A huge spot has appeared on the sun that could send dangerous solar flares down to Earth.
The sunspot, dubbed AR2665, is 74,560 miles (120,000 kilometres) wide – big enough to be seen from Earth.
Experts have warned that the spot is large enough to produce 'M-class' solar flares, which can cause radio blackouts on Earth, knock out communications satellites and create radiation storms.
Nasa's Solar Dynamics Observatory first detected the huge spot last week, and it appears to have lingered through to this week.
Sunspots are darker, cooler areas on the surface of the sun, caused by interactions with the sun's magnetic field.
They tend to appear in regions of intense magnetic activity, and when that energy is released, solar flares and huge storms erupt from sunspots.
Such a storm could create stunning auroras around the world, as well as play havoc with power grids, potentially causing blackouts in some areas.
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