New Horizons probe successfully arrives at Pluto

[Eternal_Freedom]

Minor nitpick, it's rogue not rouge[/]. Rouge is a colour.

[Borgholio]

No, all rouge planets found are bigger than Jupiter, not smaller than Mercury. They aren't planets because they don't orbit a star, they wander around the galaxy as "rouge" objects.

Ok see we were talking about planets within the solar system, not the objects wandering in interstellar space. In that case, they are all bigger than Jupiter and may in fact be brown dwarfs. So they are either labeled as brown dwarf, sub-brown dwarf, or rogue planet. So they are given their own unique name because they are obviously not the a typical planet that you would find orbiting a star.

Your question was why you can't have a really large dwarf planet? Well again one of the definitions of a dwarf planet is that it has not cleared out it's orbital path of debris. If it's really large, such as one of the current 8 planets, then it would be expected to have enough gravity to clear it's path. If it didn't, they it would probably be classified as something new, since it doesn't fit the standard idea of a dwarf planet. Here is (IMO) a reasonable way to think about it:

Of all the current planets with the current definition, Mercury is the smallest planet at twice the size of Pluto. If an object is found in the Kuiper belt that is smaller than Mercury and hasn't cleared it's orbital path, then it's a dwarf planet. If it HAS cleared it's path, then it's a planet. If in the unlikely event it's Mercury-sized or bigger and has not cleared it's path, then either it will be defined as a planet that's in an area of the solar system too volatile to be permanently cleared, or it will be defined as something new...but like hell if I know what it could be.

[Borgholio]

Minor nitpick, it's rogue not rouge[/]. Rouge is a colour.

So would Mars be a Rouge planet?

[Eternal_Freedom]

I see what you did there. And it was bad.

[Borgholio]

I see what you did there. And it was bad.

You're welcome.

[Borgholio]

Update - New Horizons takes first color images of Pluto and Charon.

http://www.wired.com/2015/04/plutos-fir ... ons-probe/

[Iroscato]

It's not much, but it's still fucking incredible.
What a strange and beautiful paradox

[SpottedKitty]

Pretty good, considering how far away Pluto still is — about 3/4 the distance from the Earth to the Sun. We can see Charon; I wonder how soon the smaller satellites will become visible?

[Simon_Jester]

The 'second and third' satellites are about one tenth to one twentieth the size, so they will likely be visible from one tenth or one twentieth the distance.

The 'fourth and fifth' satellites are in turn about one tenth the size of THOSE, so they will likely be visible from about one tenth of THAT distance.

[Borgholio]

Yeah the other moons are pretty tiny. We should get a nice closeup look at them though in a couple months.

[Borgholio]

And right on schedule, New Horizons just got a pic of the entire Pluto family.

http://www.nasa.gov/image-feature/nasa- ... nown-moons

I'm getting excited here. Not too much longer and we get closeups of the surface!

[SpottedKitty]

I'll try not to <squee> too loudly when that happens.

Some fascinating stuff coming down from Dawn as well now that it's finally closed in enough for mapping orbits — those big bright spots on Ceres are apparently tight clusters of little bright spots and even tinier bright spots, the smallest so far visible maybe a mile or two across.

[Borgholio]

New images from Pluto. The probe has gotten close enough to begin seeing some surface details. Still quite fuzzy, but getting there!

http://www.nasa.gov/feature/different-f ... w-horizons

[Iroscato]

Is it me, or is that not exactly a smooth sphere? Looks very lumpy, though it's probably trick of the light/too soon to tell anyway...

[Eternal_Freedom]

Is it me, or is that not exactly a smooth sphere? Looks very lumpy, though it's probably trick of the light/too soon to tell anyway...

I can see what you mean, but it's probably just illumination.

[Broomstick]

Might even be a little of both - if it's truly much more lumpy than the average "full size" planet that's yet another argument for the "dwarf planet" or "Kuipier object" status.

It's very exciting for us geeks.

[Borgholio]

Yeah it's still 24 million miles away. The pics we'll be getting next month are going to be fantastic though!

[orbitingpluto]

Is it me, or is that not exactly a smooth sphere? Looks very lumpy, though it's probably trick of the light/too soon to tell anyway...

A Planetary Society blog post touched on this, it is a trick of light and how the camera works.

A lot of people are commenting that Pluto does not look round in these photos. You're right, it doesn't look round, but that's just an artifact of the way the camera works and the way the images have been enlarged and processed. The processing tends to turn anything that is especially bright into something that looks like a mountain, and anything that is especially dark into something that looks like a hole. In fact, since Pluto is quite large enough for the force of its self-gravity to overcome the strength of its icy material, there is no question that it will be very much round, more round than Ceres. (Pluto has the same density as Ceres, so has similar ice/rock composition, but Pluto has more than 14 times Ceres' mass, so its gravity is significantly stronger.) Roundness is one of the very few things that we can confidently predict about Pluto before New Horizons' flyby, because basic physics does a remarkably good job of predicting bulk physical properties of space objects.

[Iroscato]

Is it me, or is that not exactly a smooth sphere? Looks very lumpy, though it's probably trick of the light/too soon to tell anyway...

A Planetary Society blog post touched on this, it is a trick of light and how the camera works.

A lot of people are commenting that Pluto does not look round in these photos. You're right, it doesn't look round, but that's just an artifact of the way the camera works and the way the images have been enlarged and processed. The processing tends to turn anything that is especially bright into something that looks like a mountain, and anything that is especially dark into something that looks like a hole. In fact, since Pluto is quite large enough for the force of its self-gravity to overcome the strength of its icy material, there is no question that it will be very much round, more round than Ceres. (Pluto has the same density as Ceres, so has similar ice/rock composition, but Pluto has more than 14 times Ceres' mass, so its gravity is significantly stronger.) Roundness is one of the very few things that we can confidently predict about Pluto before New Horizons' flyby, because basic physics does a remarkably good job of predicting bulk physical properties of space objects.

I thought it might be something like that given Pluto's mass. Thanks

[Borgholio]

Only one million miles to go! Probe is close enough to be picking out surface features such as craters and mountains.

http://www.nasa.gov/feature/one-million ... -than-ever

And here's a live progress tracker for the probe too:

http://eyes.jpl.nasa.gov/eyes-on-pluto.html

[Borgholio]

And we have flyby!

http://www.nasa.gov/mission_pages/newho ... index.html

First closeup color images of Pluto:

http://www.nasa.gov/image-feature/a-por ... and-charon

Beautiful. This is sweet. It's a shame we can't get live video from the probe, but distance and all that.

Edit - check out the Google doodle for today. heh

Edit - live briefing on NASA TV:

http://www.nasa.gov/multimedia/nasatv/

[Eternal_Freedom]

Damn, are those two objects actually that close to each other?

[Borgholio]

Damn, are those two objects actually that close to each other?

I think so. The images are composites of the black and white + color data taken recently but I see nothing saying it's a composite of separate images of Pluto and Charon. I think they really are that close...which screams "binary planet" to me.

[Eternal_Freedom]

Well I knew they were pretty close in but I thought it'd be, I dunno, half the Earth-Moon distance or something, not "We can get them both in one neat photograph and still see surface detail."

[Borgholio]

I'm sure that's just one of many surprises waiting for us once the full data starts coming back.

Oh and watching NASA TV - it's hilarious to see the head engineers and mission planners complaining that they arrived at Pluto a minute and a half early, missing the exact aim point by 70km.