Talk:2010 XC15

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1976[edit]

How can an object, discovered in 2010, be noted for a close pass of earth in 1976? - ak2011 — Preceding unsigned comment added by 174.89.52.101 (talk) 12:23, 8 November 2011 (UTC)[reply]

Just as orbits can be computed into the future, they can be computed into the past. -- Kheider (talk) 15:55, 8 November 2011 (UTC)[reply]

It seems to me, if nobody was aware of it when it happened, then there was nothing noteworthy, and it's only known for a hypothetical course we believe it took. - ak2011 — Preceding unsigned comment added by 174.89.52.101 (talk) 22:06, 8 November 2011 (UTC)[reply]

By integrating the equations of motion astronomers know that the 2010 XC15 passed near the Earth in 1976. The nominal orbit shows that it passed 0.002AU from the Earth. -- Kheider (talk) 22:21, 8 November 2011 (UTC)[reply]

I get the math; you can chart a course for it backward, that's fine. But that's still only hypothetical. Without evidence, or at least a witness to its passing, we can't really say with certainty that it did. Only that it probably did. Very probably, if you like. I suppose it's a question of semantics; but no worries. - ak2011 — Preceding unsigned comment added by 174.89.52.101 (talk) 11:31, 10 November 2011 (UTC)[reply]

The "evidence" is the nominal orbital solution. Do you think the future "hypothetical" trajectory of 99942 Apophis is semantics? -- Kheider (talk) 18:31, 12 November 2011 (UTC)[reply]