This artist's concept depicts the pulsar planet system discovered by
Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope
in Puerto Rico to find three planets - the first of any kind ever found
outside our solar system - circling a pulsar called PSR B1257+12. Pulsars
are rapidly rotating neutron stars, which are the collapsed cores of
exploded massive stars. They spin and pulse with radiation, much like a
lighthouse beacon. Here, the pulsar's twisted magnetic fields are
highlighted by the blue glow.
All three pulsar planets are shown in this picture; the farthest two from
the pulsar (closest in this view) are about the size of Earth. Radiation
from charged pulsar particles would probably rain down on the planets,
causing their night skies to light up with auroras similar to our Northern
Lights. One such aurora is illustrated on the planet at the bottom of the
picture.
Since this landmark discovery, more than 160 extrasolar planets have been
observed around stars that are burning nuclear fuel. The planets spotted
by Wolszczan are still the only ones around a dead star. They also might
be part of a second generation of planets, the first having been destroyed
when their star blew up. The Spitzer Space Telescope's discovery of a
dusty disk around a pulsar might represent the beginnings of a similarly
"reborn" planetary system.
