EVENTS AND NAKED EYE VIEWING
NOTE: All Sky Charts Courtesy of SkyGuide App Unless Otherwise noted.
September 7 (Friday) Zodiacal Light Returns. The summer of 2018 is drawing to a close and the autumnal equinox is nigh. Along with this seasonal change is a view of our solar system from a different perspective. The near equinox sun angle illuminates our solar system's plane of rotation where most of the "stuff" is located. That stuff includes lots and lots of dust left over from the collapse of the gas and dust cloud that formed our sun, planets, dwarf planets, asteroids, and comets. It appears as a triangular shaped foggy spike above the eastern horizon in September's predawn sky. The reason I selected September 7 as the first early morning view of the Zodiacal Light is it is so dim that even the shine from a thin crescent Moon is bright enough to wash out this ghostly light. So if you have a clear view of the eastern horizon with no interfering light pollution or the Moon, you'll see this rather large display rising from the ENE and tilted slightly south long before morning twilight. My recommendation is to look for the Zodiacal Light from about 1 to 5 AM. After 5, the morning twilight begins to brighten the horizon washing out your view of this phenomenon. During very early morning (around 1 AM) if the Moon isn't shining, you can also see the Gegenschein (German for "countershine") high in the sky along the band of Zodiacal Light. This is the antisolar point (point directly opposite the Sun's position relative to Earth) which shines brighter than the rest of the Zodiacal Light.
September 7 (Friday) Neptune at Opposition. For planets relatively nearer to Earth such as Mars, Jupiter, and Saturn, opposition is a good time to view them because we are tens of millions of miles closer to these planets during this period. In fact, orange tinted Mars which achieved opposition in late July, is still brightly visible on this night over the SSE horizon. The trouble with Neptune is it is so far away that opposition brightens it by only a tenth of a magnitude. Still, this is significant for astrophotographers who wish to image this distant ice giant along with its largest and surprisingly bright moon Triton. Neptune's icy blue cloud tops will shine dimly at magnitude 7.8 and Triton at magnitude 13.4 (just a hair brighter than Pluto which barely shines at magnitude 13.6). The best view you can expect through a telescope will show Neptune as a tiny blue disk not much different than blue colored background stars. Triton will be a much smaller and dimmer white pinpoint of light next to the farthest major planet in our solar system. I've viewed Neptune many times over the years and sometimes I've had to view it over a series of nights to see it move relative to the background stars in order to verify that it indeed was Neptune that I was looking at.
If you care to learn more about Neptune and its sister ice giant Uranus as well as poor demoted Pluto, I recommend a new profusely illustrated book "Uranus, Neptune, Pluto A longer view" (73 pages) by Guy Ottewell through universalworkshop.com. Guy has written and illustrated many books and for several decades a most excellent Astronomical Calendar (no longer in print) that amateur and professional astronomers have enjoyed immensely! I guarantee you will like to curl up with a cup of hot tea or coffee and read this artistic, creative, and scientific review of these three distant denizens of our Solar System.
You'll need at least a 6 inch telescope equipped with a high power eyepiece (10mm or less) to distinguish the disk shape of Neptune from the pinpoint background stars. A ten inch aperture will be necessary to see Triton. Don't be discouraged if Neptune doesn't live up to your expectations. Think of it this way. Very few people see Neptune in real time over their lifetimes. You can say you're one of the lucky few to do so! Of course, Mars is only 45 degrees to the right of Neptune and Saturn only another 20 degrees from Mars if you want to view planets that look more interesting.
September 21 (Friday) Venus at Greatest Illuminated Extent. Venus has been "nosediving" toward the Sun since its time of Greatest Elongation East on August 17. As it catches up to us in its faster orbit around the Sun, it gets larger and brighter. It also gets lower over the western horizon and displays an ever thinning crescent shape as we see more of its night time side. This is the brightest Venus will look as the "Evening Star" for 2018. As the days roll on, Venus will continue to get larger, but its ever thinning crescent phase will cause it to lose brilliance.
This is an event you can see only if you have an unobstructed view to the west because Venus will be only 7 degrees above the horizon (width of seven fingers stacked onto each other at arms length) about 30 minutes after sunset when it will be dark enough for you to see it and Jupiter in the evening twilight.
September 22 (Saturday) Fall Equinox. At 7:54 PM, the Sun will be exactly halfway between its farthest north and south travel along Earth's horizon. Immediately afterwards, the Sun will rise further and further south as the Autumn season progresses. Once again we will have almost equal hours of day and night on the following day, same as Spring. Only now, the trend will be for earlier sunsets and longer nights. This is a great season for astronomers because the summer Milky Way will still be prominent in the night sky and the Fall constellations like Capricornus, Aquarius, Pices, and Pegasus come into view. These constellations display some wonderful globular star clusters, planetary nebulae, and colorful double stars that compliment the hues of the changing leaves as our trees prepare for winter.. Stay tuned for a trip through these deep space wonders as well as visits with the ice giant planets in the coming months!
September 23 (Monday) Full Harvest Moon. This Full Moon is defined two ways. First, it's the Full Moon that is closest to the Autumnal Equinox. Second, it's name is derived from when corn is supposed to be harvested. This year, the Harvest Moon occurs only one day after the equinox which is almost as close as you can get! For most of North America, the bulk of our sweet corn has already been harvested, but our feed corn is allowed to dry in the fields to make it better for storage in silos. So I suppose you can call this the Feed Corn Harvest Moon! There's another phenomena that makes the Harvest Moon special. Earth's tilt this time of year makes the nearly Full Moon rise at almost the same time for three nights in a row. That makes people think that the day before and after the full Moon are also full Moon nights. So whenever you decide to celebrate it, the Harvest Moon will be there for you! So, Shine on Shine on Harvest Moon for Me and My Gal!