The Zodiac Constellations are a group of 12 constellations that fall on either side of the ecliptic. The ecliptic is the path that the sun traces through the sky, from the perspective of Earth, throughout the year. Put another way, if you were to take a giant celestial crayon and draw a line through all 12 Zodiac Constellations, you would end up drawing a ring in the sky that goes all the way around the Earth. The sun would always be near that ring, as would all of the planets (not Pluto, though... add that to the ever-lengthening list of reasons Pluto is only a "plan-ette").
Below is a video that quite effectively shows the relationship between the Earth, the Sun, the ecliptic, and the Zodiac Constellations. The upper right corner shows which constellation is being highlighted, and the bar at the bottom shows the time of year. Notice that if it's night time on Earth (facing away from the sun) then the Zodiac Constellation you see in the video will not be visible, because it is "up" during the daytime. You'll have to wait 6 months for that constellation to be visible in the dark. The music is nice and soothing, but beware: the end of the video will audibly jar you back to reality.
We'll go through each of the 12 Zodiac Constellations below, traveling to the "left" along the ecliptic as we go. Some Zodiac Constellations can be found using others we've learned about, but others you may just have to learn to find on your own.
When you're stargazing, if you can find any two Zodiac Constellations, you know that the ecliptic goes through them and continues on either side. Use that knowledge to find any others that might be visible at that moment.
We're already familiar with this one. Remember, you can use Orion's belt to find Taurus's nose. Follow the belt up and to the right.
Gemini, the Twins:
We are also already familiar with the twins. Find the blue star Rigel, in Orion's ankle, and the red star Betelgeuse, in Orion's shoulder. Connect them and continue to find Gemini.
Next to Gemini, you'll find Cancer. The stars in Cancer are very faint, so he'll be difficult to see most nights. The easiest way to find him is to find Gemini and Leo, and then look between them.
Leo, the Lion:
Leo's head, neck, and front left foot form a distinct backwards question mark shape. That shape will be your key to finding Leo in the sky. Those stars are brighter than the rest of Leo.
Find the handle of the big dipper, and follow the arc to the red star, Arcturus. Now, instead of bouncing back up to Corona Borealis, "spike down" to a blue star, Spica (SPAI-kuh).
Spica is a fairly bright star, and is the only bright star in Virgo. Frequently, you'll be able to find Spica, and be unable to find any other stars in Virgo.
Libra is the only non-living object represented by the Zodiac. The scales are usually depicted as those old-fashioned two-sided balances. This version is one side of the balance.
Scorpius, the Scorpion:
The scorpion has a red star right at its heart, called Antares (an-TAHR-ees). The Milky Way goes through Scorpius, as well as Cygnus and Cassiopeia. Follow the path from Cassiopeia, through Cygnus, and onward until you find the red star. It will be low to the horizon in the summer.
Sagittarius, the Archer:
The archer shoots his bow toward Scorpius. Sagittarius also appears very low to the horizon in the northern hemisphere, so it may be difficult to see most of the time.
In this depiction, the goat is leaning down to eat some grass near his feet, with his tail in the air, and horns pointed toward Aquarius. Following the point of the Summer Triangle through Altair may be helpful in finding Capricorn's tail.
Aquarius, the Water Bearer:
Aquarius is leaping over Capricorn, and water is spilling out of the bucket that he bears (see what happens when you run with a full bucket of water?)
Pisces is two fish with their tails tied together. The "V" shape is the rope that holds them together, and the circle and triangle at the ends of the rope are the fish.
Aries, the Ram:
Aries leaps toward the rope in Pisces, and away from Taurus (yep, we've come all the way around again).
• On to Lesson 7: (coming soon...) •