Giant Unstable Sunspot 4 Times the Size of Earth Now Visible With Naked Eye

One of the sunspots facing the Earth is now so large that it can be seen with the naked eye—with proper viewing protection, of course.

The sunspot, AR3190, is around four Earths in diameter, according to an infographic on SpaceWeather.com made by Bum-Suk Yeom from Iksan, South Korea, and is twice as large as any of the other sunspots currently facing in our direction.

Sunspots are areas of the sun's surface where the magnetic field holds a higher level of energy as a result of their magnetic field lines being twisted. Historically, sunspots have been occasionally visible from Earth without a telescope, with one such giant sunspot drawn by observers in East Asia in 1769.

"The minimal visibility threshold is estimated as [roughly] 425 millionths of the visible solar disk—0.04 percent of the solar disk)—whereas larger sunspot area and favorable meteorological conditions improve their visibility," Hisashi Hayakawa, a solar physicist at Nagoya University in Japan, told Newsweek.

The entire surface area of the Earth is around 169 millionths of the solar disk.

One recent example of a huge sunspot seen from Earth occurred in 2014, when sunspot AR2192 was measured as being 2,740 millionths of the solar disc, making it the largest sunspot recorded since 1990. This sunspot was roughly the same size as Jupiter, The Washington Post reported at the time.

While the sunspot can be viewed from right here on Earth, under no circumstances should you look directly at the sun without some degree of eye protection.

"I would recommend you to use eclipse glasses," Hayakawa said. "Don't directly see the sun, even through smoked glass. Your eyes will be burnt. Some historical astronomers significantly reduced their eyesight owing to their solar observations," he added, citing Galileo and Thaddäus Derfflinger.

The giant sunspot visible today may also be about to explode because it has an especially unstable magnetic field. AR3190 has a "beta-gamma-delta" magnetic field, meaning that it is more prone to spewing out more powerful solar flares and coronal mass ejections.

Solar flares are powerful jets of electromagnetic radiation shot out from the sun, usually from sunspots when their twisted magnetic field lines suddenly realign. Coronal mass ejections are clouds of solar plasma that are spat out from the sun's surface during periods of intense activity.

X-class flares are the rarest but most powerful type of solar flare. If they directly hit the Earth's atmosphere they can result in geomagnetic radiation storms and radio blackouts.

The National Oceanic and Atmospheric Administration puts the chances of an X-class flare occurring in the next 24 hours at 15 percent.

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