A huge eruption on the sun last Thursday sent a wave of solar particles toward Earth and resulted in some amazing views of the Aurora Borealis from Alberta to the United Kingdom.
[ Related Gallery: More images from recent Aurora Borealis show ]
NASA calls what happened a coronal mass ejection (CME).
"Not to be confused with a solar flare, which is a burst of light radiation, CMEs are a phenomenon that can send solar particles into space and can reach one to three days later," wrote NASA officials in a statement. They said the CME was travelling at about 400 miles per second toward Earth.
CMEs are the most powerful explosions on the sun. When aimed directly at Earth, strong CME events "can affect electronic systems in satellites and on Earth," NASA officials said.
[ Related Gallery: Spectacular Northern Lights of the past ]
A red alert was issued just after 7 p.m. on Monday evening. The alert is sent out by AuroraWatch and means there was a very good chance of seeing the lights. You can sign up with the group for information on the next time the Aurora Borealis will be visible in Alberta.
The sun is currently in the middle of an active phase of its 11-year solar weather cycle. The current cycle, called Solar Cycle 24, is expected to peak in 2013.