What’s Up this Week: November 13 – November 19, 2006

Greetings, fellow SkyWatchers! Here’s the week you’ve been waiting for… It’s almost time for the annual Leonid meteor shower! Although it won’t reach its peak until later this week, there will still be plenty to explore as we look at everything from the Andromeda family to the mighty M13. Time to get out your binoculars or telescopes, because…

Here’s what’s up!

Monday, November 13 – Today is the birthday of James Clerk Maxwell. Born in 1831, Maxwell was a leading theoretician on electromagnetism and the nature of light. On this day in 1971, Mariner 9 became the first space probe to orbit Mars.

Tonight we return to the Andromeda Family companions. Both galaxies were discovered by a Herschel. Father William found NGC 185 on November 30, 1787, while son John discovered NGC 147 on September 8, 1829. Both galaxies are thought to be about 2.5 million light-years away. NGC 185 presents nearly face-on, while NGC 147 is seen more obliquely. In 1944, Walter Baade resolved both galaxies photographically using the 100 inch Mt Wilson reflector. The two are bound together as a true pair and lie within 100,000 light-years of one another.

Tuesday, November 14 – Viewers in Turkey and Africa are urged to visit IOTA. Asteroid Froeschle will occult star 76 Tauri on this Universal Date.
Like the visible Andromeda galaxy and its telescopic family, there are also two more visible members of the overall “Local Group.” For Southern Hemisphere observers, tonight would be a great opportunity to study the Small Magellanic Cloud. At 210,000 light-years away, this near neighbor to the Milky Way will be apparent to the naked eye just north of Beta Tucanae. Easily viewed in binoculars and incredible in telescopes, the Small Magellanic Cloud is home to the rich globular cluster 47 Tucanae. As the second brightest globular cluster in the sky, 47 was once believed to be a star until the 1750s when French astronomer Nicolas Louis de Lacaille discovered its true nature.

Wednesday, November 15, 2006 – Today marks a very special birthday in history. On this day in 1738, William Herschel was born. Among this astronomer-musician’s many accomplishments were the discoveries of the planet Uranus in 1781; the motion of the Sun in the Milky Way in 1785; Castor’s binary companion in 1804; and infrared radiation. Herschel also discovered many of the clusters, nebulae, and galaxies that make up Dreyer’s New General Catalog (NGC) as well as a staggering number of double stars. Tonight let’s look towards Cassiopeia as we remember this great astronomer!
Almost everyone is familiar with the legend of how Queen Cassiopeia came to be bound to her chair, destined for eternity to turn over and over in the sky, but did you know this constellation holds a wealth of double stars and galactic clusters? Seasoned sky watchers are long familiar with Cassiopeia’s many objects, but let’s begin our exploration with two of its primary stars.

Looking much like a flattened “W,” the southern-most bright star is Alpha. Also known as Schedar, this magnitude 2.2 spectral type K star was once suspected of being variable, but no changes have been seen since the advent of modern astronomy. Binoculars reveal Schedar’s orange-yellow coloring, but a telescope brings out more. In 1781, Sir William Herschel discovered a 9th magnitude companion star. Today’s telescopes easily separate the blue-white component’s distance of 63″. A second, even fainter companion at 38″ is mentioned in lists of doubles, and a third 14th magnitude companion was spotted by S.W. Burnham in 1889. All three stars are optical companions only, but make 175 light-year distant Schedar a delight to view!

Just north of Alpha is our next destination – Achird (Eta Cassiopeiae). Discovered by Herschel in August 1779, Achird is among the most widely known binary stars. The 3.5 magnitude primary is spectral type G, meaning it has a yellowish color much like our own Sun, but is 10% larger than Sol and 25% brighter. Its 7.5 magnitude secondary is a dwarf M-type star and appears distinctively red. It has half the mass of our Sun, crammed into a quarter of Sol’s volume and is 25 times dimmer. Beyond the reach of binoculars, Eta B angles off to the northwest some 12 arc seconds distant and makes this pairing a true pair of color – one of the season’s finest!

Thursday, November 16 – Today in 1974, there was a celebration at Arecibo, Puerto Rico, as the gleaming new surface of the giant 1000-foot radio telescope was dedicated. At the time, a quick radio message was broadcast in the direction of the globular cluster M13 by of a group of astronomers interested in SETI research.
Tonight, let’s see what signals are being sent to us from the 21,000 years ago as we view the “Great Hercules Cluster.” What wavelengths shall we use? We suggest 400 – 740 nanometers. What kind of instrument sees in this range? Your very own eyes. Look northwest to the far side of the Hercules “keystone” around 2 finger-widths south of the most northwestern star – Eta. Although you’ll need a very dark sky to see 5.9 magnitude M13 unaided, add a pair of binoculars or a telescope and have a look back in time!
And if you have time, be sure to begin observations of the Leonid meteor shower. The peak begins after midnight.

Friday, November 17 – On this day in 1970, long running Soviet mission Luna 17 successfully landed on the Moon. Its Lunokhod 1 rover was the first wheeled vehicle to leave tracks on the surface. Expected to function three lunar days, Lunokhod 1 continued to operate for eleven. In that time, Lunokhod traversed 10,540 meters, transmitted more than 20,000 television pictures, some 200 television panoramas and performed more than 500 lunar soil tests. Spaseba!

Get up very early this morning because the annual Leonid meteor shower is underway – but for those seeking a definitive date and time, we just can’t do that. The meteor shower itself depends on debris shed by comet 55/P Tempel-Tuttle as it passes through the inner solar system every 33.2 years. Once assumed to be strictly a 33 year cycle, astronomers came to realize that the debris dispersed irregularly from the cloud that lagged behind the comet. With each successive pass of Tempel-Tuttle, new debris filaments are left in space near older ones. This creates the different streams the Earth crosses at varying times, making blanket predictions unreliable.

We may never know precisely where and when the Leonids might decide to be their most active, but we do know that a good time to look for them is well before dawn on November 17, 18, and 19. With the Moon mostly out of the way, wait until radiant Leo rises and your chances of spotting the offspring of periodic comet Tempel-Tuttle becomes high. Improve your luck by traveling to a dark sky location; and be sure to dress warmly and be comfortable!

Saturday, November 18 – Keep watching for the Leonids before dawn this morning.
Tonight let’s take a closer look at M31. Many observers often mistake the core region of the Andromeda Galaxy as being the whole picture, but this galaxy is so extensive that we often overlook its true size. For larger apertures, head to the southern edge and look for a slightly nebulous condensation. This is a 12.0 magnitude HII region with its own designation – NGC 206. Discovered by William Herschel on October 17, 1786, this 2.9 million light-year distant study is some 2,000 light-years in size and could be very similar to our own Orion Nebula.

Now look to the eastern edge and trace the perimeter to the north where you’ll discover the arc of a dark lane distinguishing the core region from an outer spiral arm. Be sure to look for a second fainter dark arc north of that. Both lanes sweep down and dissipate roughly between the bright central region and companion galaxy M110.

Sunday, November 19 – With dark skies, it’s time to hunt down difficult NGC 404 – a bright star and galaxy pair. Center on Beta Andromedae and look for 10.1 magnitude NGC 404. For an equally tough challenge, let’s return to the “Box and One” roughly a fist width from Polaris towards Ursa Minor. “The One” is 11.2 magnitude NGC 6217 – a face-on barred spiral with two faint wispy arms taking the form of an “S.” This one requires all the aperture possible to make out structure.

May all your journeys be at light speed… ~Tammy Plotner with Jeff Barbour.