Showing posts from June, 2021

Gap in Exoplanet Size Shifts with Age. Source: By  Katherine Kornei , Eos/AGU.  Excerpt: Smaller planets are scarcer in younger systems and larger planets are lacking in older systems, according to new research that analyzed hundreds of exoplanets. ...Planets just a bit larger than Earth appear to be relatively rare in the exoplanet canon. A team has now used observations of hundreds of exoplanets to show that this planetary gap isn’t static but instead evolves with planet age—younger planetary systems are more likely to be missing slightly smaller planets, and older systems are more apt to be without slightly larger planets. This evolution is consistent with the hypothesis that atmospheric loss—literally, a planet’s atmosphere blowing away over time—is responsible for this so-called “radius valley,” the researchers suggested....

Fifteen Years of Radar Reveal Venus’s Most Basic Facts Source: By  Kimberly M. S. Cartier , Eos/AGU .  Excerpt: Venus’s heavy atmosphere tugs the planet’s surface enough to change the length of its day by up to 21 minutes [per day]. ...In a recent paper in  Nature Astronomy , astronomers used 15 years of radar measurements to reveal a few of these fundamental properties of our closest planetary neighbor that have long remained elusive. ...The 70-meter radio antenna at the  Goldstone Deep Space Communications Complex  in California served as the flashlight, ...The researchers carefully measured the timing of the returned waves with two radio telescopes: Goldstone in California and the  Green Bank Telescope  in West Virginia. ...they found that Venus’s spin axis is tilted 2.6392° from its orbital plane and that tilt precesses once every 29,000 Earth years, 3,000 years longer than Earth’s precession. These measurements are 5–15 times more precise than what was achi