Speaking of Pluto, one of my favorite web comics, Big Fat Whale, has a pretty funny one up about tabloid science.

Poor Pluto. First Mike Brown demotes it, then it’s caught in a custody battle.

I’m a big fan of satire, and BFW is a great mirror on society. I suppose some of it is NSFW, but then, that’s one of the reasons I work from home. Everything is SFW for me!

Astronomer Mike Brown is a friend of mine. He’s a pretty nice guy, and while he’s not exactly sad that he was instrumental in getting Pluto demoted from its planethood status — his Twitter handle is @PlutoKiller, after all — I don’t think he deserves all the slings and arrows he’s received.

And he certainly doesn’t deserve an elbow to the nose, as LA Laker Ron Artest recently said. I can understand Mr. Artest’s lament at some level, but physical punishment will only redouble Mike’s efforts, and who knows what will happen then! We might lose Neptune.

So if I had to think of suitable punishments, they’d be

1) a pie to the face,

2) a Benny Hill-style rapid-repeat slap on the top of the head,

3) a dressing down by Goofy, or just possibly

4) more telescope time.

I don’t think he’d disagree with any of these, with the exception of getting a pie to the face before more time on a telescope. Whipped cream is hard to get off a 10-meter mirror.

Tip o’ the nose guard to Jerome Clemente. Image credit: Ball Don’t Lie.

When Pluto was discovered 80 years ago, it happened to be moving through Gemini, a part of the sky that had a lot of stars. Clyde Tombaugh did an amazing job finding it, since it was almost lost among those stars.

I wonder if he could’ve found it had he been looking earlier this year? "Amateur" astronomer Anthony Ayiomamitis sent me this image he took of Pluto as was in Sagittarius, the most densely-packed area of the sky!

[Click to undwarfplanetate.]

Hard to spot, isn’t it? Pluto is unresolved in the picture, so it looks like just another star. And there are a lot of stars here; this region of sky is actually a cluster called Messier 24 (or just M24, and it’s pronounced "MEZ-ee-ay", since Charles Messier was French); the two dark splotches are thick dust clouds called Barnard 92 and 93. Finding Pluto in this ain’t easy.
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Pity poor Pluto. The debate over its planethood has caused much consternation over the years. Part of the problem is that it’s so dinky and so far away! If it were closer, or bigger, we almost certainly wouldn’t be having this debate.

But whether or not you think Pluto should be part of the gang or not, one thing is certain: it’s a world unto itself. And to bring this point literally home, the Hubble Space Telescope has revealed the changing face of this tiny iceball:

These images, just released today (but taken in 2002), represent the most detailed surface map of Pluto ever taken. Even in Hubble’s Advanced Camera for Surveys Pluto is only a few pixels across, but it’s possible using sophisticated image processing techniques to tease out the detail seen.

Here’s a nifty animation of Pluto rotating using these maps:

Very cool. But these maps are more than just eye candy. They show significant changes on Pluto’s surface since the last maps were made using Hubble 16 years ago. Pluto’s north pole is brighter and the south pole darker, implying that material has migrated from one pole to the other, or at least that the poles are changing in different ways. Pluto orbits the Sun "on its side", dramatically more tilted than Earth’s mere 23.5°. Right now, the north pole of the world is facing the Sun, meaning it’s summer on Pluto’s northern hemisphere (as it’ll remain for a long time, given Pluto’s 248 Earth-year long year).

Not only that, these images show that Pluto has reddened quite a bit in the past few years. This is one reason it took so long to release the images; Marc Buie, the astronomer who took them, saw some things in the data that were difficult to understand, and wanted to make sure they were correct. These images are composites of pictures taken using a blue and a green filter. During the time these observations were made, in 2000 – 2002, Pluto got much darker in blue, which was unexpected. Pluto’s moon, Charon, did not get any bluer, indicating that the cause was something intrinsic to Pluto and not that something weird happened with Hubble.

So why is Pluto redder now? That’s not clear. In general, ultraviolet light from the Sun interacts with the chemicals on Pluto, creating reddish organic molecules; this is seen on lots of distant, icy objects in the Kuiper Belt (the region past Neptune where Pluto orbits). Incredibly, even at the numbing distance of over 4 billion kilometers (3 billion miles) from the Sun, Pluto is still strongly affected by it. But this is happening while overall the northern hemisphere got brighter and the southern darker. You’d expect Pluto to get darker if it gets redder, so clearly there’s more going on here than meets the eye.

These maps will prove crucial in planning the imaging run of the New Horizons probe, which will scream past Pluto in 2015. Having even a crude map in advance of the encounter will help scientists plan their limited time more carefully.

Plus, these Hubble images may very well be the best view we’ll get until New Horizons gets to Pluto, for that matter. And whether you think Pluto is the littlest planet or one of the biggest of the Kuiper Belt Objects, it’s a fascinating place worthy of a lot more study. And in just a little more than five years we’ll see fantastic images of it, too. I can’t wait!

Video courtesy Emily Lakdawalla (and my thanks to her for a helpful conversation). Image and video credit: NASA, ESA, and M. Buie (SwRI)

I follow the New Horizons Pluto probe Twitter feed, and recently it linked to a graphic showing where the spacecraft is right now:

Man, is that way out in the black. The probe is now closer to the orbit of Uranus than it is to Saturn, though both planets are over a billion kilometers away from New Horizons right now.

The solar system is frakkin’ BIG (if I may mix my colorful scifi metaphors). If you’re still not sure just how roomy things are out there, even at its current speed of 16.5 km/sec (10 miles/sec) — fast enough to cross the entire United States in five minutes — New Horizons won’t pass the orbit of Uranus until March 18, 2011, more than a year from now. Neptune’s orbit isn’t until August 24, 2014.

One thing to notice: from this point of view, planets revolve around the Sun in a counterclockwise fashion. Given the position of Pluto, you can see the two are heading for a close encounter soon. Well, for a sufficiently broad definition of "soon": July 14, 2015.

Space is big.

Today, December 29, 2009, the New Horizons Pluto probe crosses an arbitrary but psychologically important line: it is now closer to Pluto than it is to Earth.

If there were people on board the small interplanetary probe, no doubt they’d be popping champagne. I’m sure that back on Earth, the team behind NH are pretty happy. This probe has a checkered history, having been planned, canceled, re-planned, delayed, on and on. It’s amazing it got to launch at all. But on January 19, 2006 the small, half-ton probe was sent on its way, and on July 14, 2015 it’ll sail past Pluto and its collection of moons, snapping pictures and taking data.

Today marks the official halfway point, where New Horizons has half its path already behind it. Here’s a plot of its distance to Earth (in blue) and Pluto (red) care of the New Horizons site:

Distance in the graph is measured in Astronomical Units (a yardstick used by astronomers for convenience; it’s the distance of the Earth to the Sun, about 150 million km (93 million miles)). The distance to Earth is wiggly because the Earth goes around the Sun as New Horizons moves out, and the distance to Pluto decreases steadily as the spacecraft catches up on its journey. Where the two lines cross is where the distances are equal, and that’s now, today!

You may be wondering about the timing: New Horizons is halfway in distance to Pluto, but the mission timeline halfway point isn’t until October 16, 2010 (if I’ve done the math correctly). The probe was launched at high speed, slowed down due to the Earth’s and Sun’s gravity, picked up a kick from Jupiter in early 2007, and has been slowing ever since. Since it was moving faster before, it reached the distance halfway point before the schedule halfway point.

New Horizons is now 16.37 AU – 2.449 billion km, or 1.522 billion miles — from home. But maybe now, home is no longer Earth. Once it crossed that line today, home became deep space. Even Pluto and its moons Charon, Nix, and Hydra are only milestones for it. It won’t be stopping when it gets there; New Horizons will sail on by, continuing into deep space. It’ll become one of several other spacecraft we’ve sent out of the solar system itself, set to wander interstellar space forever.

That is, unless one day we catch up to them ourselves. I imagine in a few hundred years they’d make fine museum pieces. Or maybe, if poetry still exists in humans all those far-flung centuries from now, we’ll let those probes continue on. I rather like that idea better.

You can follow the New Horizons probe on Twitter, which is how I found out about this milestone today.

Art credit: ESO/L. Calçada

Speaking of web pages showing scale (OK, it was almost two weeks ago, but still cool), BABloggee Mike Sperry reminded me of this site which shows the solar system to scale… all on one web page! The Sun is displayed when you go to the page, and you can scroll to the right to see the planets, drawn in scale both in size and distance.

The Sun is about 560 pixels wide, putting Pluto something like 2 million pixels to the right. And some people wonder why it’ll take the New Horizons mission 9 years to get to Pluto…