An outburst of charged particles known as a coronal mass ejection erupts from the surface of the Sun in this 2012 image, shot by a satellite at wavelengths that are not visible to the human eye. Such eruptions can blast billions of tons of material toward Earth. When it hits us, it can disrupt satellites and ground power systems and trigger bright aurorae. Scientists recently discovered evidence of a particularly nasty eruption about 2,700 years ago in ice cores and tree rings. [NASA/SDO]