Some scientists believe that diamonds are not exclusive to earth. Diamonds may exist on Neptune and Uranus, where the high temperatures and pressure create a perfect environment to convert methane in their lower atmosphere into diamonds. The diamonds would then fall toward the planets’ centers.
”The prospect of Neptune, and perhaps Uranus, creating diamonds sounds entirely plausible,” says Professor Fred Watson, the head astronomer of the Anglo-Australian Observatory at Coonabarabran. “The pressures and temperatures in the lower atmosphere of a gas giant are very high indeed.”
Neptune’s upper layer temperatures could drop to minus 220 degrees and below. The planet’s core could heat up to 7000 degrees.
Both Neptune and Uranus are made of similar gases and ices. Both planets also contain more methane than other planets do. Some believe that the blue color of the two planets could be attributed to the diamonds, while some believe that the diamonds have nothing to do with the color difference.
“I think attributing the color difference between Uranus and Neptune to diamonds might be drawing a very long bow,” Watson said. “The difference is due to some complex variation in their atmospheres caused by differing element abundances, rather than black body thermodynamics.”
Professor Mike Bessell of the Australian National University’s Research School of Astronomy and Astrophysics agrees. “The color of Neptune and Uranus is to do with the absorption and reflection of sunlight in the gases of their atmospheres. It has nothing to do with whether they give off more heat than they receive from the sun.”
“Some scientists have claimed that diamonds may form inside both Uranus and Neptune, but I do not believe that is true since the methane is confined to the surface where the pressures are much less,” says Monash University astrophysicist Dr. Andrew Prentice. “I think that is wishful thinking. In any event, the ‘falling diamonds’ would hardly have any influence whatever on the internal heat budget of Neptune or Uranus.”
Prentice believes that the difference in color can be attributed to the fact that Neptune has twice the concentration of methane as Uranus does. “Methane is a great absorber of red light. The light reflected from Neptune thus appears bluer since it is missing the red component.”