A constellation is a group or cluster of stars that appear to be the outline of certain figures. These figures do not actually exist, but are used as mnemonics to help people spot and recognize stars in the night sky. On a clear night one can see thousands of stars in the sky, and being able to recognize and remember these shapes can help to identify them.
Due to the rotation of the earth, and the movement around the sun, there are two different groups of constellations: circumpolar and seasonal constellations. Circumpolar constellations are technically always visible; they never "rise" or "set". Where as seasonal constellations are only visible during certain parts of the year, depending on where on the earth they are viewed from. 
Constellations are often used to find other constellations or stars of importance. One famous example of this is finding the North Star by examining the Big Dipper and Little Dipper. First one must locate the two stars that form the outer edge of the Big Dipper, then draw an imaginary line straight through the two stars of the dipper edge toward the Little Dipper. The line will point very close to the handle of the Little Dipper; the brightest star in the Little Dipper is at the end of its handle. This is the North Star.
Constellations have been around for many generations in society. People kept track of constellations long before telescopes existed. In fact, a telescope is not at all necessary to view constellations because they were designed to be able to see with the naked eye. It is thought that the process of naming and identifying constellations was originated by farmers long ago. They followed seasonal constellations to help them know when the right time was to plant or reap their crops.
Interestingly though, almost every ancient civilization has kept records of constellations, but many of the constellations have been given very similar names, or represented very similar figures. These were recorded thousands of years ago; long before communication would have allowed for civilizations scattered across the globe to have shared ideas or thoughts. However, one hypothesis by Jonathan Henry, is that much like the story of a worldwide flood is found in almost every culture, the shapes and figures of constellations of stars are very congruent as well. He thinks this is because of the fact that when the people of Babel spread out their separate ways, they took popular beliefs or ideas with them. If when people dispersed from Babel, they took their ideas about constellations with them, it would explain why so many cultures around the world shared the same thoughts before communication between continents was a reality.
The Zodiac is a ring of constellations that is directly in line with where the sun "passes" over the earth during the year. More accurately, it is where the earth rotates so that it appears that the sun is moving, when really it is the earth orbiting. This band is broken up into twelve parts, which are visible at different times throughout the year. Each Zodiac is 30o of spherical rotation throughout the year. All twelve of them put together make up one year, with a different Zodiac for each month. For this reason, they were used in ancient times as a sort of calendar to keep track of the months. Especially in more mild climates where the summers and winters are hardly distinguishable. The twelve signs of the Zodiac are: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Serpentarius, Sagittarius, Capricorn, Awuarius, and Pisces. 
- Main Article: Biblical astronomy
Can you bind the beautiful Pleiades? Can you loose the cords of Orion? Can you bring forth the constellations in their seasons or lead out the Bear with its cubs?.(NIV) Job 38:31-32
Constellations are some of the most ancient astronomical observations. Interestingly enough there are marked similarities in constellation names and the images they form, similarities that extend across cultures. Dr. Jonathan Henry proposes that these commonalities point back to the dispersion after Babel, and that the constellations are representative of shared historical events like the global Flood. The pervasiveness of flood legends all over the world is well-supported, found in various cultures like that of the Mayans, Egyptians, and Scandinavians. Some secular researchers claim that the similarities of the constellations were a result of "a kind of convergent cultural evolution that happened spontaneously in many cultures"; that is, widely dispersed and entirely unique civilizations all develop the same general interpretation of the stars all around the same time period. One must understand however, that stars within a constellation have no actual connection to one another until the shape of the constellations is imagined by the viewer. Thus, it is next to impossible that people groups in very different regions of the world all “imagined” the same general images in the stars. Estimates of the date and location of the origin of the ancient constellations are consistent with the height of Assyrian power (in both the biblical period and physical location on earth allotted to Babel.) Examination of Roman, Greek, and Indian planispheres, or sky maps, further support this fact in that they incorporated previously known information; the Indian and Greek ones are so similar that they are nearly identical. 
Naturally, over time the similarities in the ancient constellations would be altered, allowing for differences, but without diminishing the common threads of general interpretation. For example, according to Babylonian tradition, the star Sirius is part of a bow and arrow image; in China, this star is in a constellation resembling a dog that is being targeted by a different bow and arrow constellation; in the West, Sirius is a star in the Big Dog, or Canis Major, constellation. The constellation of Orion as a hunter, or as one with a bow and arrow, is recognizable in Mesopotamian, Egyptian, Chinese, Norwegian (Norse), Mexican, Iranian, and Indian art and legends, albeit with slight modifications. The Pleiades too, were known as "The Seven Sisters" from the aborigines in Australia to the native peoples of ancient Europe, Africa, and America. This commonality is especially interesting in that very often only six of the prominent Pleiades are visible, and the fact that they are referred to as The Seven Sisters is most unusually considering that the seven stars of the Great Bear constellation are far brighter. Concerning the Great Bear constellation, scientists estimated that the association of the Ursa Major star group as a bear may go as far back as the 'ice-age Euro-Asia' (the location of Babel would have existed in this general region); also, the constellation's association with a bear in regions of the world where there are no bears, like in Egypt, further prove the theory that the interpretation stems from a common origin. Another fact that indicates an origin of the major constellations near Babylon is that the most ancient ones are only seen in the northern sky and are absent around the southern pole. Therefore, the creators of the oldest constellations must have been in the northern hemisphere. 
Rising evidence has raised speculation that the major constellations are "corrupted memories of significant events happening early in history" or, perhaps more specifically, the global flood during the time of Noah as recorded in Genesis 6-9. Michael Ovenden of Glasglow University noted that early depictions of the massive constellation of Arago the Ship often set it upon a mountaintop with the Centaur emerging from it and sacrificing an animal upon the altar. Corvus, a raven, is also seen eating the flesh of Hydra, the water-snake. In these pictures, even the location of the Milky Way galaxy appears as smoke rising from the altar. Genesis 9:12-13 reads, "And God said, 'This is the sign of the covenant I am making between me and you and every living creature with you, a covenant for all generations to come: I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth.' " Some speculate that the bow of the constellation Sagittarius, which points in the direction of the cloudy Milky Way, is directly linked to the bow mentioned in this verse. Even the Pleiades are associated with a flood by the natives of Australia and the Jews. The aborigines viewed the Pleiades as givers of rain, but because the aborigines were not an agricultural people, there is no logical explanation as to why they would draw that association except from tribal tradition. A Jewish legend tells of the Flood, saying: "The upper waters rushed through the space left when God removed two stars out of the constellation Pleiades"; an explanation for this connection however, remains unknown.
Some propose that God placed the stars in such a way as to display the gospel prior to the compilation of the written Word, but there is very little biblical evidence to support this theory. Rather, the majority of biblical references to the constellations act as reminders of God's omnipotent control of the heavens. Psalm 147:4 and Isaiah 40:26 speak of God naming and controlling each individual star, asserting the unrivaled power of God over all of the cosmos. As to the existence of an actual "gospel in the stars," controversy reigns. Proponents like Frances Rolleston and Joseph R. Seiss refer to Genesis 1:14-15, in which God sets the stars in place that they may "serve as signs to mark seasons and days and years." Dr. Jonathan Henry however, counters this position, pointing out that these verses speak only of stars, not of constellations. He believes that projecting a "gospel in the stars" into these verses is a form of eisegesis ("the reading in of a concept not mentioned in the passage but present in the mind of the reader"). Advocates also invoke the names of ancient stars that have biblical themes as proof of God's divine placement of specific stars in certain constellations. One must recall however, that, as the Bible does not reveal what God named the stars, man designated these stars with their given names, and that the translations of these names vary.
Supporters for a gospel in the stars typically associate each of the twelve ancient zodiac constellations with a symbolic part of the gospel story. Libra for example, which depicts scales, is seen to represent that sin must be paid for, that justice must be served; sacrifice is ascribed to the constellation Aries, which is an image of a ram; the virgin in the constellation Virgo is identified as the Virgin Mary. These explananations seem relatively reasonable, but others, like how Cancer (a crab) symbolizes the gathering of the redeemed or how Sagittarius (an archer) portrays the element of demonism, are not as straightforward. Looking to the constellations for biblical messages is something that must be done with extreme caution because there is a wide variety of interpretations, and such searches are dangerously close to that of astrology. Thus, the debate continues as to the correct interpretation of Genesis 1:14-15 and the role of the constellations and stars in the heavens. In the end, the Bible is the only infallible source of the gospel, and Christian doctrine is not founded on elements in nature, but rather on the written Word of God. 
There are currently 88 official constellations as defined by the International Astronomical Union. Listed in alphabetical order they are:
*Andromeda * Antlia * Apus * Aquarius * Aquila * Ara * Aries * Auriga * Boötes * Caelum * Camelopardalis * Cancer * Canes Venatici * Canis Major * Canis Minor * Capricornus * Carina * Cassiopeia * Centaurus * Cepheus * Cetus * Chamaeleon * Circinus * Columba * Coma Berenices * Corona Austrina * Corona Borealis * Corvus * Crater * Crux * Cygnus * Delphinus * Dorado * Draco * Equuleus * Eridanus * Fornax * Gemini * Grus * Hercules * Horologium * Hydra * Hydrus * Indus * Lacerta * Leo * Leo Minor * Lepus * Libra * Lupus * Lynx * Lyra * Mensa * Microscopium * Monoceros * Musca * Norma * Octans * Ophiuchus * Orion * Pavo * Pegasus * Perseus * Phoenix * Pictor * Pisces * Piscis Austrinus * Puppis * Pyxis * Reticulum * Sagitta * Sagittarius * Scorpius * Sculptor * Scutum * Serpens * Sextans * Taurus * Telescopium * Triangulum * Triangulum Australe * Tucana * Ursa Major * Ursa Minor * Vela * Virgo * Volans * Vulpecula
- Constellations: legacy of the dispersion from Babel Dr. Jonathan F. Henry. Journal of Creation 22(3), March 30, 2010.
- The 12 Signs of the Zodiac
- Is the gospel spelled out in the stars? Dr. Donald DeYoung, Ph.D. (Physics) as excerpted from Astronomy and the Bible, pgs. 69-70. Published by Baker Book House. Supplied by Eden Communications (used with permission). Copyright © 1997. www.ChristianAnswers.Net
- Constellations- The Official List of Constellations
- Creation And The Constellations by Henry Morris, Ph.D. Sep 26, 1999
- Constellations: legacy of the dispersion from Babel by Jonathan F. Henry, Journal of Creation 22(3), 2008
- The Gospel Message-Written in the Stars by Danny Faulkner, Answers Magazine, 3(1) January – March 2008