Interstellar Interlopers, Coming in from the great beyond |
Interstellar Interlopers, Coming in from the great beyond |
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#1
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Member ![]() ![]() ![]() Group: Members Posts: 541 Joined: 17-November 05 From: Oklahoma Member No.: 557 ![]() |
They finally found a chunk of something coming into the Solar System. Something much bigger than cosmic rays or dust particles.
Asteroid/comet in hyperbolic trajectory |
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#2
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 ![]() |
Adding to nprev's comments, the lightcurve only pins down the ratios of the axes (and only roughly). To estimate actual dimensions, all they can do is compare the observed brightness (since it's only a point source) with assumptions about how dark the surface is (albedo). A different assumption for the albedo gives different dimensions (eg with darker albedo it must be larger to appear as bright from earth). So that may explain part of the variation out there.
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#3
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 ![]() |
In real estate, the three most important things are location, location, location.
With fragments from another place, the three most important things are selection bias, selection bias, selection bias. Meteorites found on Earth are disproportionately irons because they (1) Survive the trip and (2) Are easily distinguished from terrestrial rocks. Meteorites from Mars appear to be disproportionately from volcanic surfaces because, it's been hypothesized, they (1) Survive the trip and (2) Begin their departure from Mars at high elevation, already above some of the martian atmosphere. So if this thing from outside the solar system looks very odd, we have to consider that it has been through several rounds of exceptional selection, and therefore selection bias. Its inbound velocity of 26 km/s relative to the Sun would indicate, if it escaped from earthlike distance from a sunlike star an initial velocity of about 70 km/s. Not a lot of structures would survive that. So it may be less surprising to see that it's remarkably rigid: Snowballs aren't going to survive the trip that it survived. |
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