By Dr. Robert Thorson
Optimism. Pointless optimism, even on a cold day in January. That’s what we need to whack our psychic ball out of the rough and reach the green of spring.
I know it sounds stupid, but one tiny bit of planetary trivia has been making me happier than I should be, given the time of year. I learned that on exoplanet CoRoT-7b, the precipitation is not made of water, but probably of quartz and other familiar minerals. Ouch!
This interpretation was reported in last October’s “Astrophysical Journal” by Laura Schaefer and Bruce Fegley Jr., from the planetary chemistry laboratory of Washington University in Saint Louis. From theory, they believe that a planet only 500 light-years from us consists of rock comparable to that of Earth and other terrestrial planets in our solar system. From gravity measurements, they know it’s massive enough to hold an atmosphere.
But of what? From the planet’s estimated surface temperature of about 2,000 degrees Celsius, it’s too hot to have held on to the lighter, more volatile elements that dominate Earth’s atmosphere; for example hydrogen, carbon, nitrogen and sulfur. These would have long been boiled off into space from CoRoT-7b because it lies 23 times closer to its sun than does the planet Mercury in our solar system.
Being curious to know what its atmosphere might be composed of, the authors constructed a mathematical model to fiddle around with the chemistry. Regardless of which type of rock they used as input, the model always yielded the same output. The surface of CoRoT-7b melts, vaporizes and fills the atmosphere with molecular oxygen and silicon monoxide.
If cooled to solid condensation, these molecules spontaneously form silicate tetrahedra, the building blocks of earthly rock. If metal ions are present (they probably are), the result would be minerals such as enstatite, corundum, spinel, wollastonite, and others, constituents of Earth’s continental crust. Rain would resemble red-yellow drops of molten glass.
Solid precipitation, which probably falls near the poles or on the side facing away from the sun, would probably come down like a snow or hailstorm of granite or basalt. We’re not talking about a dusting of volcanic ash, but of snow made of something other than frozen water. Ouch!
Even if I’ve got the mineralogy wrong, knowing about CoRoT-7b has improved my mood so much that I’ve caught myself breaking into song during my walk to work. Changing only one word of this holiday lyric, and giving it my best baritone, I sing:
“Oh the weather outside is frightful,
But the Earth is so delightful,
And since we’ve no place to go,
Let it snow! Let it snow! Let it snow!”
Indeed. Why should we worry about the fluffy white stuff when we might otherwise be stoned by silicate stuff heavier than volcanic bombs because it lacks the frozen froth of pumice?
“Cloudy with a chance of rain or snow” sure beats the hell out of “cloudy with a certainty of shards.”
In addition to the holiday song, these intrusive astrochemical ideas also precipitate a fond family memory in my mind. One of my three sons used to rave about the beloved children’s book: “Cloudy With a Chance of Meatballs,” by Judi and Ron Barrett, now a delightful animated film. This reminiscence helped snap me out of the empty-nest doldrums of midwinter.
On the short term, the world throws plenty of bad things our way, making passing squalls of anger, sadness, grief and shock unavoidable. But on the long term, each of us gets to choose whether our personal planetary climate will be optimistic or pessimistic. At that time scale, attitude is everything.