Comet C/1999 S4: A comet discovered in September 1999 by the
Lincoln Near Earth Asteroid Research (LINEAR) project. Caption:
On July 14, 2000 Chandra observed the comet LINEAR for a total
of 2½ hours. The X-ray emission proved to be due to collisions
of electrically neutral elements in the atmosphere of the comet
with nitrogen and oxygen ions in the solar wind. Observed
variations in the amount of X-rays produced by the comet were
probably due to an increase in the intensity of the solar wind
from recent solar flares. The colors represent the intensity of
the X-rays with white being the most intense, then yellow,
orange, and red. Scale: Image is 10 x 10 arcmin on a side.
Chandra X-ray Observatory ACIS Image