An enormous storm is growing on the surface of the Sun - and could send massive solar flares our way soon.
The colossal sun spot is large enough to swallow six Earths.
Sun spots usually grow out of shifting magnetic patterns on the star, and can 'pool' together to create very large features or blemishes on the surface. Sun spots are actually cooler than the rest of the Sun, but can lead to violent eruptions.
Nasa said the sun spot is still growing, and is increasingly volatile.
Above: the sun spots on the Sun's surface
"It has grown to over six Earth diameters across, but its full extent is hard to judge since the spot lies on a sphere, not a flat disk," wrote Nasa spokeswoman Karen Fox.
The space agency's Solar Dynamics Observatory spotted the sunspot as it swelled to its current giant size over 48 hours earlier this week.
The magnetic fields in the area are pointing in opposite directions, Nasa explained - making it even more likely to combust.
"This is a fairly unstable configuration that scientists know can lead to eruptions of radiation on the sun called solar flares," Fox said.
While it is unlikely any solar flare would cause physical harm on Earth, extreme space weather was recently discussed as a potential threat by the UK government - and can seriously affect communications satellites.