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SkiesIdaho
Skies
November 2007
Vol. 4 No. 10
Idaho Skies is a column for beginning amateur astronomers and those interested in astronomy. Suggestions about the column are gladly accepted by the columnist, at paul.verhage@boiseschools.org
At the beginning of the month, look to the south at 8:00 PM to see the Solitary Star, Fomalhaut (pronounced, fo-ma-low). It’s the brightest star south of Pegasus (the 17th brightest star overall) and close to the southern horizon. Fomalhaut is Arabic for Mouth of the Fish and it’s the lucida of the constellation of Piscis Austrinus, the Southern Fish (a faint constellation). Fomalhaut is 16 times brighter than the sun and a lot like Vega in Lyra (which appears a bit brighter than Fomalhaut but it’s the same distance away). If you were born in 1982, then Fomalhaut is your birthday star this year, because the light you see left the star 25 years ago. Fomalhaut emits excess infrared radiation compared to other stars of its type. This extra infrared radiation indicates the presence of a cool disk of dust and gas in orbit around it. Images from the Hubble Space Telescope show a hollow in the center of the disk, possibly hollowed out by a Neptune-sized planet. This doughnut of dust and gas leads astronomers to believe Fomalhaut is forming a solar system.
On the morning of the 1st, the moon leads the way to the Beehive star cluster. Before leaving for work, you’ll find the Beehive 3-1/2 degrees below the moon (or seven lunar diameters). That’s close enough to see both at the same time through a pair of binoculars. If you place the moon at the top of the binoculars field of view, then the sprinkle of stars in the Beehive is in the binoculars center. For your best view of the cluster, move the moon completely out of the binocular’s field of view.
While you’re looking at the Beehive, the moon is at the last quarter phase.
Ninety years ago on the 2nd, the 100 inch telescope on Mt. Wilson saw its first star light. Until 1948, the 100 inch telescope was the world’s largest telescope. In 1907, it appeared that the stars uniformly filled the universe. However, photographs taken through the 100 inch telescope showed that some fuzzy nebulae were really pancake-shaped collections of billions of stars rotating about their center. That discovery marks the recognition of galaxies, or island universes as some astronomers called them. The 100 inch telescope on Mount Wilson led to the discovery that shape can classify galaxies. Some galaxies are shaped like a Frisbee, some like a spherical swarm of bees, and others are irregularly shaped. Later studies through the 100 inch showed that older stars of Frisbee-shaped galaxies reside within their spherical core and younger ones reside within their outer flattened disk. So not only did astronomers learn that stars come in galaxies of different shapes, but also that the stars segregate into two distinct classes based on their age. Finally, through the 100 inch telescope, astronomers discovered that the galaxies were receding from each other, or that the universe was expanding.
Since the telescope is located above Los Angeles, its night time sky is too bright for serious astronomical observations. So instead of serious scientific research, today the 100 inch telescope educates the public about astronomy and its history. However, the two solar telescopes located next to it are still taking daily measurements. You can visit Mt. Wilson from 10:00 AM to 4:00 PM from April to November. There’s a museum and picnic tables on site. You can learn more at its website, www.mtwilson.edu.
On the morning of the 3rd, between 4:45 AM and 5:15 AM, (3:45 for Oregon and 5:45 for the Midwest) the moon slips just below the lucida of Leo, Regulus. This will be a close call for Boise, but if you head south, you’ll see the moon cover Regulus. Get your binoculars out, as this will be nice.
The 3rd marks the 50th anniversary of the first animal launched into earth orbit. Flush with the success of Sputnik 1, Nikita Khrushchev asked the Soviet Union’s Chief Space Craft Designer, Korolev, to create another space spectacular in time for the Russian Revolution anniversary. This gave the Korolev crew less than 30 days to pull it off. Since their booster rocket was powerful enough to launch a satellite heavier than Sputnik 1, they took a copy of Sputnik 1 and attached it to a canister used to carry dogs on suborbital rides into the atmosphere. The dog they selected was a stray from the streets of Moscow. Laika, which means Barker, rode Sputnik 2 into space on November 3, 1957. Shortly after reaching orbit, it became apparent that the insulation for her spacecraft had failed as temperatures inside her capsule began to rise. The Soviets didn’t mention it, but Laika died a few hours after launch from heat and stress. Her flight did show however, that organisms could survive in space, if flown in a well-designed spacecraft.
Sputnik 2 was cone shaped, 13 feet tall and 6 feet wide at the base. At its tip was a radio transmitter housed inside a sphere identical to Sputnik 1. At its base was Laika’s canister. Laika’s orbit was 132 miles at its closest to earth and 1,031 miles at its greatest. The total weight of Sputnik 2 was 1,117 pounds, or six times greater than Sputnik 1. Sputnik 2 decayed from orbit and reentered the atmosphere 162 days after launch.
Daylight savings ends on the morning of the 4th, so set your clocks back one hour before going to bed on the night of the 3rd. Enjoy your extra hour of sleep.
The thin crescent moon rises next to Venus on the morning of the 5th. This is a nice photographic opportunity if you have a camera with a telephoto lens. Keep the camera steady during its exposure by mounting it to a tripod and using a cable release.
NASA launched its second to last Surveyor 40 years ago on the 7th. Surveyor 6’s target was the center of the moon, in a bay called Sinus Medii, or Central Bay. The 660 pound spacecraft safely landed on November 10, 1967. One week after landing, JPL commanded Surveyor 6 to fire its small attitude engines for a few seconds. In response, Surveyor 6 lifted around 12 feet above the lunar surface and set back down about 10 feet away. That was the first powered ascent from another celestial body. After the two week lunar night, earth made contact with Surveyor 6 and found that the cold lunar night had damaged the lander. JPL could interpret none of the data from Surveyor 6. Surveyor 6 returned nearly 30,000 images of the lunar surface and confirmed that the surface consisted of basalt, or lava rock.
Mercury is at its greatest western elongation on the morning of the 8th. This means the innermost planet is as far away from the sun as it’s going to get this month. To see this elusive planet, go outside around 6:30 AM. Mercury will be the brightest star very low to the horizon. Mercury is only about one quarter as high above the horizon as Venus and is located to the lower left of the brighter Morning Star.
The moon is at apogee and new on the 9th. This means the moon is at its farthest from the earth and located in the direction of the sun. The moon’s greatest distance this month is 252,693 miles
435 years ago on the 11th, Danish astronomer Tycho Brahe discovered a new, and very bright, star in Cassiopeia. Brahe, born Tyge Ottesen Brahe, on December 14, 1546, caught sight of what astronomers today call SN1572 on November 11, 1572. Since new objects were not supposed to appear in the heavens, most people believed the nova was an atmospheric event. However, Brahe’s observations indicated that the new star did not shift positions from night to night. Therefore he concluded that the new star was indeed just that, a new star. The appearance of the nova convinced Tycho to go into astronomy. Tycho used his wealth, along with financial help from the king of Denmark and Norway, to build the most capable observatory of his time, Uraniborg. Tycho’s careful measurements of star and planet positions (all done before the invention of the telescope) became the raw data that his later assistant, Johannes Kepler, needed to prove that the planets, including the Earth, orbited around the sun (in what astronomers call the heliocentric model). Brahe died October 24, 1601 after a short illness.
It will be difficult to see, but on the evening of the 12th, the moon is to the lower left of Jupiter. Binoculars will make it easier to see this event. Look very low in the southwest at 6:00 PM. Located about one binocular field of view above the horizon is Jupiter. In the same field of view and to the lower left of Jupiter is the thin crescent moon.
On November 13th, the Rosetta spacecraft makes its second flyby of Earth. Rosetta is a European Space Agency (ESA) deep space mission launched. Its destination is the comet 67P/Churyumov-Gerasimenko. The Rosetta spacecraft, named after the Rosetta stone that taught the western world to ready Egyptian hieroglyphics, weighs three tons and is roughly the size of a compact car. That is, a compact car with solar panels 105 feet across. Launched three years ago, Rosetta will rendezvous with, and orbit, comet 67P/Churyumov-Gerasimenko in May 2014. Once there it will spend 18 months studying the composition and behavior of this comet with its suite of 11 instruments. Rosetta carries a second spacecraft named Philae and it will attempt the first landing on the surface of a comet. On its way to its target, Rosetta will fly passed two asteroids, 2867 Steins in September 2008 and 21 Lutetia in July 2010.
The moon is at first quarter on the 17th. If it’s not too cold, grab a pair of binoculars and go moon watching.
The Leonid meteor shower peaks on the night of the 17th and morning of the 18th. Expect to see only 10 meteors per hour from this shower. The moon will set around 1:00 AM, so moonlight will not interfere significantly with the shower. Look for fast meteors streaking out of the east after midnight. Since there are other active showers this night, you’ll see more than 10 meteors per hour. As a comparison, on nights with no active meteor showers, you can expect to see an average of 7 meteors per hour.
Here’s an opportunity to see the planet Uranus in your binoculars. At 10:00 PM (9:00 for Oregon and 10:00 for the Midwest) on the 18th, Uranus is located half a binocular field of view to the moon’s upper left. Half a binocular field of view is 3 degrees, or 6 times the moon’s diameter. If you put the moon in the lower right of your field of view, then Uranus will be near the center. Look for the kite-shaped pattern of stars shown below.
The moon reaches perigee, or its smallest distance from earth on the 23rd. This month, perigee has a distance of 221,950 miles. That’s roughly 74 times across the United States. Since the moon is full tomorrow, those living near the coast can expect to see greater than average tides.
On the evening of the 23rd, the nearly full moon is 3-1/2 degrees west from the Pleiades. As the night grows older, the moon moves closer to this star cluster. So by 4:30 AM on the 24th, you’ll see the moon begin to cross the northern portion of the Pleiades.
The moon is full on the 24th. Many people call the full moon in November the Frost Moon
That orange star you see to the moon’s right on the evening of the 26th is the planet Mars. The moon and Mars together should make a nice photographic and binocular object. If you plan to take a photograph of this alignment, then use a telephoto lens, tripod, and cable release.
The moon is our guide to the Beehive star cluster a second time this month just after midnight on the 29th (that’s very early morning on the 29th). Though binoculars, you’ll see the star cluster 2-1/2 degrees to moon’s upper right. The stars in the cluster span an area larger than the moon.
Regulus is three degrees to the left of the moon on the morning of the 30th. Saturn forms a straight line with them, but is 8 degrees further away.
This Month’s Topic
The ringed world has at least sixty natural satellites, or moons. However, when I was young, only nine were known. The first Saturnian satellite discovered was Titan, in 1655 by Christiaan Huygens. By the end of the 17th century, astronomers discovered four additional satellites. Today the American spacecraft Cassini is in orbit around Saturn. In the first three years of its mission, it has flown pass several of these satellites. The discoveries of Cassini have transformed our knowledge about them.
Titan
Titan is the second largest satellite in the solar system and 50% larger than our moon. So picture an orange orb 1-1/2 times larger than our moon in the sky. Titan is the only satellite with a substantial atmosphere. That atmosphere makes liquids stable on its surface. On any other satellite in the solar system, liquids would evaporate into the vacuum of space. But the liquid on Titan isn’t water. Instead, the satellite has lakes of liquid methane and ethane. Water is frozen solid on Titan and as hard as rock on earth. Titan has clouds like Earth, but they’re clouds of methane. On Titan, methane behaves like water on earth. So it rains liquid methane on Titan. The methane rain flows across the satellite’s surface eroding away the icy ground. As a consequence, the surface of Titan contains land forms familiar to us on earth, including sand dunes, hills, and river beds. With its thick cloud cover, Titan is impossible to see from orbit. Radar and infrared images from Cassini and images from the Huygens lander are our only means to see the surface of this satellite.
Enceladus
Enceladus is a 300 mile wide satellite. In the early 1980s, the Voyager spacecraft discovered that Enceladus is smooth in many regions and very bright. The processes responsible for covering up old craters and keeping the surface covered in clean ice were unknown until the Cassini mission. Early images from Cassini showed “Tiger Stripes” near the southern pole of the satellite. The stripes covered the southern region of the satellite and were warm compared to the rest of Enceladus. A small satellite like Enceladus should be cold due to the loss of heat from its formation. Therefore, the warmth of the stripes puzzled scientists. Equally puzzling was the detection of a cloud of water ice around the south pole of Enceladus. Long exposure images later showed plumes of water ice rising from around Enceladus’ Tiger Strips. The ice is responsible for coating the satellite and burying some of its old cratered terrain. Some of the ice escapes the weak gravity of Enceladus to fill Saturn’s E Ring. The energy source creating the warm cracks in Enceladus’ surface and expelling water appears to come from orbital resonances between Saturn and other satellites. As the satellites move past Enceladus, their gravity tugs on the satellite’s surface, causing cracks that rub back and forth. Friction from the rubbing ice warms the ice and ejects water into space.
Hyperion
Now here’s a strange little satellite. Large satellites are spherical, due to their gravity. Hyperion is the largest irregular shaped satellite, or non-spherical satellite. It measures 224 miles across its largest dimension and 140 miles across its smallest dimension. Hyperion looks a lot like a sponge, with its deep and strangely shaped craters. The unusual shape of this satellite may be due to it being porous. Perhaps as much as 40% of its interior is open space. So when meteoroids impact its surface, the satellite may dent like Styrofoam. In addition to its strange shape and strange craters, Hyperion rotates strangely. The satellite tumbles chaotically, as opposed to having a single rotational axis like the other satellites. This means there is no fixed days and nights on Hyperion. Sunrise and sunset come at unpredictable times.
Iapetus
Iapetus is one of the early discovered satellites. When he looked through his telescope, Cassini discovered he could see the satellite on one side of Saturn but not on the other. Cassini reasoned that the satellite is two toned. One side, the leading side, was as dark as charcoal and the trialing side was as bright as freshly fallen snow. In bright craters, a dark filling is present in their bottoms. Something, perhaps surface material from the satellite Phoebe, has coated the surface of Iapetus.
Iapetus has another strange feature, a mountain range seven miles tall straddling its equator. The presence of the equator leads researchers to believe Iapetus rotated very fast after its birth. Its rapid rotation rate flattened it poles and widened its equator. Later the satellite froze and contracted. The contraction raised the equatorial ridge we see on its equator today and gives Iapetus its distinctive walnut shape. Iapetus is 928 miles wide and 884 miles from pole to pole.
Observer’s Handbook 2007, The Royal Astronomical Society of Canada
Space Calendar, Baalke, Ron, <www.jpl.nasa.gov/calendar/>
Night Sky Explorer (software)
Stars, Kaler, James, <www.astro.uiuc.edu/~kaler/sow/>
Leonids, 30 august 2007, <http://meteorshowersonline.com/leonids.html>
Mount Wilson, 30 August 2007, <http://www.mtwilson.edu/>
Sputnik 2, 17 August 2007, 30 August 2007, <http://en.wikipedia.org/wiki/Sputnik_2>
http://www.seds.org/~spider/spider/Vars/sn1572.html
Tycho Brahe, 23 September 2007, 24 September 2007, <http://en.wikipedia.org/wiki/Tycho_Brahe>
Surveyor 6, 7 May 2007, 30 September 2007, <http://nssdc.gsfc.nasa.gov/nmc/tmp/1967-112A.html>
Rosetta, 30 August 2007, <http://rosetta.esa.int/science-e/www/area/index.cfm?fareaid=13>
Dark Skies and Bright Stars,
Your Interstellar Guide