Welcome to multiwavelength astronomy [
http://imagine.gsfc…multiwavelength.html ]! From top to bottom, these stacked panels show the largest sunspot group in a decade in visible, extreme ultraviolet, and x-ray light. All were taken on March 29, around the time [
http://sohowww.nasc…] the famous solar active region, cataloged as AR 9393 [
http://antwrp.gsfc.…], was at its peak size -- over 10 times the size of planet Earth. The panels illustrate how the "appearance" of the active region changes, when imaged in electromagnetic radiation [
http://www.colorado…waves_particles/ ] (light) of progressively shorter wavelengths. In the visible light panel, dark islands [
http://antwrp.gsfc.…] of sunspots stand out against the bright solar surface, but the situation seems to be reversed in the extreme ultraviolet panel with a bright active region seen against a darker background. Finally, the x-ray panel reveals majestic loops of glowing plasma arcing far above the sunspot group. Why do pictures [
http://www.lmsal.co…] of the same part of the Sun [
http://observe.ivv.…] look so different? Made at different wavelengths, each panel actually records a different layer [
http://www.lmsal.co…Structure.html ] in the solar atmosphere. Top to bottom, the altitude of each layer (along with temperature) increases; starting with the Sun's visible surface or photosphere [
http://solar-center…photosphere.html ] (about 5 thousand kelvins), then the chromosphere [
http://science.nasa…chromos.htm ] / transition region [
http://science.nasa…] (ten to a hundred thousand kelvins [
http://lamar.colost…]), and finally the solar corona [
http://www.lmsal.co…corona2.html ] (millions of kelvins).
Explanation
Welcome to multiwavelength astronomy [
http://imagine.gsfc…multiwavelength.html ]! From top to bottom, these stacked panels show the largest sunspot group in a decade in visible, extreme ultraviolet, and x-ray light. All were taken on March 29, around the time [
http://sohowww.nasc…] the famous solar active region, cataloged as AR 9393 [
http://antwrp.gsfc.…], was at its peak size -- over 10 times the size of planet Earth. The panels illustrate how the "appearance" of the active region changes, when imaged in electromagnetic radiation [
http://www.colorado…waves_particles/ ] (light) of progressively shorter wavelengths. In the visible light panel, dark islands [
http://antwrp.gsfc.…] of sunspots stand out against the bright solar surface, but the situation seems to be reversed in the extreme ultraviolet panel with a bright active region seen against a darker background. Finally, the x-ray panel reveals majestic loops of glowing plasma arcing far above the sunspot group. Why do pictures [
http://www.lmsal.co…] of the same part of the Sun [
http://observe.ivv.…] look so different? Made at different wavelengths, each panel actually records a different layer [
http://www.lmsal.co…Structure.html ] in the solar atmosphere. Top to bottom, the altitude of each layer (along with temperature) increases; starting with the Sun's visible surface or photosphere [
http://solar-center…photosphere.html ] (about 5 thousand kelvins), then the chromosphere [
http://science.nasa…chromos.htm ] / transition region [
http://science.nasa…] (ten to a hundred thousand kelvins [
http://lamar.colost…]), and finally the solar corona [
http://www.lmsal.co…corona2.html ] (millions of kelvins).
Explanation
