Natural Calendar September 2015

Natural Calendar - September 2015

The purpose of this feature is to give scout leaders, educators and naturalists an idea of some of the natural events coming up each month. We will try to cover a variety of natural events ranging from sky events to calling periods of amphibians, bird and mammal watching tips, prominent wildflowers and anything else that comes to mind. We will also note prominent constellations appearing over the eastern horizon at mid-evening each month for our area for those who would like to learn the constellations. If you have suggestions for other types of natural information you would like to see added to this calendar, let us know!

Note: You can click on the hyperlinks to learn more about some of the featured items. To return to the Calendar, hit the "back" button on your browser, NOT the "back" button on the web page. All charts are available in a "printer friendly" mode, with black stars on a white background. Left clicking on each chart will take you to a printable black and white image. Please note that images on these pages are meant to be displayed at 100%. If your browser zooms into a higher magnification than that, the images may lose quality.

Though we link book references to nationwide sources, we encourage you to support your local book store whenever possible.

Notes and Images From August 2015

Sometimes in August we get a nice cold front that clears out some of the summer haze. There's a fall-like coolness to the nights. The katydids slow down their songs and the air is filled with the low trills of tree crickets and the rat-a-tat-tat calls of Lesser Anglewings. Southern Leopard Frogs begin calling again as the temperatures mirror their spring breeding season. Pegasus, the great flying horse, comes over the eastern horizon like it's halfway through a snap roll, upside down, its legs extending upward towards the zenith. Galaxies seem to fly from its path as it gallops through the heavens.

On August 7th, we had just such a night, and with the clear skies we decided to image a tiny and faint group of galaxies called Stephan's Quintet. There are brighter galaxies throughout Pegasus, but the quintet seems to have a magnetic pull. To find it, you follow the stars along the front foreleg of the horse to locate the relatively bright galaxy NGC 7331. Then you offset from that galaxy about 1/2 degree to the south to find the quintet.

The image below was made from 10 hours total exposure made over four nights with our 12-1/2 inch Newtonian reflector, beginning on the 7th.

Stephan's Quintet, August 7th, 8th, 12th and 13th. 12-1/2 inch Newtonian Reflector and SBIG ST-2000XCM CCD Camera. Total Exposure 10 hours in 10-minute subexposures.

The quintet was discovered in 1877 by Edouard Stephan of the Marseille Observatory, using a 40cm reflector. Stephan originally described the group as a quartet, as he saw a single object for the galaxies 7318A and B, which are quite close together. The quintet was the first compact group of galaxies discovered.

I'm not sure when I first saw an image of Stephan's Quintet, but I think it was in the mid 1990's. From the moment I saw the image, I knew it was something I wanted to see in my own telescope. At that time we had a 17-1/2 inch reflector, and had a lot of fun star-hopping to the group and spotting the faint misty glows. Our most memorable view of the quintet was from a campground at Luna Lake, Arizona with our 20 inch Newtonian. At 8,000 feet above sea level, the Milky Way cast a shadow! Even the tiny barred spiral galaxy NGC 7320C, to the left of the quintet in the image above, was visible with averted vision.

When you look at the image above, remember that all of the stars you see are part of our own galaxy and quite close to us compared with the quintet. The bluish galaxy, NGC 7320, is 40 million light-years distant, and is much closer than the other members of the quintet, which are around 300 million light-years away. So there are at least three distinct levels of distance in the image. To better illustrate this, we made a 3D version of the image that you can see below.

To view the 3D image, simply place the image at normal reading distance, then relax your eyes so that you're looking "through" your screen into the distance. Pretend your listening to a particularly boring speaker. When you do that, a third image will come into view between the original two images. Relax your eyes a little more, and the third image becomes crisp and in 3D. It may take a little practice to adjust your eyes. If you use reading glasses, keep them on to do this.

A 3D version of the Quintet from the image above

You can also download a Leaps bookmark with this 3D Quintet by right-clicking here. Select "Save Target As" and save it to your hard drive. We would recommend using your best color printer settings. It looks best when printed on photo paper, but it will also work on regular card stock. Printing at 100% will insure that the spacing between the two images of the quintet will remain around 2.2 inches, which seems to work well for us.

You can find the Hubble space telescope image of Stephan's Quintet here. Because NGC 7320 is much closer than the other members of the quintet, you can see individual stars in this galaxy. This is not possible for the more distant members.

Edwin Hubble did his pioneering work on the relationship between the recessional velocities of galaxies and their distances (Hubble's law) while at Mount Wilson. The observatory is on the north side of Los Angeles. Hollywood was only 18 miles away as the crow flies, and about 35 miles by car. Occasionally Hollywood stars of the 30's would make the trip up the mountain for a look through the 100 inch scope.

Hubble and movie director Robert Capra were friends, and Capra sometimes visited Hubble at Mount Wilson for a little observing. Capra was once asked where he would have ended up if he had not become a film director. He answered, "With Hubble. As an astronomer. I could study the stars and the planets forever." Capra invited Hubble to attend the 1937 Academy Awards ceremony and introduced him as the world's greatest living astronomer.

It's not too surprising, then, that Capra decided to use an image of Stephan's Quintet in the opening scenes of his 1946 movie, "It's a Wonderful Life." The quintet was used in the scene where Clarence, the apprentice angel, is given his instructions. As part of the movie, this small group of galaxies have been viewed by many people over the years. Most do not realize they are looking at an actual galaxy cluster.

Our most memorable views of the quintet have all been visual looks beneath the stars. It is not an easy target, and to see it well you need at least a 12 inch scope. But for those who don't mind the difficulty of the journey, it's a wonderful trip. Hubble said in his book, The Realm of the Nebulae, "Eventually, we reach the dim boundary – the utmost limits of our telescopes. There, we measure shadows, and we search among ghostly errors of measurement for landmarks that are scarcely more substantial." These galaxies will test the limits of both you and your scope, but there's a connection that you feel when you visually spot them. The galaxies appear as they were 300 million years ago, when reptiles had just become established on earth. Listening to the night sounds as the ancient photons fall upon your retina is a an awe-inspiring experience.

Sky Events for September 2015:

A Total Lunar Eclipse occurs on the evening of September 27th. The partial eclipse begins at 8:07pm. Totality begins at 9:11pm and lasts till 10:23pm. Don't miss totality - the Moon, lit by the combined sunsets and sunrises around the world, is stunning! A good pair of binoculars will enhance your view.

The Autumnal Equinox, marking the beginning of fall in the Northern Hemisphere, occurs at 3:21 am CDT on September 23rd.

Evening Sky:

Saturn, May 3rd, 2015, 20 Inch Newtonian Telescope and ZWO ASI 120MMS camera

Look for Saturn in the southwest at dusk about 30 degrees above the horizon at the beginning of the month. The planet will remain in Libra this month. Saturn's rings have opened up to more than 24 degrees tilt, giving a wonderful view of the ring system through just about any aperture telescope. Observe Saturn early in the evening to get the best view.

Morning Sky:

Venus rises about 4:30am at the beginning of the month and is dazzling in the eastern sky before sunrise. It will climb steadily higher in the sky each morning as the month progresses.

Mars is in Gemini as the month begins, and can be found to the left of Venus, about a fist-width at arm's length away. Mars will be much dimmer than Venus, and is only about 3.7 arc-seconds in apparent diameter. It will become more visible as the month goes on.

Jupiter is the lowest member of the planetary group in the dawn twilight, and can be seen later in the month below Mars.

All times noted in the Sky Events are for Franklin, Tennessee and are in Central Daylight Time. These times should be pretty close anywhere in the mid-state area.

The Great Andromeda Galaxy, Messier 31, October 25, 2013. Nikon D5100 Camera and Nikon 300mm lens. For a larger version of the image click the image above.

Constellations: The views below show the sky looking east at 10:00pm CDT on September 15th. The first view shows the sky with the constellations outlined and names depicted. Star and planet names are in green. Constellation names are in blue. The second view shows the same scene without labels. Pegasus appears higher above the eastern horizon, as does Andromeda. Perseus is above the horizon now, and Cetus is also beginning to appear. The faint stars of Pisces should be easier to pick out this month.

Find the "Square of Pegasus" and work your way outward from it to the constellations around it. See if you can pick out the faint glow of the Andromeda Galaxy, over 2 million light years away! When you look at this galaxy you're seeing light that began its journey to us in the Pleistocene epoch. To get the best view, wait until the galaxy climbs high in the sky.

The Andromeda Galaxy was first shown on star charts prepared in 905AD by the Persian astronomer, Al Sufi, and was referred to as the "Little Cloud." That describes well its appearance to the naked eye. Binoculars will greatly improve your view, as will driving out of the city and finding darker skies.

Simon Marius, in 1610, was among the first to observe the Andromeda Galaxy through a small telescope. He compared its soft glow to "the light of a candle shining through horn." In dark skies, those using small telescopes may pick out the small satellite galaxies M32 (above and left of the nucleus of M31 in the above image) and NGC 205 (below). A faint tidal bridge connects NGC 205 to Messier 31.

Our Milky Way Galaxy and the Andromeda Galaxy are approaching each other and are expected to collide in approximately 4.5 billion years. The two galaxies may merge into a single giant elliptical galaxy at that time.

September 15th, 10:00pm CDT, Looking East

On Learning the Constellations:

We advise learning a few constellations each month, and then following them through the seasons. Once you associate a particular constellation coming over the eastern horizon at a certain time of year, you may start thinking about it like an old friend, looking forward to its arrival each season. The stars in the evening scene above, for instance, will always be in the same place relative to the horizon at the same time and date each September. Of course, the planets do move slowly through the constellations, but with practice you will learn to identify them from their appearance. In particular, learn the brightest stars for they will guide you to the fainter stars. Once you can locate the more prominent constellations, you can "branch out" to other constellations around them. It may take you a little while to get a sense of scale, to translate what you see on the computer screen or what you see on the page of a book to what you see in the sky. Look for patterns, like the stars that make up the "Square of Pegasus."

The earth's rotation causes the constellations to appear to move across the sky just as the sun and the moon appear to do. If you go outside earlier than the time shown on the charts, the constellations will be lower to the eastern horizon. If you observe later, they will have climbed higher.

As each season progresses, the earth's motion around the sun causes the constellations to appear a little farther towards the west each night for any given time of night. If you want to see where the constellations in the above figures will be on October 15th at 10:00pm CDT, you can stay up till midnight CDT on September 15th and get a preview. The westward motion of the constellations is equivalent to two hours per month.

Recommended:

Sky & Telescope's Pocket Star Atlas is beautiful, compact star atlas.

A good book to learn the constellations is Patterns in the Sky, by Hewitt-White. You may also want to check out at H. A. Rey's classic, The Stars, A New Way to See Them.

For skywatching tips, an inexpensive good guide is Secrets of Stargazing, by Becky Ramotowski.

A good general reference book on astronomy is the Peterson Field Guide, A Field Guide to the Stars and Planets, by Pasachoff. The book retails for around $14.00.

The Virtual Moon Atlas is a terrific way to learn the surface features of the Moon. And it's free software. You can download the Virtual Moon Atlas here.

Cartes du Ciel is a great program for finding your way around the sky. It is also free, and can be downloaded here.

Apps: We really love the Sky Safari Pro application described here. For upcoming events, the Sky Week application is quite nice. Both apps are available for both I-phone and Android operating systems. The newest version, Sky Safari 4, is available from Play Store or from i-tunes.

Amphibians:

Spring Peeper

The frog and toad choruses start waning in September but some frogs and toads are still calling. Another name for the Spring Peeper is the "Autumn Piper", and these small frogs can be heard calling from patches of woods in the fall. Listen also for a very dry, scratchy version of the Upland Chorus Frog's song on rainy days and nights in September. We've been hearing Southern Leopard Frogs quite a bit this August, and they should really pick up in September as the cooler temperatures mirror their early spring breeding period. You can locate many of the frogs and toads that have been calling more frequently earlier in the year by driving the back roads slowly on rainy nights.

Marbled Salamander

This is a two person job. One person watches the road for amphibians and one person looks out for other vehicles. Anything over about 15mph is "speeding." On wet nights in September, look for breeding Marbled Salamanders in flooded woodland areas. We found one such area where we had previously heard a breeding chorus of Upland Chorus Frogs.

Recommended: The Frogs and Toads of North America, Lang Elliott, Houghton Mifflin Co.

Insects:

Lesser Anglewing

With cooler temps moving in, there are changes in the insect chorus. Species that peak in late July and August, like the Nebraska Conehead and the Robust Conehead are heard much less frequently. The sounds of other species, like the tree crickets, dominate cool fall nights.

Two species that we hear a lot this time of year are the Lesser and Greater Anglewings. I heard these species for years without knowing what they were. But the calls are easy to identify and you get lots of practice hearing them in the fall.

The Lesser Anglewing has a very rapid fire rat-a-tat-tat call of four or five notes, all delivered staccato. To hear one we recorded in October 2013, click here. The Greater Anglewing has two types of calls. It sometimes gives a single raspy note every few seconds, but the call I'm most familiar with is a series of very high, very short "tics"; tic-tic-tic-tic-tic-tic-tic-tic. It's quite distinctive and easy to learn. I can't find one of our recordings of it, but you can go to The Songs of Insects online link below and listen to it there.

Both species are pretty hardy and will call through the fall months.

Recommended:

The Songs of Insects, by Lang Elliott & Will Hershberger (Houghton Mifflin) - Beautifully written and including many spectacular images, this book includes an audio CD and detailed range maps. It was a real bargain for $19.95, and you can now get it from Amazon for less than $14.00.

Crickets and Katydids, Concerts and Solos, Vincent G. Dethier (Harvard University Press) - In this book Vincent Dethier writes of his experiences in the 1930's working as a field assistant gathering insects so that their songs could be recorded and analyzed. Now out of print, you should still be able to locate a copy by clicking the link above. An inspiring book and one of our favorites.

Online:

Singing Insects of North America - This is a terrific online reference.

Songs of Insects - Another great reference from Lang Elliott and Will Hershberger.