A massive coronal hole that formed last May 17 to 19 engulfed 40 percent of the Sun underscores how much scientists still don't understand about our home star.

Coronal holes are low-density regions of the sun's atmosphere or corona. They look like enormous holes punched into the sun because they contain little solar material. Their lower temperatures make them look blacker compared to the surrounding regions of the Sun.

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They are, nevertheless, spectacular to view in extreme ultraviolet light as the accompanying photos show.

NASA says a huge hole visible from May 17 to 19 was the largest observed in more than a year. The space agency said this one observed by its Solar Dynamics Observatory isn't a cause for any concern since coronal holes are regular phenomena exhibited by the sun.

NASA noted that coronal holes are important to understanding the space environment around Earth through which satellites and astronauts travel. Coronal holes are also the source of a high-speed wind of solar particles that streams off the sun some three times faster than the slower wind elsewhere.  The solar wind escapes and creates a lower density and lower temperature in areas of the coronal hole.

These solar winds cause the Aurora Borealis or Northern Lights to form and degrade terrestrial communications. It also increases the amount of cancer-causing UV rays reaching the Earth, but which are deflected by the Earth's magnetosphere.

This recent coronal hole isn't the largest observed. On July 18, 2013, a humungous coronal hole sprawled across 400,000 miles across or almost half the Sun's diameter.

Humans on the outer fringe of reason, however, are yelling online the recent monster coronal hole is a sure sign the sun is dying. Brethren of these folks also claimed the recent discovery of Planet 9 in the Oort Cloud is a sure sign the Apocalypse is around the corner.

 You can view a gif of a coronal hole here.

Tagscoronal hole, NASA, Solar Dynamics Observatory