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MIRA CETI IS A
VARIABLE STAR
A NEW KIND OF STAR
IN CONTEXT
KEY ASTRONOMER
David Fabricius (1564 –1617)BEFORE
350 bce Greek philosopher
Aristotle asserts that the stars
are fixed and unchanging.AFTER
1667 Italian astronomer
Geminiano Montanari notes
that the star Algol varies
in brightness.1784 John Goodricke discovers
Delta Cephei, a star that varies
in brightness over five days;
English astronomer Edward
Pigott discovers the variable
Eta Aquilae.19th century Different kinds
of variable star are discovered,
including long-period variables,
cataclysmic variables, novae,
and supernovae stars.1912 Henrietta Swan Leavitt
discovers a relationship
between the periods and the
brightness of variable stars
such as Delta Cephei.B
efore the work of German
astronomer David Fabricius,
it was thought that there
were only two types of star.
The first were those of constant
brightness, such as the 2,500 or
so that can be seen with the naked
eye above the horizon on a clear
dark night. The second type were
the “new stars,” such as those
seen by Tycho Brahe in 1572
and Johannes Kepler in 1604.
The constant stars were
synonymous with the fixed,
permanent stars in the ancient
Greek cosmos—those that
mapped out the patterns in the
constellations and never changed.
The new stars, by contrast, would
appear unexpectedly, apparently
from nowhere, then fade away,
never to be seen again.A third kind of star
While observing the star Mira Ceti
(also called Omicron Ceti), in the
constellation of Cetus the whale,
Fabricius realized that there was
a third type of star in the sky—one
that regularly varied in brightness.
He made his discovery in August
1596 as he was plotting the
movement of Jupiter across the
sky in relation to a nearby star.Mira Ceti is a
variable star.The star Mira Ceti is
observed to change in
brightness periodically.Some stars are
variable.Aristotle was
wrong when he asserted
that the stars are fixed
and eternal.