Perhaps the most significant contribution that
Galileo
Galilei made to science was the discovery of the four largest moons
around
Jupiter. The so-called "Galilean Moons" -- Ganymede, Callisto, Io
and Europa -- were first observed on January 7, 1610 through a homemade
telescope. Galileo originally saw three stars near Jupiter,
strung
out on a line with the planet. The next evening, he noticed that
the stars had not only moved but moved the wrong way!
Unable
to explain this, Galileo continued to observe Jupiter and its stars for
another week. On January 11, a fourth star (which later turned
out
to be Ganymede) appeared. After yet another week, Galileo had
noticed
that the four stars never left the vicinity of Jupiter and appeared to
be carried along with the planet; and also, that they changed their
position
with respect to each other as well as to Jupiter. Finally,
Galileo
decided that the stars were not stars but moons in orbit around
Jupiter.
This discovery provided timely and important evidence in support of the
upwelling Copernican Hypothesis -- which proposed that not all
celestial
bodies revolved about the Earth. The idea that the Earth was not
the center of the universe was sending shock waves through the
Catholic
world. So it was in this atmosphere in 1610 that Galileo
obliquely
published his news in the clever and now famous "Starry Messenger".
One of Galileo's contemporaries, Giordano Bruno,
who had earlier written that "... innumerable suns exist; innumerable
earths
revolve about these suns in a manner similar to the way the seven
planets
revolve around our sun ...." had the great misfortune of being
burned
at the stake on February 17, 1600, for his heretical views.
Galileo
however, being much more illustrious than the obscure Bruno, did not
suffer
the same fate. Instead, after a trial, he was placed under house
arrest in 1633; where he remained until his death in 1642.
Galileo
was eventually pardoned by Pope John Paul II, 350 years later.
On December 7, 1995 the satellite Galileo, arrived
at Jupiter to begin its remarkable (and still ongoing) survey of our
largest
planet. NASA today maintains a comprehensive website as a
repository
for all of Galileo's data.
Charles Messier
(1730-1817)
Charles Messier was a Parisian astronomer dubbed
"The Ferret of Comets" by none other than King Louis XV. Messier,
always on a comet hunt, was annoyed when a non-stellar object he
had spied on the night of September 12, 1758, turned out to be not a
comet
but a "whitish light spreading like a flame." He decided to warn
others of these non-cometary objects he was always bumping into;
and the "whitish light" became object number 1 in the Messier
catalog.
Unbeknownst to him, Messier had discovered the famous, supernova
remnant
known as the Crab Nebula in Taurus.
All in all, Messier's celebrated list, with its
100+ objects, became the cream of today's so-called "deep-sky"
objects.
He is revered as the essence of telescopic virtuosity, the king of the
skies. By and large however, Messier was interested only in
finding
comets, and showed no further interest in these comet decoys.
Legend
has it that he was upset to have missed out on the discovery of a new
comet
the night his wife died.
Today, all of the Messier objects have been
identified
for what they really are. A few are actually naked-eye
objects.
All of them can be found in good binoculars; and, all give up their
secrets
easily under the scrutiny of the modern, backyard telescope. To
know
the Messier objects intimately is considered a badge of honor.
There
are even "Messier marathons" where all the Messier objects are perused
in one night (in March).
The Herschels
William, John and Caroline
The Herschels were an amazing, untiring
family
of astronomers in the late 1700s and early 1800s who were the first to
conduct a systematic investigation of every nook and cranny of the
northern
skies.
Sir William Herschel (1738-1822) earned an
excellent living as a classical musician, an oboist and composer of
considerable
talent. But he is today best remembered as a great stargazer,
considered
by many as the finest astronomical observer ever seen. His hobby
was so consuming that he built and operated the largest telescope of
his
day, a 48-inch reflector that, even by today's standards, would be
considered
a very respectable telescope indeed. With it, he made numerous
important
discoveries including the discovery of the planet Uranus (and later,
two
of its moons) in 1781, the first planet to be discovered in modern
times.
It was not uncommon for Herschel to run out and observe the stars
during
intermission of concerts he was conducting.
Sir William, along with his son John
(1792-1871),
gave us our first modern, comprehensive, celestial survey of the
northern
skies. Sir John Herschel's 1864 General Catalog is still
in
use today and forms the basis for the well-known New General Catalog,
the so-called "NGC" which serves as the astronomer's Bible.
One night, William Herschel came upon an
immense
swarm of dim and cloud-like nebulae. In due time, he counted no
less
than 323 of the tiny fuzzballs and referred to his amazing find as "The
Realm of the Nebulae". Unbeknownst to him, Sir William had
discovered
the Virgo Cluster of Galaxies; a great assemblage of galaxies of all
types
and sizes believed to contain no less than
10,000 galaxies. Today, the area is a favorite haunt of
galaxy-gazers
and is known, more precisely, as "The Realm of the Galaxies". The
Virgo Cluster is now known to be a giant supercluster of galaxies, the
nearest such supercluster to our own galaxy. It lies some 50
million
light-years away.
Caroline Herschel (1750-1848), William's
younger sister by 12 years, became William's assistant from early
on.
In 1787, Caroline was awarded an annual stipend by the King of England
as a clear acknowledgment of her importance as a professional
astronomer.
She eventually discovered no less than seventeen nebulae and eight
comets.
In later years, she received the Royal Astronomical Society's coveted
Gold
Medal, was elected to the Royal Irish Academy of Science, and received
yet another gold medal from the King of Prussia. She lived to be
97.