Corona

Definition

The corona is the outermost layer of the Sun's atmosphere, characterized by its high temperature and low density. It extends millions of kilometers into space and is visible during a solar eclipse as a white halo around the Sun.

5 Must Know Facts For Your Next Test

1. The temperature of the corona can reach up to several million degrees Kelvin, much hotter than the surface of the Sun.
2. The corona is primarily composed of ionized gases such as hydrogen and helium.
3. It emits X-rays and ultraviolet light due to its high temperatures.
4. Coronal mass ejections (CMEs) originate in the corona and can affect space weather, impacting satellites and power grids on Earth.
5. The phenomenon known as 'coronal heating problem' refers to the question of why the corona is so much hotter than the Sun’s surface.

Review Questions

• What is the temperature range typically observed in the Sun's corona?
• How does the composition of the solar corona differ from that of its surface?
• What are coronal mass ejections (CMEs), and how do they originate?

Related terms

Photosphere:

The visible surface layer of the Sun from which most of its radiation escapes into space.

Chromosphere:

The second layer of the Sun's atmosphere located between the photosphere and corona, characterized by its reddish color during eclipses.

Solar Wind:

A stream of charged particles released from the upper atmosphere of the Sun, including from its corona, affecting space weather throughout our solar system.