A new study suggests that Earth may not be so unique after all, and that other planets with similar composition are much more common in our galaxy. What’s more, the scientists behind the research have even added as a bonus a simple “recipe” for creating habitable worlds. Science project, anyone?
“Our solar system is not as unique as we might have thought,” said Courtney Dressing, research team leader and graduate student at the Harvard-Smithsonian Center for Astrophysics.
The team looked for planets similar in composition to Earth with the High-Accuracy Radial velocity Planet Searcher (HARPS)-North instrument on the Telescopio Nazionale Galileo in the Canary Islands. The machinery is specifically designed to accurately measure the masses of Earth-sized planets. Once the mass of a planet is calculated, researchers can determine its density, which is then used to figure out its composition.
“Our strategy for using HARPS-North over the past year has been to focus on planets less than two times the diameter of Earth and to study a few planets really well,” said astronomer David Charbonneau of Harvard, who currently heads the HARPS-North Science Team.
According to the National Monitor, there were 1,781 confirmed exoplanets as of December 2014. From this buffet of worlds, the Harvard team specifically honed in on Kepler-93b. The planet is in a tight 4.7-day orbit around its star and is roughly 1.5 times the size of Earth. The Harps-North also revealed that it has a mass 4.02 times that of Earth, meaning it features a rocky composition.
After, the team compared the 10 known exoplanets with a diameter of less than 2.7 times that of Earth and calculated their masses. According to the scientists, the five planets less than 1.6 times the size of Earth had a well founded relationship between their mass and size; that relationship is also reflected in our solar system between Earth and Venus. This finding indicates that all of these planets have similar rock to iron compositions.
On the other hand, the larger exoplanets that contained more mass proved to have lower densities, suggesting that that they contain a large amount of water, hydrogen or helium. They also featured more diverse compounds, as opposed to the constricted relationship demonstrated by the smaller, rocky planets.
“To find a truly Earth-like world, we should focus on planets less than 1.6 times the size of Earth, because those are the rocky worlds,” said Dressing.
However, just because a planet is similar to Earth does not mean that it is inhabited or habitable. For instance, Venus, which is Earth-like, has a poisonous atmosphere and surface temperatures in excess of 1 thousand degrees Fahrenheit.
So, what’s the recipe for an Earth-like, habitable world? Presented by the team in a meeting of the American Astronomical Society this week, the formula includes the following:
“Ingredients: 1 cup magnesium, 1 cup silicon, 2 cups iron, 2 cups oxygen, 1/2 teaspoon aluminum, 1/2 teaspoon nickel, 1/2 teaspoon calcium, 1/4 teaspoon sulfur, dash of water delivered by asteroids; Blend well in a large bowl, shape into a round ball with your hands and place it neatly in a habitable zone area around a young star. Do not over mix. Heat until mixture becomes a white hot glowing ball. Bake for a few million years. Cool until color changes from white to yellow to red and a golden-brown crust forms. It should not give off light anymore. Season with a dash of water and organic compounds. It will shrink a bit as steam escapes and clouds and oceans form. Stand back and wait a few more million years to see what happens. If you are lucky, a thin frosting of life may appear on the surface of your new world.”