New Horizons Becomes Closest Spacecraft to Approach Pluto(pluto.jhuapl.edu)
pluto.jhuapl.edu
New Horizons Becomes Closest Spacecraft to Approach Pluto
http://pluto.jhuapl.edu/news_center/news/20111202.php
10 comments
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.
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.
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_...
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_...
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.
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.
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.
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.
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.
Still, I think there will be plenty to see. I am quite excited about this actually.
Fantastic replies. Thanks all. Very excited to see what's out there.
My understanding (which I got from an astronomer looking for moons) is that it'll be enough to get a clear look at major features on most (not all!) of Pluto's surface, but nothing spectacular. Realize that even today, we don't really know what Pluto looks like, so any knowledge is big knowledge.
There are some images from Hubble:
http://en.wikipedia.org/wiki/File:Pluto_animiert.gif
Pluto only fills up a few pixels on Hubble's camera, but it's possible over time to generate a rough image:
http://www.boulder.swri.edu/~buie/pluto/mapstory.html
http://en.wikipedia.org/wiki/File:Pluto_animiert.gif
Pluto only fills up a few pixels on Hubble's camera, but it's possible over time to generate a rough image:
http://www.boulder.swri.edu/~buie/pluto/mapstory.html
> … 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.