What is the hottest layer of the sun's atmosphere?

Hottest Layer of the Suns Atmospere.

The core is the hottest layer of the sun. Its temperature is nearly 15 million degrees F.The reason that the core is the hottest is due to the gravitational pressure.

This being said, there are individual spots in the corona of the sun which from time to time is known to be hotter than the core. The corona is an outer atmosphere of the sun (if you see a picture of a solar eclipse, the corona is typically the edge of the sun not covered by the earth).