Pluto!!!

[Atheon]

After a journey of almost a decade, the New Horizons space probe is less than a week away from its Pluto flyby! Every day, better pictures are coming in! By this time next week, we should have beautiful, crisp, clear photos of the ninth (yes, ninth) planet (yes, planet)!

I can't wait!!

http://www.nasa.gov/feature/nasa-s-new-horizons-a-heart-from-pluto-as-flyby-begins

[SGOS]

Modern man has only been on Earth for maybe 50 to 100 thousand years, and now he's flying by the outermost planet of our solar system.  That's actually a pretty spectacular quirk of evolution.  Just think of all the good man could have done while he was fighting all those wars, arguing over which god is the right god, and trying to subdue everyone else on the planet.  We are an odd species.

[Munch]

It's humbling knowing our species did this, and we're get to see clear images of it.

It's just a shame only now that it's reached Pluto, do they decide it isn't a true planet. Always did feel bummed out it got cut down like that.

It doesn't even show Pluto on my orrery app anymore

[Draconic Aiur]

pluto is a planet again

[Munch]

pluto is a planet again

Wasn't it up for debate but its not been classed as of yet?

[trdsf]

It's just a shame only now that it's reached Pluto, do they decide it isn't a true planet. Always did feel bummed out it got cut down like that

Why?  Ceres isn't a planet either and we have a probe there, to say nothing of the Rosetta/Philae mission.  Pluto is vastly important as both the nearest (known) plutino and KBO - maybe even moreso as the prototype object of a whole new class, rather than as the oddball outermost tiny rock/ice cube.

The 'demotion' isn't unprecedented -- Ceres was considered the fifth planet until it was realized that there was a whole class of objects of which it was the first discovered.

While I'll agree that the IAU's definition isn't completely satisfactory, they're right.  Pluto's not a planet.  I still can't wait for what New Horizons sends back, planet or not.  The red color is weird; it kinda looks like old two-tone Technicolor.

The problem with Pluto's planethood (or not) is that it's not possible to define a planet in a consistent way so that we end up with just nine.  The IAU's first definition promoted Ceres, Eris, and Pluto's moon Charon to planet status so we'd've had 12 (and counting).  I'd've been perfectly happy with that -- it was a rigorous definition (an object that is sufficiently massive for gravity to force it to be round, and in direct orbit around a star, and not a star itself).  Likewise, the current definition makes sense -- an object in hydrostatic equilibrium in direct orbit that has cleared its local space and isn't a star or in orbit around another object.

There are problems with the current definition -- the main ones are that it's heliocentric so it doesn't apply to exoplanets, and that it should say 'controls' rather than 'has cleared' its local space.  Neptune's local space isn't cleared, Pluto crosses into it.  Jupiter's local space isn't cleared, it has hundreds, maybe thousands, of Trojan asteroids both leading and trailing.  But these planets control their orbital zones -- Pluto is in a 3:2 resonance with Neptune because of Neptune's greater gravity, and the Jovian Trojans are there because of Jupiter's gravity.

[Atheon]

pluto is a planet again

Link?

I've always maintained that it is a planet (in a "once a planet, always a planet" kind of way). However, I have heard of no official announcement by the IUA that it has been reclassified as a planet.

[Cocoa Beware]

At 1:06 almost it looks like a drawing, but its actually a composite image taken by the craft on July 7, amazing:

https://www.youtube.com/watch?v=EB1qGrCLKao

Its surreal. Apparently Pluto might even have clouds, they just aren't close enough yet to determine either way.

[AllPurposeAtheist]

Hey! I thought I saw Jesus back there!

[Mike Cl]

I don't care what they call it--being this close and having pictures is absolutely amazing!  And besides, if Mickey thinks Pluto is cool, then Pluto, is cool!!

[Atheon]

Pluto and its moon Charon

[Shiranu]

A. Pluto isn't a planet, get over it >:-).

B. Oh lawrdy, these photos... they make me feel things.

[trdsf]

It's so red!  But it's not iron oxide like on Mars... weird.  This is so awesome.  :D

I think what's really getting me about this is that this is the first time Pluto has been a place, not just a fuzzy blob.  It amazes me that it can get such great pictures moving as fast as it is, and with so much less light to work with.

[Atheon]

[Cocoa Beware]

That is astonishing, and the best part is these images are going to get even better at an accelerated rate over the next few days.

I think this image is about 75 pixels in diameter;

on the 10th it will be 89;

on the 11th it will be 120;

on the 12th 189;

I believe the best quality image is expected to be about 5000 pixels across.