My first Magazine Sky & Telescope - 02.2019 | Page 39

lgol
How John Goodricke and
Edward Pigott discovered
and interpreted a new
variable star.
O
n November 12, 1782, 18-year-old John Goodricke
of York, England, compared the brightness of the
star Algol (Beta Persei) to neighboring stars in Per-
seus and Andromeda. Astonished at what he’d seen, he wrote
in his journal:
This night I looked at Beta Persei and was much surprized [sic]
to find its brightness altered — It now appears of about the 4th
magnitude. I observed it diligently for about an hour — I hardly
believed that it changed its brightness because I never heard of
any star varying so quickly in its brightness. I thought it might
perhaps be owing to an optical illusion, a defect in my eyes, or
bad air, but the sequel will show that its change is true and that I
was not mistaken.
t AN ASTRONOMER’S POSE Born in
the Netherlands, John Goodricke spent
most of his life in the United Kingdom.
This portrait, composed in pastels by
James Scouler the year Goodricke turned
21, originally hung in the astronomer’s
own home in Lendal, York.
Goodricke and Pigott
John Goodricke (1764–1786) was
born in Groningen, the Dutch
Republic (present-day Nether-
lands), where his father Henry
was a diplomat. An early illness
(perhaps scarlet fever) left John
completely deaf — a significant
handicap in those times when the
deaf were still subject to prejudice.
Fortunately, the Goodricke family
had the resources and the insight to help a child with special
needs. Had he lived a longer life, John Goodricke would have
eventually become a baronet and inherited a large estate.
Goodricke attended Braidwood Academy, the first school
for the deaf in the British Isles, and then the Warrington
Academy. The Warrington mathematics curriculum included
a significant amount of astronomy, and John’s mathematics
notebook includes a sketch of the sky. From the position of
the Moon and the times indicated in the text, it’s clear that
The next night, Goodricke returned for another look at Algol
and wrote, “Beta Persei is now much changed. It now appears
of the second magnitude. . . . very unexampled change!”
Goodricke didn’t observe Algol’s dimming by chance. He
and Edward Pigott, his mentor and friend, were searching
for stars whose light varied. At that time the best-studied
variable star, with a period of about 11 months, was Mira
(Omicron Ceti). Hence, Goodricke expected any change
in brightness to take weeks, not hours. Although earlier
astronomers remarked that the light of Algol (imagined since
ancient times to represent the winking eye of the Gorgon,
Medusa, in the constellation of Perseus) didn’t seem con-
stant, no one had systematically observed the star. Over the
next three years, the two young Englishmen would charac-
terize the variation of Algol, another eclipsing binary system
(Beta Lyrae), and the first two known Cepheid variables.
u WRITTEN RECORD This sketch of the Moon (top center) and stars
comes from the inside back cover of John Goodricke’s mathemat-
ics notebook from Warrington Academy for the year 1779–1780. The
position of the Moon and the descriptive note about the star positions
(bottom) make it possible to determine that Goodricke drew the sketch
in November 1779.
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