Nicolaus Copernicus
1473-1543
Before the 16th century, the common belief was that the sun and all the other planets revolved around
the Earth. This theory had been developed by the ancient Greek astronomer Ptolemy around A.D. 150, but the
Polish astronomer Copernicus found that the Ptolemaic system could not explain the observed motions of the
planets.
In 1543, he published a book calledThe Revolutions of the Heavenly Orbs, which argued that the Earth was not
the center of the universe but was one of the planets and, like them, revolved around the sun. This model of
the solar system is known as the Copernican system
.
Copernicus also said that the Earth spins on its axis once per day, which accounts for why the sky appears to
revolve around the Earth.
Copernicus’s theory explained why superior planets—those further from the sun than Earth—sometimes appear
to be moving backward (inretrogrademotion) with respect to the stars, while those closest to the sun—Mercury
and Venus—always appear to move in only one direction. The Earth is moving in a faster orbit around the sun
than the more distant planets—periodically “passing” them, making them appear to move backward. But Mercury
and Venus are moving in even faster orbits closer to the sun. Copernicus was right about the basic arrangement
of the solar system, but he had no real proof
.
.jpg "ستاره بنیادی آواتار ها")
Famous Stargazers
پاسخ با نقل قول
نوشته اصلی توسط fampersi
