SKY & TELESCOPE NEWS BULLETIN
MAY 2, 1997
Last week more than 300 scientists met in Williamsburg, Virginia, to
announce the latest discoveries from the Compton Gamma Ray Observatory
(CGRO). John R. Mattox (Boston University) and his colleagues have been
using CGRO to time clocklike blips from Geminga, an enigmatic pulsar some
500 light-years from Earth. Their data reveal a 5.1-year cycle that may be
due to a planet with 1.7 times the mass of Earth. Mattox stresses that the
pulsar's shifting emissions have been traced reliably for only one cycle;
they could simply reflect changes in the pulsar's internal structure.
Confirming the planet hypothesis will require further timing data or other
evidence, like an eclipse of Geminga.
Although there are a few other promising suspects, only one other pulsar,
PSR 1257+12 in Virgo, is widely believed to harbor three (and possibly four)
planets. Unfortunately for SETI fans, pulsar planets are unlikely homes
for life; they are bombarded by showers of energetic particles that vastly
dwarf even the most energetic solar flares.
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