So an object—asteroid? lump? comet? spaceship?—from outside our solar system, but inside the Milky Way, one of many galaxies, recently zipped past the sun & only 15 millions from us. Astronomers can tell it's from away because of its orbit. But how is that they know it's from our galaxy & not from even farther away? And how is it possible that, as the astronomers assert, it's the "first interstellar object known to have visited Earth’s neighborhood," according to The Economist Espresso. Is this a big deal? Why? And to whom?
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