What is the approximate temperature of the Sun's corona in Kelvin?

The Sun’s corona has an approximate temperature of 1 million K. In many regions, coronal temperatures range from about 1 to 3 million kelvin, making this a useful rounded answer for a general trivia question.

The corona is the Sun’s outer atmosphere. It is extremely thin compared with the photosphere, yet it is dramatically hotter: the visible solar surface averages about 5,772 K. This surprising temperature difference is known as the coronal-heating problem because ordinary heat conduction cannot simply explain why the outer atmosphere is hotter than the layer below it.

Scientists investigate magnetic reconnection, waves, and other processes as possible sources of coronal heating. During solar eclipses, the corona becomes visible as a pale, structured halo around the dark Moon. It is also the source region of the solar wind, a continuous flow of charged particles outward through the Solar System.

The corona is not a single-temperature shell. Active regions and flares can reach still higher temperatures, while coronal holes are cooler and less dense.