The Pleiades in Red and Blue
If you have looked at the sky and seen a group of
stars about the size of the full Moon, that's the
Pleiades (M45).
Perhaps the most famous
star cluster in the sky, its brightest stars can be seen even from the
light-polluted cities.
But your unaided eye can also see its nebulosity --
the gas and dust surrounding it --
under dark skies.
However, telescopes can catch even more.
The bright blue stars of the Pleiades, also known as the
Seven Sisters, light up their surrounding dust,
causing it to appear a diffuse blue that can only be seen under long exposures.
But that's not all.
The cosmic dust appears to stretch upward like
ethereal arms.
And the entire structure is surrounded by a
reddish glow from the most abundant
element in the universe: hydrogen.
The featured image is composed of nearly 25 hours of exposure
and was captured last year from
Starfront Observatory, in
Texas,
USA