1 / 8

# Seasonal Motion - PowerPoint PPT Presentation

Seasonal Motion. The Zodiac throughout the Year. Example : In Winter sun in Sagittarius, Gemini at night sky; in summer sun in Gemini, Sagittarius at night sky. How do we “see” that the earth is moving around the sun or v.v.?. Small discrepancy between sun’s motion and motion of stars

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about ' Seasonal Motion' - zytka

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Seasonal Motion

Example: In Winter sun in Sagittarius, Gemini at night sky;in summer sun in Gemini, Sagittarius at night sky

• Small discrepancy between sun’s motion and motion of stars

• Sidereal vs solar day

• At noon, say, the sun is not exactly in front of the same stars on the next day.

• It is exactly in the south

• The stars are faster, so a little west of south

• Earth axis is tilted w.r.t. ecliptic by 23 ½ degrees

• Equivalent: ecliptic is tilted by 23 ½ degrees w.r.t. equator!

•  Sun appears to be sometime above (e.g. summer solstice), sometimes below, and sometimes on the celestial equator

Note: Three Coordinate Systems! or v.v.?

Two rotations about differently oriented axes, plus an observer that is oriented in a third direction!

Homework: Use Proportions or v.v.?

• Angle traveled compared to full 360 degrees = time elapsed while traveling the angle compared to total time to complete a 360 degree, full rotation

• angle/360 = time elapsed / x

• x is the period we are looking for, will come out in same units as we put in “time elapsed”