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Comet SWAN: October 30 - November 5, 2006.
The Moon has returned again to the night sky and what perfect timing. Be sure to give your visiting “trick or treat” monsters a view of the lunar surface. Or better yet? Comet SWAN! Mid-week also brings on the Taurid meteor shower along with plenty of history and other objects to explore. It's time to set sail on the wings of the night
Monday, October 30 - Tonight along the terminator west of the Caucasus Mountains, two craters - Aristillus and Autolycus - will stand out impressively. The larger and northernmost is Aristillus. If the sunlight is high enough, you may be able to see ridges in its thick walls or the Sun rising over its multiple center peaks. Watch in the days ahead as it gains a ray system. To the south is much smaller Autolycus. Its walls are not as impressive, but it, too, will gain a ray system.
Tuesday, October 31 - Happy Halloween! Many cultures around the world celebrate this day with a custom known as “Trick or Treat.” This evening instead of tricking your little ghouls and goblins, why not treat them to a view of the lunar surface? Tonight the Apennine Mountain Range will appear exceptionally beautiful, and if one of them asks you what that crater is that is caught on the Apennine southern tail? You can tell them it's Eratosthenes!
After the lovable little ghouls, goblins, ghosts, and witches cease their wanderings, let's have a look at our own “treat.” Tonight's astronomical adventure will be about exploring an ancient and well renowned star cluster associated with this holiday - the Pleiades! Easily found from a modestly dark site with the unaided eye, the Pleiades can be spotted well above the north-eastern horizon within a couple of hours of nightfall. Under average skies, many of the 7 bright components will resolve easily without the use of optical aid, but to Telescopes and binoculars? M45 is stunning...
First let's explore a bit of history. The recognition of the Pleiades dates back to antiquity and they're known by many names in many cultures. The Greeks and Romans referred to them as the “Starry Seven,” the “Net of Stars,” “The Seven Virgins,” “The Daughters of Pleione” and even “The Children of Atlas.” The Egyptians referred to them as “The stars of Athyr,” the Germans as “Siebengestiren” (the Seven Stars), the Russians as “Baba” after Baba Yaga, the witch who flew through the skies on her fiery broom. The Japanese call them “Subaru,” Norsemen saw them as packs of dogs and the Tongans as “Matarii” (the Little Eyes). American Indians viewed the Pleiades as seven maidens placed high upon a tower to protect them from the claws of giant bears, and even Tolkien immortalized the stargroup in The Hobbit as “Remmirath.” The Pleiades have even been mentioned in the Bible! So, you see, no matter where we look in our “starry” history, this cluster of seven bright stars has been part of it.
But let's have some Halloween fun!
The date of the Pleiades culmination (its highest point in the sky) has been celebrated through its rich history by being marked with various festivals and ancient rites - but there is one particular rite that really fits this occasion! What could be spookier on this date than to imagine a bunch of Druids celebrating the Pleiades' midnight “high” with Black Sabbath? This night of “unholy revelry” is still observed in the modern world as “All Hallows Eve” or more commonly as “Halloween.” Although the actual date of the Pleiades' midnight culmination is now on November 21 instead of October 31, why break with tradition?
Thanks to its nebulous regions M45 looks wonderfully like a “ghost” haunting the starry skies. Treat yourself and your loved ones to the “scariest” object in the night. Binoculars give an incredible view of the entire region, revealing far more stars than are visible with the naked eye. Small Telescopes at lowest power will enjoy M45's rich, icy-blue stars and fog-like nebulae. Larger Telescopes and higher power reveal many pairs of double stars buried within its silver folds. No matter what you chose, the Pleiades definitely rocks!
And what dark and creepy night would be complete without the sad tale of Andromeda and Perseus? Tonight let's have a look at Beta Persei - the most famous of all eclipsing variable stars. Now, identify Algol and we'll learn about the “Demon Star.”
Ancient history has given this star many names. Associated with the mythological figure Perseus, Beta was considered to be the head of Medusa the Gorgon, and was known to the Hebrews as Rosh ha Satan or “Satan's Head.” 17th century maps labeled Beta as Caput Larvae, or the “Spectre's Head,” but it is from the Arabic culture that the star was formally named. They knew it as Al Ra's al Ghul, or the “Demon's Head,” and we know it as Algol. Because these medieval Astronomers and astrologers associated Algol with danger and misfortune, we are led to believe that Beta's strange visual variable properties were noted throughout history.
Italian Astronomer Geminiano Montanari was the first to note that Algol occasionally “faded” and its methodical timing was cataloged by John Goodricke in 1782, who surmised that it was being partially eclipsed by a dark companion orbiting it. Thus was born the theory of the “eclipsing binary” and it was proved spectroscopically in 1889 by H. C. Vogel. At 93 light-years away, Algol is the nearest eclipsing binary of its kind and is treasured by the amateur astronomer, for it requires no special equipment to easily follow its stages. Normally Beta Persei holds a magnitude of 2.1, but approximately every three days it dims to magnitude 3.4 and gradually brightens again. The entire eclipse only lasts about 10 hours!
Although Algol is known to have two additional spectroscopic companions, the true beauty of watching this variable star is not telescopic - but visual. The constellation of Perseus is well placed this month for most observers and appears like a glittering chain of stars that lie between Cassiopeia and Andromeda. To help further assist you, locate Gamma Andromedae (Almach) east of Algol. Almach's visual brightness is about the same as Algol's at maximum.
Thanks for “haunting” the night with me....
Wednesday, November 1 - On this day in 1977, Charles Kowal made a wild discovery - Chiron. This was the first of a multitude of tiny, icy bodies found in the outer reaches of the solar system. Be on the lookout as the Moon will occult another solar system body tonight - Uranus. Be sure to check IOTA for times and locales.
Tonight one of the most impressive of all lunar features will emerge to the south - crater Clavius. Within Clavius you will see a near-spiraling curve of progressively smaller craters beginning with Rutherford breaking the southeast wall. Steady seeing and high power will go on to reveal numerous smaller craters populating its broad floor. Be sure to check out crater Porter to the northeast echoing Rutherford. After delighting in Clavius' extraordinary interior detail, use it to locate other interesting features. Between its southwest wall and the terminator lies another major (but smaller) mountain-walled plain known as Blancanus, which may be deeply shadowed. Return to Clavius and head about the crater's width northwest for pentagonal Longomontanus.
Thursday, November 2 - Today celebrates the birth of an astronomy legend - Harlow Shaply. Born in 1885, Shaply paved the way in determining the distances to stars, clusters, and the center of our Milky Way galaxy. Among his many achievements, Shaply directed the Harvard College Observatory. Today in 1917 “first light” was captured by the Mt. Wilson 100″ Hooker reflector.
Although we don't have that much aperture to study with tonight, we can still get a very satisfactory look at the lunar surface. Through binoculars head north and look for old favorite, Sinus Iridum. Around central, follow the emergence of sharply-etched Copernicus. Those with Telescopes should attempt to locate the similarly sized “ghost crater” Stadius to the east.
Now let's turn those binoculars towards a pair of intriguing asterisms of 5th and 6th magnitude stars located near Ursa Minor - the Little Dipper. The first is a large group of four bright stars with a slightly fainter member in its midst. You'll find the “Butterfly Asterism” about a fist width south-southeast of Gamma Ursae Minoris towards Eta and Zeta Draconis. Now let's try for the slightly smaller “Box and One Asterism” - a group of four primarily 6th magnitude stars taking the form of a parallelogram less than two finger-widths east of Zeta Ursae Minoris.
What's in the box? That awaits a darker night and far more aperture...
Friday, November 3 - On this day in 1955 one of the few documented cases of a person struck by a falling meteorite occurred. What are the odds on that?
In 1957, the Russian Space Program launched its first “live” Astronaut into space - Laika. Carried aboard Sputnik 2, our canine hero was the first living creature to reach orbit. Sputnik 2 was designed with sensors to transmit ambient pressure, breathing patterns and heartbeat of its passenger, and carried a television camera. The craft also monitored ultraviolet and x-ray radiation to further study the impact of space flight on human occupants. Unfortunately, the technology of the time offered no way to return Laika to Earth, so she perished in space. On April 14, 1958, Laika and Sputnik 2 returned to Earth in a fiery re-entry after 2,570 orbits.
The Moon will be closest to the Earth tonight, so let's revisit crater Copernicus and put some power its way. Through steady skies, high magnification easily brings out its central mountain peaks, but look closely at that east wall. Can you resolve the small A crater lodged within it? The shock region around Copernicus' exterior is equally fascinating with its runneled appearance. At the limits of this these ramparts, you'll see the double impact of tiny crater Fauth to the south, and Gay-Lussac to the north. If conditions are good you might also spot the Gay-Lussac Rima running diagonally southwest to northeast tangential to Copernicus. About a Copernicus-width southwest look for impressive, but smaller impact crater Reinhold. Now let's walk...
To the southeast of Reinhold, you will spot very similar crater Lansberg. At this crater's southern boundary will begin a series of low ridges which may be the remains of extinct crater walls. Almost directly in the center of these is the landing area for the Luna 5 mission. If you continue southeast about the same distance into the smooth sands of Mare Insularum, you'll be in the landing area for Surveyor 3 and Apollo 12.
Since we've got the scope out, let's revisit M57. To the southwest is an asterism of six stars called “The Chalice of the Ring.” The faintest of these stars is magnitude 12.3. Power up to darken the sky as much as possible. To aid in identifying this asterism, most eyepieces at 200X will feature M57 in the middle of the field and leave the stem of the “Chalice” visible at its farthest extent to the southwest.
Saturday, November 4 - This morning will be the peak of the Southern Taurid meteor shower. Historically noted around the world for producing fireballs, the Taurids are best seen in the early morning hours as the Moon heads far west. The radiant for this shower lies near Aldebaran, but did you know the Taurids come in two streams?
It is believed the parent Comet shattered while passing the Sun 20,000 to 30,000 years ago. The larger “chunk” is now known as periodic Comet Encke. The remaining debris turned into a few very small asteroids, and many meteoroids. The larger meteors pass through the atmosphere creating astounding “fireballs” known as bolides. Although the fall rate for this particular shower is rather low at 7 per hour, these slow travelling meteors (27 km per second) are usually very bright and appear to almost “trundle” across the sky. With chances of seeing a bolide high all week, be sure to get out early and often!
Tonight the Moon will play havoc with the skies almost all night, but it can't stop us from seeing double! Binoculars should have a look at 3.8 magnitude Algedi (Alpha Capricorni) and its widely-spaced 4th magnitude companion. Both stars are solar spectral types (G stars) - but that's where their resemblance to our Sun ends. These two are yellow giants...and a rare alignment of two bright stars, for they are not a true binary. Alpha 1 is 690 light-years distant while Alpha 2 is six times closer.
If you brought your scope out tonight, challenge yourself to Pi Capricorni. Look for an 8.5 magnitude companion 3.2 arc seconds southeast. Pi is the more southerly of two stars south of Alpha.
Sunday, November 5 - It's officially full moon once again. Native American legend refers to this as the Full Beaver Moon. Because the northern climate is now getting colder, it became the time to set beaver traps before swamps froze - leaving trappers a supply of warm furs to survive the winter months. Some also believe that the Beaver Moon may have been so named for the beavers themselves, who ready their homes for coming cold. No wonder this is also called the Frosty Moon as well!
And frosty is just how the Moon will appear to binoculars or telescopes. Look at both the west and eastern limbs. Is the Moon truly “Full” tonight, or can you still see a bit of the terminator?
Tonight let's look to a very “cool” star - Enif. Magnitude 2.5 Epsilon Pegasi has a photospheric temperature of 4500 K, and is a class K supergiant around 700 light-years distant. Its total luminosity is nearly 7000 times that of our Sun. Enif's “surface” has a diameter of 150 million miles - a size which would leave the orbit of planet Earth only 18 million miles above a sea of orange flame! Assuming that such a planet could exist with a moon, nothing ever resembling an eclipse could occur. That Moon would “transit” across Enif's ruddy face taking three and half days to complete a single pass. Imagine sunsets and sunrises lasting more than 3 hours!
Until next week? May all your journeys be a light speed... Tammy Plotner with Jeff Barbour
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