Kitt Peak Nightly Observing Program
Splendors of the Universe on YOUR Night!
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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.
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.
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.
Orion is a famous constellation, well known especially for the Belt of Orion—three stars in a line at what seems to be the waist of a human figure. The bright stars Rigel and Betelgeuse are two of the brightest stars in the sky. Between the Belt and Rigel you can see the Orion Nebula—the closest star forming region to our Solar System. A beautiful object in a telescope or binoculars, you can also just make out the nebula naked-eye.
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.
M42 The Orion Nebula
M42, the Orion Nebula is a region of star formation about 1,300 light-years away—the closest to our Solar System. It is roughly 30 light-years across, and contains enough material to make 2,000 stars the size of our sun.
M15 is a distant globular cluster, 33,000 light-years away. It has 100,000 stars, and is one of the oldest known globular clusters, having formed about 12 billion years ago.
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.
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 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.
The Hyades is the nearest open star cluster to the Solar System at about 150 light-years away and thus, one of the best-studied of all star clusters. It consists of hundreds of stars sharing the same age, place of origin, chemical content, and motion through space. In the constellation Taurus, its brightest stars form a V shape along with the brighter red giant Aldebaran, which is not part of the cluster, but merely lying along our line of sight. The age of the Hyades is estimated to be about 625 million years. The cluster core, where stars are most densely packed, has a diameter of about 18 light-years.
M103 is one of many open star clusters in the constellation Cassiopeia. At a distance of about 10,000 lightyears, this is one of the most distant open star clusters known. The apparent brightest star in the cluster is not actually a member of the cluster at all, but actually a foreground star. The brightest star in the cluster is a red giant star; it has a redish orange tinge.
M45 The Pleiades
M45, the “Pleiades,” is a bright, nearby star cluster, in the last stages of star formation. About seven stars stand out as the brightest in the cluster, and is why the cluster is also known as the “Seven Sisters,” alluding to the Pleiades, or Seven Sisters from Greek mythology. In Japanese, the cluster is known as “スバル,” “Subaru,” and is featured as the logo of the automobile manufacturer of the same name. The Pleiades lies about 440 light-years away and is a very young (for an open star cluster) 100 million years old.
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.
Albireo (β Cyg)
Named long before anyone knew it was more than one star, Albireo (β Cygni) comprises of a set of stars marking the beak of Cygnus, the swan. Through a telescope, we see two components shining in pale, but noticeably contrasting colors: orange and blue. The difference in color is due to the stars’ difference in temperature of over 9000°C! The brighter orange component, Albireo A, is actually a true binary system, though we can’t resolve two stars in the telescope. The fainter blue component, Albireo B, may be only passing by, and not gravitationally interacting with Albireo A at all. Albireo is about 430 light-years away.
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.
Mesarthim (γ Arietis)
Mesarthim is one of the brighter stars making up the constellation Aries—the ram. It is actually a pair of stars—a double star—204 light-years away. It’s component stars are of similar brightness and both white. They are separated by about 500 times the distance between the Earth and the Sun, and take approximately 5,000 years to orbit each other. The apparent (slightly) dimmer star, Gamma-1, is actually the hotter and more luminous star. Much of its light is ultraviolet, and invisible to human eyes. The apparent (slightly) brighter star, Gamma-2, has some interesting characteristics that suggest not only that it may be evolving from a dwarf to a subgiant, but also that it is highly magnetized.
Rigel (β Ori)
Rigel (β Orionis) is the brightest star in the constellation Orion, and the seventh brightest star in the night sky, with a visual magnitude of 0.13. Rigel is a triple star system. The primary star (Rigel A) is a blue-white supergiant around 120,000 times as luminous as the Sun. It has exhausted its core hydrogen and swollen out to 79 times the Sun’s radius. An Alpha Cygni variable, it pulsates periodically. Visible in small telescopes and 500 times fainter than Rigel A, Rigel B is itself a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9V that are themselves estimated to be 2.5 and 1.9 times as massive as the Sun.
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