Back in February I handed down the definitive ranking of all the planets in our Solar System. Today, I'm going to finish the job with a corresponding ranking of the Solar System's moons—rich and varied worlds in their own right, some larger than the smallest planets. This will not be an exhaustive list. Jupiter alone... Continue Reading →
The Slow Dances of Asteroid Moons
An astronomy pop quiz for you: How large does a planet have to be before it can have a natural satellite of its own? It's a trick question, you see. There's no lower limit. In fact, moons aren't just the province of planetary-mass bodies like Jupiter, Pluto, and our own Planet Earth---asteroids have them, too.... Continue Reading →
The Planets, Ranked
Not all the worlds in our solar system are created equal. Some are enormous, some are vanishingly small; some are scorching hot, others freezing cold; some (one) are clement to human life, while some (all the rest) are inhospitable deathtraps. And if I may be frank---some are just better than others. For today's post, we... Continue Reading →
Secrets of the Valles Marineris
The first and only time I ever saw the Grand Canyon was when I was eight years old, traveling through the southwestern United States on a family road trip. I knew roughly what it looked like, of course, but nothing had prepared me for the sheer scale of that thing. It was a sculpted, dizzyingly... Continue Reading →
The Many Planets of TRAPPIST-1
Wherever you see an alien planet in sci-fi films or television, there's always something weird going on in the sky. How else would you know you're not looking at Earth? So in everything from Avatar to Star Wars we get double stars, panoplies of moons, other planets in the same system---so many disks visible even... Continue Reading →
Dawn: Exploring Vesta and Ceres
When I was young, Ceres and Pluto were the biggest blank spots on the map of the Solar System. Most of the other interesting places had been long since explored, from Mercury all the way out to the moons of Neptune, but when I opened my astronomy books to the two minor planets, I saw... Continue Reading →
Icy Mysteries of Europa
I originally had another topic planned for today---it was written and scheduled, and of course I will still upload it at some point---but then my area had a rare winter storm, blanketing everything in ice and snow, and I thought to myself that it would be appropriate to do a blog post on Europa, one... Continue Reading →
That Time the USAF Nearly Nuked the Moon
The Space Race was a wild time, especially in its early years, when the United States was shocked and humiliated by Sputnik and Gagarin, and threw money at various insane ways to take the lead. I've already written about the proposed one-way trip to the Moon; other highlights include an inflatable re-entry pod and flying to... Continue Reading →
The New Antarctica
Somewhere between the current human presence in the space—zilch, save for three people aboard the ISS—and the most ambitious, wide-eyed, optimistic visions for colonization—Musk's million people on Mars, Bezos' trillions throughout the solar system—there's a middle ground where we work on and explore other planets, but inhabit them only in the same sense that we... Continue Reading →
An Obituary for Kepler
Post by Nic Quattromani: I’ve got some tragic news to share today: NASA’s Kepler space telescope, formerly our premier planet-hunter floating in the sky, has ceased operations. This was not due to any technical failure aboard the craft. Rather, it simply ran out of fuel, rendering it unable to conduct stationkeeping or even orient itself... Continue Reading →





































