Pluto On the Horizon!

Artist's concept of a Pluto landscape, with moon Charon on
the horizon. NASA.I've been waiting for some new news from the outer reaches of our solar system. Sometimes it seems the very cold, very dark netherworld beyond Neptune is a very uneventful region. Things move more slowly, the Sun's dim light only tickles the frigid atoms and molecules out there, and being so far removed from our robotic and telescopic scrutiny, we don't see much to begin with. But, thanks to the Hubble Space Telescope, my favorite dwarf planet, Pluto, is on the horizon again!

Observations of Pluto have been made by Hubble before, bringing us the most detailed images of that small world ever taken. Still, the images reveal little more than variations in shading, and in the most recent observations, some color.
The recent images show the dwarf planet from different angles, grabbed at different times as Pluto slowly rotates, once about every six days. The darker areas have been characterized as having a "molasses" color—I'm assuming that means very dark brown, as that's the color of molasses in the bottle in our kitchen.

So, is Pluto's surface oozing with syrupy sugars? First of all, nothing should be oozing at all under the temperatures Pluto routinely experiences. Since Pluto reached its closest approach to the Sun back in the 1980s—something that happens only every 248 years—temperatures have risen to their highest in our lifetimes, and are now up to about -385 degrees Fahrenheit. Yeah, minus. Global warming on Pluto….

While scientists don't yet know what the deep brown regions are, some expect it has something to do with Pluto's methane, the existence of which we've known for some time from spectroscopic measurements. Methane is a hydrocarbon—an "organic molecule"--whose chemistry is part of the basis of life on Earth.

That's not to say there's life on Pluto—but one theory about the molasses-colored patches is that it may be some sort of tar-like substance that has developed over millions of years from the Sun's weak rays interacting with Pluto's methane. Over its seasonal and orbital gyrations, Pluto's methane cycles from being frozen solid on the ground to being a gas and forming a thin atmosphere; right now that atmosphere is as thick as it's ever been in our lifetimes.

Will astronauts in the distant future have to worry about getting stuck in something sticky when they walk around on Pluto? Too early to tell….

Since childhood I've been fascinated by Pluto—probably more for our lack of knowing it than for anything we actually know (which isn't a whole lot: small, cold, dark, slow, patchy brown, methane, three moons; that's the lion's-share of our knowledge). It's a place of mystery, not unlike Mars and Venus, or Jupiter's Galilean moons, were long ago (like in my childhood), before we sent spacecraft to see them up close, and before we had the powerful eye of Hubble. Mars, at least, we're getting to know pretty well; it still holds plenty of mysteries, but somehow feels not so far removed, and familiar.

And, something else is on the horizon in the exploration of Pluto: in five years, NASA's New Horizons spacecraft will whiz by and in a few short hours collect an amount of information that will absolutely dwarf all that we have learned since Pluto was discovered in 1930. It's like the treks of Pioneer and Voyager all over again, back in the 1970s and 1980s, when we first visited the Gas Giant planets, and moons like Io and Europa went from being fuzzy blobs with variations in surface shading and color to worlds with craters and volcanoes and ice fissures and…well, let's just say I can hardly wait to get that up-close glimpse of Pluto.

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