The Sun has an 11-year cycle of activity over which the number of sunspots and solar flares oscillates with time.  It is making a late return to activity from the most recent Solar Minimum, when its level of activity is quite low. During levels of heightened activity, the sun produces solar flares that send charged particles out into space and sometimes these particles collide with the earth’s atmosphere, producing aurorae.

Recent observations by GOES-15 (Geostationary Operational Environmental Satellite), which is operated by the US National Oceanic and Atmospheric Administration (NOAA), indicate that a solar flare may be possible during the next few days.

GOES-15 X-Ray image of the Sun's lower atmosphere

Above is an image of the Sun today, from the high-energy X-Ray part of the electromagnetic spectrum. The bright spot just below and to the left of the center of the Sun’s disk is hot gas that lies directly above an active sunspot group. The extended halo around the Sun is hot gas in the lower atmosphere, the bottom portion of the solar Corona. If a solar flare were to go off, it would head right toward the Earth and below, you can see that the amount of activity, indicated by the X-Ray flux levels, have increased over recent days.

Solar X-Ray surface flux, February 2011 (NOAA Space Weather Prediction Center)

Most solar flares do not do much harm to human activity, though they can produce radio and cell phone interference. On rare occasions, strong solar flares might damage satellites or bring down the power grid. It is much more likely that when the charged particles from solar flares collide with Earth’s atmosphere, we will be treated to a nice display of aurorae at night. The best time and place to see the aurorae are at mid- to high-latitudes on a clear, dark night between 10pm and 2am. See the NOAA Space Weather Prediction Center website or Space for updates on solar activity.