Explanation:
Stars come and go as you slide your cursor over
this engaging image of M8, aka
the Lagoon Nebula.
Of course, the nebula is itself a
star-forming region,
but the stars that appear and
disappear here include background and
foreground stars that by chance lie along the same
line of sight.
In
this "for fun" comparison of two nearly
identical digital images, the stellar point sources
were removed from
one
image by computer processing to leave
only the diffuse emission from the glowing gas clouds.
In both pictures,
red emission (H-alpha emission)
from atomic hydrogen dominates the cosmic lagoon's visible light,
but narrow band
filters were used to record the image data and
map the hydrogen emission to green hues, with
emission from sulfur atoms in red and oxygen in blue.
The lovely
Lagoon Nebula spans about 30 light-years at an
estimated distance of 5,000 light-years toward the constellation
Sagittarius.
