202 Lecture 4

202 Lecture 4 - The Origins of Modern Astronomy Planets: o...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
The Origins of Modern Astronomy Planets: o Some of the brightest objects in the Sky, after the Sun and the Moon. o Their positions over the days change with respect to the fixed stars (the Celestial Sphere). o The planets follow trajectories more involved than those of the Sun or the Moon. o The name “planet” derives from the Greek word for wanderer. o The planets are never too far away from the Ecliptic. The Sun, the Planets, the ecliptic: o Half of the ecliptic is above the celestial equator and the other half underneath. o When the Sun is low in the sky (in winter), the planets that can be seen at night are in the opposite side of the ecliptic. Thus, the planets appear high in the sky in winter. o The situation reverses in Summer. Summary of Celestial motions: o Every night, stars, planets, the Sun and the Moon rise on the East and set on the West. o Stars move East to West during the year, as seen from the Earth. o We can use the Meridian as a reference to verify that the stars shift their positions westward. o The Sun remains near the Meridian at noon every day. Therefore, the Sun moves West to East with respect to the fixed stars (the celestial sphere). o The planets move East to West with respect to the Meridian, but West to East with respect to the fixed stars, except when the planets are in retrograde motion. Geocentric Models: o The first astronomical models placed the Earth at the center of the universe: Geocentric Models . o
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

202 Lecture 4 - The Origins of Modern Astronomy Planets: o...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online