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55

There are two forces that can cause the formation of a tail: the solar wind and radiation pressure. The first misconception in your question is "the dust [travels] slower than the nucleus". The tail is not left trailing behind the comet, it is pushed away from the comet by the sun. When the comet is moving away from the sun, the tail is in front of the ...


35

First, there is not just one tail, it is several, but when traveling far from a star, they are "aligned". When it gets closer the different materials behave differently, both depending on the temperature they start to vaporise and how they are affected by solar winds. I think this picture shows it in a good way. https://community.dur.ac.uk/physics....


6

The Hill sphere radius of Pluto is about $r$ = 6 million km. Most of the Kuiper belt is in prograde motion around the Sun (like Pluto). Pluto's average speed is under a lazy 5 km/s for an orbital period of about 248 years. If the difference in orbital speed between Pluto and an average KBO is just 1 km/s, then Pluto will "sweep out" $\pi r^2 *86,...


5

tl;dr No additional data of interest, but I explain how I searched, and I can explain the green color. It seems that there have not been any additional observations of that object, which perhaps isn’t too surprising given how faint it is - 21st magnitude is possible only with big telescopes. Simbad lists that object under the name of “EQ J103712-274051” but ...


4

Black holes are often studied (and discovered!) by observing their effects on objects around them. Stellar-mass black holes, for example, can be found by determining the orbit of any luminous companion. Supermassive black holes, by comparison, affect the motion of numerous stars and clouds of gas in their immediate vicinity. By fitting the motions of those ...


4

Well, I managed to contact the person I heard this from. Apparently it was Walter Baade who was asked: If you had your life to live over, would you be an astronomer again? To which he answered: Only if the ratio of total to selective absorption is everywhere the same. I will not accept this answer as I have not been able to find a source yet. If ...


2

(I have tracked down the reference that I made in my comment on the question.) Presumably earth rocks once blasted into space (by volcanism or meteorite impact) gain or lose energy primarily by orbital interactions with planets or moons. Since these interactions will occasionally give enough energy to escape the solar system entirely, presumably anything ...


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