Whether you want to call it a planet, dwarf planet, Kuiper Belt Object, or some or none of the above, there’s no denying that Pluto and its family of moons are true curiosities in the Solar System. Not only does little Pluto have one moon — Charon — that’s so massive in comparison that they both actually orbit each other around a central point outside the radius of either (if you feel like adding “binary” to whatever term you prefer to use, go right ahead) but it also has four other smaller moons in orbit that kinda sorta break the rules of how moons are “supposed to” behave.
What a difference half a century makes! This week marks 50 years since the Soviet Luna 9 spacecraft made humanity’s first-ever soft landing on the surface of the Moon. Launched from Baikonur on Jan. 31, 1966, the Luna 9 lander touched down within Oceanus Procellarum at 18:44:52 UTC on Feb. 3. Over the following three days Luna 9 sent us our first views of the Moon’s surface from the surface and, perhaps even more importantly, confirmed to scientists that a landing by spacecraft was indeed possible (which, by the way, was achieved on this day in 1971 by Al Shepard and Ed Mitchell with Apollo 14.)
When New Horizons made its close pass pf Pluto on July 14, 2015, it did much more than just take pretty pictures; it was also scanning the planet with a suite of science instruments designed to determine the nature of its surface, atmosphere, composition, and other key characteristics. One of these instruments was the Linear Etalon Imaging Spectral Array (LEISA), an infrared scanner that can detect the unique molecular “fingerprints” of particular elements and compounds like methane, nitrogen, carbon monoxide… and water (one of our favorites!)
At first the data returned from LEISA showed only a surprisingly small amount of water ice across Pluto’s surface. But that was water ice in its pure form; when researchers took into consideration ice containing a mixture of water and other materials they found a much more widespread distribution across the surface area visible to New Horizons.
An image like this could only be captured by an observer who’d traveled the 3.2 billion miles to take it beyond the orbit of Pluto! Luckily for us, in July 2015 we had exactly that: the New Horizons spacecraft, which had spent the previous nine and a half years soaring across the Solar System.
This bumpy wrinkled pucker is actually an enormous ice volcano — i.e., a cryovolcano — on the surface of Pluto, imaged by the passing New Horizons spacecraft on July 14, 2015. Informally called Wright Mons, the feature is about 90 miles (150 km) across and 2.5 miles (4 km) high, about as high as some of the tallest Alps. The entire volcanic mountain spans an area half the width of the state of Massachusetts!
See the region in context on a global view of Pluto below:
A planet-killing astronomer is now attempting to introduce a new world into the Solar System.
Self-professed “Pluto killer” Mike Brown — the Caltech professor and astronomer whose discovery of Eris in 2005 prompted the reclassification of what constitutes a full-fledged planet, thus knocking Pluto from the list a year later — is now offering up evidence for the existence of a “real” ninth planet, far beyond the orbit of Pluto and possibly even traveling farther than the Kuiper Belt extends. This “Planet Nine,” say Brown and co-researcher Konstantin Batygin — also of Caltech — could be nearly the mass of Neptune, although it has not been directly observed by any Solar System surveys performed to date.
(And for those long-time Planet X fans who will assuredly cry “told you so,” this hypothesis is based on actual observations and not just wishful thinking or sci-fi dreams. There’s a difference.)