Ecliptic

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The ecliptic is the year-long path of the Sun against the background of fixed stars. Is it the same as the Celestial Equator, or different?

Different. The celestial equator is a projection of the earth's equator, and is inclined to the path of the sun (the ecliptic) by 23.5 degrees. The ecliptic is important because where the Sun travels, the planets follow. Constellations containing portions of the ecliptic are zodiac constellations, and bright stars in zodiac constellations that don't appear on star charts are probably visiting planets.

The Ecliptic and the motions of the Sun

Seasons

Zodiac Sign
Celestial Longitude
Declination
# Days Sun is in this sign
Season Sun is in each Sign
Aries 0 degrees 0 degrees 00' 30.5 Spring
Taurus 30 degrees 11 degrees 28.5' 31.0 92.8
Gemini 60 degrees 20 degrees 09.3' 31.3
Cancer 90 degrees 23 degrees 26.6' 31.5 Summer
Leo 120 degrees 20 degrees 09.3' 31.3 93.7 days
Virgo 150 degrees 11 degrees 28.5' 30.9
Libra 180 degrees 0 degrees 00' 30.4 Autumn
Scorpio 210 degrees -11 degrees 28.5' 29.9 89.8 days
Sagittarius 240 degrees -20 degrees 09.3' 29.5
Capricorn 270 degrees -23 degrees 26.6' 29.4 Winter
Aquarius 300 degrees -20 degrees 09.3' 29.6 89.0 days
Pisces 330 degrees -11degrees 28.5' 30.0

 

  1. Do all of the zodiac constellations occupy equal lengths in celestial longitude?
  2. If the celestial longitude of the Sun is 190 degrees...
    • What season is it?
    • Which sign will contain the Sun?
  3. Declination is measured north and south above the... (check one):
    • ecliptic
    • celestial equator
  4. Which signs have the same declinations?
  5. Which signs have opposite declinations?
  6. Is the Sun north or south of the celestial equator...
    • When it is in Gemini?
    • When it is in Sagittarius?
  7. In which sign does the Sun move...
    • Fastest?
    • Slowest?
    • Does the Sun move faster at higher or lower declinations?
  8. For each pair, circle the time at which the Sun moves faster:
    • Equinoxes, Summer Solstice
    • Equinoxes, Winter Solstice
    • Summer Solstice, Winter Solstice
  9. Which season is the...
    • Longest?
    • Shortest?

 

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