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

Experts had predicted a geomagnetic storm would occur once again, 27 days after the initial geomagnetic activity — this Thursday — but as the coronal hole faced Earth once again, “it was clear that it had diminished, and we adjusted our forecast accordingly,” Brasher said.

From Seattle Times

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

“And there’s a high-speed solar wind coming our way from a coronal hole,” said EarthSky.

From Seattle Times

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