400 Years of Modern Astronomy

Four hundred years ago, an Italian professor of physics and mathematics called Galileo Galilei demonstrated a simple contraption to the Venetian Senate that would set in motion one of the most profound revolutions in human thought — a revolution that 
continues today.

By Saswato R. Das (Science)

  • Follow us on
  • google-news
  • whatsapp
  • telegram

Published: Sun 30 Aug 2009, 10:19 PM

Last updated: Thu 2 Apr 2015, 8:50 AM

Galileo’s device was a simple telescope — two glass lenses at the ends of a leather tube that magnified objects nine times — and it would forever change our understanding of the universe. Established theories, centuries old, would fall; it would embarrass and anger the Roman Catholic Church; and it would mark the birth of modern astronomy. But on August 25, 1609, the practical Galileo focused on the telescope’s military benefits: He told the Venetian senators that it would be invaluable in war, since one could see ships sailing into Venice’s harbour a full two hours before they became visible to the naked eye. The Senate, duly impressed, doubled his salary. (The tradition perseveres: Scientists routinely tout military and other applied uses for their research in hopes of securing funding.)

Galileo was not the first to invent the telescope. The previous year, a Dutchman called Hans Lipperhey had filed for a patent on the device in The Hague. (It was not granted since two others had filed similar claims.) In the summer of 1609, Thomas Harriot of England made telescopic observations of the moon. But it was Galileo who made the telescope famous, and with it created modern astronomy.

He worked incessantly to improve his “optick tube.” He first observed the moon, and saw that its surface was marred by craters, mountains and valleys. Nor was it perfectly spherical, as Aristotelian dogma held would be true for heavenly bodies. Turning his telescope to Jupiter, he discovered its moons Io, Europa, Ganymede and Callisto. Observing the Milky Way, he noted that he could see 10 times the number of stars that were visible to the naked eye. Galileo would go on to catalogue sunspots on the surface of the Sun, in direct conflict with the prevailing view that the heavens were perfect and unchanging, as had been held from the time of the Greeks, and had gotten enshrined by the Church.

Galileo realised that his observations supported the Copernican view of the universe, and not the geocentric view espoused by the Church.

In March, 1610 Galileo published Siderius Nuncius (Starry Messenger), a 24-page booklet that documented his observations. Unlike scientific treatises of the day that tended to be voluminous and written in baroque prose, Galileo’s remarkable treatise was highly readable. It started an intellectual fever that spread contagiously across Europe.

It was all heresy to the Catholic Church, and Galileo was persecuted by the Inquisition for his views. It took almost four centuries, but in 2000, Pope John Paul II formally apologised for the trial of Galileo.

Today, Galileo’s intellectual heirs continue to expand our horizons. There have been huge improvements in the science of telescopes. State-of-the-art, Earth-based telescopes are now mammoth structures, with mirrors that exceed 30 feet across — devices that would have been completely unimaginable to Galileo and his immediate successors.

Kepler, a NASA space telescope named after Johannes Kepler that was launched in March, is currently looking for Earth-like planets that have suitable conditions to support life. And just last week, we learned that the amino acid glycine — a key building block of life — had been found in a comet, strengthening the case for extraterrestrial life. While we do not know whether extraterrestrial life will ever be found, if it is found, it will only extend the revolution that Galileo started 400 years ago.

Saswato R. Das writes about science and technology


More news from