Charon and Pluto

We were wowed in July when the New Horizons spacecraft sent back initial photos as it sped past Pluto. Since then it has been gradually sending back data and now, more detailed photos. Recent pictures have been published of Pluto and it’s dwarf planet partner, Charon.

Charon in Enhanced Color NASA’s New Horizons captured this high-resolution enhanced color view of Charon just before closest approach on July 14, 2015. The image combines blue, red and infrared images taken by the spacecraft’s Ralph/Multispectral Visual Imaging Camera (MVIC); the colors are processed to best highlight the variation of surface properties across Charon. Charon’s color palette is not as diverse as Pluto’s; most striking is the reddish north (top) polar region, informally named Mordor Macula. Charon is 754 miles (1,214 kilometers) across; this image resolves details as small as 1.8 miles (2.9 kilometers).

Charon is half the diameter of Pluto but that makes it the largest moon in the solar system relative to it’s planet (Pluto is now classified as a dwarf planet).

This composite of enhanced color images of Pluto (lower right) and Charon (upper left), was taken by NASA’s New Horizons spacecraft as it passed through the Pluto system on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surface properties, and to highlight the similarity between Charon’s polar red terrain and Pluto’s equatorial red terrain. Pluto and Charon are shown with approximately correct relative sizes, but their true separation is not to scale.

Source and more details: Pluto’s Big Moon Charon Reveals a Colorful and Violent History

Pluto orbits around the joint gravitational centre due to the proximity and relative size of Charon.

Some comparative sizes

  • Charon 1,208 km
  • Pluto 2,370 km
  • Moon 3,475 km
  • Mercury 4,879 km
  • Mars 6,779 km
  • Venus 12,104 km
  • Earth 12,742 km

There’s been more detailed pictures of Pluto published too, including:

Sputnik Planum is the informal name of the smooth, light-bulb shaped region on the left of this composite of several New Horizons images of Pluto. The brilliantly white upland region to the right may be coated by nitrogen ice that has been transported through the atmosphere from the surface of Sputnik Planum, and deposited on these uplands.

In this extended color image of Pluto taken by NASA’s New Horizons spacecraft, rounded and bizarrely textured mountains, informally named the Tartarus Dorsa, rise up along Pluto’s day-night terminator and show intricate but puzzling patterns of blue-gray ridges and reddish material in between. This view, roughly 330 miles (530 kilometers) across, combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC) on July 14, 2015, and resolves details and colors on scales as small as 0.8 miles (1.3 kilometers).

High-resolution images of Pluto taken by NASA’s New Horizons spacecraft just before closest approach on July 14, 2015, are the sharpest images to date of Pluto’s varied terrain—revealing details down to scales of 270 meters. In this 75-mile (120-kilometer) section of the taken from the larger, high-resolution mosaic above, the textured surface of the plain surrounds two isolated ice mountains.

More at

First Charon close-up

Here is the first closeup photo of Charon, the binary or major moon of Pluto.

New Horizons Close-Up of Charon’s ‘Mountain in a Moat’

Craters are prominent, in contrast to the first close-up of Pluto.

This new image of an area on Pluto’s largest moon Charon has a captivating feature—a depression with a peak in the middle, shown here in the upper left corner of the inset.

The image shows an area approximately 240 miles (390 kilometers) from top to bottom, including few visible craters. “The most intriguing feature is a large mountain sitting in a moat,” said Jeff Moore with NASA’s Ames Research Center, Moffett Field, California, who leads New Horizons’ Geology, Geophysics and Imaging team. “This is a feature that has geologists stunned and stumped.”

This image gives a preview of what the surface of this large moon will look like in future close-ups from NASA’s New Horizons spacecraft. This image is heavily compressed; sharper versions are anticipated when the full-fidelity data from New Horizons’ Long Range Reconnaissance Imager (LORRI) are returned to Earth.

The rectangle superimposed on the global view of Charon shows the approximate location of this close-up view.

The image was taken at approximately 6:30 a.m. EDT (10:30 UTC) on July 14, 2015, about 1.5 hours before closest approach to Pluto, from a range of 49,000 miles (79,000 kilometers).

The next NASA briefing will be Friday 1 pm EDT where more images will be released.  That’s 5 am Saturday New Zealand time so we should have a weekend of revelations.

Pluto views through the years

This week is the first time we have seen what Pluto actually looks like. Previously we have only had light blobs and artist’s impressions.

NASA have put together an animation of Views of Pluto Through the Years (it’s too fast for me to see properly) but also helpfully provided links to the source images.

Clyde Tombaugh, Lowell Observatory, 1930:
Note: This image is property of the Lowell Observatory Archives. Any public use requires written permission of the Lowell Observatory Archives.

Hubble Space Telescope, 1994: Hubble Portrait of the “Double Planet” Pluto & Charon

MAY 16, 1994: This is the clearest view yet of the distant planet Pluto and its moon Charon, as revealed by the Hubble telescope.

Hubble snapped this image when the planet was 2.6 billion miles (4.4 billion kilometers) from Earth, or nearly 30 times the separation between Earth and the Sun. The two objects are shown as clearly separate and sharp disks.

Hubble’s corrected optics show the two objects as clearly separate and sharp disks. This now allows astronomers to measure directly (to within about 1 percent) Pluto’s diameter of 1440 miles (2320 kilometers) and Charon’s diameter of 790 miles (1270 kilometers). The Hubble observations show that Charon is bluer than Pluto. This means that both worlds have different surface composition and structure. A bright highlight on Pluto suggests it has a smoothly reflecting surface layer.

A detailed analysis of the Hubble image also suggests there is a bright area parallel to the equator on Pluto. This result is consistent with surface brightness models based on previous ground-based photometric observations. However, subsequent HST observations will be required to confirm whether the feature is real.

Hubble Space Telescope, 1996: Hubble Reveals Surface of Pluto for First Time

MARCH 7, 1996: For the first time since Pluto’s discovery 66 years ago, astronomers have at last directly seen details on the surface of the solar system’s farthest known planet.

The Hubble telescope’s snapshots of nearly the entire surface of Pluto, taken as the planet rotated through a 6.4-day period, show that Pluto is a complex object, with more large-scale contrast than any planet, except Earth. Topographic features such as basins, or fresh impact craters may cause some of the variations across Pluto’s surface.

The two smaller inset pictures at the top are actual images from Hubble. North is up. Each square pixel (picture element) is more than 100 miles across. At this resolution, Hubble discerns roughly 12 major “regions” where the surface is either bright or dark.

The larger images (bottom) are from a global map constructed through computer image processing performed on the Hubble data. The tile pattern is an artifact of the image enhancement technique.

Opposite hemispheres of Pluto are seen in these two views. Some of the variations across Pluto’s surface may be caused by topographic features such as basins, or fresh impact craters. However, most of the surface features unveiled by Hubble, including the prominent northern polar cap, are likely produced by the complex distribution of frosts that migrate across Pluto’s surface with its orbital and seasonal cycles and chemical byproducts deposited out of Pluto’s nitrogen-methane atmosphere.

The picture was taken in blue light when Pluto was at a distance of 3 billion miles from Earth (4,800,000,000 kilometres).

Hubble Space Telescope, 2002-2003: New Hubble Maps of Pluto Show Surface Changes

(The dates look odd from this link)

FEBRUARY 4, 2010: Since its discovery in 1930, Pluto has been a speck of light in the largest ground-based telescopes. But NASA’s Hubble Space Telescope has now mapped the dwarf planet in never-before-seen detail. The new map is so good, astronomers have even been able to detect changes on the dwarf planet’s surface by comparing Hubble images taken in 1994 with the newer images taken in 2002-2003. The task is as challenging as trying to see the markings on a soccer ball 40 miles away.

Hubble’s view isn’t sharp enough to see craters or mountains, if they exist on the surface, but Hubble reveals a complex-looking and variegated world with white, dark-orange, and charcoal-black terrain. The overall color is believed to be a result of ultraviolet radiation from the distant Sun breaking up methane that is present on Pluto’s surface, leaving behind a dark, molasses-colored, carbon-rich residue. Astronomers were very surprised to see that Pluto’s brightness has changed — the northern pole is brighter and the southern hemisphere is darker and redder. Summer is approaching Pluto’s north pole, and this may cause surface ices to melt and refreeze in the colder shadowed portion of the planet. The Hubble pictures underscore that Pluto is not simply a ball of ice and rock but a dynamic world that undergoes dramatic atmospheric changes.

Hubble Space Telescope, 2011: NASA’s Hubble Discovers Another Moon Around Pluto

These two images, taken about a week apart by NASA’s Hubble Space Telescope, show four moons orbiting the distant, icy dwarf planet Pluto. The green circle in both snapshots marks the newly discovered moon, temporarily dubbed P4, found by Hubble in June.

P4 is the smallest moon yet found around Pluto, with an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Pluto’s largest moon Charon is 746 miles (1,200 km) across. Nix and Hydra are roughly 20 to 70 miles (32 to 113 km) wide.

The new moon lies between the orbits of Nix and Hydra, two satellites discovered by Hubble in 2005. It completes an orbit around Pluto roughly every 31 days.

The moon was first seen in a photo taken with Hubble’s Wide Field Camera 3 on June 28, 2011. The sighting was confirmed in follow-up Hubble observations taken July 3 and July 18.

P4, Nix, and Hydra are so small and so faint that scientists combined short and long exposures to create this image of Pluto and its entire moon system. The speckled background is camera “noise” produced during the long exposures. The linear features are imaging artifacts.

New Horizons, April 9, 2015: First Pluto-Charon Color Image from New Horizons

This image of Pluto and its largest moon, Charon, was taken by the Ralph color imager aboard NASA’s New Horizons spacecraft on April 9. It is the first color image ever made of the Pluto system by a spacecraft on approach. The image is a preliminary reconstruction, which will be refined later by the New Horizons science team. Clearly visible are both Pluto and the Texas-sized Charon. The image was made from a distance of about 71 million miles (115 million kilometers)-roughly the distance from the Sun to Venus.

New Horizons, May 12, 2015: More Detail as New Horizons Draws Closer

The image of Pluto on the right is part of series of New Horizons Long Range Reconnaissance Imager (LORRI) photos taken May 8-12, 2015; the image at left shows LORRI’s view of Pluto just one month earlier. In the month between these image sets, New Horizons’ distance to Pluto decreased from 68 million miles (110 million kilometers) to 47 million miles (75 million kilometers), as the spacecraft speeds toward a close encounter with the Pluto system in mid-July.

Between April and May, Pluto appears to get larger as the spacecraft gets closer, with Pluto’s apparent size increasing by approximately 50 percent. Pluto rotates around its axis every 6.4 Earth days, and these images show the variations in Pluto’s surface features during its rotation.

New Horizons, June 2, 2015: Faces of Pluto

New Horizons, June 15, 2015: Features on the Close Approach Hemisphere

New Horizons, July 1, 2015: Three Views of Pluto

Image details are as follows.
Left: Taken on July 1st at 22:53 UT, from a range of 9.2 million miles (14.9 million km), with a central longitude of 133°.
Center: Taken on July 3rd at 04:38 UT, from a range of 8.3 million miles (13.5 million km), with a central longitude of 63°.
Right: Taken on July 3rd at 23:25 UT, from a range of 7.8 million miles (12.5 million km), with a central longitude of 19°.

New Horizons, July 3, 2015:  A Pluto Color Combo

New Horizons, July 7, 2015: A Heart on Pluto

Just under 5 million miles (8 million kilometers) from Pluto

This view is centered roughly on the area that will be seen close-up during New Horizons’ July 14 closest approach. Most prominent are an elongated dark feature at the equator, informally known as “the whale,” and a large heart-shaped bright area measuring some 1,200 miles (2,000 kilometers) across on the right. Above those features is a polar region that is intermediate in brightness.

New Horizons, July 8, 2015: Signs of Geology

3.3 million miles (5.4 million kilometers) away. At this range, Pluto is beginning to reveal the first signs of discrete geologic features. This image views the side of Pluto that always faces its largest moon, Charon.

Same image of Pluto with Charon.

New Horizons, July 11, 2015: New Horizons’ Last Portrait of Pluto’s Puzzling Spots

2.5 million miles (4 million kilometers) from Pluto. New Horizons’ last look at Pluto’s Charon-facing hemisphere.

New Horizons July 11: A Portrait from the Final Approach to Pluto and Charon

A portrait from the final approach. Pluto and Charon display striking color and brightness contrast in this composite image from July 11, showing high-resolution black-and-white LORRI images colorized with Ralph data collected from the last rotation of Pluto. Color data being returned by the spacecraft now will update these images, bringing color contrast into sharper focus.

New Horizons, July 14, 2015: Pluto’s Big Heart in Color

476,000 miles (768,000 kilometers) from the surface. This is the last and most detailed image sent to Earth before the spacecraft’s closest approach to Pluto on July 14. The color image has been combined with lower-resolution color information from the Ralph instrument that was acquired earlier on July 13. 

This view is dominated by the large, bright feature informally named the “heart,” which measures approximately 1,000 miles (1,600 kilometers) across. The heart borders darker equatorial terrains, and the mottled terrain to its east (right) is complex. However, even at this resolution, much of the heart’s interior appears remarkably featureless—possibly a sign of ongoing geologic processes.

New Horizons, July 15, 2015: Mountains on Pluto

Icy mountains on Pluto and a new, crisp view of its largest moon, Charon, are among the several discoveries announced Wednesday by NASA’s New Horizons team, just one day after the spacecraft’s first ever Pluto flyby.

A new close-up image of an equatorial region near the base of Pluto’s bright heart-shaped feature shows a mountain range with peaks jutting as high as 11,000 feet (3,500 meters) above the surface of the icy body.

The mountains on Pluto likely formed no more than 100 million years ago — mere youngsters in a 4.56-billion-year-old solar system. This suggests the close-up region, which covers about one percent of Pluto’s surface, may still be geologically active today.

“This is one of the youngest surfaces we’ve ever seen in the solar system,” said Jeff Moore of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California.

Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape.

“This may cause us to rethink what powers geological activity on many other icy worlds,” says GGI deputy team leader John Spencer at SwRI.

The new view of Charon reveals a youthful and varied terrain. Scientists are surprised by the apparent lack of craters. A swath of cliffs and troughs stretching about 600 miles (1,000 kilometers) suggests widespread fracturing of Charon’s crust, likely the result of internal geological processes. The image also shows a canyon estimated to be 4 to 6 miles (7 to 9 kilometers) deep. In Charon’s north polar region, the dark surface markings have a diffuse boundary, suggesting a thin deposit or stain on the surface.

New Horizons also observed the smaller members of the Pluto system, which includes four other moons: Nix, Hydra, Styx and Kerberos. A new sneak-peek image of Hydra is the first to reveal its apparent irregular shape and its size, estimated to be about 27 by 20 miles (43 by 33 kilometers).

The observations also indicate Hydra’s surface is probably coated with water ice. Future images will reveal more clues about the formation of this and the other moon billions of years ago. Spectroscopic data from New Horizons’ Ralph instruments reveal an abundance of methane ice, but with striking differences among regions across the frozen surface of Pluto.

Comparing Pluto and Charon to another planet:

This graphic presents a view of Pluto and Charon as they would appear if placed slightly above Earth’s surface and viewed from a great distance.  Recent measurements obtained by New Horizons indicate that Pluto has a diameter of 2370 km, 18.5% that of Earth’s, while Charon has a diameter of 1208 km, 9.5% that of Earth’s.

First pictures from Pluto fly-by

NASA is revealing the first photos from the New Horizons fly-by of Pluto (the spacecraft is already 1.5 million kilometres past Pluto already). Better quality images will come later.

They start by looking at some of Pluto’s moons. This is the first picture ever of Hydra:


Since its discovery in 2005, Pluto’s moon Hydra has been known only as a fuzzy dot of uncertain shape, size, and reflectivity. Imaging obtained during New Horizons’ historic transit of the Pluto-Charon system and transmitted to Earth early this morning has definitively resolved these fundamental properties of Pluto’s outermost moon. Long Range Reconnaissance Imager (LORRI) observations revealed an irregularly shaped body characterized by significant brightness variations over the surface. With a resolution of 2 miles (3 kilometers) per pixel, the LORRI image shows the tiny potato-shaped moon measures 27 miles (43 kilometers) by 20 miles (33 kilometers).

Like that of Charon, Hydra’s surface is probably covered with water ice, the most abundant ice in the universe. Observed within Hydra’s bright regions is a darker circular structure with a diameter of approximately 6 miles (10 kilometers). Hydra’s reflectivity (the percentage of incident light reflected from the surface) is intermediate between that of Pluto and Charon. “New Horizons has finally nailed the basic physical properties of Hydra,” says Hal Weaver, New Horizons Project Scientist and LORRI science operations lead. “We’re going to see Hydra even better in the images yet to come.”

Image Credit: NASA-JHUAPL-SwRI

Hydra was approximately 400,000 miles away from New Horizons when the image was acquired.

Charon natural colour image:


Pluto’s largest moon Charon has youthful terrain & dark area nicknamed ‘Mordor’ in north

Remarkable new details of Pluto’s largest moon Charon are revealed in this image from New Horizons’ Long Range Reconnaissance Imager (LORRI), taken late on July 13, 2015 from a distance of 289,000 miles  (466,000 kilometers).

A swath of cliffs and troughs stretches about 600 miles (1,000 kilometers) 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 (7 to 9 kilometers) deep.

Mission scientists are surprised by the apparent lack of craters on Charon. South of the moon’s equator, at the bottom of this image, terrain is lit by the slanting rays of the sun, creating shadows that make it easier to distinguish topography. Even here, however, relatively few craters are visible, indicating a relatively young surface that has been reshaped by geologic activity.

In Charon’s north polar region, a dark marking prominent in New Horizons’ approach images is now seen to have a diffuse boundary, suggesting it is a thin deposit of dark material. Underlying it is a distinct, sharply bounded, angular feature; higher resolution images still to come are expected to shed more light on this enigmatic region.

The image has been compressed to reduce its file size for transmission to Earth. In high-contrast areas of the image, features as small as 3 miles (5 kilometers) across can be seen. Some lower-contrast detail is obscured by the compression of the image, which may make some areas appear smoother than they really are. The uncompressed version still resides in New Horizons’ computer memory and is scheduled to be transmitted at a later date.

The image has been combined with color information obtained by New Horizons’ Ralph instrument on July 13.

Now Pluto zoomed in, the first of a mosaic that will:


New close-up images of a region near Pluto’s equator reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body.

The mountains likely formed no more than 100 million years ago — mere youngsters relative to the 4.56-billion-year age of the solar system — and may still be in the process of building, says Jeff Moore of New Horizons’ Geology, Geophysics and Imaging Team (GGI). That suggests the close-up region, which covers less than one percent of Pluto’s surface, may still be geologically active today.

Moore and his colleagues base the youthful age estimate on the lack of craters in this scene. Like the rest of Pluto, this region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered — unless recent activity had given the region a facelift, erasing those pockmarks.

“This is one of the youngest surfaces we’ve ever seen in the solar system,” says Moore.

Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape.

“This may cause us to rethink what powers geological activity on many other icy worlds,” says GGI deputy team leader John Spencer of the Southwest Research Institute in Boulder, Colo.

The mountains are probably composed of Pluto’s water-ice “bedrock.”

Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. “At Pluto’s temperatures, water-ice behaves more like rock,” said deputy GGI lead Bill McKinnon of Washington University, St. Louis.

The close-up image was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 478,000 miles (770,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across.

Image Credit: NASA-JHUAPL-SwRI

The lack of impact craters observed in this picture and on all of Pluto suggests that it is geologically a very young planet.

An isolated small planet that’s showing recent activity. Very active.

The bedrock that makes those mountains must be made of water ice – H2O.

They have no idea at this stage how the mountains have formed.

The youthful surface is a major surprise.

There will be heaps more details and photos to come. This is just the tip of the ice planet.

For reference here is the long distance shot of Pluto from a couple of days ago.


The zoomed image above is of the bottom edge of what you see here.