Natural Calendar - September 2016

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 2016

Back when we were building our observatory, one goal was to be able to control everything connected with the telescope remotely via the internet.  We enjoy being outside with the scope.  But sometimes it's nice to be able to take images when we're not at home, or return to a warm living room on a cold winter evening.  We installed everything for that, and it all works just fine.  But lately I've been rolling the roof off of the observatory manually. 

The reason is that all summer long I've had an observing companion in the form of a Cope's Gray Treefrog.  It's not unusual while I'm working on the telescope to see a blur out of the corner of my eye and hear the soft thump of the treefrog as it lands on the wall of the observatory.  Most of the time it spends its days on the wooden rail of the observatory, shaded by the roof from the summer sun.  It sits watching me while I work, its front feet tucked beneath it.

 
A Cope's Gray Treefrog sitting on the rail of our observatory, August 30th. 
Nikon D5100 Camera and Nikon 105mm Micro Lens.

This treefrog is so used to my presence that I can just reach over and pick it up if I need to move it elsewhere.  The eyes are quite striking.  The designs that surround its pupils are like intricate scrollwork.  It sits there with a cryptic expression on its face, pondering who knows what.

It's so docile that I worry it will be injured by the roof as it opens.  Now, when I plan on opening or closing the observatory, I slowly open the roof manually while watching the treefrog.  I don't mind doing it that way.  It's nice to enjoy the evening bird chorus, and to experience all of the twilight sights and sounds as the stars come out.

 

We encountered another set of interesting eyes earlier in the month.  We were carrying our kayaks inside after a float trip, and I looked down and saw a horsefly on a stalk of grass.  From above, its eyes were very light blue, but below they had a wild striped pattern that made it look like the horsefly was wearing a pair of high-tech sunglasses.  We put the kayak down and I ran inside to get my camera.

 
Male Horsefly, August 12th, Nikon D5100 and Nikon 105 Micro Lens

 

Male Horsefly, August 12th, Nikon D5100 and Nikon 105 Micro Lens

This is a male, as evidenced by the eyes appearing to touch at the top.  Male horseflies feed on the nectar of flowers, while the females, tasked with obtaining the nutrients to bear young, feed on blood.  The mouthparts of the female horsefly are a little scary looking, and they contain, as someone observed, a veritable Swiss army knife's worth of tools for penetrating the skin and drawing blood.

Horseflies are in the family Tabanidae.  This species appears to be Tabanus sulcifrons. 

My first thought on seeing the compound eye pattern close up was that it reminded me of the pattern of tiny micro-lenses on the pixels of modern color cameras.  Those tiny colored lenses in a camera impart color information to the camera's central processing unit.  Could the colors serve the same purpose for the horsefly?  That is, could the tinting of some of the lenses impart information to the horsefly about its environment?  Or was the pattern just decorative? 

So far, we haven't been able to find anything definitive on this.  We found references to some studies that suggested that some species of horseflies were able to preferentially detect horizontally polarized light, and that this might influence or enhance prey selection.  The difference in color between the upper surface of the eye might indicate that the upper facing part of the eye is optimized to detect danger from above, while the downward facing parts of the eye are used for prey selection or for interpreting other aspects of the environment.  But this is pure conjecture, and if anyone has knowledge of the specifics of why these colors are used, please let us know!

 

Sky Events for September 2016:

The Autumnal Equinox occurs on September 22nd at 9:21am CDT, marking the beginning of fall in the Northern Hemisphere.

Evening Sky:  

Look for bright Venus low in the west-southwest about 20 minutes after sunset at the beginning of the month.  It will gradually set later and later after the sun as the month progresses.   Jupiter is very low in the western sky about 5 degrees below and to the right of Venus.  If you look on September 2nd, look also for a very thin crescent Moon just to the right of Jupiter.

Mars is in Scorpius as the month begins.  Look for it about 28 degrees above the southern horizon at dusk.  Mars will begin the month around 10.5 seconds of an arc in diameter.

 
Saturn, Tethys and Dione, June 11th, 2016, 20 Inch Newtonian Reflector and
ZWO ASI120MCS Camera

Saturn is in Ophiuchus, above and to the right of Mars as you are facing south.  Look for it about 31 degrees above the southwest horizon.  The tilt of the rings has now opened to 26 degrees, and the view is spectacular in any size telescope.  The globe of Saturn is now 16.6 seconds of an arc in diameter. 

Saturn is highest above the horizon about dusk, so if you're planning on viewing it with a telescope you'll want to view it as soon as it becomes visible in the southern sky.

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.

Morning Sky:

Late in the month Mercury makes its best appearance in the morning sky this year.  Start looking for it the last week of the month.  It will be easiest to see at its greatest elongation from the Sun on September 28th.  Look for it starting about 45 minutes before sunrise low in the east.

 
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
 
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 (described in the monthly notes above) 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 here.

Another great app is the Photographer's Ephemeris.  Great for finding sunrise, moonrise, sunset and moonset times and the precise place on the horizon that the event will occur.  Invaluable not only for planning photographs, but also nice to plan an outing to watch the full moon rise.  Available for both androids and iOS.

 

Amphibians:

Southern Leopard Frog

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.  Needless to say, it requires a road that has little or no traffic on it.  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.

 

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Nature Notes Archives:  Nature Notes was a page we published in 2001 and 2002 containing our observations about everything from the northern lights display of November 2001 to frog and salamander egg masses.

Night scenes prepared with The Sky Professional from Software Bisque

All images and recordings 2016 Leaps.