system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How long would it take for us to notice if the sun's mass suddenly became "zero"? How long does it take for Gravity to effect objects?
gpt
The sun is a balance forces, between fusion explosions and gravity. If its mass became zero, we would notice in nine or ten minutes. Solar observatories would note that the sun was rapidly expanding. Of course, a few minutes later, the rapidly expanding cloud of plasma would encompass the earth and we would all die.

If you somehow made that not happen (a magical gravity barrier to disrupt Earth's orbit without destroying the sun), we would notice that the sun was in the wrong position and had the wrong magnitude, since we'd be moving away from it at right angles from the earth-sun line at the time of mass disruption.

How long would it take for us to notice? Well, we already know with high accuracy where the sun will be. And small enough changes will be thought instrument error rather than a physically impossible circumstance. But when a lot of observatories report the same change, or consistent changes over a longer period, we'll figure it out.

After one hour, the sun's position will be off by 0.082 degrees. Is that enough to notice? For some observatories, perhaps, but not enough to be conclusive. We'll cross 0.5 degrees about six hours in, one degree after thirteen hours, two degrees by twenty-five hours. So probably half a day in, scientists would be willing to announce that something was seriously wrong with our orbit.

At that point, we'll be just a few light-seconds further from the sun than we currently are, well under 1% difference. (We're going *fast*, but space is *huge*. It cancels out.) We'd pull in all the observatories that could point at the sun, and that would be enough to show that the sun's apparent magnitude was shrinking.

If you didn't have scientists and observatories handy, you'd notice that your timezone shifted an hour around eight days in. Sixteen days would give you another hour of change. The earth would be cooling off noticeably during this time -- our incoming solar radiation would drop over 7%. This doesn't mean the temperature would drop that much -- thanks, greenhouse gases! -- but the difference in temperature between the coldest and hottest parts of the sixteenth day will be something like 7% less than they would have been.

So please don't turn off the sun's gravity, and don't put up an anti-gravity barrier between the earth and the sun.