Until just a few years ago, a plot of mass versus size of other worlds would have looked pretty sparse and uninformative. But thanks to the tireless efforts of exoplanet astronomers, we now know fairly precise masses and radii for hundreds of distant worlds.
January 24 was the 30th anniversary of the Voyager flyby of Uranus. Uranian moons have been on my mind ever since New Horizons sent us close-up images of Charon. On the occasion of the anniversary, Ted Stryk produced latest-and-greatest versions of the Voyager views of these worlds.
How many planetary exploration missions are there, and where are they? These days, it's hard to keep track, because there are so many. I plan to begin the new year by taking stock of active missions, figuring out what each has set out to do and accomplished so far, but first I want to step back to consider the spread of missions across the solar system as a whole.
People often ask me to produce one of my scale-comparison montages featuring the small moons of the outer solar system. I'd love to do that, but Galileo's best images of Jupiter's ringmoons lack detail compared to Cassini's images from Saturn.
Now that I have a reasonable-resolution global color view of Pluto, I can drop it into one of my trademark scale image montages, to show you how it fits in with the rest of the similar-sized worlds in the solar system: the major moons and the biggest asteroids.
Rosetta's view of the comet is getting better and better. Today they released a new image from the high-resolution OSIRIS camera, and it's a very fresh one, taken only two days ago. Distinct features are coming into view. And it's finally detailed enough for me to compare it to the five other comets we've visited in the past.
I am very excited about 2015, more so than I have been about any year since I started working at The Planetary Society. Dawn will enter orbit at Ceres, and New Horizons, which will fly past Pluto and Charon. But if we want this kind of exploration to continue, I'm challenging you, dear readers, to tell the world why such non-planetary worlds are compelling places to go exploring.