The object larger than Pluto (July 31)

[orin stepanek]

If you were in a car going 60 miles an hour; and compared that to the speed of light. That would make Earth 8 1/2 miles back. How far can you drive in over four years non stop? So my wayward planet would be lost is space for a long time. Still I believe in the possibility.
Orin

[Empeda]

I think it's certainly possible - anything is.....but an object that far away would be incredibly unlikely to be orbiting a star, or be stuck in the middle of two. The proper motions of the two stars would have to be pretty close I would have thought, and the tiny gravitational force at that kind of distance would be open to many weak fluctuations.

Still, never write anything off.....

[Aqua]

2003 UB313's peculiar orbit and other KBO's with similarly odd orbits may prove them to be 'captured' interstellar objects? Close encounter(s) with another star, or brown dwarf, where the lesser body's gravity looses influence over its orbitals. Cassini is showing us frozen water worlds and evidence of ongoing 'brown dwarf'-like neucleosynthesis within Saturn. Could Saturn be a captured 'brown dwarf'? That would go a long way into explaining what happened to Uranus? Where Jupiter got its water moons, and how Venus was resurfaced? Or even why Phobos appears to be part of MUCH larger body? There are more answers than questions.. right?

[Empeda]

Could Saturn be a captured 'brown dwarf'? T

Yep - the more we discover the less we know...

Saturn isn't likely to be captured as it orbits along the same plane as the rest of the planets, suggesting that it was formed in an accretion process.

[Aqua]

Saturn's rings and equator are inclined by 27° while its Inclination to the Solar Ecliptic is 2°29'17". Only Mercury, Venus and Pluto have higher inclinations to the solar ecliptic. Add 27° with 2°29'17" and you get an even higher angular inclination of almost 30°! Uranus' equator is inclined a whopping 97.86°, while Venus' inclination of Equator to Orbit is 177.3°! Tell me again how these orbital eccentricities originated.... why not speculate?

[Zaha]

No it's not just you (well... maybe, it could be).

Actually, I think APOD sometimes does a disservice with illustrations.

Objects that distant (100 AU) are just not going to be that well lit.

In fact, I think they would. At 100AU from Sun, the planet receives 1/10000 of the sunlight intensity Earth does. By comparison, the Sun's apparent magnitude on Earth is -26.7 and full Moon's -12.6, therefore we have by the definition of magnitude that Sun is 100^(26.7-12.6)/5) = 437000 times as bright as the full Moon. So an object at 100AU is 43.7 times brighter than Earth in full Moon's light, and as humans can see quite well (even colors) in good direct moonlight they would see the object fairly well lit with eyes adapted to dark.

With long enough exposures, it might even be possible to photograph the dark side in just starlight (even better if the object is illuminated by its own moon too) - though not in the same picture with the sunlit side.

[makc]

Thank you, Zaha, I've almost forgot what this thread originally was about.