Astronomy Picture of the Day

Cassiopeia A Light Echoes in Infrared

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#75404 by @ 16.06.2005 00:00 - nach oben -
Cassiopeia A Light Echoes in Infrared

Why is the image of Cassiopeia A changing?

Two images of the nearby supernova remnant taken a year apart in
infrared light
appear to show outward motions at tremendous speeds.
This was unexpected since the
that created the
picturesque nebula was seen 325 years ago.

The reason is likely light echoes.

Light from the supernova heated up distant ambient
dust that is just beginning to show its glow.

As time goes by, more distant dust
lights up,
giving the appearance of outward motion.

above image is a composite of
optical, and infrared light exposures that have been digitally combined.

infrared light image was taken by the orbiting
Space Telescope
and was used in the discovery of the
light echo.

The portion of
Cassiopeia A
shown spans about 15
light years and lies 10,000 light years away toward the
constellation of

Credit & Copyright
#75430 by @ 16.06.2005 13:25 - nach oben -
warum habne wir eigentlich ein APOY ? Astronomy Picture of Yesterday ?
auf der APOD Seite ist ein anderes zu sehen, nämlich das Jubiläumsbild, welches heute ist...

naja vermutlich weil die amis um CEST 0:00 halt noch gestern haben oder so....

freuen wir uns also auf morgen und das jubiläumsbild..
#75434 by @ 16.06.2005 14:08 - nach oben -
richtig! genau drum isch da so.