Nicolas Lacaille
Nicolas
Louis de Lacaille was a prominent French astronomer who lived during the 18th
century. Born on the 29th of December, 1713 in Rumigny, France, Lacaille
attended school in what is now known as Mantes-la-Jolie, and eventually went on
to study philosophy and rhetoric at the Collège de Lisieux, and then theology
at the Collège de Navarre. After graduating, Lacaille became an Abbé, a
position in the Catholic Church. Lacaille worked in a few universities as a
professor throughout his life, and one of his earliest accomplishments was the
correct re-measurement of the French arc of the meridian. For this, a pyramid
was built in his honor.
One
of the primary desires of Lacaille was to measure the distances of the planets trigonometrically.
He wished to travel to the Cape of Good Hope, at the Southern tip of Africa.
His voyage was sanctioned by Roland-Michel Barrin de La Galissonière, a French
governor. Lacaille stayed there for two years, making observations on a nightly
basis. His observations resulted in a thorough catalog of roughly 10,000 stars.
In addition, he also observed and recorded 42 nebulous objects. Along with
these catalogs, Lacaille was able to successfully determine the parallax of the
moon and the sun, using Mars as an intermediary. This tedious work required
simultaneous observation from a partner of his in an observatory in France, Jérôme
Lalande. His astronomical catalogs were published posthumously, resulting in 14
newly discovered constellations, which have since become standard. During his 2
year stay in the Cape of Good Hope, Lacaille also measured the radius of the
Earth in the Southern Hemisphere. Being a very meticulous and astute calculator
and mathematician, Lacaille used triangulation to determine these measurements.
During
his return to France, Lacaille realized how difficult it was to make
measurements and determining positions while at sea. On his return to Paris, he
produced a set of tables of the Moon’s position that was accurate enough to use
for determining time and longitude by Lunars, or Lunar distances. In addition
to these impressive calculations, Lacaille also produced a table of eclipses
that occurred, spanning 1800 years. A colleague of his, Jérôme Lalande, said of Lacaille that during a
relatively short life, he was able to make more calculations than any other
astronomer until then. He also stated that the quality of his work was just as
high as the quantity, and that his strong, respectable personality earned him a
great deal of universal admiration.
In
Paris in 1757, Lacaille published his Astronomiae Fundamenta Novissimus, which
contained a list of 400 bright stars with their positions corrected due to atmospheric
aberration. He also carried out calculations on the orbits of comets, and was
actually responsible for giving Halley’s Comet its name. The crater Lacaille on
the Moon was named in his honor, and the asteroid 9135 Lacaille was named after
him as well. In addition, a 60 centimeter telescope in Reunion Island will be
named Lacaille Telescope due to his studies of the Southern Hemisphere sky.
