The night sky in summer - huge post alert!
Ok, so I'm bored and on my way home last night I was star gazing, so I thought I would follow up my previous post and yabber on about some of the things we can see in our night sky at the moment.....
The Milky Way galaxy is the spiral galaxy we call home, as do roughly 100 billion other stars. It looks very much like other spiral galaxies when viewed from above. There are spiral arms and a bright central part. The Sun is far from the center of the Galaxy, halfway to the edge of the Galaxy along the Orion spiral arm.
The Sun is revolving around the center of the Galaxy at a speed of half a million miles per hour, yet it will still take 200 million years for it to go around once. Do you feel like you are moving at that speed through space? If you did, you would certainly need a seat belt! When we run, we feel the wind on our bodies because there are molecules which make up the air that push against our bodies. But there are very few molecules in the space between the stars. So there is nothing to push against our planet so that we "feel" like we are rushing around at half a million miles per hour.
Like other spiral galaxies, the Milky Way has a bulge, a disk, and a halo. Although all are parts of the same galaxy, each contains different objects. The halo and central bulge contain old stars and the disk is filled with gas, dust, and young stars. Our Sun is itself a fairly young star at only 5 billion years old. The Milky Way galaxy is at least 5 billion years older than that.
Aquila - The celestial eagle is one of the three constellations which have bright stars forming the Summer Triangle. A nearly perfectly straight line of three stars symbolizes part of the wings. The center and brightest of these three stars is Altair. The tips of the wings extend further to the southeast and northwest. The head of the eagle stretches off to the southwest.
To the ancient Greeks, Aquila was the servant of Zeus who held the god's thunderbolts and performed errands for him. He may also be the great eagle who devours Prometheus' liver as punishment for giving fire to humans. The line of three stars which includes Altair is revered by Indians as the footprints of the god Vishnu. Some Asian traditions see the bright star Vega as the Weaving-Princess star who marries a shephard, the star Altair.
Cygnus - the Swan, is also known as the Northern Cross because of it's shape. The tail of the swan is marked by the bright star Deneb, Arabic for "tail". Three fainter stars cross the line between Deneb and the head of the swan, Albireo. Cygnus flies southward along the summer Milky Way, and into the Summer Triangle.
Deneb is a bright, blue supergiant star, very young as stars go. Albireo, the bill of the swan, is actually two stars which show a spectacular amber and blue contrast. Cygnus is also sprinkled with a variety of nebulae, including the North American Nebula and the Veil Nebula.
Albireo
The identity of Cygnus is uncertain. He could be Zeus in the guise in which he seduced Leda, the mother of Helen of Troy. In one myth, Cygnus is a friend of Phaethon, the son of Apollo, the sun god. Phaethon fell into the river Eridanus, trying to drive the sun-gods chariot. Cygnus dove repeatedly into the water to search for Phaethon. Out of pity, Zeus turned the boy into a swan
Hercules - the great Greek warrior, can be seen kneeling in the sky for northern latitudes throughout the Spring months. Hercules first becomes visible in the east in April, and works his way high across the night sky through October. From the southern hemisphere, he appears low in the north. Four relatively bright stars form what is commonly known as the Keystone. Hercules' arms and legs extend from this central square.
By far the most exciting object to see in Hercules is the magnificent globular cluster M13, which is visible in dark night skies even without binoculars or a telescope. This cluster of 300,000 stars appears as a faint fuzzy spot to the naked eye. It is located between the stars which form the western side of the Keystone.
M13
Many other constellations, like Leo, the Lion, Hydra, the nine-headed Serpent, and Draco, the Dragon, were unfortunate victims of Hercules, and thus were also placed in the sky. Cancer, the Crab was sent by Hera to annoy Hercules in his battles, and became yet another victim of the hero.
Lyra - the Lyre, is a type of small harp held in the player's lap. The brightest star in Lyra, Vega, is placed in the handle of the harp. A small parallelogram of four faint stars just to the southeast of Vega outline the harp itself. Lyra is one of three constellations whose brightest stars form the Summer Triangle.
Vega is a very bright star (the fifth brightest in the whole sky) and is very close. Lyra is also home to one of the brightest, loveliest planetary nebulae, the Ring Nebula. It can be viewed with binoculars, although it's distinctive smoke-ring shape cannot.
Ring Nebula
According to Greek mythology, the lyre was invented by Hermes as a child when he strung a tortoise shell. He traded the lyre to Apollo, who then gave it to his son, Orpheus, a great poet and musician. Some Asian traditions see the bright star Vega as the Weaving-Princess star who marries a shephard, the star Altair.
Ophiuchus - the Serpent Bearer. This large constellation can be seen in the night sky from June through October. Although most of the stars are dim, Ophiuchus' teapot shape makes it easy to find.
The constellation is a combination of three different figures. Ophiuchus is holding Serpens Caput in his left hand, and Serpens Cauda in his right. He is located south of Hercules and north of Scorpius.
In Greek myth, Ophiuchus represents the god of medicine, Asclepius. Asclepius was the son of Apollo and was taught by Chiron, the Centaur. He learned how to bring people back from the dead, which worried Hades. The god of the underworld asked his brother Zeus to kill the medicine god. Zeus did strike him dead, but then put the figure of Asclepius in the sky to honor him.
There aren't many bright stars in this constellation, but there is a rather unique one. RS Ophiuchi is a type of star called a recurrent nova. These strange objects stay dim for long periods of time, and then suddenly brighten. The brightest star is called Ras Alhague, and is the head of the serpent bearer.
Ophiuchus is full of celestial objects. There are numerous clusters and one nebula in the constellation.
Sagittarius - the centaur, with the torso of a man atop the body of a horse. Unlike the wise and peaceful centaur Chiron (Centauron), Sagittarius is aiming his giant bow at his neighbor, Scorpius. While this is a very large constellation, its stars are relatively faint and most people easily recognize just the central figure which resembles a teapot with a lid, handle, and spout.
More than a dozen objects reside in Sagittarius, including globular clusters. Recently, astronomers have discovered a small galaxy in Sagittarius that is crashing through the Milky Way.
Exactly who is Sagittarius? The Mediterranean people viewed him as Enkidu, the close friend of Gilgamesh, believed to be represented by Orion. Greek mythology associates Sagittarius with Crotus, the son of the goat-god Pan and Eupheme, the nurse of the Muses. He grew to be a skilled hunter, as well as a man with an artistic soul. The Muses, with whom he was raised, begged Zeus to honor him with a constellation equal to his great talents
Scorpius - the scorpion. More than any other constellation, Scorpius resembles its given name. If you live in the northern hemisphere of the Earth, Scorpius crawls across the southern sky, close to the horizon. But if you live in the southern hemisphere, it passes high in the sky. The bright star Antares marks the heart of the arachnid, and its long curving tail trails to the south. The scorpion once had claws, but they were cut off by Julius Ceasar to form the constellation Libra.
Where stars are concerned, whatever you are looking for, you can probably find it in Scorpius. Antares is an unmistakable, brilliant red supergiant star at the heart of the scorpion. One of the largest, brightest globular clusters in the sky is in Scorpius.
Antares
The scorpion holds an infamous place in Greek mythology as the slayer of Orion. One story tells that Orion fled the scorpion by swimming the sea to the island of Delos to see his lover, Athena. Apollo, seeking to punish Athena, joined her and challenged her hunting skills, daring her to shoot the black dot that approached in the water. Athena won the challenge, unknowingly killing her lover by doing