

New Horizons Becomes Closest Spacecraft to Approach Pluto - carbocation
http://pluto.jhuapl.edu/news_center/news/20111202.php

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jarin
I'm glad I'm not the only one who still calls it a planet :)

> … until its closest approach – about 7,767 miles (12,500 kilometers) from
> the planet – on July 14, 2015

> But by the time New Horizons sails through the Pluto system in mid-2015, the
> planet and its moons will be so close that the spacecraft’s cameras will
> spot features as small as a football field.

~~~
ehthere
The new 'dwarf planet' designation was a stroke of genius. It's not a planet
but it ends in 'planet' so everyone is happy!

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geuis
A thought struck me that I find amazing. New Horizon's is traveling over 2.6x
the distance from the Earth to the Moon in a day. Average distance is
384403km. NH is moving faster than 1 million km per day.

It took the Apollo crafts about 3 days and 4 hours to reach the Moon
(specifically 3 days, 3 hours, 49 minutes).

Even at New Horizon's speed, it takes _10 years_ to reach Pluto.

Damn, space is big.

~~~
tokenadult
In elementary school, I charted out the average distance of each planet (yeah,
in those days I called Pluto a planet) from the sun on common scale on an
adding machine tape. Mercury, Venus, Earth, and Mars were all very close to
the beginning end of the tape. The outer planets were far, far away, and the
tape wrapped around several walls of my elementary school classroom. Yep,
space is big.

And all the distances within the solar system are beggared by the distances
between distinct stars in our galaxy, not to mention the distances among
different galaxies. Arthur C. Clarke wrote an essay about these facts, titled
"We'll Never Conquer Space."

[http://en.wikiquote.org/wiki/Arthur_C._Clarke#We.27ll_Never_...](http://en.wikiquote.org/wiki/Arthur_C._Clarke#We.27ll_Never_Conquer_Space_.281960.29)

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boneheadmed
I'm curious as to how much of the planet (I know, I know it's been demoted)
the craft will be able to "see". That is given the distance from the sun will
it be draped in darkness, barely visible?

I had a comic as a kid that had these really freaky cold aliens that lived on
Pluto in very dim light conditions. That's my only reference point.

~~~
celoyd
Astronomers drove digital imaging sensitivity, so I reckon they’ve got it
worked out. Skimming <http://arxiv.org/pdf/0709.4281v1> , it looks like Ralph,
the main visible-light camera, can distinguish between true blackness and a
mere 3k photons per pixel, and at the margin can detect objects of magnitude
14. Coincidentally, that’s about the magnitude of Pluto from earth, and you
can’t see it even with a small backyard telescope. So this instrument is less
like a consumer camera and more like, say, night-vision goggles.

This paragraph originally did the math for Pluto’s brightness wrong (thanks to
atakan_gurkan below for pointing that out), so instead let me refer you to a
short but interesting Metafilter thread on exactly this question:
<http://ask.metafilter.com/23197/Darkness-at-the-edge-of-town> .

One more factor – Pluto’s albedo is quite high. It reflects 0.5 to 0.66 of the
light falling on it, as opposed to e.g. 0.14 for the moon (which is fairly
dark in the scheme of things, but not at all hard to photograph; you can
easily overexpose it in a grainless photo with a recent consumer DSLR).

So: dim, yes, but still clearly visible.

~~~
atakan_gurkan
Brightness drops off inversely proportional to the square of the distance, not
square root.

Still, I think there will be plenty to see. I am quite excited about this
actually.

