Does our Sun always look the same?

Our Sun goes through an 11 year cycle of "active" periods and "quiet" periods.

This picture shows how the Sun changed between 1991 and 1995.

Changing X Ray Sun
1991 - 1995

The image at the far left shows a very active X-ray Sun (1991). The image on the far right was taken in 1995 and shows our Sun with few X-rays coming from it. The images shown in this picture are 4 months apart.

ACTIVE PERIOD - Lots of solar activity including sunspots, flares, prominences, and coronal mass ejections. Our Sun was most recently active during the late 1980's and early 1990's.

Photograph September 28, 1991
by Yohkoh Satellite

Active X-Ray Sun

QUIET PERIOD - Few, if any sunspots are seen, the corona is difficult to observe, and our Sun looks black when viewed with an X-ray telescope because few X-rays are being produced. Right now, our Sun is in a relatively quiet period.

Photograph April 7, 1995
by Yohkoh Satellite

Inactive X-Ray Sun

SOLAR CYCLE - Solar activity increases and decreases over an 11 year cycle. Scientists can pretty well predict when our Sun is going to be active and when it is going to be quiet, but not always. The new active phase has only just begun -- maximum activity should happen sometime around 2000-2001. (Data from: National Geophysical Data Center)

Solar Cycle Graph
(see below)

Sunspot Cycle

More info:

Here's a large graph showing how the Sun changes during the Solar Cycle, including pictures of the Sun between 1980 and 1989. (200 kilobytes)

One Step Back

Step Back Next Page

One Step Ahead

(Back to the Beginning of the Tour)

Image Credits:
The Changing Sun: Lockheed Martin Palo Alto Research Lab, G.L. Slater and G.A. Linford
Active Sun, and Inactive Sun: Yohkoh Science Team
Solar Cycle: Space Physics Group of University of Oulu, Finland