What is the lowest layer of the Sun's atmosphere?

The correct answer is the photosphere, which is the lowest layer of the Sun's atmosphere. It serves as the visible surface of the Sun from which light is emitted and is the layer that we typically see when observing the Sun. This layer is where sunspots and granules can be observed, with its temperature averaging around 5,500 degrees Celsius (about 9,932 degrees Fahrenheit).

The chromosphere and corona are above the photosphere. The chromosphere sits just above the photosphere and is more tenuous, generally appearing reddish during solar eclipses due to its emission of hydrogen alpha light. The corona, which is the outermost layer of the Sun's atmosphere, has a much higher temperature and extends far into space, becoming visible during a total solar eclipse.

The core, while crucial to the Sun's processes as the site of nuclear fusion that produces energy, is not part of the atmospheric layers but rather the Sun's innermost layer. Therefore, understanding the structure of the Sun, including the proper order of its layers, is essential in distinguishing these terms clearly.