If the Sun disappears right now, when the absence of its gravity affects on Earth?
As we know by General Relativity, gravity propagates by the speed of light c = 299,792,458 m/s in a vacuuum (like space).
The average distance between the earth and sun is about 149.6 million kilometers, so it takes light about 8.3 minutes from the sun to earth.
This means, if the sun were to disappear right now, we would have to wait 8 minutes and 20 seconds until we would realize. Luckily, by all known laws of physics, this is not possible :)