planetary evolution Archives

December 4, 2024December 4, 2024 by Brian Koberlein

Maybe Venus Was Never Habitable

Earth and Venus. Why are they so different and what do the differences tell us about rocky exoplanet habitability? Image Credit: NASA

Although they are very different today, Venus, Earth, and Mars were very similar in their youth. All three were warm, with thick, water-rich atmospheres. But over time, Mars became a cold, dry planet with a thin atmosphere, and Venus became superheated, with a crushing, toxic sky. Only Earth became a warm ocean world teeming with life. But why?

October 4, 2023October 4, 2023 by Brian Koberlein

Old Stars Don't Have Hot Jupiters

Hot Jupiters may not last long near Sun-like stars. Credit: NASA/JPL-Caltech

As we began to discover hundreds, then thousands of exoplanets, we found that there were two types of worlds unlike anything in our solar system. The first are super-Earths. These worlds straddle the line between large rocky worlds like Earth and small gas planets like Neptune. The second are hot Jupiters. Large gas giants that orbit their star in a matter of days. While there may be a super-Earth lurking at the outer edge of our solar system, we know our Sun has no hot Jupiters. This is a little surprising since close-orbiting gas giants seem to be fairly common. But a new study could explain why our solar system has no planet Vulcan.

September 11, 2022September 11, 2022 by Brian Koberlein

If Jupiter's Orbit got Weirder, it Would Actually Make Earth More Habitable

Io Eclipse on Jupiter from Juno Perijove 22 - NASA/JPL/Kevin Gill

Earth is not just habitable, it’s unusually habitable. It’s rather wet for a planet so close to its Sun, it’s geologically active, and it has a stable orbit, all of which are necessary for life as we know it. But there are also secondary advantages, such as not being constantly bombarded by large asteroids, and having a rotational axis that is fairly stable. This is due in part thanks to the planet Jupiter. The giant planet has helped clear the solar system of asteroid debris and may have helped stabilize the orbits of the inner planets. So life is good. But a new study shows that if Jupiter had a different orbit, life could be even better.

February 24, 2022February 24, 2022 by Evan Gough

Mini-Neptunes can Lose gas and Turn Into Super-Earths

An artist's illustration of the mini-Neptune TOI 560.01 losing its atmosphere and transitioning to a super-Earth. Image Credit: Image Credit: Adam Makarenko (Keck Observatory)

Can one type of planet become another? Can a mini-Neptune lose its atmosphere and become a super-Earth? Astronomers have found two examples of mini-Neptunes transitioning to super-Earths, and the discovery might help explain a noted “gap” in the size distribution of exoplanets.

January 28, 2021January 28, 2021 by Evan Gough

Exoplanetary System Found With 6 Worlds in Orbital Resonance

This artist’s impression shows the view from the planet in the TOI-178 system found orbiting furthest from the star. New research by Adrien Leleu and his colleagues with several telescopes, including ESO’s Very Large Telescope, has revealed that the system boasts six exoplanets and that all but the one closest to the star are locked in a rare rhythm as they move in their orbits. Image Credit: ESO/L. Calçada/spaceengine.org

200 light-years away from Earth, there’s a K-type main-sequence star named TOI (TESS Object of Interest) 178. When Adrian Leleu, an astrophysicist at the Center for Space and Habitability of the University of Bern, observed it, it appeared to have two planets orbiting it at roughly the same distance. But that turned out to be incorrect. In fact, six exoplanets orbit the smallish star.

And five of those six are locked into an unexpected orbital configuration.