Astronomy Observations Before Telescopes

Stars and Light

• Stars reflect light from the sun, whereas light from distant stars is not as steady as light from nearer planets.
• Twinkling is a characteristic of starlight, which can be observed by covering one eye or looking at the star from a different angle.

Tycho Brahe's Contributions

• Tycho Brahe (1546-1601) was a Danish nobleman who made accurate observations of heavenly bodies and collected important data on their motion.
• He measured the positions of stars, planets, the Moon, and the Sun every night and day, recording these measurements for years.
• Brahe observed a new star in the constellation of Cassiopeia in 1572, which challenged the belief that the celestial realm was fixed and unchanging.
• He also observed a comet in 1577, providing evidence that things moved in the celestial sphere.

Brahe's Model of the Cosmos

• Brahe's model proposed that all planets orbited the Sun, while the Sun and the Moon orbited the Earth.
• His model allowed for the path of Mars to cross through the path of the Sun.

Johannes Kepler's Contributions

• Johannes Kepler (born 1571) made significant contributions to astronomy, combining mathematics and astronomy with mystical ideas about astrology.
• Kepler worked for Tycho Brahe, publishing Brahe's data in Rudolphine Tables.
• Unlike Brahe, Kepler accepted a heliocentric (sun-centered) model of the universe.

Astronomical Phenomena Known Before the Telescope

• Ancient civilizations, such as the Egyptians, Chinese, Mayans, and Polynesians, observed and recorded various astronomical phenomena.
• These phenomena included the yearly cycle of Sirius, comets, meteors, dark spots on the Sun, and the movements of Venus.
• The Babylonians and Egyptians used a primitive sundial, called a gnomon, to observe the motion of the Sun and record seasonal changes.

Phases of the Moon

• Ancient people observed that the Moon changes its path and appearance within a period of 29.5 days.
• They recorded the phases of the Moon, from a thin semi-circular disk to a full circular disk, which formed the basis of ancient calendars.