A group of sunspots has emerged on the Earth-facing side of the sun, just in time for Thanksgiving.
Researchers identified the sunspots before they were even visible from Earth, via a technique called helioseismology, which uses acoustic waves beneath the sun's surface to probe for the features.
"We measured a change in acoustic signals on the far side of the sun," Alexei Pevtsov, associate director for the National Solar Observatory (NSO) program that generates solar predictions, said in a statement. "We can use this technique to identify what is happening on the side of the sun that faces away from Earth, days before we can catch a glimpse from here."
Photos: Sunspots on Earth's closest star
The scientists predicted that the sunspots, the largest of which appears to be several times bigger than Earth, would rotate into view by Thanksgiving, which falls this year on Nov. 26. And this has indeed come to pass.
You may be able to see the sunspots with proper filters on binoculars or a small telescope, but be careful: You must have ISO-certified filters on the equipment at all times to observe the sun safely. Never look at the sun directly without such protective gear, especially when using astronomy equipment; doing so can cause permanent eye damage, including blindness.
Researchers use sunspots to make predictions about space weather, the activity the sun generates in the vicinity of Earth. Eruptions of charged particles can disrupt satellite communications and power lines, making it essential to know when sunspots — hubs of magnetic activity that serve as launch pads for such outbursts — will be coming around the bend and facing our planet.
"Having up to five days' lead time on the presence of active sunspots is extremely valuable to our technology-heavy society," Pevtsov added.
The sun is in the early months of its 11-year sunspot cycle and in a relatively quiet period. The sunspot group produced the strongest signal yet observed in this cycle, added Kiran Jain, the scientist who is leading the far-side prediction at NSO, in the same statement.
NSO has six monitoring stations worldwide that monitor the sun through the Global Oscillation Network Group (GONG), which is funded by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration.
NSO officials added that the group anticipates needing to upgrade GONG in the coming years, as the network is almost three decades old and requires more modern instrumentation.
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