The team of researchers from Southwest Research Institute (SWRI), in San Antonio, Texas, U.S.A., aren't sure about all of the details about why dwarf planet Pluto because the Hubble Space Telescope only can provide 'fuzzy' (at best) images of one of the outermost celestial bodies in the solar system.

However, 'new' help in just over the 'horizon', compliments of NASA's robotic, unmanned space program.

According to the NASA Science News (April 16, 2010) article 'The Mysterious Molasses Markings of Pluto,' new images of Pluto has just been released, and they are the best resolution images we have of the recently demoted planet Pluto, which is now classified a dwarf planet.

Check out three such images'”90 degrees, 180 degrees, and 270 degrees'”from the Hubble telescope at 'Pluto Faces.' The images are courtesy of NASA, the SWRI, and the European Space Agency (ESA).

There is a lot about Pluto scientists just don't know about Pluto.

U.S. planetary astronomer Mike Brown, of California Institute of Technology, who studies dwarf planets in the outer solar system, comments on Pluto: "It's baffling. For now, we can only guess. Although these images are the best we have to date, they just aren't clear enough to answer all the questions they raise."

These scientists do know that Pluto has a thin atmosphere made up of primarily nitrogen and methane.

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Between mid-1880s and mid-1980s, its northern hemisphere was tilted away from the Sun. During these one hundred years or so, its atmosphere froze and fell to the ground as frost.

However, since the 1980s, the northern hemisphere has gradually become tilted toward the Sun, which warms up that half of the body. (Thus, the southern hemisphere is not tilted away from the Sun.)

According to the NASA article, Dr. Marc W. Buie, the lead researcher at Southwest Research Institute, compared images taken by Hubble from 1994 and again taken in 2003.

Dr. Buie, who researches Pluto and other Kuiper Belt objects (KBOs) verified that the northern hemisphere of Pluto has brightened while the southern hemisphere has darkened.

And, during this same time, the atmosphere of the northern hemisphere has doubled in mass due to more of it converting from solid frost to a gaseous state, once again in the atmosphere above its surface.

The overall atmosphere of Pluto is also larger in mass than it has been since we've been tracking it. Astronomers think this is due to Pluto's highly eccentric orbit.

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NASA states, 'During the late 1980s, Pluto approached as close to the sun as it ever gets (about 2 1/2 billion miles) and gradually started warming. Now the temperature on Pluto is up to a balmy -385 degrees Fahrenheit! Surface frosts exposed to such "warmth" may be subliming'”that is, changing back into a gas.'

And, Brown adds, "Now, Pluto is headed away from the sun again. It will gradually get colder and colder and its atmosphere will refreeze to its surface. In fact, that should have already started happening, but apparently it has not. It's a mystery."

Thus, with all of this going on, scientists have concluded that a lot of activity takes place on Pluto'”more than they expected and much of it still a mystery to them.

For instance, one interesting, but yet unexplained feature on Pluto are molasses-colored patches. Astronomers do not know why they exist.

Here is their hypothesis: 'Researchers think these dark areas may be primordial organic matter.' [NASA]

Dr. Brown states, "We know there's methane on Pluto. Here's what we think happens: Sunlight hits the methane and breaks it apart into its chemical components -- hydrocarbons. Over millions of years this process makes a dark reddish-brown oil or tar like substance that sticks to the ground. These darker areas spread larger as they absorb more sunlight and cause additional frost to sublimate." [NASA]

Sublimate is a term that means turning from a solid to a gas.

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If you go to the NASA article mentioned earlier, you'll see an artist's drawing of what scientists think Pluto looks like. A frozen wasteland comes to mind!

Although astronomers have only a spotty knowledge of Pluto, that spottiness may change when the New Horizons spacecraft arrives for a scheduled visit around Pluto in July 2015. Its mission is called the Pluto-Kuiper Belt Mission.

Launched on January 19, 2006, the spacecraft is racing toward the dwarf planet. In fact, its speed is the fastest for any spacecraft to leave Earth. When its engines shut down it was traveling at a speed of about 16.26 kilometers per second (58,536 km/h), or 10.10 miles per second (36,373 mi/h).

Dr. Buie states, "New Horizons will map the entire sunlit portion of Pluto. And as it swings closer, it will get very detailed images, maybe as good as 50-100 meter resolution."

He adds, "This will allow us to explore some of the interesting areas we've pinpointed. For example, the recent Hubble images reveal a very bright spot - brighter than anything else on Pluto - near the equator.'

'And just to the left of that bright spot is some of the darkest terrain on Pluto's surface. We want to examine the area where these bright and dark areas are touching and figure out what's causing the differences. This is a good target because it includes every kind of terrain Pluto has to offer."

Buie concludes, "We know there are surprises waiting for us on Pluto.'