Kitt Peak Nightly Observing Program
Splendors of the Universe on YOUR Night!
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The Big Dipper (also known as the Plough) is an asterism consisting of the seven brightest stars of the constellation Ursa Major. Four define a “bowl” or “body” and three define a “handle” or “head”. It is recognized as a distinct grouping in many cultures. The North Star (Polaris), the current northern pole star and the tip of the handle of the Little Dipper, can be located by extending an imaginary line from Big Dipper star Merak (β) through Dubhe (α). This makes it useful in celestial navigation.
The Engagement Ring: Through binoculars, the North Star (Polaris) seems to be the brightest on a small ring of stars. Not a constellation or cluster, this asterism looks like a diamond engagement ring on which Polaris shines brightly as the diamond.
Constellation Ursa Minor is colloquially known in the US as the Little Dipper, because its seven brightest stars seem to form the shape of a dipper (ladle or scoop). The star at the end of the dipper handle is Polaris, the North Star. Polaris can also be found by following a line through two stars in Ursa Major—Alpha and Beta Ursae Majoris—that form the end of the ‘bowl’ of the Big Dipper, for 30 degrees (three upright fists at arms’ length) across the night sky.
The Summer Triangle is an asterism involving a triangle drawn on the northern hemisphere’s celestial sphere. Its defining vertices are the stars Altair, Deneb, and Vega, which are the brightest stars in the constellations Aquila, Cygnus, and Lyra, respectively.
The brightest stars in the zodiac constellation Sagittarius form the shape of a teapot, complete with lid, handle, and spout. The plane of the Milky Way runs through Sagittarius, and just over the spout and lid of the teapot, making it look as if steam is rising from the spout of the teapot. The center of our Milky Way galaxy is in the direction of this starry steam.
Also called Cr 399, or Brocchi’s Cluster, this group of stars might remind you of a closet. The stars that make up The Coarhanger are not a part of a cluster, but instead, have randomly arranged themselves in a coathanger-like shape. Chaotic stellar orbital motion can sometimes make interesting shapes!
Andromeda was the princess of myth who was sacrificed by her parents to the sea monster Cetus. Fortunately, the hero Perseus came along to save her, and they were eventually married. The constellation Andromeda is host to the Andromeda Galaxy. Although there are smaller, dwarf galaxies that are closer to our galaxy, Andromeda is the closest big galaxy like our own; in fact, it’s bigger.
Aquarius, the water-carrier is said to resemble a figure carrying a jug of water. This aquatic constellation is one of the zodiac constellations, so the planets, Sun, and Moon move across its boundaries. Aquarius and other nearby aquatic-themed constellations make up a region of the sky known as “the Sea”.
The brightest star in Aquila is Altair—one of the brightest starts in the summer sky, and a point of The Summer Triangle. The name aquila is latin for eagle, and the brightest stars in this constellation do seem similar to the shaape of an eagle standing upright with its wings spread out at its sides. Altair is at the head, or more precisely, the eye of the eagle. In Greek mythology, Aquila carried Zeus’s thunderbolts.
Aries is a medium-brightness constellation, but with few stars and an indistinctive shape, which makes it more challenging to recognize.
Auriga is located north of the celestial equator. Its name is the Latin word for “charioteer”, associating it with various mythological charioteers, including Erichthonius and Myrtilus. Auriga is most prominent in the northern Hemisphere winter sky, along with the five other constellations that have stars in the Winter Hexagon asterism. Auriga is half the size of the largest constellation, Hydra. Its brightest star, Capella, is an unusual multiple star system among the brightest stars in the night sky. Because of its position near the winter Milky Way, Auriga has many bright open clusters within its borders, including M36, M37, and M38. In addition, it has one prominent nebula, the Flaming Star Nebula, associated with the variable star AE Aurigae.
Boötes has a funny name. Pronounced boh-OH-deez, this constellation’s name means sheepherder, or herdsman. It looks kind of like a kite, or a shoe. Some remember that “Boötes look like a boot” to help pick it out in the sky.
Cassiopeia is widely recognized by its characteristic W shape, though it may look like an M, a 3, or a Σ depending on its orientation in the sky, and your position on Earth. However it’s oriented, once you’ve come to know its distinctive zig-zag pattern, you’ll spot it with ease. The plane of the Milky Way runs right through Cassiopeia, so it’s full of deep sky objects—in particular, a lot of open star clusters. Cassiopeia is named for the queen form Greek mythology who angered the sea god Poseidon when she boasted that her daughter Andromeda was more beautiful than his sea nymphs.
King Cepheus from Greek mythology was husband to Cassiopeia and father of Andromeda. The brightest stars in the constellation Cepheus seem to form a kind of crooked house, with the roof pointing to the North. this constellation is very near the Celestial North Pole, so it’s not visible from the Southern Hemisphere. The star Delta Cephei was the first ever identified cepheid variable star, a very important kind of variable stars that helps astronomers determine distances to nearby galaxies.
Cygnus is a large constellation, prominent in the Northern Hemisphere. Its name comes from the Greek for “Swan” and can be imagined as a giant, celestial swan, flying overhead, with its wings fully extended. The brightest star in Cygnus is Deneb, which is one of the brightest stars in the sky, and a whopping 800 lightyears away! Deneb is one point of an asterism called the Summer Triangle—three very bright stars that form a large triangle shape prominent in the Northern hemisphere summer skies.
Draco the dragon lies close to the North polar point of the celestial sphere. Thus, it is best viewed from north of the equator. This celestial dragon has a long serpentine shape that winds around the constellation Ursa Minor (better known by the name Little Dipper), which is far fainter than it’s companion, Ursa Major. The tail of Draco separates these two constellations.
Hercules is named for the famous hero of Greek mythology by the same name. It’s one of the larger constellations, but its stars are of only moderate brightness. The Keystone is a well known trapezoid-shaped asterism (association of stars that are not an official constellation) within Hercules. This constellation is host to M13 (Messier 13), a globular star cluster. Otherwise known as the Hercules Globular Cluster, M13 is home to 300,000 stars, and is just over 22,000 light-years away.
Lyra is a small, but notable constellation. It is host to Vega—the fifth brightest star in the sky (or sixth, counting the Sun). Not far from Vega is Messier object 57—the Ring Nebula, which is perhaps the best known planetary nebula in our sky. Lyra’s name is Greek for lyre—a kind of harp.
The name Ophiucus comes from Greek and means serpent-bearer. This constellation goes hand-in-hand with the constellation Serpens—a constellation that is uniquely divided into two parts, the head and tail of the serpent, on either side of Ophiucus. The ecliptic actually runs through the very southernmost part of the area of sky defined as this constellation, making it—technically—a zodiac constellation.
This constellation is named for one of the most beloved creatures of Greek mythology—the winged horse named Pegasus. Within Pegasus is a well known asterism containing the 3 brightest stars in the constellation (+ 1 in Andromeda) called The Great Square of Pegasus. Alpheratz, the brightest star in the square, actually belongs to the constellation Andromeda, but in the past, this star had been considered to belong to both constellations.
Hero of Greek mythology, Perseus is the character who slayed Medusa and rescued the Princess Andromeda from the sea monster Cetus. This is why you will find the constellations Andromeda, Cetus, and Andromeda’s parents Cassiopeia and Cepheus, nearby each other in the sky. Perseus’s brightest star is called Mirfak (Arabic for elbow). The plane of the Milky Way runs through Perseus, so there are many deep sky objects to be found.
Sagittarius, the archer, is often depicted as a centaur wielding a bow and arrow. Within Sagittarius, is a fairly recognizable teapot shape known to many simply as The Teapot (the teapot is not a true constellation, but an asterism). The plane of the Milky Way passes through Sagittarius, and in fact, the center of the Milky Way is in the direction of the westernmost edge of this constellation—just above the spout of The Teapot. With the plane of the Milky Way passing through, there are a plethora of deep sky objects to be found in Sagittarius.
Serpens, the serpent, is the only constellation that is broken into two parts, each on either side of Ophiucus, the serpent bearer. Serpens Caput (serpent’s head) is to the west, and Serpends Cauda (serpent’s tail) is to the east. The galactic plane of the Milky Way passes through Serpens Cauda, which means there are many deep sky objects to be found there, including the Eagle Nebula, a star formation region host to the famous Pillars of Creation.
Triangulum is a small and simple constellation, and perhaps the only constellation that truly looks like its namesake—a triangle. Within the boundaries of the constellation lies one of our nearest neighbor galaxies—a galaxy known as the Triangulum Galaxy (Messier 33). At only 3 million light-years away, Triangulum is one of our closest neighbors.
Ursa Major, or, the Big Bear, is one of the best known and most well recognized constellations, but you might know it by a different name. Contained within the boundaries of the constellation Ursa Major is the Big Dipper, which is not a true constellation, but an asterism. The Big Dipper is useful for finding both the North Star and the bright star Arcturus. Follow the curve of the handle to “arc to Arcturus” and use to two stars in the dipper opposite the handle to point to the North Star.
Ursa Minor, the Little Bear, is much fainter than it’s companion the Big Bear, Ursa Major. Within Ursa Minor is the well known asterism The Little Dipper. The end of the tail of the bear, or the end of the handle of the dipper, is a star called Polaris—the Pole Star, or the North Star. This special star happens to sit at the point where the Earth’s axis of rotation intersects the sky
M31 Andromeda Galaxy
The Andromeda Galaxy is our nearest major galactic neighbor. It is a spiral galaxy 2,500,000 light-years away, and has a diameter of 220,000 light-years. This galaxy contains as much material as 1.5 trillion suns.
Kitt Peak has an abundance of clear nights, but that doesn’t mean the clouds never move in. We hope you’ll join us again another time when our dark mountain skies are at their best!
That clumpy band of light is evidence that we live in a disk-shaped galaxy. Its pale glow is light from about 200 billion suns!
Human technology! There are almost 500 of these in Low Earth Orbit (we can’t see the higher ones). We see these little “moving stars” because they reflect sunlight.
The twinkling of star light is a beautiful effect of the Earth’s atmosphere. As light passes through our atmosphere, its path is deviated (refracted) multiple times before reaching the ground. Stars that are near to the horizon will scintillate much more than stars high overhead since you are looking through more air (often the refracted light will display individual colors). In space, stars would not twinkle at all. Astronomers would like it if they could control the effects of this troubling twinkle.
The Green Flash
What we call “The Green Flash” is not so much a flash as a flicker of green color, seen on the top of the sun as it sets (or rises). This rare event needs just the right atmospheric conditions.
M7 Ptolemy Cluster
M7, also known as the “Ptolemy Cluster” is an open star cluster near the “stinger” of Scorpius. It is a group of suns in a gravitational dance, 25 light-years across and about 1,000 light-years away.
M57 Ring Nebula
M57: The Ring Nebula. This remnant of a dead star looks exactly as it’s name says – a ring or doughnut shape cloud of gas. The nebula is about 2.6 lightyears across and lies about 2,300 lightyears away.
Jupiter is the largest planet in the Solar System, a “gas giant” 11 Earth-diameters across. Its atmosphere contains the Great Red Spot, a long-lived storm 2-3 times the size of the Earth. The 4 large Galilean satellites and at least 63 smaller moons orbit Jupiter.
The same side of the Moon always faces Earth because the lunar periods of rotation and revolution are the same. The surface of the moon is covered with impact craters and lava-filled basins. The Moon is about a fourth of Earth’s diameter and is about 30 Earth-diameters away.
51 Pegasi is a Sun-like star located about 50 lightyears from Earth. The 51 Pegasi system is home to the first exoplanet to ever be discovered, known as 51 Pegasi b or Dimidium. 51 Peg b is a large planet, about half the mass of Jupiter, orbiting very close to its parent star. The star 51 Pegasi can actually be seen with the naked eye under fairly dark skies.
61 Cygni is a binary star system in the constellation Cygnus consisting of a pair of K-type stars, similar to each other in radius, mass, and brightness. The pair orbit each other in a period of about 659 years. This binary system can be seen with the naked eye in areas with low light pollution. 61 Cygni became of interest to astronomers in the early 19th century when its large proper motion was discovered—meaning its position moves slightly respective to the other stars around it. 61 Cygni currently has the highest proper motion among naked-eye visible stars. The distance to stars with large proper motion can be measured using the parallax method, and 61 Cygni became one of the first stars to have its distance measured.
Algol (β Persei)
Algol is a famous variable star. The Arabic name, “al Ghul” (related to the English “ghoul”), means “the demon.” It comes from a longer phrase that refers to the demon’s head. In Greek mythology, the star Algol represented the head of Medusa, held up by Perseus’s fist. To the eye, this star appears slightly bluish white. Close observation will reveal an interesting characteristic. Every 2.9 days, the brightness of Algol drops to just 30 percent of normal. The drop in brightness lasts only a few hours. This variation in brightness may be the reason the star was once considered to be unlucky. The cause of the variation in brightness is a stellar eclipse. Algol is a close double star whose components orbit each other every 2.9 days. Its companion is much fainter than Algol itself, but is actually larger in size. When it passes in front of Algol, it eclipses the light of the brighter companion.
Double Double (ε Lyr)
The Double-Double (ε Lyrae) looks like two stars in binoculars, but a good telescope shows that both of these two are themselves binaries. However, there may be as many as ten stars in this system! The distant pairs are about 0.16 light-year apart and take about half a million years to orbit one another. The Double-Double is about 160 light-years from Earth.
Mizar & Alcor
In the handle of the Big Dipper, Mizar & Alcor (ζ & 80 Ursae Majoris) or the “Horse & Rider” form a naked-eye double star. They are traveling through space together about 80 light-years away from us, separated by about a light-year. However, it is unknown if they are actually gravitationally bound to each other. A telescope splits Mizar itself into two stars, but these both are again doubles, bringing the total in this system to six.
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