Moss Spreading Target Name:   Sun Spacecraft:   TRACE Produced by:   NASA/GSFC Copyright:  Public Domain Date Taken:   1 August 1999 Date Released:  14 December 1999

• Trace Spacecraft Discovers Moss on the Sun

This sequence of 4 images shows the rapid formation and spreading of moss following a minor flare event. The blue circle in each image shows the approximate size of the Earth in the field-of-view. Image times are as follows.

1: 20:54 UT t = 0 seconds.
2: 21:01 UT t = 420 seconds.
3: 21:09 UT t = 900 seconds.
4: 21:28 UT t = 2030 seconds.

The bright "front" of moss advancing across the image moves with an average speed of about 17 km/sec (10 miles/sec or about 38,000 miles/hour). The moss forms in response to the spreading of the flare heat in the hot coronal loops above the moss; the loops are not visible in this TRACE 195 Angstrom image series because they are so hot that they radiate in x-rays, which are invisible to the TRACE instrument.