L
INCONSTANT STAR by Linda FrenchGOODRICKE: ROYAL ASTRONOMICAL SOCIETYJohn Goodricke and Edward Pigott discovered
and interpreted a new variable star. On November 12, 1782, 18-year-old John Goodricke
of York, England, compared the brightness of the star
Algol(BetaPersei)toneighbouringstarsinPerseus
and Andromeda. Astonished at what he’d seen, he wrote in
his journal:This night I looked at Beta Perseiand 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.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). Thus, Goodricke expected any change in brightness
to take weeks, not hours. Although earlier astronomers had
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 constant, no one had
systematically observed the star. Over the next three years,
the two young Englishmen would characterise the variation
of Algol, another eclipsing binary system (Beta Lyrae) and the
first two known Cepheid variables.Goodricke and Pigott
John Goodricke (1764–86) was born in Groningen, the
Dutch Republic (present-day Netherlands), 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 WarringtonS 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.22 AUSTRALIAN SKY & TELESCOPE April 2019