Re:Voyager 2’s Discoveries from Interstellar Space
by iamcreasy on Monday November 04, 2019 @08:08PM
(#21448616)
> To Voyager, the Sun looks like an ordinary star – although one much brighter than the others. Not much energy can be harvested there.
This blew my mind. Do you have a reference that talks more on this topic?
Re:Voyager 2’s Discoveries from Interstellar Space
by RosanaAnaDana on Monday November 04, 2019 @09:44PM
(#21449117)
Inverse square law: https://en.wikipedia.org/wiki/Inverse-square_law
>(...) Intensity is inversely proportional to the square of the distance from the source of that physical quantity.
Shit gets dimmer at the square of the distance. So if at a distance of 1 a thing has a brightness of one, at a distance of 2 it has a brightness of 1/(2^2), or 1/4. At a distance of 8, you are looking at a brightness of 1/(8^2) or 1/64th.
Voyager 2 is ~122 AU distant. So the sun's apparent brightness would be 1/(122^2), or 1/14884, or 0.00067 % as bright as the sun as perceived at the earth-sun distance (ignoring the atmosphere of course).
Re:Voyager 2’s Discoveries from Interstellar Space
by Daniel_sk on Tuesday November 05, 2019 @04:30AM
(#21450925)
Voyager snapped a picture of our Earch (sorry I thought it was the Sun) in 1990. It's the famous Pale Blue Dot picture. It's the small blue-white speck (or almost pixel) halfway down the brown band on the right.
https://en.es-static.us/upl/2012/07/Pale_Blue_Dot.png
EDIT: Ooops, sorry - this is Earth and not Sun :-(.
Re:Voyager 2’s Discoveries from Interstellar Space
by gpderetta on Tuesday November 05, 2019 @05:12AM
(#21451082)
The pale blue dot is Earth, not our Sun.
Re:Voyager 2’s Discoveries from Interstellar Space
by rimliu on Tuesday November 05, 2019 @05:15AM
(#21451099)
That's Earth, not Sun.
Re:Voyager 2’s Discoveries from Interstellar Space
by brownbat on Monday November 04, 2019 @11:53PM
(#21449724)
Not as far out as Voyager, but I enjoyed this series of depictions of the sun from each planet, which illustrates the general point:
https://www.iflscience.com/space/sun-looks-like-every-planet...
Re:Voyager 2’s Discoveries from Interstellar Space
by Cthulhu_ on Tuesday November 05, 2019 @06:45AM
(#21451485)
You should look up or play Elite Dangerous, it's (I believe) a fairly accurate / to scale simulation of solar system navigation. You can go at several hundred times the speed of light and you're still waiting for ten minutes to reach your destination.
Re:Voyager 2’s Discoveries from Interstellar Space
by wyldfire on Monday November 04, 2019 @08:48PM
(#21448853)
If you're talking about its apparent size in the sky -- just a guess but I think this one is relevant: [1]
Consider that light emitted from the Sun will decay with the square of the distance – as it is irradiated in all directions. To Voyager, the Sun looks like an ordinary star – although one much brighter than the others. Not much energy can be harvested there.
Until recently, photovoltaics were useless as far away as Jupiter. Given the tech advancements, we can now use them there (and have). Farther than that and you are bumping into practical limits.