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.
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.
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.
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.
Little Delphinus looks like a tiny celestial dolphin breaching the waves of a vast cosmic sea. It is small and faint, but has a distinctive dolphin shape, and is right in the middle of the plane of the Milky Way.
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.
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.
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.
M13 Hercules Globular
M13, the “Great Globular Cluster in Hercules” was first discovered by Edmund Halley in 1714, and later catalogued by Charles Messier in 1764. It contains 300,000 stars, and is 22,000 light-years away. Light would need over a century to traverse its diameter.
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 “Double Cluster” (NGC 884 and NGC 869) is a pair of two open star clusters that are a treat for binoculars and telescopes alike. Each is a congregation of many hundreds of stars, around 50-60 light-years in diameter. These clusters are both about 7,500 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.
The Galilean Moons
Jupiter’s four largest moons are known as the Galilean Moons, named for Galileo, who was the first astronomer to study them in depth and determine that they were orbiting Jupiter. Their individual names are Io, Europa, Ganymede, and Callisto—in orbital order from closest to Jupiter to furthest out. Ganymede is the largest of these four moons, and is the largest moon in our Solar System. Io, the closest of these four moons to Jupiter, is the most volcanic world in our Solar System. Io is home to hundreds of active volcanos. Its neighbor, and the next furthest from Jupiter of the four, Europa, is a dramatic contrast to Io with its icy surface. Europa is covered by water, which is frozen solid at the surface. The furthest our of the four, Callisto is a fascinating world in our Solar System because it is so utterly geologically dead. Without weather, moonquakes, volcanism, or any other surface-altering processes, Callisto’s surface is billions of years old—a kind of record of the history of the Solar System.
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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