SMITHSONIAN MAGAZINE - Are we alone in the universe? While no one can say for sure, space scientists know where to start looking—exoplanets. An exoplanet is a planet beyond the cradle of Earth’s eight-membered solar system. Hundreds of billions of these extraterrestrial kingdoms swarm our galaxy, and hundreds of sextillions of others exist beyond that.
While scientists know innumerous foreign worlds are out there, researchers have only pinpointed the existence of a tiny fraction. Being generally smaller, colder and much darker than a star, exoplanets are also harder to detect, so specialized techniques are required for capturing their faint signals. Planets exert gentle influence on nearby stars, so by watching the wobble, dimming or distortion of starlight, scientists can infer the presence of these elusive targets.
Since the turn of the millennium, thanks to advancing technology, we have been in a golden age of exoplanet discovery. Space-based telescopes such as Kepler and the Transiting Exoplanet Survey Satellite (TESS) have helped comb through patches of sky to identify interesting targets, while the James Webb Space Telescope and ground-based observatories allow for a deeper second look. As a result, we now know that the universe is littered with other worlds—they even surpass the number of stars. Understanding each new cosmic island in the dark ocean of space will help us answer important questions, such as how Earth came to be the way it is. Each exoplanet is a celestial companion that may reveal something about our place in the vast cosmos. Here are some of the most exciting of Earth’s distant neighbors.
A planetary sibling fight has driven one of the most volcanic worlds discovered to date. Twenty parsecs away from Earth, three planets encircle the star HD 104067, but the innermost one, TOI-6713.01, has been bossed around by the larger outer planets, to fiery consequences. Planets naturally prefer a circular orbit around their star, but in the case of TOI-6713.01, the outer planets’ gravitational influence bends it onto a more eccentric path. The result of this gravitational tug-of-war is that the planet is internally heated, so that excess heat bubbles out as active volcanism on the surface.
“It’s what I refer to as a tidal storm,” says Stephen Kane, a planetary astrophysicist at the University of California, Riverside, who discovered the planet from analysis of TESS’s registers. “Essentially, this planet is being squeezed so much that it has the surface temperature of a small star.”
Kane’s team calculated that temperatures soar to 2,600 Kelvin on TOI-6713.01’s surface. “This thing must be erupting volcanoes all over the place,” Kane says.