As for your question, it looks like Pluto has an atmosphere in the picture because, well, it does. Although it's very thin, Pluto's atmosphere is primarily nitrogen, so if you stood on the surface during daytime the sky would appear a very familiar blue color.

Here's another shot taken by New Horizons where you can see it much more clearly: https://upload.wikimedia.org/wikipedia/commons/0/02/Blue_hazes_over_backlit_Pluto.jpg

[–] wjrii@lemmy.world 26 points 1 day ago (2 children)

Short answer? Because it does. It doesn't take much to be visible compared to space.

[–] ShittyBeatlesFCPres@lemmy.world 13 points 1 day ago (1 children)

I don’t think any planet^1^ has surprised us more than Pluto.

^1^ I know. If anyone gets pedantic, they’re reclassified as a dwarf clown.

[–] FaceDeer@fedia.io 5 points 1 day ago (1 children)

Pluto's atmosphere has been studied since the 1980s, using spectroscopy and stellar occultation (watching starlight flicker as Pluto passed in front of it). It wasn't a surprise when New Horizons observed it.

[–] ShittyBeatlesFCPres@lemmy.world 6 points 1 day ago

I wasn’t thinking about the atmosphere. I meant in general, Pluto surprised more than other first fly-bys. Uranus is obviously extra weird in a lot of ways but who was expecting Pluto to be as interesting?

[–] Sibbo@sopuli.xyz 6 points 1 day ago

Oh wow that's really cool! I didn't know.

It's about one millionth of the pressure of earth's atmosphere at sea level.

[–] metaStatic@kbin.earth 9 points 1 day ago (1 children)

(Old)

Hey, fuck you this only happened ... checks watch ... 9 years ago? God Damn, we are getting old.

[–] very_well_lost@lemmy.world 8 points 1 day ago* (last edited 1 day ago)

Hey, if you wanna feel really old, look up how long it's been since Pluto was demoted from being a planet.

spoiler alert: its been 18 freaking years

[–] Shotgun_Alice@lemmy.world 3 points 1 day ago

I use this photo as my computer background, it looks so good with a multiple monitor setup or extended display. Sadly I have only my laptop, I do miss having an extra monitor.

[–] ThotIWasSomebody@lemmy.world 7 points 1 day ago (2 children)

That's a friggin planet....

[–] threelonmusketeers@sh.itjust.works 4 points 1 day ago

Always "Pluto, Pluto, Pluto". Why does no one ever remember Ceres, Eris, Haumea, and Makemake? They're each as much of a planet as Pluto is. Dwarf planets, but planets nonetheless.

[–] Zannsolo@lemmy.world 3 points 1 day ago* (last edited 1 day ago)

It's smaller than the moon, and six other moons

[–] doomcanoe@sh.itjust.works 2 points 1 day ago

The Old Adventures of the New Horizons

[–] cyberpunk007@lemmy.ca 0 points 1 day ago

Probably reflection of light from the other side if I had to guess.