Researchers started cataloguing them with the Kepler space telescope a few years ago. They're easy to spot, even on distant stars, since they crank out about 10,000 times more energy than normal flares.
And in a new study published in Nature, researchers say the sun is capable of emitting a superflare of its own — even if that's unlikely.
Most superflares come from stars that are more magnetically active than our home star, but about 10 percent of the superflare examples researchers analyzed came from stars with similar or even weaker fields.
See photos of solar flares:
Solar flares (the sun)
We probably don't need to worry about a solar superflare
The sun emitted a significant solar flare, peaking at 7:28 p.m. EST on Dec. 19, 2014. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. (Photo via NASA/SDO)
On Feb. 24, 2014, the sun emitted a significant solar flare, peaking at 7:49 p.m. EST. NASA's Solar Dynamics Observatory (SDO), which keeps a constant watch on the sun, captured images of the event. These SDO images from 7:25 p.m. EST on Feb. 24 show the first moments of this X-class flare in different wavelengths of light -- seen as the bright spot that appears on the left limb of the sun. Hot solar material can be seen hovering above the active region in the sun's atmosphere, the corona.
Solar flares are powerful bursts of radiation, appearing as giant flashes of light in the SDO images. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. (Photo via NASA/SDO)
The bright flash of an X1.6-class flare can be seen on the right side of the sun in this image captured by NASA's Solar Dynamics Observatory. This image shows extreme ultraviolet light of 131 Angstroms, which highlights the intensely hot material of a flare and which is typically colorized in teal. (Photo via NASA/SDO)
On Oct. 25, 2014, the sun emitted its fifth substantial flare since Oct.19. This flare was classified as an X1-class flare and it peaked at 1:08 p.m. EDT, as seen as a bright flash of light in this image from NASA's SDO. The image shows extreme ultraviolet light in the 131-angstrom wavelength, which highlights the intensely hot material in a flare and which is typically colorized in teal. (Photo via NASA/SDO)
NASA's Solar Dynamics Observatory captured this image of an X2.0-class solar flare bursting off the lower right side of the sun on Oct. 27, 2014. The image shows a blend of extreme ultraviolet light with wavelengths of 131 and 171 Angstroms. (Photo via NASA/SDO)
The bright flash of an M-class flare is seen exploding on the left side of the sun in this image from Nov. 5, 2014. The image was captured by NASA's Solar Dynamics Observatory in extreme ultraviolet light that was colorized in red and gold. (Photo via NASA/SDO)
On Jan. 27, 2012, a large X-class flare erupted from an active region near the solar west limb. X-class flares are the most powerful of all solar events. Seen here is an image of the flare captured by the X-ray telescope on Hinode. This image shows an emission from plasma heated to greater than eight million degrees during the energy release process of the flare. (Photo via JAXA/Hinode)
IN SPACE - JANUARY 23: In this handout from the NOAA/National Weather Service's Space Weather Prediction Center, shows the coronal mass ejection (CME) erupting from the sun late January 23, 2012. The flare is reportedly the largest since 2005 and is expected to affect GPS systems and other communications when it reaches the Earth's magnetic field in the morning of January 24. (Photo by NOAA/National Weather Service's Space Weather Prediction Center via Getty Images)
IN SPACE - JANUARY 23: In this handout from the NOAA/National Weather Service's Space Weather Prediction Center, shows a solar flare erupting from the sun late January 23, 2012. The flare is reportedly the largest since 2005 and is expected to affect GPS systems and other communications when it reaches the Earth's magnetic field in the morning of January 24. (Photo by NOAA/National Weather Service's Space Weather Prediction Center via Getty Images)
The sun erupted with one of the largest solar flares of this solar cycle on March 6, 2012 at 7PM ET. ?This flare was categorized as an X5.4, making it the second largest flare -- after an X6.9 on August 9, 2011 -- since the sun's activity segued into a period of relatively low activity called solar minimum in early 2007. The current increase in the number of X-class flares is part of the sun's normal 11-year solar cycle, during which activity on the sun ramps up to solar maximum, which is expected to peak in late 2013. (Photo by NASA/SDO/AIA/Handout/Corbis via Getty Images)
ABERDEEN, UNITED KINGDOM - NOVEMBER 27: EXCLUSIVE. Northern Lights near Torphins at 00.34Hrs on November 27, 2003 in Aberdeen, Scotland. The purple and green rays appear to flare as well as move rapidly sideways. Dancing across the skies these images Britain's most spectacular psychedelic light shows over the past 20 years. Over the last two decades photographer, Jim Henderson, 62, has witnessed 350 aurora displays in the UK, and has only ever had to travel more than a few miles from his cottage 25 miles west of Aberdeen to capture his amazing images. Dedicated Jim has collected an archive of over 5000 images in the 22 years he has been painstakingly recording auroras. Most people think to truly witness the magnificence of the aurora borealis - or northern lights as they are commonly known- they need to travel thousands of miles to the freezing Icelandic tundra or remote Canadian mountains. And last weekend's lack of any aurora appearance - despite widespread reports that one was imminent - will have done nothing to quash this view. But as these pictures prove the incredible sight can be just as visible in the familiar British countryside as the frozen landscape of the Arctic circle. (Photo by Jim Henderson / Barcroft Media / Getty Images)
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The closest thing we've ever seen to a superflare from the sun is probably the Carrington Event.
In 1859, the sun launched a flare so energetic it damaged Earth's ozone layer and set telegraph offices on fire.
Experts say a flare that powerful today could do billions of dollars in long-term damage to satellite networks and electrical transformers. Those aren't the sort of things we keep plenty of spares for.
And Carrington was a relatively weak example compared to the energies involved in superflares.