Coronal holes

Definition

Coronal holes are regions on the Sun's surface that appear darker and are less dense than surrounding areas. They are associated with open magnetic field lines and high-speed solar wind streams.

5 Must Know Facts For Your Next Test

1. Coronal holes can last for several solar rotations, sometimes persisting for months.
2. These regions are cooler compared to the surrounding corona, which is why they appear dark in ultraviolet and X-ray images.
3. They are significant sources of solar wind that can affect space weather and geomagnetic storms on Earth.
4. Coronal holes are more prevalent during the declining phase of the solar cycle.
5. The open magnetic field lines in coronal holes allow charged particles to escape into space more easily.

Review Questions

• What causes coronal holes to appear darker than other regions of the Sun?
• How do coronal holes influence space weather and geomagnetic storms on Earth?
• During which phase of the solar cycle are coronal holes most commonly observed?

Related terms

Solar Wind: A stream of charged particles released from the upper atmosphere of the Sun, primarily composed of electrons and protons.

Solar Cycle: The approximately 11-year cycle that includes variations in sunspot numbers and solar activity levels.

Magnetic Field Lines: Imaginary lines used to represent the direction and strength of a magnetic field; in coronal holes, these lines extend outward into space.