Diamonds in the sky: Uranus isn’t the only planet in the universe raining treasures – Salon
This science is bizarre enough on its own, and the suggestion that Uranus might rain diamonds makes for great headlines. Yet given that there are many similar ice giants scattered all over the galaxy, this suggests that diamond-raining is quite common in the universe, even though it’s unheard of on Earth. Indeed, because of our Earthly perspectives, many things that are quite normal in the universe seem anomalous, particularly when mined for their sensational aspects in a brief news dispatch.
What is normal in the universe and strange on Earth? Take helium, for example: it’s almost nonexistent on Earth, as it is so light it escapes our atmosphere easily — and yet 25 percent of the elemental matter in the universe is helium. The opposite is true, too: There are many anomalous things about Earth compared to the rest of the solar system. Life, for one, but also plate tectonics and our unusually large moon for a rocky planet. Perhaps two planets in the solar system have diamond rain, but only one has humans. Which is weirder?
Diamonds floating in ice giants make for good headlines because diamonds are something humans tend to treasure. And yet there are many pretty weird, seemingly valuable (to us) things floating around in space. Still, many news dispatches about strange planetary conditions focus on those worlds individually, as though they exist in a vacuum — which they do, technically. But that ignores how these kinds of strange discoveries tie into a larger story of how solar systems and galaxies evolve over time. I’ve compiled some of the strangest astronomy discoveries that involve the rare things that we treasure here on Earth, while telling the story of how said oddities come to be.
The diamond planet
Gem precipitation sounds nice, but what about a world made of diamond? 55 Cancri E is a literal gem of a planet. The planet orbits a neutron star — a collapsed sun with so much mass that its protons and electrons merged into neutrons. Neutron stars are kind of like giant atoms, with their neutrons bound in similar close quarters as the particles in atomic nuclei. Hence, neutron stars are so dense that a teaspoon of neutron star material would weigh 10 million tons, the equivalent mass of 130 million humans or so.
55 Cancri E’s neutron star, known as PSR J1719-1438, is only 12 miles in diameter, yet possesses a mass 140 percent of our sun’s. Neutron stars’ surfaces are generally hundreds of thousands of degrees Celsius, hot enough to radiate X-rays. They are not pleasant stars to orbit.
The peculiar planet orbiting PSR J1719-1438 has a mantle that may be mostly diamond. That’s because the planet’s composition contains high levels of carbons, which, at the pressures and temperatures that it is exposed to, would suggest that its carbon has crystallized and compacted at the appropriate temperatures to render it into diamond.
But there are two epilogues to 55 Cancri E’s story. First, some later observations called into question whether the diamond hypothesis theory was correct, as one study suggested the star had more oxygen than accounted for — which does not turn into diamond, or anything like it, under high pressures.