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.
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.
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”.
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.
This faint zodiac constellation’s name means “horned goat”, and is often depicted as not only a goat, but a sea-goat. It’s faint and hard to spot, but is roughly triangular-shaped. Zodiac constellations are the constellations along the ecliptic—the plane of the Solar system. This means planets pass through Capricornus from time to time.
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.
Libra is a fainter constellation, but easy enough to spot, once you’re familiar with the shape. It lies along the ecliptic (the plane of the Solar System), so planets pass through now and then. The names of the two brightest stars of Libra, which are Zubeneschamali and Zubenelgenubi, come form Arabic, and mean “the northern claw”, and “the southern claw”, respectively. Libra was once considered to be part of the constellation Scorpius, the scorpion. Zubeneschamali and Zubenelgenubi were seen as the claws of the scorpion.
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.
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.
Both the plane of the Solar System (called the ecliptic) and the plane of the Milky Way pass through Scorpius—the scorpion. As a result, you can find both the planets of our Solar System (which move along the ecliptic), and many kinds of deep sky objects in this constellation. Scorpius’s brightest star, Antares, is also known as the Heart of the Scorpion, because of it’s reddish hue and location in the chest of the scorpion. Being both red in color, and near the ecliptic, Antares is a rival of sorts to the planet Mars, which is also reddish in color, and occasionally passes through Scorpius. The name Antares means “opposing Mars”.
Virgo’s brightest star Spica is found by following the curve of the handle of the Big Dipper (“arc to Arcturus, in Boötes, then spike to Spica”).The rest of the constellation isn’t particularly bright, but Virgo lies along the ecliptic—the plane of the Solar System, so bright planets pass through occasionally.
M17 Swan Nebula
M17, also known as the “Swan Nebula,” or the “Omega Nebula” is a vast cloud of gas—mostly hydrogen, in which clumps of gas are contracting to make new stars. The nebula is 15 light-years across, and 5,500 light-years away.
M8 Lagoon Nebula
M8: The “Lagoon Nebula.” A huge cloud of gas and dust beside an open cluster of stars (NGC 6530). The Lagoon is a stellar nursery, 4,100 lightyears away, towards the galactic core.
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.
M32 Smaller Satellite of Andromeda
M32 is a small, but bright companion galaxy to M31. It orbits M31 much like the Moon orbits the Earth. It lies at the same distance as M31 but is much smaller (6,500 light-years across).
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.
Near the top of the “teapot” in Sagittarius, M22 is one of the brightest globular star clusters in our sky, and therefore, was probably the first globular cluster ever discovered. Its 80,000 stars span a diameter of about 100 light-years.
The ecliptic is a path in the sky, forming a great circle around the Earth, which the Sun and other planets of the Solar System move along. It is formed where the plane of the Solar System intersects with the Earth’s sky.
Quick streaks of light in the sky called meteors, shooting stars, or falling stars are not stars at all: they are small bits of rock or iron that heat up, glow, and vaporize upon entering the Earth’s atmosphere. When the Earth encounters a clump of many of these particles, we see a meteor shower lasting hours or days.
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.
M6 The Butterfly Cluster
M6, the “Butterfly Cluster” is an open star cluster, located near the tail of Scorpius, next to another open cluter: M7. Containing a few hundred stars, it is smaller than neighbor cluster M7, at about 12 light-years across, and is 1,600 light-years away.
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.
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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