sun). Energy released by diamonds falling and settling towards the planet’s core is thought to boost the magnetic field of Neptune, thus increasing the heat radiated from the planet (Sanders 1999 and Kerr 1999). Although diamond rain has not been a proven phenomenon, it is pretty amazing to imagine. Given the experimental evidence, it is also not an unlikely occurrence.
Thanks for Reading! Works Consulted:
Eggert, J., D. Hicks, P. Celliers, D. Bradley, R. McWilliams, R. Jeanloz, J. Miller, T. Boehly and G. Collins. (2010). Melting Temperature of Diamond at Ultrahigh Pressure . Nature Physics. 6: 40-43.
Hirai, H., K. Konagia, T. Kawamura, Y. Yamamoto and T. Yagi. (2009). Polymerization of Diamond Formation from Melting Methane and their Implications in Ice Layer of Giant Planets . Physics of the Earth and Planetary Interiors. 174: 242-246.
Kerr, R. (1999). Neptune May Crush Methane into Diamonds . Science. 286(5437): 25.
Ross, M. (1981). The Ice Layer in Uranus and Neptune- Diamonds in the Sky? Nature 292: 435-436.
Sanders, R. (6 Oct 1999). It’s Raining Diamonds on Neptune and Uranus. The Berkeleyan . Retrieved from http://www.berkeley.edu/news/berkeleyan/1999/1006/diamonds.html.
Tyson, P. (2000). Diamonds in the Sky . Retrieved from http://www.pbs.org/wgbh/nova/diamond/sky.html.