A lot happened in the solar system this summer, from Pluto flybys to comet closeups. So, as the long summer shadows begin drifting into memory, let's take a quick tour of all we accomplished.
The 10-year journey of New Horizons to the dwarf planet was the big story of the summer — and it was the global view of Pluto seen at the top of this post that made headlines. The combined images used to make the image were taken on July 13, when the spacecraft was 280,000 miles away from Pluto. As NASA explains:
"This enhanced color image helps scientists detect differences in the composition and texture of Pluto's surface. The data hint that Pluto may still be geologically active, a theory that could explain how Pluto's escaping atmosphere remains flush with nitrogen."
Then, there's this closeup above. It tells an even more complex story about the distant world of Pluto. Here, we see a mountain range near the southwestern margin of Pluto's now-famous heart-shaped Tombaugh Regio (Tombaugh Region). According to NASA:
"These frozen peaks are estimated to be one-half mile to one mile (1-1.5 kilometers) high, about the same height as the United States' Appalachian Mountains."
And, just above, is an image of another world never, ever seen before — at least in any detail. This is Pluto's largest moon, Charon, revealed from a distance of 289,000 miles. NASA explains the coolest of the features:
"A swath of cliffs and troughs stretches about 600 miles from left to right, suggesting widespread fracturing of Charon's crust, likely a result of internal processes. At upper right, along the moon's curving edge, is a canyon estimated to be 4 to 6 miles deep."
The Dawn mission to dwarf planet Ceres, in the asteroid belt, gave us another new world to see up close. The best things about Ceres this summer were viewing its mysterious white spots and its pyramid-shaped mountain. As NASA explains:
"Ceres rotates in this sped-up movie comprised of images taken by NASA's Dawn mission during its approach to the dwarf planet. The images were taken on Feb. 19, 2015, from a distance of nearly 29,000 miles. Dawn observed Ceres for a full rotation of the dwarf planet, which lasts about nine hours. The images have a resolution of 2.5 miles per pixel."
Above is a still image of the bright spots on Ceres that lie in a crater named Occator, which is 60 miles across and 2 miles deep. The image comes from an animation, generated using Dawn mission data.
And, above, is a closeup of Ceres' mountain. According to NASA: "Among the highest features seen on Ceres so far is a mountain about 4 miles high, which is roughly the elevation of Mount McKinley in Alaska's Denali National Park."
Let's not forget that our good friend the Rosetta probe is still out there tagging along with a comet — which can be seen here, above, in three distinct images. From the European Space Agency's website:
"This series of images of Comet 67P/Churyumov–Gerasimenko was captured by Rosetta ... on 12 August 2015, just a few hours before the comet reached the closest point to the Sun along its 6.5-year orbit, or perihelion. The image at left was taken at 14:07 GMT, the middle image at 17:35 GMT, and the final image at 23:31 GMT. The images were taken from a distance of about 330 km from the comet. The comet's activity, at its peak intensity around perihelion and in the weeks that follow, is clearly visible in these spectacular images. In particular, a significant outburst can be seen in the image captured at 17:35 GMT.
And, finally, goodbye Dione.
We have to include this image above, which is the last closeup we will see of Saturn's icy moon Dione for a long, long time. That's because the Cassini probe, which has been orbiting the ringed giant for more than 10 years, is at the end of its mission. It won't be flying by Dione again. As NASA explains:
"This view from NASA's Cassini spacecraft looks toward Saturn's moon Dione, with giant Saturn and its rings in the background, just prior to the mission's final close approach to the moon on August 17, 2015. At lower right is the large, multi-ringed impact basin named Evander, which is about 220 miles wide. The canyons of Padua Chasma, features that form part of Dione's bright, wispy terrain, reach into the darkness at left."
Adam Frank is a co-founder of the 13.7 blog, an astrophysics professor at the University of Rochester, a book author and a self-described "evangelist of science." You can keep up with more of what Adam is thinking on Facebook and Twitter:@adamfrank4.