Astronomical Potpourri in September
September 2008 :
Note: This article may contain outdated information
This article was published in the September 2008 issue of The Skyscraper and likely contains some information that was pertinent only for that month. It is being provided here for historical reference only.
While we have to wait until September 22 at 11:44 am for the autumnal equinox (Fall for the northern hemisphere) to occur, usually we begin to see a change in the weather by the time of the Labor Day weekend celebration. I can't wait.
But before then, there are several astronomical events I'd like you to check out, weather permitting of course.
On September 1st you can try to see a nice gathering of planets and the Moon just above the western horizon after sunset. You'll need to see right down to the horizon. Providing there are no clouds or heavy thick haze to spoil your view, you will be able to observe bright Venus, reddish/orange Mars, Mercury, and a very thin crescent Moon. This scene could be a little difficult to view. However, if you find a high spot from which to observe, or a flat location at a beach with a good view to the west, you should be well rewarded. Try to take a picture if you can and send your best images to Skyscrapers webmaster jim@distantgalaxy.com.
Each successive night Mercury will rise higher and higher into the sky. By the 11th this fast moving world will be at its highest position off the western horizon...about 10 degrees (a fist held at arm's length gives this approximate measurement). After that evening Mercury will move closer to the horizon each night until it eventually disappears into bright twilight.
After the first of the month you will continue to see Venus and Mars as well. In fact, the two will be at their closest to one another on the 11th. Use binoculars or a telescope to see how close they come to one another.
Just more than a week later, on September 19, the Moon, now in waning gibbous phase, will pass in front of the Pleiades star cluster. The event begins with the objects very low on the eastern horizon just after moon rise at around 9:00 pm. Soon thereafter the Moon will occult (pass in front of) some of the cluster's major stars. The first will be Electra at about 9:12 pm, followed later by Maia and Alcyone. The Moon clears the cluster by 11:00 pm. Since the Moon will be quite bright, binoculars or a small telescope or spotting scope will provide the best view.
September's event will be the fourth time the Moon has occulted stars in the cluster this year. Two more occultations are scheduled for the remainder of 2008. The next one on October 17 cannot be observed here, whereas the last one on December 11 can be watched after 2:00 am.
And finally, we cannot overlook bright Jupiter in our sky the entire month. On September 1st at 9:00 pm Jupiter can be found about 25 degrees above the southern horizon. You can't miss him. It will be the brightest object in that area of the sky. While a few keen-eyed children, and even fewer adults, can see some of Jupiter's moons without optical aid, to really appreciate the Jovian system requires at least a small telescope.
On January 7, 1610, Galileo Galilei focused his 1-inch in diameter, three foot long, 28 power refractor on Jupiter and not only saw the bands and zones of the planet's cloud tops, but also saw three, and then later four of his moons. We call them the Galilean Satellites in his honor. They are: Io, Europa, Ganymede and Callisto.
It didn't take Galileo long to realize the moons were revolving around Jupiter. This evidence was proof that the Copernican system was correct... the Sun was at the center of the solar system and the planets revolved around it...just like Jupiter's moons revolved around him.
Despite Galileo's indisputable proof, it was still disputable. Some people even refused to look through the scope to see for themselves, else they'd be corrupted by the device. Eventually everyone "came around," but Galileo remained under house arrest by the Church for the rest of his life.
You too can observe what Galileo did back in 1610. And with the telescopes at Seagrave Observatory in North Scituate and Ladd Observatory in Providence, you will see much more detail than Galileo could have dreamed of.
You'll easily notice the more prominent dark bands or belts in Jupiter's cloud tops. The once dominant feature of Jupiter (from at least Galileo's time through the mid 1970s) was the famous Great Red Spot. It is nothing more than a giant storm in Jupiter's clouds that has been active for more than 400 years. Unfortunately the storm's not as red or great as it once was, so it might be difficult to detect in smaller instruments without special filters to enhance the image. In recent years the red coloration has come back somewhat, making the Great Red Spot a little easier to see than it had been for the last 15 or so years.
In addition, the Galilean Satellites will immediately catch your eye. While these satellites parade around Jupiter in the plane of his equator, many interesting events occur for us earth-bound astronomers to observe. You can observe one of Jupiter's moons pass in front of his disk, and you can observe a moon casting a shadow on his cloud tops. You may also be fortunate to observe a moon disappear into Jupiter's shadow, or simply pass behind the planet.
If you own your own telescope get outside and view the fascinating system of Jupiter. If you don't have access to a telescope or you'd like to explore the universe with larger instruments, then by all means visit Seagrave Memorial Observatory on Peeptoad Road in North Scituate. We offer public viewing free of charge every clear Saturday night. More information, including open times, directions and membership, can be found at our website: www.theskyscrapers.org
Furthermore, you can visit Ladd Observatory on the corner of Hope Street and Doyle Avenue on Providence's East Side every clear Tuesday night. Admission is also free. More information, including open times and directions, can be found at Ladd's website: http://www.brown.edu/ladd. Please note this is a new web address. The web site has recently been redesigned and improved. Additional content, including a wealth of weather data collected right at the observatory, will be coming soon, so log on often.
Let's all hope the transition to Fall will provide us with clear skies to observe every one of the astronomical happenings I've highlighted. And remember two things. Keep your eyes to the skies. And in true Rhode Island style...If you don't like New England weather ... complain about it!!
