Astronomy Practice Exam 2025 – Complete Preparation Guide

The term 'chromosphere' specifically refers to a layer of the sun’s atmosphere located just above the photosphere. It is a transitional zone characterized by a relatively thin layer where temperatures can reach up to 20,000 Kelvin. The chromosphere is notable during solar observations, particularly during a solar eclipse, when its reddish glow can be seen surrounding the sun's disk. This glow is primarily due to hydrogen emission lines, reflecting its composition.

The chromosphere plays an essential role in the solar atmosphere, acting as a bridge between the solar surface and the outer layers, such as the corona. Its dynamics contribute to solar phenomena like solar flares and prominence. Understanding the chromosphere is crucial for studying solar activity and its effects on space weather, which can impact satellite communications and Earth’s magnetosphere.

The other options do not accurately describe the chromosphere. The core refers to the innermost part of the sun where nuclear fusion occurs, and the surface temperature pertains to the sun's photosphere rather than the chromosphere. The outermost layer of the sun's atmosphere is the corona, which sits above the chromosphere.