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| Artist’s impression of `Oumuamua, our first interstellar asteroid - ESO/M.Kornmesser |
Looking over my last few posts, just to retrace my travels over the last week, kind of like how you might want to retrace the route you took to get somewhere on a map, I saw Pluto and what I said about it was:
Pluto wasn't discovered until 1930, so we don't know that it was actually in orbit around our sun at the time of the American Revolution.
Which immediately brought to the mind the question: Well, if it wasn't in orbit around the sun back in 1776, where was it? And when did it get here? And is that even possible?
So went to Quora and, as you might expect, I didn't even have to completely enter my question before Quora has popped up with several suggestions, among which I found this amusing story by Abe Guler:
Actually Pluto is the bastard child of Juno and the Queen of the Space Aliens Forinsec. They had an illicit affair 300 million years ago, and the little Dwarf Pluto was born 20 million years later. The sun did not want to include Forinsec’s malformed, cold, with too-many-poke-marks-on the face baby in the solar system and said so to Juno. And Juno did not take this insult lying down, and he threw a big temper tantrum which played havoc with the orbital trajectories of other solar system planets. Mercury approached the sun so close all held their breaths, fearing a collision. Earth and Venus started twirling around each other, you would think it was choreographed by Mikhail Baryshnikov. Mars turned completely red from anger and fear, and Uranus suffered a nervous breakdown, permanently lying down on its side and pointing the sun in anger. Poor thing is so old and remote from the sun, goes around once every 84 years. There was some serious belt tightening in the Kuiper to prevent all those Himalaya-size-rocks raining on Juno.
Finally the sun decided to include Pluto in the solar system, but it had to be the last planet, and in the boondocks, a billion miles away from the sun. Juno initially protested vehemently throwing his weight around, but the sun said, “that is my decision and I am sticking with it.” Juno and Pluto once in awhile see each other Juno deepens the red spot to send a signal to his son that he saw him and he should pay more attention to his grooming habits and gathering his room, if he wants to be a planet. But poor Pluto, far removed from the family and lonesome, keeps on treading like everyone else. Ad Astra! [To the Stars]
Great story, but it doesn't really answer my question - could Pluto be a rogue planet that was somehow captured by the sun, but without any interference from the gods? I did a little more reading on the subject and I came to realize that velocity is the problem.
Standing around down here in the mud, the big problem, the one we are exerting all our energies on, is getting more velocity. We now manage to launch capsules into orbit with a velocity of 8 kps (kilometers per second), that is nowhere near planetary velocities. Launching an interplanetary probe requires enormous exertion after you have already reached orbit, and then you have to wait for years before you get any pictures. But once you get up to planetary velocities (planetary velocities and basically the same as interplanetary velocities. Once you have matched the planet in speed you are pretty much free to drift out of your lane and coast across the medium between the travel lanes of two adjacent planets, and when the other planet comes within range you'll be caught up in his slipstream which you can use to your advantage, be it slowing down or speeding up. Simply alter your angle of attack three years advance. No changing your mind at the last minute. You want to grab some more speed from the planet, you aim to cross close behind him on a path just slightly tangent to his. Plot your course accordingly. If you want to go slower, you aim to cross in front of him, also at a slight tangent. From a zillion miles away you cannot even measure the difference between the two paths.
A rogue planet approaching the solar system would have to come in at just the right angle and following a trajectory that would take it just the right distance from the sun. Come in little farther out and you are just going to fly off into space, never to be seen again. Come in a little too close and you are going to go into an eliptical orbit which will make you into a comet. Coming in too fast would give the same result as passing too far away. Up to a limit, there is a right distance to go into a perfect orbit for every speed. However, it is near impossible to meet both of those criteria, which is why all good astrophysicists agree that all of the planets were formed from the accretion disk that gave rise to the sun.
Pluto, you will note, is not a good planet. It even got kicked out the good planet club a few years ago for being, among other things, too eccentric in its habits, er, orbits. So why is Pluto's orbit so eccentric? Is it possible that it wasn't formed at the same time as the other planets? Could it possibly be a rogue that was captured in the sun's gravity well when it wandered by? Enquiring minds want to know.
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