Fix your camera to a tripod, lock the shutter open, and you can easily record an image of star trails [
http://www.astropix…I0601.HTM ], the graceful concentric arcs traced by the stars as planet Earth [
http://antwrp.gsfc.…] rotates on its axis. Gradually change the focus of the camera lens during the exposure, and you could end up with a dramatic picture like this one where the out-of-focus portion of the trail shows off the star's color [
http://antwrp.gsfc.…]. In this case, the subject is one of the most famous constellations in the night sky, Crux [
http://www.hawastso…], the Southern Cross. Gacrux or gamma Crucis [
http://www.solstati…] is the bright red giant star only 88 light-years distant that forms the top of the Cross seen here near top center. Acrux [
http://www.astro.ui…], the hot blue star at the bottom of the Cross is about 320 light-years distant. Actually a binary star system, Acrux is the alpha star of the compact Southern Cross [
http://www.astro.ui…cru-t.html ] and lies along a line pointing from Gacrux to the South Celestial Pole [
http://antwrp.gsfc.…], off the lower right edge of the picture. Adding a separate short exposure to the end of the step-focussed trails to better show the positions of the stars themselves [
http://flagspot.net…], astronomer Stefan Seip recorded this remarkable image [
http://www.astromee…040523cruxa_d.htm ] last May in the dark night skies above Namibia.
Explanation
Fix your camera to a tripod, lock the shutter open, and you can easily record an image of star trails [
http://www.astropix…I0601.HTM ], the graceful concentric arcs traced by the stars as planet Earth [
http://antwrp.gsfc.…] rotates on its axis. Gradually change the focus of the camera lens during the exposure, and you could end up with a dramatic picture like this one where the out-of-focus portion of the trail shows off the star's color [
http://antwrp.gsfc.…]. In this case, the subject is one of the most famous constellations in the night sky, Crux [
http://www.hawastso…], the Southern Cross. Gacrux or gamma Crucis [
http://www.solstati…] is the bright red giant star only 88 light-years distant that forms the top of the Cross seen here near top center. Acrux [
http://www.astro.ui…], the hot blue star at the bottom of the Cross is about 320 light-years distant. Actually a binary star system, Acrux is the alpha star of the compact Southern Cross [
http://www.astro.ui…cru-t.html ] and lies along a line pointing from Gacrux to the South Celestial Pole [
http://antwrp.gsfc.…], off the lower right edge of the picture. Adding a separate short exposure to the end of the step-focussed trails to better show the positions of the stars themselves [
http://flagspot.net…], astronomer Stefan Seip recorded this remarkable image [
http://www.astromee…040523cruxa_d.htm ] last May in the dark night skies above Namibia.
Explanation
