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Comment by strictnein | Hacker News Reader

Pluto being that red never crossed my mind. Although I'm a little unclear on whether or not it even gets enough sun for the human eye to see that color. If it was daytime on Pluto, would one even be able to, say, read outside?

I wonder if the light from the stars of our galaxy would provide more or less light than the sun?

Edit: To answer my own question, Phil Plait wrote about this here: http://blogs.discovermagazine.com/badastronomy/2012/03/15/ba...

> "[on Earth] the Sun is about 400,000 times brighter than the full Moon, so even from distant, frigid Pluto, on average the Sun would look more than 250 times brighter than the full Moon does from Earth"

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NASA have a tool here:

http://solarsystem.nasa.gov/plutotime/

Tell it where you live, and it'll tell you what time the light there matches an average day on Pluto, so you can go out and try it. It's surprisingly bright.

Quite surprised by that - it said 7:10pm for here in Edinburgh - which is just after sunset so still fairly bright.

I checked at 7:10pm and perfectly easy to read a book - really not what I would have thought at all.

Oh, wow. That's really neat. A little after 7pm for me. I'll be stepping outside with a book to see if I can read it.

Careful: Pluto would not look like these latest pictures to the naked eye. This image is constructed from blue, red, and near-IR color channels that have been mapped to blue, green, and red in the pictures. There's a bit more about how this image was constructed here: http://www.planetary.org/blogs/emily-lakdawalla/2015/0924142...

(The earlier "true color" pictures shared over the summer were created indirectly: my understanding is that they fit a spectral curve to the raw blue, red, IR data and then used software to reconstruct the green channel.)

Another HN commentator once gave me an excellent tip for getting an intuition for that sort of question: the ratio between a mile and an inch (63,360) is almost exactly the same as a lightyear and an astronomical unit (63,239). Pluto is at 40 AU, and the closest stars are at ~4 ly. So if you're sitting on Pluto and the sun is 40 inches (~ 1 m) away, the closest stars are about 4 miles (~6 km) away.

As far out as Pluto is, it is nowhere close to the next star, and the Sun is still overwhelmingly the brightest thing in the sky.

What's even weirder to think about, is the edge of the Oort cloud is about half way to the next star. So if it is possible for some sort of bacterial (or proto-life material) to survive, life could jump from one star to another via the intersecting oort clouds.

It's not. That's an "enhanced" color picture, meaning the colors you see include information from stuff like infrared images and whatnot. Maybe the contrast has been increased, or colors added to make certain features visible. Well, certainly a lot of work has been done to that image as the article suggests. Not surprising considering the extreme conditions the photograph was taken in (the speed of New Horizons, the light available, the instruments used, the fact that the data has to be sent over such a long distance, etc).

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