# If the sun disappeared

if the sun disappears, the earth would go dark and life would end ...

it would also go out of orbit

but how soon? immediately?

even the light takes 8 minutes to reach earth, as they are so far away....

if the whole mass of sun disappeared suddenly... would earth go out of orbit immediately? if not how fast? and how does it work? would a further planet, say, saturn go out of orbit later for example?

phinds
Gold Member
8 minutes after the sun disappeared, the now dark Earth would leave orbit in whatever direction it was traveling at that time.

Dale
Mentor
2020 Award
if the whole mass of sun disappeared suddenly
This is not possible according to physics so the questions which follow cannot be answered according to physics.

That would be a cool video to see, a computer simulation of 'poof', there goes the sun, and where do the planets go? I think the earth would keep it's moon... probably all the other planets too?

Fredrik
Staff Emeritus
Gold Member
if the sun disappears, the earth would go dark and life would end ...

it would also go out of orbit

but how soon? immediately?

even the light takes 8 minutes to reach earth, as they are so far away....

if the whole mass of sun disappeared suddenly... would earth go out of orbit immediately? if not how fast? and how does it work? would a further planet, say, saturn go out of orbit later for example?
Newton's theory of gravity says that the answer is "immediately". But Newton's theory is built up around a formula that says that the force that one mass exerts on another depends only on the distance. So to apply Newton's theory to this problem is essentially to just assume that the answer is "immediately".

Einstein's theory of gravity (general relativity) can't answer the question, since there's no solution of Einstein's equation that describes a suddenly disappearing star. So the question contradicts the theory. You clearly can't use a theory to answer a question that contradicts that theory.

There's nothing instantaneous about gravity... gravity travels/changes at the spped of light. The moon is just where you see it to be, at the same time it's pulling on the tides

davenn
Gold Member
There's nothing instantaneous about gravity... gravity travels/changes at the spped of light. The moon is just where you see it to be, at the same time it's pulling on the tides
not quite.
do some reading up on tides. There is a significant time lag ( tho not totally due to gravity)

IF your statement was correct, then there would be a high tide at YOUR location every time the moon was directly overhead ( highest point in the sky at your location).
But this doesn't happen.

It would happen IF the earth had a completely water surface ( no dry land)

Dave

IF your statement was correct, then there would be a high tide at YOUR location every time the moon was directly overhead ( highest point in the sky at your location).
But this doesn't happen.

It would happen IF the earth had a completely water surface ( no dry land)

Dave
The surface you're talking about is called a geoid, and my statement is correct. A lag in tides is due to geography, bays or isthmus or whatnot.

Last edited:
haruspex