Are we alone in the universe? For scientists working on NASA's proposed Habitable Worlds Observatory, that question is no ...

A pair of sibling gas giants originally spotted by citizen scientists are so lightweight that their density resembles wispy cotton candy more than a standard atmosphere. The rare duo detailed today in ...

Our definition of a planet has changed over the years — causing a bit of confusion. | Credit: wasan prunglampoo/Getty Images Over the past 250 years, the number of "planets" in our solar system has ...

NASA’s New Horizons spacecraft recently came out of hibernation to continue its journey through an unexplored part of the ...

From 6 to 9 to 11 to 7 to 8: What 250 years has done to our solar system planet count. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works.

Over the past 250 years, the number of "planets" in our solar system has ranged from six to nine — and, briefly, even 11 — depending on what astronomers knew at the time and how they defined a planet.

The Solar System is far more diverse in size than it appears from Earth. From tiny rocky worlds to massive gas giants, each planet differs dramatically in scale. To truly understand these differences, ...

The solar system is a dynamic place, and objects located 180° from a planet don’t stay that far from the planet for long. The reason is the differences in their orbits. Orbits come in all shapes and ...

Astronomers have discovered two of the least dense giant planets ever found worlds roughly the size of Jupiter but so extraordinarily light that their density is lower than cotton candy. Named TOI-791 ...

Throughout June 2026, SETI Institute scientists, affiliates, and collaborators contributed to discussions spanning ...

Space-Based Solar Power (SBSP), a technology Japan is currently pioneering to ensure a sustainable future, has the ability to ...

Two newly confirmed "super-puff" planets are so diffuse that they are less dense than cotton candy, despite being about the size of Jupiter. Their rare orbital relationship and enormous, lightweight ...