Comments on: BAFact math: how big does the Sun look from Pluto?

By: Matt B.

Matt B. — Tue, 24 Apr 2012 18:54:28 +0000

I hope that New Horizons will look back at the Sun, and that other stars will be visible in the shot. That would be amazing.

Burton MacKenzie somewhat mistakenly says “confronted by that giant ball of nuclear radiation”. In terms of what it looks like, the Sun is a ball of thermal radiation. That diagram is really interesting, though, because it also shows the inverse of the sizes of the planets’ orbits.

By: Leon

Leon — Tue, 20 Mar 2012 19:50:15 +0000

Hey Phil! Wouldn’t it be cool if NASA turned the probe and got a shot of the Sun from out there? Maybe when it’s made its flyby and they’re mostly done taking pictures of the Pluto system, they could turn the probe, take a couple pictures, and publish photos of the Sun from (roughly) Pluto’s orbit. I bet that would get some public interest, or at least curiosity. I know I’ve wondered what it would look like–and if I remember right, Heinlein speculated about it himself in “Have Spacesuit, Will Travel”.

By: Nigel Depledge

Nigel Depledge — Mon, 19 Mar 2012 10:23:32 +0000

Jeffersonian (12) said:

How bright would it be standing on Pluto – bright enough to read a book?

Booboo (4) said:

Of course, luminous flux associated with sunlight is about 10^5 lux. Divided by 40^2, the luminous flux of daylight on Pluto is about 60 lux, not really dark at all…many household interiors in the US run ~100 lux at night.

Hey, who’d ‘a thunk it, Jeffersonian? Your question was already answered in a previous comment.

By: Nigel Depledge

Nigel Depledge — Mon, 19 Mar 2012 10:22:03 +0000

MTU (11) said:

I can’t wait to see Pluto – my fave planet . . .

[Inhales]

[Thinks again]

No, I won’t open that can of worms again.

By: Jeffersonian

Jeffersonian — Sun, 18 Mar 2012 23:30:14 +0000

How bright would it be standing on Pluto – bright enough to read a book?

By: Messier Tidy Upper

Messier Tidy Upper — Sun, 18 Mar 2012 04:59:18 +0000

Great post BA – Cheers!

@11. Kimberly Says:

In 2014, the spacecraft does cross the orbit of Neptune. Specifically, on August 25, 2014 — exactly 25 years after Voyager 2 made its historic exploration of that giant planet. .. ( link snip) .. It’s hard to imagine it traveling at 15 km/s (34,000 mph), snapping images & taking data as it goes, but that is precisely what the scientists have designed the instruments aboard New Horizons to do for encounter fly-by. New Horizons: a mission of extremes. Takes a very long time to get there (9.5 years) for a brief (9 days of core science, with ancillary science plus/minus a few months) visit, followed by up to 300+ days to get the data down to Earth due to the immense distances and slow data rates supported by the Deep Space Network. In the post-Pluto era, New Horizons has enough fuel and power to move on to the next terra incognita, the realm of the icy Kuiper Belt Objects, after a few more years. The solar system is indeed very large and empty, but it is home.

Cheers for that informative comment too.

I can’t wait to see Pluto – my fave planet – examined in close-up detail and New Horizons sure is a wonderful mission. Any word on whether /which Edgeworth-Kuiper cometary belt objects New Horizons might be visiting after its Pluto fly-by yet?

By: L. McNish

L. McNish — Sat, 17 Mar 2012 06:37:21 +0000

Burton MacKenzie’s “The Sun as seen from other Planets” diagram caused me to stop and think for a minute… Pluto, Mercury and Mars have orbits that are pretty highly elliptical (as do many of the Trans-Neptunian objects), so the Sun looks accordingly bigger when they are at aphelion versus perihelion. Pluto is also closer to the Sun than Neptune at times so the Sun could occasionally look bigger from Pluto than from Neptune. (The Sun even looks 3.4% bigger at Earth’s perihelion than its aphelion due to our nearly circular orbit.) So I created a new diagram with all the planets (plus the dwarf planets), with the Sun scaled to show the relative maximum and minimum size as seen from each orbit. These images can be found at: calgary.rasc.ca/images/Sun_Angular_Size_From_Planets_Scaled.png (similar size to Burton’s) and calgary.rasc.ca/images/Sun_Angular_Size_From_Planets_Full.png (larger and clearer)

By: Chris A.

Chris A. — Sat, 17 Mar 2012 01:49:06 +0000

@Andrew W (#6):
“Aren’t Venus and Jupiter about 1 arcminute across when best seen from Earth?”

Venus, a tad more (62 arcsec). Jupiter, considerably less (47 arcsec).

By: K. Halse

K. Halse — Sat, 17 Mar 2012 01:23:13 +0000

“so if you were standing on Pluto (hopefully, in a well-heated and insulated spacesuit!)”

How insulated would it really have to be? Aside from the part where your feet are touching the ground, (where you can lose heat through conduction) how much colder would it be on the surface of Pluto; in comparison to a astronaut, on a spacewalk, in Earth’s shadow.

By: Hephaestus

Hephaestus — Sat, 17 Mar 2012 00:28:57 +0000

Space is big
Space is dark
It’s hard to find
A place to park

- Burma Shave