NASA's Got a New Planet Hunter to Differentiate Between Rocky and Gaseous Worlds
NASA's got a new tool in its planet-detecting arsenal that will allow them to differentiate between rocky planets, and – theoretically, at least – the so-called "Super Puff" planets that have the density of cotton candy or styrofoam. NEID (pronounced NOO-id) is a precise spectrometer installed on the Kitt Peak National Observatory's WIYN telescope, which is located in Tohono O'odham Nation territory. NEID's name is inspired by a Tohono O'odham word that roughly translates as "to see."
According to NASA, NEID can find and study planets by measuring the degree to which a star with an orbiting planet "wobbles" because of the gravitational pull exerted by the planet, a measurement known as radial velocity. A massive planet, as you may have surmised, exerts more pull on its star, causing a faster wobble. Jupiter, for example, causes our sun to wobble back and forth at around 43 feet per second, while Earth only causes about 0.3 feet per second of solar wobble. These speeds are proportional to planetary mass, solar mass, and distance.
"Armed with measurements of a planet's diameter and mass, scientists can determine its density as well," NASA writes, "which can typically reveal whether the planet is rocky (like Earth, Venus and Mars) or mostly gaseous (like Jupiter and Saturn). This is a first step toward finding potentially habitable worlds similar to Earth."
Beyond doing its own work, NEID can also measure the mass of planets found by TESS, which locates planets by measuring tiny fluctuations in light caused by planets as they transit across a star's face, called its disk. In short, NEID grants NASA the ability to find and sort exoplanets that have a higher likelihood of being able to support life, given what we know about our own world as well as those in our solar system. It's exciting work that could, one day, lead to discoveries that will literally wobble our world.