Water world stuns, delights scientists
By Amanda Jermyn

“Somewhere, something incredible is waiting to be known.” So said Carl Sagan, and how right he was. As our knowledge of the universe expands and builds on itself new discoveries constantly challenge our preconceived notions and delight us with their strangeness. Just recently, observations by NASA’s Hubble Space Telescope have revealed a new type of planet, a water world surrounded by a thick, steamy atmosphere. The planet was discovered back in 2009 by David Charbonneau and colleagues at the ground-based MEarth Project of the Harvard-Smithsonian Center for Astrophysics. This project uses robotic telescopes to observe nearby M dwarf stars in the search for Earth-like exoplanets. It was only recently, however, that analysis by the Project’s Zachory Berta and colleagues revealed the planet’s unexpected composition. Known by the misleadingly mundane name of GJ1214b, the planet is, according to Berta, “…like no planet we know of. A huge fraction of its mass is made up of water.”

This strange water world is smaller than Uranus but larger than Earth. It weighs almost seven times as much as Earth and is about 2.7 times Earth’s diameter. It orbits a red dwarf star every 38 hours at a distance of 1.3 million miles, and has an estimated temperature of 450 degrees Fahrenheit. Berta and his team used Hubble’s Wide Field Camera 3 to study the planet when it crossed in front of its star. During such a transit the star’s light, filtered through the planet’s atmosphere, gives an indication of the mix of gases present. What they found was a dense atmosphere of water vapor. The density of the planet itself is less than half that of Earth’s, an indication that it has a very different internal structure from Earth, with much more water and less rock. According to Berta, “the high temperature and high pressures would form exotic materials like ‘hot ice’ or ‘superfluid water,’ substances that are completely alien to our everyday experience.”

For a while the planet was dubbed “Kevin,” after Kevin Costner who starred in and produced the science fiction film “Waterworld.” However, Berta suggests naming it after Annie Jump Cannon, a pioneering woman astronomer at the Harvard College Observatory in the early 20th Century who was instrumental in creating the classification system for more than a quarter million stars, including the M dwarf star, the type of star this water world orbits.
Scientists surmise that the planet formed farther out from its star in a region with plentiful water ice, and migrated early in its history. During this migration it would have passed through the star’s habitable zone where temperatures are similar to Earth’s. Whether it remained there long enough for life to have an opportunity to develop is unknown. GJ1214b is just 40 light-years from Earth, in the direction of the constellation Ophiuchus, making it a prime candidate for study by the James Webb Space Telescope, due to be launched in 2018. As more and more exoplanets are discovered that differ dramatically from those found within our solar system, who knows what alien worlds are out there just waiting to be revealed? I just wish Carl Sagan could have lived to witness these discoveries.

Join the Springfield Stars Club on Tuesday, April 24th at 7:30pm at the Springfield Science Museum for a talk on Radio Astronomy. Refreshments will be served, and the public is welcome free of charge. Stars Club board member, Dr. David Wexler, will speak on his experiences studying at the National Radio Astronomy Observatory in Green Bank, West Virginia last summer. He will review concepts and highlights from his radio astronomy course which included data gathering from the world’s largest single-dish telescopes at Green Bank and Arecibo. Dr. Wexler studied neuroscience and engineering at Case Western Reserve University, and completed medical studies at Stanford University. He is an Ear, Nose and Throat specialist at Wing Memorial Hospital in Palmer. After completing a three year remote education program last year, Dr. Wexler received his Masters degree in astronomy from James Cook University.