The Best Picture from Pluto So Far

The New Horizons spacecraft, which flew by Pluto in July, is slowly continuing to send back the images and data it took. The latest batch contains some of the most detailed close-up pictures of Pluto we have ever seen and they are fascinating!
Let’s take a look at the most intriguing new picture for a minute. We are seeing the greatest detail the spacecraft cameras were capable of. In a scene about 50 miles wide, we can make out details as small as half a city block. We see the shoreline of the Sputnik plains (part of the giant heart-shaped feature that caught everyone’s attention on the early pictures.)

The “rocks” that make up the mountains in the upper left are made of water – which is harder than rock at Pluto’s freezing temperatures. Some of these mountains are more than a mile and half high, with some of their sides bright with ice and others coated in a darker material that we are still learning about. This darker material may fall out of the sky, when ultraviolet light from the distant Sun causes chemical changes in Pluto’s thin atmosphere.

Notice how abruptly and cleanly the mountain end and give way to the softer, nitrogen-rich ice that makes up the Sputnik plains. In that ice, you can see huge but subtle cell-like structures. What makes up and drives this cell-like structure is still being debated by astronomers. Material in and around these cells may be moving up or down, like the cells you see when you boil miso soup. (If you've never boiled miso soup, ask a Japanese friend to tell you about it.) Cold nitrogen and methane ice might behave similarly when it is heated by the slightly warmer insides of Pluto and the faint heat of the Sun.
In an earlier photo, you can see some dark hills poking up at the boundary between cells, so this is very complicated terrain we are looking at. See the picture below. 
But just enjoy looking at the alien vista New Horizon’s cameras revealed. Pluto is not simple or boring!

New Pluto Images Reveal Glaciers Flowing from the Heart

New images released from the New Horizons spacecraft's encounter with Pluto reveal a reddish world, where water is as hard as rock, and substances that are gas on Earth have become ice glaciers. The beautiful color picture with this post shows you a section of Pluto that includes the heart-shaped feature named after Clyde Tombaugh, Pluto's discoverer. The left lobe (section) of the heart is being called the "Sputnik region," after the first satellite humanity ever sent into outer space.

Why is Pluto reddish? The team's first thought is that ultra-violet light from the Sun acts on the gases in the thin Pluto atmosphere -- methane (natural gas) in particular -- and breaks them apart and reforms them into more complicated combinations of hydrogen and carbon. Eventually, the molecules get so complex and heavy, they fall out of the air and coat the surface. Such hydrocarbons tend to be reddish when we see them on other worlds.

The New Horizons craft has only returned about 5% of the data it has stored in its memory, but even first results show haze layers in the Pluto atmosphere that support the notion of the air having chemical reactions going on, despite the cold.

If you look at the Heart in the picture, you can see that the left Sputnik region (which is about the size of Texas) has a thicker covering of ice than the right half of the Heart. Our black-and-white image shows a close-up about 250 miles wide in the northern part of Sputnik. At the top you see some of the older, cratered terrain that is above the Heart. But below that, the Heart itself is smooth and young-looking (no craters, which are a sign of age.)

The smooth ice we see is made of nitrogen, methane, and carbon monoxide, its top layers freezing out of the air when Pluto gets further from the Sun. (Pluto was closest to the Sun in its almost 250-year orbit in 1989, so we are just moving away from the time that Pluto is warmest.)

At Pluto temperatures, an ice made of nitrogen will very slowly flow, like a glacier flows across the landscape on Earth. The arrows on our black-and-white image show the direction scientists think the ice is flowing in Sputnik. At Friday's press conference, the experts said that their impression of Sputnik is that it's a very young region (geologically speaking) -- perhaps only tens of millions of years old. (For comparison, we think Pluto, like the rest of the solar system, is 4600 million years old.) Its glaciers have moved into any available regions next to Sputnik, and have filled valleys and craters on all sides.

Look also at the intriguing "polygon" patterns (many-sided figures) in the ice of Sputnik on our picture. They look like huge, geometric cells in the ice, perhaps half a mile or more deep. One possibility is that in these cells, hotter material from deeper inside is slowly rising, a process called "convection."

These images and ideas are just the (pardon the expression when discussing Pluto), just the tip of the iceberg. It will take 16 months for the full set of pictures and data to be sent back from New Horizons. Better images are expected in September, for example. Stay tuned.

In this last image, you see Pluto (left) and its large moon Charon in realistic color.  Such a dramatic pair at the outskirts of our solar system!