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Old 07-16-2019, 09:12 AM   #1
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Default If the Sun dissapeared...?

Was wondering if we could be hit by Mercury if the Sun disappeared.

I'm assuming as soon as the Sun's gravity is removed Mercury continues at its orbital velocity in whichever direction its moving then?

There are 5 light-minutes between Earth and Mercury, and Mercury average orbital velocity is about 47km/s, 2820km per minute.
So Mercury travels about 14000 km before the Earth starts moving at a tangent. Average distance between Mercury and Earth is 77 Million km.

I think we'll be all right, but I can't promise anything.

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Old 07-16-2019, 10:19 AM   #2
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Logic can be a funny thing. If we formally define the conditional statement "If the sun suddenly disappears, then Mercury will hit the Earth" as

p: the sun suddenly disappears
q: Mercury hits Earth
p -> q

then the statement p -> q is only false if p is true and q is false.(ex falso quod libet).

From all we know about physics, p is false. Therefore, p -> q is true. If the sun were to disappear, then we will indeed be struck by Mercury!
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Old 07-16-2019, 10:32 AM   #3
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Yes, I was going to phrase it like that....
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