The chromosphere is a layer of the Sun's atmosphere lying between the visible surface (photosphere) and the outermost layer, the corona. It's characterized by a reddish glow, visible during solar eclipses.
Characteristics of the Chromosphere
- Location: Situated above the photosphere and below the corona.
- Thickness: Extends approximately 2,000 kilometers (1,200 miles) above the photosphere.
- Temperature: The temperature increases with altitude, ranging from about 4,000 K at the base to 25,000 K at the top. This is the opposite of what happens in the photosphere.
- Density: Significantly less dense than the photosphere.
- Appearance: Appears reddish due to the emission of hydrogen-alpha (Hα) radiation. This is the red light emitted when a hydrogen electron falls from its third to its second lowest energy level.
- Visibility: Typically only visible during solar eclipses or with specialized filters that block out the intense light of the photosphere.
- Features: The chromosphere is home to several dynamic features, including:
- Spicules: Jet-like eruptions of hot gas that shoot upwards into the corona.
- Plages: Bright regions, often associated with sunspots below in the photosphere.
- Filaments and Prominences: Cool, dense clouds of plasma suspended in the corona by magnetic fields. Filaments are seen against the solar disk, while prominences are seen against the blackness of space during eclipses.
Differences from the Photosphere and Corona
| Feature | Photosphere | Chromosphere | Corona |
|---|---|---|---|
| Position | Visible Surface | Layer above the Photosphere | Outermost Layer |
| Temperature | Decreases with altitude | Increases with altitude | Extremely Hot (millions of degrees Kelvin) |
| Density | High | Low | Very Low |
| Appearance | Bright yellow-white | Reddish | Faint and diffuse |
Significance
The chromosphere plays a crucial role in the transfer of energy from the Sun's interior to the corona and the solar wind. Understanding its properties and dynamics is essential for comprehending the overall behavior of the Sun and its influence on the solar system.
