This bright blue sperm, in fact a swirling mass of dust and gas, doesn’t need an egg to impregnate: it’s producing baby stars all by itself.
The tadpole-shaped clump of stellar matter — IRAS 20324+4057 to its friends — is actually home to a number of protostars. You can see some in the ‘head’ of the sperm, and one in particular glowing bright yellow which will at some point emerge as a fully fledged young star. The ESA explains where the cloud’s blue hue comes from:
The intense blue glow is caused by nearby stars firing ultraviolet radiation at IRAS 20324+4057, which also sculpts its tail into a long, wiggly shape. In total, this clump spans roughly a light-year from head to tail-tip, and contains gas weighing almost four times the mass of the Sun.
Pictured against a background of really very pretty stars, the cloud is currently making its way through the Cygnus OB2 association. [ESA]