Blackbody Blacklight
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Feb
6
awarded  Self-Learner
Jan
26
awarded  Scholar
Jan
26
accepted How can the Kuiper belt coexist with the 9th planet?
Jan
24
awarded  Teacher
Jan
24
answered How can the Kuiper belt coexist with the 9th planet?
Jan
24
awarded  Commentator
Jan
24
comment How can the Kuiper belt coexist with the 9th planet?
Hmm, it seems I wrongly lumped more distant objects into the Kuiper belt. The objects relating to Planet 9 are beyond 50 AU and not considered to be KBOs.
Jan
24
comment How can the Kuiper belt coexist with the 9th planet?
@HDE226868 I'm not an expert, but Wikipedia presents the "Kuiper Cliff" at 50 AU as the outer edge of Neptune's 2:1 resonance. 30 AU (1:1) to 48 AU (2:1) plus some margin makes 20 AU; is that where you get that figure?
Jan
24
awarded  Student
Jan
23
asked How can the Kuiper belt coexist with the 9th planet?
Sep
20
comment Can ground based telescopes use a starshade in space?
I was going to ask the same question, but with a high-altitude drone (or such) instead of a satellite. The satellite would need to avoid apparent motion relative to the stars, which would be difficult to impossible. The nearest I can imagine is a highly elliptical orbit with the apoapsis velocity equal to the ground velocity at the observatory. You'd need an array of such shade-satellites, and you'd have to move them all when switching to a new target.
Sep
24
awarded  Autobiographer
May
14
comment A black “superhole” possibility?
@frodeborli No, the closer you get to the singularity, the harder it rips you apart. Imaginative, but whatever you're thinking of is not a black hole.
May
14
comment How many black holes exist?
Supermassive black holes in particular? Why the supermassive tag?
May
14
comment A black “superhole” possibility?
"As this matter continues to travel down the gravity well, the tidal effects of gravity will average out" — due to what? They just get stronger and stronger up to the singularity. Also, I don't think this is on-topic for this site because none of it is observable. Physics would be a better forum.
May
14
comment Can Mercury hit Earth or Mars in the next 5 billion years?
@Gerald That would essentially be capture as a moon. The Wikipedia article's elaboration seems to be referring to a cause of instability, not an outcome. Probably what they meant is an integer resonance, say 49:1. But none of the sources are clear about what's supposedly normal and what's risky, and it's hard to trust the numerical accuracy of just one simulation code.
May
12
comment Can Mercury hit Earth or Mars in the next 5 billion years?
A 1:1 orbital resonance would imply that they have the same orbital period, i.e. year length. Obviously that's not possible. In conclusion, Wikipedia is not a reliable source.
May
12
awarded  Supporter
May
11
comment Is the moon only 60 pixels?
This is wrong. According to the Nyquist sampling theorem‌​, to model a waveform with a frequency cutoff, you should sample at twice the cutoff and then low-pass filter the reconstructed result. In other words, it's a 120x120 image blurred according to the ideal point spread function in the illustration.
May
11
comment Is the moon only 60 pixels?
Pausing a video will reveal either VHS or digital compression artifacts. "Sub-pixel" eye vibrations would already be accounted for in any visual acuity test. Taking advantage of atmospheric lensing, or moments of good seeing, is the domain of adaptive optics and I wouldn't assume the brain is capable of that sort of processing.