Eta Carinae and the Homunculus Nebula

How did the star Eta Carinae create this unusual nebula? No one knows for sure.
About 165 years ago, the southern star Eta Carinae mysteriously became the second
brightest star in the night sky. In 20 years, after ejecting more mass than our Sun,
Eta Car unexpected faded. This outburst appears to have created the Homunculus
Nebula, pictured above in a composite image from the Hubble Space Telescope taken
last decade. Visible in the above image center is purple-tinted light reflected from
the violent star Eta Carinae itself. Surrounding this star are expanding lobes of
gas laced with filaments of dark dust. Jets bisect the lobes emanating from the central
star. Surrounding these lobes are red-tinted debris captured only by its glow in a
narrow band of red light. This debris is expanding most quickly of all, and includes
streaming whiskers and bow shocks caused by collisions with previously existing material.
Eta Car still undergoes unexpected outbursts, and its high mass and volatility make it
a candidate to explode in a spectacular supernova sometime in the next few million years.