74 ASTRONOMY • DECEMBER 2015
The Owl and
the Snake
One of the sky’s brightest
planetary nebulae — the
Owl Nebula (M97) in
Ursa Major — lurks just
below the bowl of the Big
Dipper. But the southern
sky harbors a fainter ver-
sion of this stealthy preda-
tor. The Southern Owl
Nebula (ESO 378-1) seen
here soars among the
stars of Hydra the Water
Snake. Like all planetaries,
the Southern Owl repre-
sents the death throes of
a Sun-like star. After the
star puffs off its outer
layers, its white-hot core
energizes the ejected gas
and causes it to glow. ESO
378-1 spans nearly four
light-years and lies about
3,500 light-years from
Earth. ESOBREAK
THROUGH