The Path of the Ecliptic and the Zodiac
Constellations the Sun and Planets Pass Through
Mar 30, 2009
The ecliptic is defined by the path the Sun takes through the night sky. Because the entire solar system orbits in one plane, this means the planets and moon will also be found close to the ecliptic most of the time.
What is the Zodiac?
The zodiac refers to 12 of the 13 constellations the Sun passes through. People who trust "zodiac signs" set by astrologers to determine when the Sun passes through each constellation will be greatly mistaken. The Sun is not in the same constellations at the same time of year as it was 2,000 years ago when astrology was begun. Below is an accurate table of where the Sun can be found throughout the year. The location is taken at noon Central Time, therefore, some days are included in both constellations as the Sun is passing from one constellation into another at noon.
- December 18 - January 19: The Sun is in Sagittarius
- January 19 - February 15: The Sun is in Capricornus
- February 16 - March 11: The Sun is in Aquarius
- March 12 - April 18: The Sun is in Pisces
- April 18 - May 13: The Sun is in Aries
- May 14 - June 20: The Sun is in Taurus
- June 21 - July 20: The Sun is in Gemini
- July 20 - August 10: The Sun is in Cancer
- August 10 - September 16: The Sun is in Leo
- September 16 - October 30: The Sun is in Virgo
- October 31 - November 22: The Sun is in Libra
- November 23 - November 29: The Sun is in Scorpius
- November 30 - December 17: The Sun is in Ophiuchus
Of course, for observers, knowing which constellation the Sun is in is not important because the Sun's light drowns out all the stars during the day. But knowing the path of the ecliptic and its constellations at night can help observers to find the planets.
Finding the Planets in the Sky
Most of the planets are not inclined very far from the ecliptic. Mercury strays farthest out at up to 7% from the ecliptic. The location of the planets changes from day to day and year to year. Some planets will be visible in the evening, some in the early morning, and some can be too close to the Sun to be viewed during night.
The five planets that can be seen without optical aid are usually better for helping observers learn the constellations they are in than the other way around. But dim planets such as Uranus and Neptune need to be found by first locating the zodiac constellation they are in and then which of its stars it is nearby. And because the planets orbit in the ecliptic plane together, a brighter planet can help locate a dimmer planet. For example, from mid-May until late July 2009, Jupiter and Neptune are less than a degree apart.
The ecliptic gets its name because when the Moon, Sun, and Earth all line up just right along this line, eclipses can occur.
So although the path of the ecliptic is defined by the route of the Sun across a set of constellations, knowing the path of the ecliptic is helpful in locating where the planets and moon will be found as it describes the plane of our solar system.
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