Charon’s Red Cap at its North Pole? We Might Have an Answer

Pluto’s largest moon, Charon, started off as a beautiful, smooth red grape until someone came along, mostly peeled it, tried to smoosh it, then just gave up and walked away, leaving the poor moon to look like the absolute travesty that it is. Okay, so maybe that’s not exactly what happened, but Charon just looks like a mess and scientists want to know why. Never mind its smooshed equator, but what’s the deal with its red cap? Where did it come from and why is it red?

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Eight Missions are Getting Extensions, Most Exciting: OSIRIS-REx is Going to Asteroid Apophis

An artist's illustration of NASA's OSIRIS-REx spacecraft approaching asteroid Bennu with its sampling instrument extended. Image Credit: NASA/Goddard/University of Arizona

NASA has granted mission extensions to eight different planetary missions, citing the continued excellent operations of the spacecraft, but more importantly, the sustained scientific productivity of these missions, “and the potential to deepen our knowledge and understanding of the solar system and beyond.” Each mission will be extended for three more years.

One of the most exciting extensions gives a new mission to the OSIRIS-REx spacecraft, sending it to one of the most infamous asteroids of them all, the potentially hazardous asteroid Apophis.

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Pluto’s Orbit is Surprisingly Close to an Unstable Zone

According to a new study, the idea that Pluto is not a planet is unsupported in scientific literature. Credit: NASA

In 1930, astronomer Clyde Tombaugh discovered the fabled “Ninth Planet” (or “Planet X”) while working at the Lowell Observatory in Flagstaff, Arizona. The existence of this body had been predicted previously based on perturbations in the orbit of Uranus and Neptune. After receiving more than 1,000 suggestions from around the world, and a debate among the Observatory’s staff, this newfound object was named Pluto – which was proposed by a young schoolgirl from Oxford (Venetia Burney).

Since that time, Pluto has been the subject of considerable study, a naming controversy, and was visited for the first time on July 14th, 2015, by the New Horizons mission. One thing that has been clear from the beginning is the nature of Pluto’s orbit, which is highly eccentric and inclined. According to new research, Pluto’s orbit is relatively stable over longer timescales but is subject to chaotic perturbance and changes over shorter timescales.

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Pluto’s Surface was Shaped by Ice Volcanoes

New Horizons mission scientists have determined that cryovolcanic activity most likely created unique structures on Pluto not yet seen anywhere else in the solar system. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Isaac Herrera/Kelsi Singer

For all of Earth’s geological diversity and its long history, the planet has never had ice volcanoes. But Pluto has. And that cryovolcanism has shaped some of the ice dwarf’s surface features.

The resulting structures are unique in the Solar System.

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Now We Know Why Pluto has These Strange Features on its Surface

In the center left of Pluto’s vast heart-shaped feature – informally named “Tombaugh Regio” - lies a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped by geologic processes. This frozen region is north of Pluto’s icy mountains and has been informally named Sputnik Planum (Sputnik Plain), after Earth’s first artificial satellite. The surface appears to be divided into irregularly-shaped segments that are ringed by narrow troughs. Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as one-half mile (1 kilometer) across are visible. The blocky appearance of some features is due to compression of the image. Credits: NASA/JHUAPL/SWRI

After New Horizons made its close flyby of Pluto in July of 2015, scientists were astounded at the incredible closeup views of Pluto’s surface. One of the most intriguing and mysterious features was a bright plain inside the prominent heart-shaped feature on Pluto, called “Tombaugh Regio” (Tombaugh Region) named after Clyde Tombaugh, who discovered Pluto in 1930.

The region is composed of a broken surface of irregularly-shaped segments that appear to be geologically young because no impact craters are part of the terrain.

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New Horizons is Now 50 Astronomical Units Away From the Sun

Currently exploring the Kuiper Belt, New Horizons is just one of five spacecraft to reach 50 astronomical units, on its way out of the solar system and, eventually, into interstellar space. (Credit: NASA/Johns Hopkins APL/Southwest Research Institute)

As the New Horizons spacecraft hurtles out towards interstellar space, it has now reached an historical milestone. On April 17, 2021, New Horizons passed 50 astronomical units, or 50 times Earth’s distance from the Sun. It is just the 5th spacecraft to reach that distance, joining the Voyagers 1 and 2 and the Pioneers 10 and 11.

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Pluto has Snowcapped Mountains, But Why?

On the left, the region of "Cthulhu" near the equator of Pluto and on the right, the Alps on Earth. Two identical landscapes, created by very different processes. Image Credit: © NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute © Thomas Pesquet / ESA

We can thank NASA’s New Horizons spacecraft for opening our eyes up to Pluto’s complexity. On July 14th, 2015, the spacecraft came within 12,500 km (7,800 mi) of the dwarf planet. During the flyby, New Horizons was able to characterize Pluto’s atmosphere and its surface.

Among the things New Horizons saw was a region of snowcapped mountains.

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Pluto and Other Kuiper Belt Objects Started Out With Water Oceans, and Have Been Slowly Freezing Solid for Billions of Years

Far left: The New Horizons team informally named Pluto’s heart-shaped feature “Tombaugh Regio” in honor of astronomer Clyde Tombaugh, who discovered the dwarf planet. The bright expanse of the western lobe of Pluto’s “heart” is informally called Sputnik Planum. Above left: Pluto’s surface sports a remarkable range of landforms that have their own distinct colors, telling a complex geological and climatological story. Credit: Courtesy NASA / JHUAPL / SwRI Table of Contents page 2015 Annual Report Division: (15)

It seems unlikely that an ocean could persist on a world that never gets closer than 30 astronomical units from the Sun. But that’s the case with Pluto. Evidence shows that it has a sub-surface ocean between 100 to 180 km thick, at the boundary between the core and the mantle. Other Kuiper Belt Objects may be similar.

But time might be running out for these buried oceans, which will one day turn to ice.

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Astronomers Continue to Analyze Pluto’s Atmosphere

This image of Pluto taken by the New Horizons spacecraft shows the blue color of Pluto's high-altitude haze. Image: NASA/New Horizons.
This image of Pluto taken by the New Horizons spacecraft shows the blue color of Pluto's high-altitude haze. Image: NASA/New Horizons.

When NASA’s New Horizons spacecraft flew past Pluto, studying the atmosphere was a key scientific objective. Most of what we know about the ice dwarf came from that flyby. That happened in July 2015, but it took over 15 months to send all the data home, and it’s taking even longer to analyze it.

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There Are Winds Blowing On Pluto, Driven by Frozen Nitrogen

NASA's New Horizons spacecraft captured this image of Sputnik Planitia — a glacial expanse rich in nitrogen, carbon monoxide and methane ices — that forms the left lobe of a heart-shaped feature on Pluto’s surface. SwRI scientists studied the dwarf planet’s nitrogen and carbon monoxide composition to develop a new theory for its formation. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Earth and Pluto don’t have much in common. Earth is a vibrant, living world, whereas Pluto is cold, distant and lifeless. But one thing they do have in common is nitrogen. Earth’s atmosphere is about 78% nitrogen, and Pluto’s primary atmospheric constituent is also nitrogen, although the exact percentage is unclear.

On Pluto, where the surface temperature is about 42 Kelvin (-231 Celsius) most of that nitrogen is frozen. A new study says that Pluto’s frozen nitrogen drives the planet’s winds, and shapes its feature surfaces.

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