I joined the Barnard-Seyfert astronomy club in Nashville. We met at the Adventure Science Center.
E. E. Barnard (1857-1923) was born in Nashville. He was a great observer and photographed the Milky Way. He discovered the first Jovian moon since Galileo.
Carl Seyfert was instrumental in building Dyer Observatory.
In July, 2008, I attended a meeting of the BSAS. The club president gave a presentation showing constellations and the location of Messier objects. There was discussion about star parties, when and where they would be held.
I looked forward to my Messier Marathon in April. The object is to observe as many of Charles Messier's 110 objects as possible.
It was a long road from interpreting events in the sky as whims of gods and goddesses to explaining them as the interaction of natural forces. The sun, moon and planets are part of nature as are mountains, forests and seas. The ancient Greeks made inroads into science. Aristarchus (310 BC - 230 BC) knew that the earth circled the sun. He was 18 centuries ahead of Copernicus.
In astronomy, things are often not what they seem. There are apparent motions, apparent magnitudes and apparent diameters. Our senses say that the sun rises in the morning and sets at night. But this is not true! The earth is rotating. We are the ones moving. Moreover, we may think that Venus is brighter than the stars because it appears so when in reality this nearby planet reflects light from our sun. The stars are enormous suns trillions of miles away emitting their own radiation. Finally, we hold our thumbs up to cover the moon. Its diameter seems hardly an inch. We know this is not true, and the astronauts who walked on the moon will tell us. Our sensory perceptions evolved on earth to ensure our survival and capacity to function in our immediate surroundings. Knowledge of the earth's place in the solar system and that system's place in the Milky Way has come slowly over many centuries through the collaborative efforts of our greatest minds.
The sun is the source of Earth's energy. We take it for granted. Without the sun, life on earth would cease to exist. Earlier civilizations knew its importance. They worshipped the sun. People in high latitudes such as Scandinavians appreciate its annual return.
The sun is a star, one of 400 billion in the Milky Way galaxy. It only seems different from other stars because it is close. We circle it. The sun is yellow and a mere 93 million miles away. Other stars appear as points of light because they are trillions of miles away.
The sun does not rise and set. The spinning earth makes it appear so. The apparent path of the sun is called the ecliptic because it is where eclipses take place. It lies in the center of the Zodiac.
The sun formed when a cloud of gas and dust collapsed. Its core was squeezed so tight that nuclear fusion began. Hydrogen atoms combined to form helium and give off energy. The sun shines by nuclear energy, some of which takes the form of visible light.
Someday, the sun will exhaust its hydrogen. It will then burn helium to form other elements. Toward the end of its cycle, the sun will become a red giant. Its outer shell will expand, and its core will shrink. The core will become a white dwarf and eventually a burned-out ember. Heavy elements are made when massive stars explode as supernovas. These elements fly into space. The sun is a hydrogen bomb!
The 5 big circles of latitude are the Arctic Circle, Tropic of Cancer, Equator, Tropic of Capricorn and the Antarctic Circle. The Tropic of Cancer runs off the southern tip of Florida. The Tropic of Capricorn runs through Australia. The area between the Tropics of Cancer and Capricorn is called "the tropics." The word comes from the Greek "tropos," meaning "turn," because the sun appears to turn and move in the other direction after being overhead at noon in these places. The apparent movement north and south by the sun during the course of a year is caused by the 23 1/2 degree tilt of the earth's axis.
The hottest days come after the first day of summer, and the coldest days come after the first day of winter because it takes time for the earth to heat up and cool down.
The earth rotates 1,000 miles an hour at the equator. It revolves around the sun 67,000 miles an hour. Rotation causes day and night. Revolution causes the seasons.
It is easy to see why the ancients thought the stars rose nightly in the east and set in the west. It is an illusion caused by our spinning planet. Stars "rise" 4 minutes earlier each night and "set" 4 minutes earlier as the earth orbits the sun.
70% of the earth is covered by water. The 4 oceans are: Atlantic, Pacific, Indian and Arctic. 10% of the land is covered by ice.
Life began in the oceans, and our bodies are 75% water. We need it to survive. Plants came onto the land 400 million years ago. They give off oxygen, making animal life possible.
The Perseids are the most reliable meteors. Other important showers are the Leonids and the Geminids. The Leonids have been known to be spectacular. They peak November 17/18. The "id" suffix means "from."
The Leonids of 1833 are legendary. An estimated 100,000 meteors fell per hour. This was a meteor storm. The superstitious believed it was the end of the world.
Bright meteors leave trails. Objects as small as apple seeds flare up because their temperatures reach 4,000 degrees. Being seen against dark skies exaggerates their brightness. Meteors coming straight at us appear as stationary bursts of light.
PERSEID METEOR SHOWER
I became aware of the Perseid meteor shower in 1961. In 1964, the Perseids were spectacular. I counted 351 meteors the night of August 11 and morning of August 12. Many were fireballs, leaving trails. I always dreamed that one day I would experience another shower like that. Most years it was either cloudy or the moon was up. I counted over a hundred meteors from my front yard in Lebanon, Tennessee, in 1978. As the years went on, the problem became one of getting away from lights, finding skies dark enough to make the effort worthwhile.
Meteors are 50 to 100 miles up. They are no larger than grains of sand. They enter our atmosphere at 40 miles per second. Nearly all are vaporized. The radiant for the Perseids is near the top of Perseus' head.
Crescent shapes are common in the universe. The moon appears as a crescent when it is closer to the sun than we are. A 2-day-old crescent is easy to spot. Crescent moons younger than 14 hours are invisible. Thin crescents are illuminated by an almost full earth. Earthshine dims as the moon waxes.
I do not see a man in the moon. I see a foot with three toes. The arch is the Sea of Tranquillity. The heel is the Sea of Serenity. The toes are the Seas of Crises, Fertility and Nectar.
June 18, 2008, I stood outside my apartment at the Village at Vanderbilt looking at the full moon through binoculars. What I noticed was the foot with three toes and how the dark lava contrasted with the brightness of the southern highlands. The maria are dark because the iron-rich lava reflects less sunlight.
I saw Tycho and the "Y" formed by craters Copernicus, Aristarchus, Kepler and Grimaldi.
The moon orbits from west to east, rising 50 minutes later each night. It is visible in the sky less than half the time.
A full moon rises in the east at sunset and sets in the west at sunrise. I recall a full moon rising above the orchard on Aiken Road. A full moon is the only phase that is seen all night.
The sun's rays hit a full moon directly. No shadows! Lunar features are best seen along the terminator at first and last quarters when there are shadows. The terminator is the line dividing day and night.
The moon was created when a Mars-like object impacted the earth in the early period of the solar system. Part of the earth was knocked out and eventually became the moon. The impact caused the earth to tilt 23 1/2 degrees on its axis. Earth's axis is an imaginary line running through the poles.
The moon is locked by Earth's gravity. It rotates once as it orbits the earth, keeping the same side toward us.
The dark areas on the the moon are solidified lava. Lava seeped from the moon's interior and covered the lowlands. The bright highlands are covered with craters.
That there are fewer maria on the moon's far side indicates that its crust is thicker. The crust on the near side was weakened by Earth's gravity. The Russians were the first to photograph the far side.
The ancients called the planets "wanderers" because they moved among the stars. They identified these wanderers with gods and goddesses. Jupiter was named after the king of the gods. Mars was named after the god of war. Venus was named after the goddess of love. The more observant noticed that the planets, sun and moon wandered inside a narrow band of constellations. That band was called the Zodiac (zoo) because it is comprised of animals.
Of course, the planets are not gods and goddesses. Nor are they simply lights in the sky. They are places, worlds, like and unlike our own. We still talk of planets being in constellations, knowing it is another illusion. When we say a planet is in a constellation, what we mean is that it is in the direction of that constellation. That the planets, sun and moon stay inside the Zodiac demonstrates the flatness of the solar system. Its parts move in the same plane.
From the Wal-Mart parking lot in Lebanon, I used binoculars to view an alignment of Mars, Saturn and Regulus near a 4-day-old moon. I observed the moon's terminator and earthshine, that ghostly light reflected from Earth to the moon and back to Earth. The drama took place in the constellation Leo after sunset. Mars, Saturn and Regulus lined up like Orion's belt to the right of the moon. This was the night of July 6, 2008.
My cousin got out his reflector, and we observed Mars, Jupiter, Saturn and the first quarter moon. We had a nice view of the moon's craters in the southern highlands. We saw central peaks. Mars and Saturn were in conjunction in Leo, two degrees apart. Saturn was the brightest, and we saw its rings. I recalled that Galileo described them as "handles." We saw three of Jupiter's Galilean moons. The fourth was either in front of or behind the planet. We located the summer triangle, and I mentioned how massive Deneb is. Its absolute brightness is the greatest of all first magnitude stars.
Mercury circles the sun in 88 days, flitting back and forth from the western sky at sunset to the eastern sky at dawn.
Venus is the evening star for 9 months and the morning star for 9 months.
Venus transited the sun on June 5, 2012, appearing as a black dot moving across the sun's disk.
Mars circles the sun in 697 days, less than two Earth years. It is closest to us when it is at opposition, on the opposite side of us from the sun.
The Curiosity rover landed on Mars in August, 2012. The public will not become excited until a man walks on Mars or fossils are found.
Jupiter is made of hydrogen and helium. It has no surface. When we view Jupiter, we are looking at the tops of clouds. Jupiter's rapid rotation has stretched these clouds into parallel bands. The dark bands are called belts. The light bands are called zones.
The Great Red Spot is shrinking. It is a storm, and all storms eventually play out. The Red Spot has the characteristics of a hurricane, strong winds and circular motion. It has lasted because there is no land to slow it down.
Jupiter circles the Zodiac in 12 years. In June, 2008, Jupiter was in Sagittarius at -2.7 magnitude.
Saturn is also made of hydrogen and helium. Yellow and gold bands comprise its atmosphere. The Hubble Space Telescope imaged Saturn's northern and southern lights. Titan is Saturn's best known moon and the second largest in the solar system after Ganymede.
Saturn takes 29 years to circle the sun. Its rings are best seen near opposition.
Uranus circles the sun in 84 years. It is in Aquarius.
William Herschel named Uranus' moons after Shakespeare's characters. Oberon, Titania and Puck are from A Midsummer Night's Dream. Prospero and his daughter Miranda, Ferdinand, Ariel and Caliban are from The Tempest. Juliet, Ophelia, and Desdemona are three tragic females.
Neptune circles the sky in 146 years. It is in Capricornus. We seldom hear of Johann Gottfried Galle, the German who discovered Neptune.
Pluto takes 248 years to circle the sun. It will be in Sagittarius until 2024. Like Uranus, Pluto rotates on its side.
I defended Pluto for a while. Now, I think it is a Kuiper Belt Object. That Pluto crosses Neptune's orbit casts suspicion on its status as a planet. Clyde Tombaugh discovered Pluto in 1930.
Pluto is the last planet to be explored. New Horizons arrived in 2015. That Pluto has 5 companions supports the idea that it might be a planet. Pluto was the god of the underworld. Charon ferried the dead across the river Styx. Nix was the goddess of night. Hydra was a monster.
Stars "rise" four minutes earlier each night because the earth revolves around the sun. After a year, the stars are back where they were.
Changes in longitude do not affect how we see the sky. Changes in latitude affect it dramatically. Flying from Sydney to Santiago, the sky looks the same. Flying from Sydney to Reykjavik, there are big changes.
If we were at the equator, we would see all the stars in a year. If we were at the North Pole, Polaris would be overhead and we would only see the stars in the sky's northern half. They would circle us, neither rising nor setting. At the South Pole, we would see only the south circumpolar stars. If the earth were transparent, we would see all the stars in all directions.
There are 88 constellations, the number of keys on a piano. Western civilization inherited the constellations from the Greeks and Romans. Some look like what they are supposed to. Others do not. The Big Dipper looks like a dipper. As part of Ursa Major, it is circumpolar, meaning that it is close enough to the north celestial pole to neither rise nor set at mid-northern latitudes. It is seen all night. The Dipper is an asterism, a well-known group of stars that is not a constellation. Orion's Belt and the Summer Triangle are asterisms.
Constellations are not real. They are imaginary star patterns created by farmers, shepherds and poets. Farmers relied on the stars to know when to plant and harvest crops. Shepherds watched the night sky as they tended their flocks. Poets invented stories about gods and heroes that have passed through generations. The Greeks gave us the 48 classical constellations. 40 more were added by Europeans during the age of exploration. Frenchman Nicolas de Lacaille created 17 while in South Africa. The International Astronomical Union divided the entire sky into 88 sections, adhering to classical boundaries. Every object in the sky is part of a constellation.
The end stars in the bowl of the Big Dipper point to Polaris, the North Star. Polaris is inching closer to true north, the point directly above Earth's axis. Polaris was not always the north star and will not always be. Thuban was the north star 4,500 years ago. 13,000 years in the future, it will be Vega. Precession of the equinoxes causes the shift. Over 26,000 years, the earth wobbles like a top due to the moon's pull.
The constellation Draco winds between the dippers. Draco was the dragon killed by Hercules when he took the golden apples from the Garden of the Hesperides. The Hesperides were nymphs who tended the garden.
The story of Hercules is in the stars. We see the Nemean lion (Leo), vanquished by Hercules as one of his 12 labors. Hercules strangled the lion with his bare hands. The constellations in general depict man's conquest of the animal world.
The handle of the Big Dipper curves toward Arcturus. Orange Arcturus in Bootes the herdsman is the 4th brightest star. Bootes is accompanied by Canes Venatici, hunting dogs that chase the bears around the pole. The Whirlpool Galaxy (M51) is in Canes Venatici.
Spica is the first magnitude star in Virgo the virgin. Spica is found by extending the curve of the Dipper's handle through Arcturus. Spica is one of 4 bright stars occulted by the sun and moon because of their proximity to the ecliptic. Regulus, Antares and Aldebaran are the others.
Virgo is associated with the earth goddess Demeter and her daughter Persephone. When Persephone was abducted by Pluto and taken to the Underworld, Zeus brokered a deal whereby Persephone would spend summers with her mother and winters with her husband. This is how ancient Greeks explained the seasons.
The Virgo supercluster is called the Realm of the Galaxies. When we look in the direction of this supercluster, we look away from the plane of the Milky Way, out the top or bottom of our galaxy.
In Greek mythology, the Pleiades were seven sisters. Orion the hunter chased them across the sky. When Orion bonded with Apollo's sister, Artemis, Apollo got jealous and sent a scorpion to kill Orion. Therefore, Orion and Scorpius are never in the sky at the same time, at least not in the Northern Hemisphere. I saw them together while in Australia.
Some people see 7 Pleiades. Others see 6. One story names Merope as the Lost Pleiad. She married a mortal and hides herself in shame. The Pleiades are in Taurus and ride the bull. Star lore is fascinating even though it is about man's imagination rather than science.
The Hyades, an open cluster in Taurus, were half-sisters of the Pleiades. This V-shaped star cluster near Aldebaran is actually far beyond it.
Auriga the charioteer carries a goat and two kids (small goats). Capella is the 6th brightest star.
Scorpius is a constellation that looks like what it is supposed to be. From my parents' front yard, I watched it crawl silently across the sky, moving low on the horizon. First magnitude Antares is like Betelgeuse in that it is a red giant. They are near death.
Libra the scales is the only non-living constellation in the Zodiac. It was once thought to be the scorpion's claws.
Sagittarius the archer killed the scorpion to avenge Orion. Sagittarius looks like a teapot. Star clouds resembling steam rise from its spout. The Trifid Nebula is in Sagittarius. Dust lanes divide it into three lobes. The star inside causes hydrogen to glow.
The Orion Nebula (M42) is a stellar nursery like the Pleiades. Stars are forming from gas and dust. The Horsehead Nebula is in Orion below Alnitak, the first star in the belt. The Horsehead is a dark nebula. We see it in silhouette because Alnitak lights up the gas behind.
Constellations fit together to create scenes. Canis Major and Minor, Orion's dogs, chase Lepus the hare. Sirius is the brightest star because it is close, 9 light-years away. Sirius is blue and shines at -1.44 magnitude. Blue stars are young and hot. Canopus, the second brightest star, is dimmer than Sirius because it is further away.
Vega, Deneb and Altair form the Summer Triangle. Vega is in Lyra, the the only musical instrument in the sky. Orpheus played this lyre to save the Argonauts from the sirens. The Ring Nebula (M57) is a "planetary nebula." It would be better if planetary nebulas were simply called "dying stars."
Cygnus the swan flies overhead in summer. The Cygnus star cloud is a bright region of the Milky Way. The Greeks saw Cygnus as Zeus in the form of a swan. He seduced Leda, causing her to lay eggs from which Castor and Pollux were hatched. These twins sailed with Jason and the Argonauts in their quest for the Golden Fleece. Deneb is 2,600 light-years away and 60,000 times more luminous than the sun.
The constellations Aquila and Aquarius are related. Aquarius is Ganymede the water carrier. Zeus sent his eagle to fetch Ganymede because he wanted him as his cup-bearer. Ganymede brings water from the river Eridanus. First magnitude Achernar sits at the river's end.
Delphinus the dolphin, Pisces the fish and Capricornus the seagoat are in this watery part of the sky. The seagoat is Pan after he jumped in the river. Part of him got wet, and that part changed into a fish. Organizing stars into pictures that tell stories makes them easier to remember.
That Greek myths survived the Scientific Revolution is a testimony to the fertile imaginations of those ancient people. The word "myth" comes from the Greek "mythos," meaning story. There are creation myths telling how the world began, explanation myths that attempt to explain nature, and quest myths, stories of heroes and their adventures.
Magnitude measures the brightness of stars. There are 21 first magnitude stars. Four have minus magnitudes: Sirius -1.44, Canopus -0.62, Alpha Centauri -0.27 and Arcturus -0.05. Those with minus magnitudes are referred to as first magnitude. The higher the magnitude, the dimmer the star.
21 First Magnitude Stars
..1 Sirius ---------------- Canis Major
..2 Canopus ----------- Carina
..3 Alpha Centauri --- Centaurus
..4 Arcturus ------------ Bootes
..5 Vega ---------------- Lyra
..6 Capella ------------ Auriga
..7 Rigel ---------------- Orion
..8 Procyon ------------ Canis Minor
..9 Achernar ----------- Eridanus
10 Betelgeuse -------- Orion
11 Hadar --------------- Centaurus
12 Altair ---------------- Aquila
13 Acrux ---------------- Crux
14 Aldebaran --------- Taurus
15 Spica --------------- Virgo
16 Antares ------------ Scorpius
17 Pollux --------------- Gemini
18 Fomalhaut --------- Piscis Austrinus
19 Becrux -------------- Crux
20 Deneb -------------- Cygnus
21 Regulus ------------ Leo
1 Sirius fascinates Fred Schaaf. He claims to have seen it through his bedroom window at age six. I was 16 when I spotted it rising above the woods across the road from where we lived. Schaaf revels in Sirius' hues as its light passes through our atmosphere.
2 I saw Canopus from Australia. It is in Carina the keel, which was part of Argo Navis, the ship on which the Argonauts sailed. Modern astronomers split the constellation.
3 The Alpha Centauri system contains the closest star at 4.4 light-years, 25 trillion miles. Alpha Centauri A is like our sun.
4 Arcturus hovered above my parents' back yard, where we played horseshoes and croquet. Arcturus has burned its hydrogen and is now burning helium. It is 37 light-years away.
5 Vega is a blue-white sapphire dominating the Summer Triangle. There is evidence that it has a Jupiter-like planet.
6 Like so many stars, Capella turns out to be a double.
7 In Norse mythology Rigel was a big toe of the giant Orwandil. When his other big toe became frost-bitten, Thor broke it off and threw it into the northern sky as Alcor.
8 Star pronunciation varies. Procyon is pronounced pro-SY-on.
9 Achernar is the least famous of the first magnitude stars. In Australia, I pointed to it and asked a fellow stargazer what it was. He said, "That's Achernar!" The moment stayed with me. Achernar is isolated at the river's end.
10 Red giant Betelgeuse in Orion is the most famous star. If it were in the sun's place, it would reach beyond Mars.
11 Hadar is a name for Beta Centauri.
12 Altair lies between two dimmer stars in the constellation Aquila. In the movie, Forbidden Planet, the action takes place on the 4th planet from Altair.
13 Acrux is Alpha Crucis in the Southern Cross.
14 Occultation is when an object hides another. Aldebaran is one of 4 first magnitude stars that can be occulted by the sun and moon. Aldebaran is the bull's-eye in Taurus. It is converting helium into carbon.
15 Virgo is drawn with wheat in her left hand. Spica means "ear of wheat."
16 Antares in the scorpion is another first magnitude star that can be occulted. It was during an occultation that its companion was discovered. Antares is like Altair in that it is flanked by two stars.
17 Castor and Pollux were famous twins in mythology and the bright stars in Gemini. Pollux is first magnitude. Astronomers think it has a Jupiter-like planet.
18 I practiced the pronunciation of Fomalhaut. It is fom-a-lawt. The h is silent. Fomalhaut is the mouth of the southern fish and believed to have at least one planet.
19 Becrux is Beta Crucis. It is called Mimosa. It lies near the dark nebula known as the Coalsack.
20 Medieval Arabs named the stars. "Deneb" means "tail," and Deneb is the tail of the swan.
21 Regulus is a flat star. Its equatorial diameter is greater than its polar diameter. Rapid rotation caused it. Leo inspired the Sphinx.
My Messier Marathon took place, April 25, 2009, at Mark Manner's Spot Observatory, 50 miles west of Nashville off I-40. I anticipated this as a BSAS member. Fortunately, the sky was clear. Charles Messier was the 18th century comet hunter who numbered 110 fuzzy objects not to be mistaken for comets. Ironically, it is his throwaway list for which he is remembered.
It reminded me of Australia, walking out and seeing bright stars after being cooped up in the city. I even befriended a married couple. He went down the list of Messier objects with machine-like precision, locating targets in his big reflector. She worked at the Sudekum Planetarium in Nashville and spoke of the Kepler project and the search for exoplanets.
We sampled a cross-section of objects. It is unrealistic to try to see them all. After several open clusters, they start to look alike and even in late April, it gets chilly after midnight. The M numbers we saw could have been pulled out of a hat. It felt good to be under a dark sky.
M1 - The Crab Nebula in Taurus is the a supernova remnant. A star exploded, leaving expanding gas and a rotating pulsar.
M35 - This open cluster near Castor's toe in Gemini contains 200 stars.
M36 - Open cluster in Auriga. 60 stars appear as a fuzzy object in the reflector's field of view.
M37 - A dense open cluster in Auriga with a red giant in the middle. Open clusters are found along the plane of the Milky Way.
M38 - Another open cluster, this one in the central part of Auriga. Open clusters break up after a few million years because of gravitational influence from nearby stars.
M40 - Double star in Ursa Major.
M42 & M43 - M42 is the Orion Nebula and a favorite. It resembles a peacock. M43 is close.
M44 - The 200 stars of the Beehive cluster are sharp and bright. Also known as Praesepe (Latin for "manger"), the Beehive lies in the center of Cancer. In mythology, Hera sent this crab to attack Hercules.
M45 - This is the Pleiades, although we did not observe it through the telescope.
M65 & M66 - Two galaxies in Leo 35 million light-years away. M65 is edge-on. M66 dominates.
M67 - Open cluster in Cancer found by locating the Hydra's head. Colors indicate that these are mature stars: yellow, orange and red. The older a cluster is, the more red giants there are.
M81 & M82 - Two galaxies in Ursa Major. M81 is a spiral. M82 is disturbed. They are only 100,000 light-years apart, and each can be seen clearly from the other.
M95 & M96 - Two galaxies in Leo along the lion's belly. M95 is barred. M96 is a spiral.
M97 - Called the Owl Nebula because details were thought to resemble the eyes of an owl. It is a so-called "planetary nebula," a dying star giving off a shell of gas. It appears as a smudge in the middle of the eyepiece.
M105 - Elliptical galaxy in Leo.
M109 - Spiral galaxy in Ursa Major. Averted vision helps to spot this oval blur.
We saw spring constellations: Virgo and the diamond-shaped Corvus. Saturn was beneath Leo. Later on, Scorpius rose, and Vega came up. The party ended with Mark showing me his slides. He had taken a picture in Hawaii of the 1991 solar eclipse.
THE MILKY WAY
When I saw the Milky Way arching across the night sky as a teenager, I gave it little thought. It was a glowing band of light, nothing more. In my 30s I realized that the Milky Way is the galaxy in which our sun and planets reside. Our solar system lies on the edge of a spiral arm.
The Milky Way stretches from the northeast to the southwest in summer. It circles the sky, although part of it is never seen from the United States. I saw the southern piece from Australia. Light from the Milky Way is the combined glow of billions of stars thousands of light-years away. Our galaxy appears as it does because of its flat shape. It bulges in the center and tapers at the edges like a fried egg. Our solar system is located toward the outer rim. When we view the star clouds in Sagittarius, we look toward the Milky Way's center. Looking in the opposite direction, we look toward the rim. Perpendicular to the Milky Way, we look out the top or bottom of the galaxy, where stars are scarce. The Milky Way rotates. It spins once every 200,000 years, and one rotation is known as a "cosmic year." If I had known this as a teenager, I would have been a genius! It is revelation to look at the Milky Way and understand it.
Parts of the Milky Way are obscured by gas and dust. These are not holes. The Great Rift divides the stream from Cygnus toward Sagittarius. In summer, we look toward the center of the galaxy in the direction of Sagittarius. In winter, we look toward its outer rim in the direction of Orion.
Tracing the Milky Way around the summer sky, I first notice it in the direction of Perseus and Cassiopeia. From there, it flows to Cygnus. E. E. Barnard studied the Milky Way, and it was he who realized that the dark patches were clouds of gas and dust and not holes. The Great Rift starts at Deneb and extends almost to the Southern Cross. It divides one-third of the Milky Way into two apparent streams. Barnard's starry band flows on to Scutum, and he referred to the Scutum star cloud as "the gem of the Milky Way." It moves southward beyond Centaurus, coming close to the south celestial pole near Crux. I follow it past Canopus and between the dog stars, where it is less brilliant. I pass the feet of Gemini, and suddenly I am back to Perseus, where I first noticed the starry circle. Seen from afar, the Milky Way is a flat spiral with arms coiling around its central mass.
Astronomers have identified five spiral arms around the Milky Way. They are the Orion, Cygnus, Sagittarius, Perseus and Centaurus arms. Our solar system is located in the Orion arm.
Stars revolve around the galaxy but not in one piece. They move like the planets do around the sun. Stars near the hub of the galaxy move faster. Those toward the rim move slower.
The Hubble Space Telescope has added as much to our confusion as to our understanding. Hubble images illustrate the chaos of the universe and convey a feeling of being lost in space. The Pillars of Creation in the Eagle Nebula in Serpens provide some reference. Star formation goes on in these fingerlike spires of gas.
The Hubble Ultra Deep Field was the most pervasive photograph in astronomy until the eXtreme Deep Field. The HUDF imaged 10,000 galaxies and looked back 13 billion years to when the universe was 800 million years old. HUDF penetrated an area in the constellation Fornax 1/10 the size of a full moon. Astronomers compared it to "looking through an 8-foot-long soda straw."
The eXtreme Deep Field looked back even farther. We never see objects, but only the light reflected by objects. For that reason, we are forever looking back in time, whether it is a trillionth of a second when we glance at our thumb or millions of light years when we observe objects in space.
The universe was pure energy after the Big Bang. It was not long before much of it froze into matter. It may be that a wall of radiation keeps us from seeing the beginning. Even if we did see the Big Bang, what would it mean? We would still question. According to the New Testament, only when we are united with God through Jesus will there be true understanding.
Exoplanets have been the big thing since 1995. These are planets circling stars in other solar systems. 1780 are confirmed. They are found by indirect methods, not by telescopes or imaging. That most are gas giants like Jupiter is due to the limitations of current technology. There will turn out to be many terrestrial exoplanets.
Our immediate reaction is to think there must be other civilizations. And there may be! No one knows! Ours may be the only one, and the rest of the universe, regardless of its size, may be leftover material from God's creation of Earth.
Scientists believe that if matter is arranged in a certain way, there will be life. I am not sure. Life may be more than an arrangement of atoms and molecules. The Bible says it was created by a divine spark, the same spark that created the Big Bang. Without God, no universe and no life?
KEPLER SPACE TELESCOPE
The Kepler mission searched for Earth-like planets. Launched in 2009, it surveyed 100,000 stars. Of the exoplanets found, most are huge balls of gas resembling Jupiter. Kepler searched for small, rocky worlds. Scientists want planets in habitable zones capable of sustaining water.
It is hard to detect small planets orbiting stars at vast distances, and it is done by indirect means. Kepler recorded fluctuations in light as planets transited their star.
The New Horizons spacecraft was launched from Cape Canaveral in 2006. It reached Pluto in July, 2015, completing a three billion mile journey. New Horizons will study Pluto, then head toward the Kuiper Belt. It uses nuclear energy to generate electricity.
JAMES WEBB SPACE TELESCOPE
The James Webb Space Telescope is scheduled for launch in 2018. It will observe the most distant objects. It will penetrate gas and dust and gather data in the electromagnetic spectrum's infrared range.
James Webb led NASA in the years following Kennedy's moon speech.
1 Sigma Octanis
Sigma Octanis is the south pole star. It is one degree from the south celestial pole and dim at 5.4 magnitude. It is in the constellation Octans the octant. It barely moves as the southern stars revolve around it.
2 Magellanic Clouds
The Large and Small Magellanic Clouds are irregular galaxies. A supernova appeared in the LMC in 1987. The light came from a star that exploded 150,000 years ago.
3 Crux (Southern Cross)
Crux is the smallest constellation.
This dark nebula is a patch of gas and dust in the Milky Way. It is close to the Southern Cross.
5 Alpha Centauri
This is a triple star. Alpha Centauri A & B are about 4 light-years away and comparable to the sun.
Achernar is 9th on the list of brightest stars. It is flat. Rapid rotation caused it to flatten. Achernar means "river's end," and it lies at the end of the constellation Eridanus.
7 Jewel Box
The Jewel Box is an open cluster near the Southern Cross. The "jewels" are blue, orange and red. These stars formed from surrounding gas and dust.
8 Argo Navis
Nicolas de Lacaille divided Argo Navis into 3 constellations. Carina is the keel. Puppis is the stern. Vela is the sail.
9 Musca and Chamaeleon
I took a fancy to Musca the fly and Chamaeleon the chameleon. The chameleon is trying to eat the fly.
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