Northern Lights displays could illuminate the night sky over Britain as eruptions from the Sun head towards Earth.
This picture from Nasa's Solar Dynamics Observatory (SDO) shows two solar flares seen in extreme ultraviolet light over a three day period.
This is a still taken from a Nasa video that shows the flares in extreme ultraviolet light. The coronagraph images show the faint edge of a "halo" coronal mass ejection as it raced away from the Sun and began heading towards Earth.
This is another image from Nasa that shows the sun emitting its first X-class flare in over four years. X-class flares are the most powerful of all solar events that can trigger radio blackouts and long-lasting radiation storms.
Here is a blowup of the flaring region taken by Nasa's Solar Dynamics Observatory in the extreme ultraviolet wavelength of 193 Angstroms. Much of the vertical line in the image is caused by the bright flash overwhelming the SDO imager.
An active sun
The most recent flare is the largest since December 2006 and the biggest flare so far in Solar Cycle 24. Active Region 1158 is in the southern hemisphere, which has been lagging the north in activity but now leads in big flares.
The images of this flare were captured the Solar Dynamics Observatory, which took off from Cape Canaveral in February 2010. The satellite is designed to predict disruptive solar storms and scientists say the images provided by the satellite are already helping them learn new things.
This image shows a solar flare that erupted in September 2010. The eruption also hurled a bright coronal mass ejection into space, but was not directed toward any planets.
Sun and moon
The Solar Dynamics Observatory's space telescope captured this image, which shows the moon passing in front of the sun. Flares and solar activity can be seen on the sun's surface.
This was one of the first images taken by the Solar Dynamics Observatory satellite and shows an eruptive prominence blasting away from the sun. The high-resolution images are ten times more detailed than those of high-definition television.
A 500,000 mile eruption
This image was taken from a video made on 12-13 April 2010. The prominence appears to stretch almost halfway across the sun: the equivalent of a distance of about 500,000 miles.