Brightness of Sun at Pluto and Sedna when they are at (aphelion) |
Brightness of Sun at Pluto and Sedna when they are at (aphelion) |
May 3 2006, 09:58 PM
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#1
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Junior Member Group: Members Posts: 40 Joined: 20-March 06 Member No.: 720 |
What kind of experience will it be when you are on Pluto and on Sedna and they are at their farthest point from the Sun (aphelion) Pluto about 90 AU then and Sedna an unimaginable 900 AU. How bright will the Sun shine at Plutos farthest distance to the Sun at 90 AU ,and what about its brightness when you are on Sedna at its aphelion at 900! AU? When we send landers to Pluto and Sedna in the future ,do they need (extra) lights because of the dimness of the Sun? Can somebody explain these things?
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May 3 2006, 11:22 PM
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#2
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
Pluto:
Not too hard to bump up the aperture of the optics on the imaging system. Could also increase exposure time, don't think the Plutonians are going to move around enough to blur the picture. Sedna: Might need some image intensifier technology (like the starlight scopes the army has) but I suspect that they are not very accurate photometrically. Maybe they could be improved enough. Long exposures probably not a problem here, either. Radar and deep infrared will still work. If Sedna has an atmosphere, maybe a highly focused sonic range finder could build up images. |
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Guest_BruceMoomaw_* |
May 4 2006, 01:11 AM
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#3
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Guests |
Don't panic. Remember that the emitted brightness of the full Moon is only 1/500,000 that of the Sun -- less than twice as bright as the Sun at Sedna's aphelion! Our retinal rods adapt to that quite well, and light-sensitive cameras will do even better.
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May 4 2006, 01:36 AM
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#4
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Member Group: Members Posts: 809 Joined: 11-March 04 Member No.: 56 |
When we send landers to Pluto and Sedna in the future ,do they need (extra) lights because of the dimness of the Sun? Can somebody explain these things? How many years is it likely to be before a human nation sends landers to Pluto? 200 maybe? And by then it probably won't be the USA or Russia or China doing the launching -- maybe Sri Lanka or Honduras... |
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May 4 2006, 02:10 AM
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#5
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Junior Member Group: Members Posts: 40 Joined: 20-March 06 Member No.: 720 |
It will be a bit dark at noon at Sedna when it is at aphelion ,am i right? And what is the magnitude of a full moon in a clear night sky? And what is the magnitude of the Sun as seen from Sedna at aphelion and at Pluto?
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May 4 2006, 02:54 AM
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#6
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Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
And what is the magnitude of a full moon in a clear night sky? -12.7 (from google) And what is the magnitude of the Sun as seen from Sedna at aphelion ~ -11.8 According to Celestia and at Pluto? ~ -18.3 Celestia again. James -------------------- |
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May 4 2006, 03:17 AM
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#7
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
A bit of trivia stuck in my head: the magnitude of the Sun at Earth's orbit is -27; the magnitude difference of 9 (27 minus 18) between Earth's and Pluto's Sun is a brightness factor of about 4000.
FWIW... --Bill -------------------- |
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May 4 2006, 12:07 PM
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#8
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Junior Member Group: Members Posts: 40 Joined: 20-March 06 Member No.: 720 |
-12.7 (from google) ~ -11.8 According to Celestia ~ -18.3 Celestia again. James How does Celestia know the magnitude at a specified distance of a planet,Kbo object and of many stars? Will it look like a (bit) darkness when you are walking on Sedna at 900 AU distance? A lander needs lights to look around on Sedna then i think. Is that true? |
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May 4 2006, 12:32 PM
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#9
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
There's an equation to calculate the aparant magnitude ( i.e. those values ) from the absolute magnitude ( the mag of an object at a standard distance ) which we know for the sun.
Doug |
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May 4 2006, 03:21 PM
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#10
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Member Group: Members Posts: 593 Joined: 20-April 05 Member No.: 279 |
There's an equation to calculate the aparant magnitude ( i.e. those values ) from the absolute magnitude ( the mag of an object at a standard distance ) which we know for the sun. Time for a shameless plug for my brightness calculator again: setting albedo, diameter and distances (star to X, viewer from X) will give you, Rem31, a good estimate to the brightness of bodies that are fully lit by the Sun. To calculate the Sun's brightness at different ranges, Doug's right: Apparent Magnitude = 2.5*log10(dist^2) - 26.73 dist is in AU. The figure -26.73 is the Sun's Absolute Magnitude. Andy (edited the link) |
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May 4 2006, 08:25 PM
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#11
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Junior Member Group: Members Posts: 40 Joined: 20-March 06 Member No.: 720 |
Time for a shameless plug for my brightness calculator again: setting albedo, diameter and distances (star to X, viewer from X) will give you, Rem31, a good estimate to the brightness of bodies that are fully lit by the Sun. To calculate the Sun's brightness at different ranges, Doug's right: Apparent Magnitude = 2.5*log10(dist^2) - 26.73 dist is in AU. The figure -26.73 is the Sun's Absolute Magnitude. Andy Sorry but the link does not work. Can you help me to get the link succesfully? Thanks. |
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May 4 2006, 10:44 PM
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#12
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Junior Member Group: Members Posts: 40 Joined: 20-March 06 Member No.: 720 |
Celestia is a good alternative for calculating magnitudes at a specified distance. But can you help me with your link ? It doesnt work.
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May 4 2006, 10:47 PM
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#13
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Member Group: Members Posts: 114 Joined: 6-November 05 From: So. Maryland, USA Member No.: 544 |
Sorry but the link does not work. Can you help me to get the link succesfully? Thanks. Try Brightness Calculator. A very valuable resource! Michaelc |
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