1 / 12

Seeing the Sky

Seeing the Sky. Naked-Eye Astronomy. Naked-Eye Astronomy. Stars Planets (move relative to stars) Sun (disk about 1/2 degree) Moon (disk about 1/2 degree) Other (comets, meteors, UFOs, etc.). Angles.

gazit
Download Presentation

Seeing the Sky

An Image/Link below is provided (as is) to download presentation 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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Seeing the Sky Naked-Eye Astronomy

  2. Naked-Eye Astronomy • Stars • Planets (move relative to stars) • Sun (disk about 1/2 degree) • Moon (disk about 1/2 degree) • Other (comets, meteors, UFOs, etc.)

  3. Angles • Can only measure angles on the sky (circle spans 360 degrees; 1 degree = 60 minutes; 1 minute = 60 seconds) • Angular distance is the angle on the sky between two celestial objects • Use your fist (about 10 degrees at arm’s length)

  4. Sky Directions • Face South (sun at noon), then • North is to your back • West is to your right • East is to your left(Northern hemisphere!)

  5. Sky Motions • Only see angular speeds(angle covered per unit time-day, month, year) • Motions are relative with respect to some reference (stars, horizon) • Same object can have different motions at the same time relative to different references

  6. Stars • Patterns: “fixed” constellations (88 official); no visible change over human lifetimes • Daily: Rise in east, set in west(relative to horizon) • Seasonal: Different constellations visible at different seasons

  7. Moon • Daily: Rises in east, sets in west (relative to horizon) • Monthly: Cycle of phases; angle relative to the sun (opposition-full) • Monthly: Moves eastward relative to zodiacal stars • Eclipses can occur at new (solar) or full (lunar)

  8. Sun • Daily: Rise in east, set in west (relative to the horizon) • Due south at noon (northern hemisphere!); greatest angle (for the day) above horizon at noon • Seasonally: noon height varies (highest, summer, lowest winter); rising, setting points also vary

  9. Sun • Moves eastward relative to stars • Moves through constellations of the zodiac, about 360 degrees in one year (about 1 degree per day) • Path in sky relative to the stars defines the ecliptic

  10. Planets • Daily: Rise in east, set in west (relative to horizon) • Long-term: Move eastward relative to stars (zodiac) • In regular cycles, move westward relative to the stars (retrograde)

  11. Planets-Long term • Mercury, Venus stay near sun(morning, evening stars) • Mars, Jupiter, Saturn anywhere in zodiac relative to sun • Average angular speeds of eastward motion through zodiac: Mercury, Venus, Mars, Jupiter, Saturn

  12. Planets-Retrograde • Mercury, Venus retrograde only near sun (when moving from evening to morning “star”) • Mars, Jupiter, Saturn retrograde only when opposite the sun in the sky (opposition, 180 degrees apart)

More Related