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.
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.
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.
Lepus is a smaller, medium brightness constellation. It can be found immediately to the south of the constellation Orion, at the feet of the hunter. The best known star of Lepus, is not one that is visible to the naked-eye. R Leporis, also known as Hind’s Crimson Star, is a ruby red carbon star. Just take a look with a telescope and see how strikingly red it is compared to other stars. An abundance of carbon in the star’s atmosphere filters out certain wavelengths of light, giving the star its extra red appearance.
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”.
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
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.
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.
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.
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