Now over four months after the historic and long-awaited flyby of Pluto by New Horizons, planetary scientists have had a steady stream of unprecedented data arriving on Earth from the outwardly-speeding spacecraft. We’ve learned more about Pluto in the past few months than we had over the decades before and the information is still being analyzed — and is still coming. This surprising little world and its strange family of mismatched moons, 33 times farther from the Sun than us, has become in the latter half of 2015 the scientific “star of the Solar System.” (Take that all you can’t-be-a-planet folks!)
“It’s hard to imagine how rapidly our view of Pluto and its moons are evolving as new data stream in each week. As the discoveries pour in from those data, Pluto is becoming a star of the Solar System. Moreover, I’d wager that for most planetary scientists, any one or two of our latest major findings on one world would be considered astounding. To have them all is simply incredible.”
– Dr. Alan Stern, New Horizons Principal Investigator, SwRI
Phobos, the largest — yet at just 16 miles wide still quite tiny — moon of Mars is getting ripped apart by the gravitational pull of its parent planet… and it bears the scars to show it, scientists have determined.
Long parallel grooves that wrap around the surface of Phobos are thought to be stress fractures — surface evidence of the tidal forces that will one day cause the moon to break apart entirely. This fate is not surprising to scientists, but that we’re seeing it in action is fascinating.
“We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves,” said Terry Hurford of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
On Nov. 11, 2015, NASA’s Cassini spacecraft passed relatively closely by Saturn’s moon Tethys, one of the ringed planet’s larger icy satellites. The animation above was made from 29 raw images acquired with Cassini’s narrow-angle camera as it passed by; you can see part of the incredibly cratered and ancient surface of this 662 mile (1,065 km) wide moon. Talk about flyover country!
On the afternoon of Oct. 31, 2015, Earth was visited by something much creepier than the typical Halloween trick-or-treater: a dark 2,000-foot (600-meter) -wide asteroid that sped silently (because space) by, approaching at its closest only about 1.3 times the distance to the Moon.
Designated 2015 TB145, this particular near-Earth object had only just been discovered a couple of weeks earlier. And while it posed no danger of impact, its considerable size and high velocity made the close pass a topic of interest for laypeople and scientists alike. By bouncing radar waves off its surface NASA researchers were able to generate an image of 2015 TB145, capturing details that would have been otherwise impossible due to its high velocity and incredibly dark coloration.
At the beginning of September the world was treated to a fantastic view of the night side of Pluto, captured by the New Horizons spacecraft as it departed the distant icy world on July 14, 2015. Backlit by the sun, Pluto’s surprisingly complex atmospheric haze created a ghostly glow above its crescent-lit limb while frozen mountains cast reflected light upon neighboring Plutonian peaks.
On Thursday, NASA released an update to that image showing a more complete view of Pluto in its backlit glory, created from more high-resolution images that continue to stream in from the Kuiper Belt-bound spacecraft, over three billion miles away.
For decades, far-off Pluto and its moons were just a collection of bright spots in even our most powerful telescopes. Now the dwarf planet and its family of five moons has been revealed in intimate detail with the long-awaited flyby of the New Horizons spacecraft.
Last week the “family portrait” of the Pluto system was made complete when our best close-up arrived of Kerberos, a tiny 7-mile-wide moon that nobody even knew about until 2011. And surprise: it looks like a contact binary!