coronal hole

American  

noun

Astronomy.

1. a part of the solar corona that appears dark on optical and x-ray images and is characterized by low temperature and low density.

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Etymology

Origin of coronal hole

First recorded in 1970–75

Example Sentences

The initial confusion of how far the aurora would stretch was caused by the recurrence of a particular coronal hole, or a temporarily cool area on the sun where solar particles can escape.

From Seattle Times • Jul. 13, 2023

The recent coronal mass ejection’s effect may also have been amplified by another solar phenomenon observed last week, called a coronal hole, says W. Dean Pesnell, an astrophysicist on NASA’s Solar Dynamics Observatory mission.

From Scientific American • Mar. 30, 2023

The Northern Lights start at the sun when a sunspot or coronal hole allows a batch of charged particles to leave the sun and travel towards the Earth on the solar wind.

From BBC • Feb. 5, 2022