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Transit of Mercury: November 6 - November 12, 2006.
The hottest event of the year is about to happen as mid-week brings up a transit of Mercury. If you haven’t had a chance to view Comet SWAN yet, now is the time before it fades west. You’ll find it in the constellation of Hercules. There’s still many other things to explore as we take a look at the Andromeda Galaxy family this week as well. So turn an eye to the sky, because...
Here’s what’s up
Monday, November 6 - Look for the Moon and the Pleiades to be very close together tonight.
On this night in 1572, Tycho Brahe was moved enough to sit down and record the emergence of a bright new star in Cassiopeia - and begin a celebrated career in astronomy. Brahe’s "Nova Stella" was thought by him to be the first "New Star" observed in the heavens. Initially seen to be as bright as Jupiter, SN1572 went on to rival Venus and for almost two weeks and could be found in daylight. Within 16 months (March, 1574), SN1572 faded from sight. Now primarily a 10,000 light-year distant radio source, its remnant has expanded nine times faster (9000 km/s) than M1 and is now almost four arcminutes in apparent size. Seen primarily at very long wavelengths, you can view SN1572’s locale near Kappa Cassiopeia. Using Eta Cassiopeia as a starting point, extend a line to Kappa. Continue that line one degree and use binoculars to look for a line of faint stars heading northwest. The very first in this series of marks the location of SN1572.
Tuesday, November 7 - This evening the Moon rises at skydark - but that doesn’t mean we can’t observe. Start around three finger-widths west-northwest of previous study star, Enif, to view globular M15. For large aperture, power up to resolve its interior planetary nebula - Pease 1. Now head a fist width south to the expansive core of globular M2. Both studies may be seen in large finderscopes and binoculars - even under moonlight!
Now wait until the Moon clears most of the atmospheric disturbance and have a look at the brilliant ring of Manilius on the northeast edge of Mare Vaporum just north of lunar central. To its northeast, look for the grey oval of Mare Serenitatis. Follow the bright ray to the south shore and say hello to the even brighter ring of Menelaus!
Wednesday, November 8 - Born this day in 1656, Edmund Halley made his mark by determining the orbital period of the Comet now bearing his name. In 1718 Halley went on to discover that the "fixed stars" displayed motion of their own. Sir Isaac Newton - and the world - owes a debt of gratitude to Halley for helping publish a rather famous work on the laws of gravity and motion. Hang onto your hat, because orbit and motion is about to come into play. One of the biggest events of the year is about to happen...the Mercury Transit.
At least a portion of this major event can be seen from both Americas as the transit begins near the sunset hour. For lucky viewers on the western edge of North America, all of New Zealand and the eastern edge of Australia and Asia, the entire event will be visible as we move between the International Date Line and sunset and rise. The only folks who will miss out will be Europe and Africa.
Because this is such a significant occurrence, plan well in advance to get a proper solar filter or to make arrangements will a local observatory or university to view. If this isn’t possible, let’s repeat instructions on safe solar projection methods.
First off, NEVER look at the Sun through any unfiltered optical aid. Mylar, smoked glass and exposed film are NOT safe. #12 welder’s glass or solar filter film taped securely to binocular lenses is suitable for short periods, but be extremely careful that the entire viewing surface is covered. A very safe way to observe the transit with no special equipment is to project an image of the Sun through a telescope or binoculars onto a white screen. This can be something as simple as a paper plate or cardboard. Make sure that telescope finders are covered and one set of lenses for binoculars.
By using the shadow method to aim, you’ll see a circle of light on your screen - the Sun. Adjust the distance until it is about the size of a small plate, then focus until the edges are sharp. You are now ready to view the transit.
Thursday, November 9 - Today is the birth date of Carl Sagan. Born in 1934, Sagan went on to become a planetologist, exobiologist, popularizer of science and astronomy, and novelist. His influential work and enthusiasm for the Cosmos inspired us all. In his memory we have no further to look than brilliant Vega.
In Sagan’s most popular novel Contact, Vega was chosen to be the main character’s first wormhole transit stop. In the fictional work, Astronomers are puzzled that such a young star system - still filled with debris left over from formation - could possibly be the source of broadcasts from an ancient extra-terrestrial civilization. In reality, Vega was one of the first stars determined to have a large heat-radiating circumstellar cloud around it. Interestingly, that cloud may actually be a disk - since we see Vega from its pole, not its equator. This accretion disk may be the type that forms planets.
As you view Vega tonight, keep in mind that it has 2.5 times our Sun’s mass, and converts Hydrogen to helium at a more prodigious rate. It will remain on the main sequence for only about a billion years before becoming a red giant. Unlike Algol, or the many blue stars in globular clusters, Vega has no nearby red giant companion to "refuel" itself through gravitational theft.
Friday, November 10 - Unseen by observers, the planets Mars, Mercury, Venus, and Jupiter are now within nine degrees of the Sun. Venus is moving west to become an evening star. Mars has turned the corner to begin the long, slow process of moving towards its next opposition on December 24, 2007.
After astronomical dusk, Capricorn will give way to Aquarius, while overhead Cygnus will give way to Pegasus. Of the five circumpolar constellations, Cepheus will be at its highest - later to be followed by bright Cassiopeia, then faint Camelopardalis, and Lynx in turn. Draco now is to the west and Ursa Major begins its ascent in the morning hours. All is well in the heavens as we approach Zero hour.
The closest bright star marking Zero hour is Beta Cassiopeiae - Caph. The finest deep sky study lying near Zero hour in the northern hemisphere is NGC 7789 located about two finger-widths southwest. Dense, but relatively faint, this 6.7 magnitude open cluster will appear galaxy-like to smaller scopes and binoculars. Located within 3 minutes of Zero hour, this 8,000 light-year distant cluster explodes with 12th magnitude and fainter stars with large aperture and dark night skies. It is truly magnificent.
Saturday, November 11 - A true observer was born on this day in
Tonight let’s use our eyes, binoculars or small scopes take a look at a "Slipher" Galaxy as we head towards Andromeda and M31. Containing over 300 billion stars, it’s one of the largest Galaxies known. In 1912, Slipher analyzed it spectroscopically to discover its blue shift: "The magnitude of this velocity, which is the greatest hitherto observed, raises the question whether the velocity-like displacement might not be due to some other cause, but I believe we have at the moment no other interpretation for it. Hence we may conclude the Andromeda Nebula is approaching the solar system with a velocity of about 3000 kilometers per second."
For larger scopes, let’s challenge ourselves to a Galaxy lying very close to the Zero hour within the Great Square of Pegasus. Start at Gamma and head about 3 degrees northwest to locate a "scratch of light"
- NGC 7814. This magnificent 10.5 magnitude spiral is edge-on in presentation. Containing a bright nucleus, high power will reveal a razor-edge dustlane almost perfectly bisecting the galactic core, then extending out to its wispy spiral extensions!
Sunday, November 12 - Wouldn’t you love to have been there in 1949 when the first scientific observations were made with the Palomar 5-meter (200-inch) telescope? Or to have seen what Voyager I saw as it made a flyby of Saturn on this date in 1980? Or to have been around in 1833 - the night of the Great Leonid Meteor Shower! But this is here and now, so let’s make our own mark on the night sky as we begin studies of the Andromeda Family...
The two Galaxies we are about to explore are relatively easy to find but difficult to see in even a mid-sized scope. Our first study is NGC 185 - a 9.2 magnitude located precisely 6 degrees and 49 arcminutes due north of M110. Once you’ve found this distant M31 companion, the real test will be similarly-sized but fainter (9.4) magnitude neighbor NGC 147 - located almost precisely one degree due west. More about this pair later.
While you’re out, be sure to watch for members of the Pegasid meteor shower. With a radiant near the Great Square, this stream lasts from mid-October to late November and was once quite spectacular. Watch for a peak on November 17. If you’re still out when the Moon rises, look for Saturn only about a finger-width away!
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