Constellations in the sky. How often have you stood under the night sky looking at the stars and spotted the Big Dipper? How about Orion’s Belt? I don’t mean to disappoint you, but constellations are not actual.
The poets, farmers, and astronomers have made them real for us within the past 6,000 years. The sole purpose of constellations is to help us identify which stars are which.
Believe it or not, you can see between 1000 to 1500 stars on a clear night. That is a lot of leads to keep track of. What the constellations do is break the sky up into parts so that it is easier to manage. You can obtain sky maps to guide you through pinpointing the different constellations.
When you first observe, the sky looks like one giant constellation, and that is because it is. Knowing the different patterns will help you divide it, just as our ancestors did many years ago.
Importance of Constellations
Why are constellations so important? Well, first of all, farmers used them to determine when to plant and harvest. Different constellations are visible during different seasons. They can also be used to tell what month it is. When farmers saw certain constellations, they would know when certain events needed to occur. Of course, now, farmers have other means of determining when to plant and harvest
It wasn’t just the farmers that relied on the constellations; many other cultures also relied on them. Cultures began creating star charts and atlases to map the night sky. The constellations have changed over time, though, so in 1929, the International Astronomical Union adopted official constellation boundaries that distinguished the eighty-eight official constellations.
North Circumpolar Constellations
We begin in the northern sky, the realm of those always-visible star groups known as the north circumpolar constellations. These bright stars — four forming the “bowl,” three more tracing out the “handle” — create one of the most recognizable patterns in the night sky, a definitive guide for locating surrounding constellations. The most prominent figure is the Big Dipper (Note: The Big Dipper is not a constellation).
Polaris, the North Star
You can find Polaris, the North Star, by tracing a line between the stars Dubhe and Merak at the end of the bowl of the Big Dipper and extending it about five times the distance between them. When astronomical newcomers see this celebrated star for the first time, they are astonished that it isn’t much brighter than the stars in the Big Dipper.
Polaris is the shining star in Ursa Minor the Little Bear, which contains the Little Dipper. Like its big brother, the Little Dipper is made up of seven stars — four in the bowl and three in the handle. Because four of its stars are dim, the Little Dipper is hard to see in light-polluted skies.
If you trace a line from the bowl of the Big Dipper past the North Star and continue it an equal distance beyond, you’ll arrive at an eye-catching group of stars that form a distinct letter M or W. This is Cassiopeia, Queen of Ethiopia
Winter Sky
To see the constellations that come and go with the seasons, we need to turn our backs on the north circumpolar constellations and face south. If the winter sky seems alive with stars, it’s no illusion. Besides the obvious fact that the air is clear and dry then, we’re looking at a star-rich region that defines one of the spiral arms of our Milky Way Galaxy. Seven of the twenty-one brightest stars in the night sky (so-called 1st-magnitude stars) are in this area.
Orion the Hunter
On a winter evening, the sky is home to what most astronomers agree is the grandest of all constellations — Orion the Hunter. A rectangle of bright stars, which includes, at opposite corners, 1st-magnitude Betelgeuse and Rigel, is bisected by a diagonal row of three bright stars (the “belt”). Beneath the belt hangs a row of three stars — Orion’s “sword.” Don’t be fooled by their uninspiring naked-eye appearance; the middle star in the sword isn’t a star at all.
The Orion Nebula is one of the grandest telescopic showpieces of the night sky. In binoculars, it appears as a fuzzy patch of light. When you gaze at this tremendous glowing cloud, you view creation itself, for stars are being born within this luminous glow.
Canis Major the Great Dog.
Orion is the focal point of a stunning gathering of bright stars and constellations. The belt points down and to the left to a brilliant white star: Sirius, the most shining star in the night sky, leader of the constellation Canis Major the Great Dog.
Sirius always dazzles, but the star captivates when positioned near the horizon. During winter, atmospheric refraction causes Sirius to sparkle in a rainbow of colors — a beautiful sight through binoculars or a small telescope.
Taurus the Bull.
Return to Orion’s belt and continue up and to the right, and you will arrive at a V-shaped group of stars called the Hyades. This is the “head” of Taurus the Bull. The reddish-orange 1st-magnitude star at the upper-left end of the V is Aldebaran — the eye of the Bull. Each end of the V extends outward to a lead that forms one of the Bull’s horns. Continuing past the Hyades, you’ll see a little cluster of stars — one of the loveliest naked-eye sights in the night sky.
This is the Seven Sisters or Pleiades. Six are visible to the unaided eye under average sky conditions; binoculars reveal the seventh star, plus dozens more.
Auriga the Charioteer
The uppermost horn of Taurus is part of a pentagon of stars that includes the bright golden-yellow star, Capella. This pentagon is the constellation Auriga the Charioteer. Auriga lies above Orion and is overhead on a midwinter evening. The fact that these five stars represent a man on a chariot carrying a goat (Capella) attests to the vivid imagination of its ancient discoverers. That little triangle of stars beneath Capella represents the goat’s three kids!
Gemini the Twins
Orion’s heavenly court includes Gemini the Twins. From Orion, extend a line upward from Rigel through Betelgeuse to this neat rectangular constellation containing the bright stars Pollux and Castor. In 2005, Gemini will be more aptly called the “Triplets,” for Pollux and Castor will be joined by a third bright “star” — Saturn. Midway and slightly left of a line between Sirius and the stars Pollux and Castor is the 1st-magnitude star Procyon. Procyon forms an equilateral triangle with Betelgeuse and Sirius. It’s about all you’ll see of Canis Minor the Little Dog.
Spring Sky
Leo the Lion
As the days lengthen and the weather warms, Orion and his wintry retinue process slowly into the western sky. Leo the Lion now assumes center stage high in the south. Leo’s most noticeable feature is an asterism (a grouping of stars) that reminds observers of a sickle or a backward question mark.
The period on the question mark is the 1st-magnitude star Regulus. Three stars form a right triangle to the left of the Sickle. We see the Lion from the side; the Sickle outlines his head, and the triangle, his hindquarters. Viewed with a bit of imagination, Leo sports a feline profile.
During spring, the Big Dipper appears nearly overhead from mid-northern latitudes. If you follow the Dipper’s handle away from the bowl, you’ll “arc to Arcturus,” a golden-yellow 1st-magnitude star in the constellation Boötes the Herdsman. The constellation is shaped like a giant kite, with Arcturus at its base. Continuing the arc, you’ll “sprint to Spica.” This blue-white 1st-magnitude star is in Virgo, a vast, sprawling constellation.
If you look below and to the right of Spica, you’ll spot a neat little group of four bright stars resembling a sail’s outline. This is the constellation Corvus the Crow. I’m always impressed at how stately this little constellation looks, perched above the treetops to the south on a clear spring evening.
Summer Sky
The summer is a season of mixed blessings for astronomers. The nights are warm but short and often hazy. As if that weren’t bad enough, we must contend with swarms of blood-sucking mosquitoes! Haze and insects aside, the summer sky is a veritable gallery of cosmic masterpieces.
Lyra the Lyre.
The Milky Way arches high across the sky, more decadent than its winter counterpart because we now look toward the heart of our galaxy. Dominating the evening sky are three 1st-magnitude stars forming the Summer Triangle. Vega is the brightest of the three and is located in a nifty little constellation called Lyra the Lyre.
Cygnus the Swan.
Our second Summer Triangle star, Deneb, is the tail of Cygnus the Swan. Deneb and four other bright stars of the Swan form an asterism called the Northern Cross, which is immersed in the Milky Way. Deneb is at the top of the cross, and the star Albireo is at the base. Albireo is a double star famous for its rich golden yellow and sapphire blue colors. The star pair can be split with binoculars, but the colors can be seen only through a telescope.
Farther south on the Milky Way is the bright star Altair and its parent constellation, Aquila the Eagle. If you follow the Milky Way from Aquila toward the southern horizon, you should find a group of stars that looks like a teapot. This asterism is part of Sagittarius the Archer. This constellation marks the location of our galaxy’s center — incredibly bright nebulae and star clusters.
Scorpius the Scorpion
To the right of the teapot is the ruddy 1st-magnitude star Antares, the “heart” of Scorpius the Scorpion. Like the winter star Betelgeuse, Antares is a red supergiant star in the last stages of its life. A fishhook-shaped row of stars trailing down and to the left of Antares forms the Scorpion’s tail and stinger, while an upright row of three stars to Antares’s right marks the location of its claws.
Autumn Sky
Delphinus the Dolphin
As the nights begin to lengthen, the summer Milky Way exits center stage (although the Summer Triangle remains visible in the west until early winter). One of the night sky’s prettiest constellations is following the Summer Triangle — Delphinus the Dolphin. Four stars are arranged like a diamond from the Dolphin’s head, while a fifth creates the tail. You can imagine a dolphin leaping out of the water as you gaze at this constellation.
In its wake is a rather barren expanse of sky whose most prominent feature is the Great Square of Pegasus the Winged Horse
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Andromeda the Princess
Alpheratz is at the top left corner of the Great Square. From here, two rows of stars branch out and up. This is the constellation Andromeda the Princess. And yes, it is home to the great Andromeda Galaxy.
At a distance of 2.7 million light-years from Earth, it’s the most remote object readily visible to the naked eye. Using binoculars, however, you’ll see an elliptical glow (the galaxy’s bright nucleus), which appears more prominent in small telescopes.
It’s time to head out and make your friends. After learning about the constellations, the expansive night sky will become more familiar.
Conclusion
Constellation Maps and Guides
Constellation maps divide the celestial sphere into 88 parts, known as constellations, helping astronomers locate stars and deep-sky objects. The star constellations depend on the observer’s location and season and change throughout the year.
Out of the 88 constellations recognized by the (IAU), 36 are found predominantly in the northern sky. While the remaining 52 are located in the southern sky.
Moving East to West
As our planet spins on its axis, we see different constellations. Stars appear to move across the sky from east to west. As the Earth orbits around the Sun, constellations move slowly to the west over a year. We see different parts of the sky at night. It is because, as the seasons change, we are looking in another direction in space. It means that different constellations are viewable at varying times of the year.
A relatively bright star located in Ursa Minor constellation. The celestial sphere, an imaginary sphere surrounding Earth, is divided into the northern and southern hemispheres and extended into space by the line of the Earth’s equator. Similarly, the Earth’s North and South Poles, developed into space, mark the north and south celestial poles. The north celestial pole can be easily located because Polaris characterizes it. To pinpoint the south celestial pole is harder because stars are visible to the unaided eye marking their location.
Celestial Poles
Polaris and other stars near the celestial poles appear to move across a smaller area than stars lying closer to the equator. The farther they are from the bars, the wider the stars’ circle across the night sky. The stars close to the poles never set below the horizon. For observers in locations where the stars are visible: they are circumpolar. Near the equator, there are no circumpolar stars with the celestial poles on the horizon. Stars appear to rise in the east and set in the west for observers at the equator.
Observers can only see some 88 constellations from a single location on Earth. At the same time, some southern constellations can be seen from northern latitudes at certain times of the year.
Scorpius is visible over the southern horizon in the summer – others never rise over the horizon.
Crux, known as the Southern Cross, is prominent enough in the southern sky to be featured on several national flags. It can never be seen from most locations north of the equator. Similarly, the constellation Ursa Minor is the closest bright star to the north celestial pole. It cannot be seen from most places south of the equator.
All stars and deep sky objects on the celestial sphere are mapped relative to the celestial equator and poles. Just as different locations on Earth are mapped using the equator and Greenwich, England. A star’s latitude or position north or south of the celestial equator is called declination. At the same time, its longitude or place east or west is called right ascension and is measured in hours, minutes, and seconds.
