Explanation:
Over six hundred light years from Earth, in
the
constellation Aquarius, a sun-like star is dying.
Its last few thousand years have produced the
Helix Nebula (NGC 7293), a
well studied and nearby example of
a
Planetary Nebula, typical of this final phase
of stellar evolution.
Emission in this infrared
Spitzer Space Telescope image
of the Helix
comes mostly from the nebula's molecular hydrogen gas.
The gas appears
to be clumpy, forming thousands of comet-shaped knots
each spanning about twice the size of our solar system.
Bluer, more energetic radiation is seen to come from the
heads with
redder emission from the tails, suggesting that they are more
shielded from the
central star's winds and intense
ultraviolet radiation.
The nebula itself is about 2.5 light-years across.
The Sun is expected to go through
its own Planetary Nebula phase ...
in another 5 billion years.
