The ecliptic is the year-long path of the Sun against the
background of fixed stars. Is it the same as the Celestial Equator,
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
- The basic observation underlying the ecliptic:
Heliacal Rising and Sidereal year
- Which coordinate system is based on the ecliptic?
- Celestial latitude = degrees
measured above or below the ecliptic.
- Celestial longitude = degrees
measured along the ecliptic, starting from the March equinox
(intersection of the ecliptic with the celestial equator).
- Angular distances measured from the ecliptic were used in
antiquity and in the early modern period, e.g., by Ptolemy and
- Rising points of the Sun on the horizon
- Tropical year
- Does the sun always rise due east and set due west?
- Is the altitude of the Sun on the meridian at noon always
the same throughout the year?
- On what day is the sun highest in the sky?
- How close does the Sun come to directly overhead (the
zenith) in Shawnee?
- Diurnal Motion of the Sun
- If the sun rises in the northeast on the summer
solstice, will it set that evening in the southwest or in
- The Sun's annual motion is along the ecliptic, which
is a great circle. Is the sun's daily motion along
a great circle? Does it move parallel to a great circle?
- Does the angle between the ecliptic and the horizon remain the
same throughout the year?
# Days Sun is in this sign
Season Sun is in each Sign
||31.3 93.7 days
||29.9 89.8 days
||29.6 89.0 days
- Do all of the zodiac constellations occupy equal lengths in
- If the celestial longitude of the Sun is 190 degrees...
- What season is it?
- Which sign will contain the Sun?
- Declination is measured north and south above the... (check
- celestial equator
- Which signs have the same declinations?
- Which signs have opposite declinations?
- Is the Sun north or south of the celestial equator...
- When it is in Gemini?
- When it is in Sagittarius?
- In which sign does the Sun move...
- Does the Sun move faster at higher or lower declinations?
- For each pair, circle the time at which the Sun moves faster:
- Equinoxes, Summer Solstice
- Equinoxes, Winter Solstice
- Summer Solstice, Winter Solstice
- Which season is the...