September Stargazing

September 2017  :  Dave Huestis

Amateur astronomers and casual stargazers look forward to the month of September. Here in Southern New England the hazy, hot and humid days of summer are mostly behind us. With humidity levels much lower the skies become more transparent. Combine those conditions with earlier sunset times, and the nighttime heavens can be explored at a reasonable time in the evening. Let’s examine a few objects that can be observed with either your unaided eyes, binoculars, or a telescope. And if you don’t have a telescope to explore some of these in greater detail, then visit one of the local observatories and ask the volunteer telescope operators to acquire your favorite.

At the beginning of September Jupiter will be very low in the west after sunset. You’ll need an unobstructed view of the horizon to observe this Jovian world. Jupiter will soon be too close to the Sun in the sky to be seen. Beautiful Saturn will be visible through the end of October, depending on one’s view of the west south-west horizon. Its ring system is wide open, tilted 27 degrees. Crank up the magnification and marvel at the spectacle before you. On nights of steady seeing, the kids who visit Seagrave Observatory or Ladd Observatory often exclaim “cool” or “awesome,” followed by “it looks like a sticker.”

In addition, this month would be a good time to catch a glimpse of the most distant planets in our solar system. Well, two planets and one dwarf planet. Since the demotion of Pluto to dwarf planet status in 2006, those planets now are Uranus and Neptune. These gas giants look like little blue-green disks through a telescope. You won’t see any detail, but you can boast of catching a glimpse of these distant worlds.

Unless you know specifically where to look, these distant bodies can be difficult to locate. Finder charts can be accessed on the internet. While Uranus can be seen in a dark moon-less sky with the naked-eye, Neptune requires at least binoculars to find. Both planets reveal a blue-green disk under medium- to high magnification. A fairly large computer-controlled telescope is required to locate Pluto. This dwarf-planet will look like one of the many faint stars occupying the same field of view. Assuming the computer correctly positioned the telescope, Pluto will be one of those points of light you can see through the eyepiece. Computer-assisted telescopes at the local observatories can guarantee your sighting of these far away worlds.

On September 5 the distances in miles these three objects will be from the Earth and the constellations in which they can be found are as follows: Uranus (1,784,000,000 in Pisces), Neptune (2,690,000,000 at 1:13 a.m. closest to the Earth for 2017 in Aquarius) and Pluto (3,051,000,000 in Sagittarius). 

If you wish to get a good look at our own Milky Way galaxy soon after twilight fades, then the month of September provides a continued opportunity. From many light-polluted locations in Rhode Island our “island universe” may only appear as a milky patch of light spanning the sky from north to south. (That is, if it is visible at all.) Some casual stargazers may mistake this glow as thin cirrus clouds. However, it is really the light from some of the 400 billion stars of our Milky Way galaxy.

From a really dark sky location, like that found at Frosty Drew Observatory in Charlestown, one can still observe the spender of the Milky Way as it stretches from the constellation Perseus towards the southern horizon. A pair of binoculars will show beautiful clusters of stars within its boundaries. And if you have a small telescope, just scan up and down the Milky Way’s length with a wide-field eyepiece. You’ll be rewarded with many fine views of dense star fields.

In the region of the constellation of Cygnus the swan (also known as the Northern Cross), the Milky Way divides into two bands, separated by obscuring dust called the Great Rift. Take a look with binoculars to start and scan this area. It is a very beautiful region of space. If you have a telescope of any size, don’t hesitate to sweep this area. Farther along one can find a wide variety of star clusters and nebulae.

In the constellation of Scutum we come to a star cloud of the same name. In a dark sky, your eye will see a much greater expanse of milky haze. This eastern band is one of the brightest in the Milky Way because there is no intervening dust and gas to block our view of the stars. Astronomer E.E. Barnard (1857-1923) wrote, “the stars pile up in great cumulus masses like summer clouds.” A prominent open cluster known as the Wild Duck Nebula can be found here. You can spend many hours exploring the riches of our galaxy. 

Did you know that an observer in a relatively dark sky can see another galaxy with just the naked eye?  After sunset look towards the northeast sky for the constellation of Andromeda. At the top of a chain of fairly bright stars you will notice an elongated fuzzy path of light. This object is the Great Andromeda Galaxy, the nearest spiral galaxy to our own Milky Way. It is a barred spiral like the Milky Way, containing about 400 billion stars. Recent measurements indicate it is 2.5 million light years distant. A pair of 7 X 50 binoculars will reveal a little more of its elongated shape.

Telescopes of increasing aperture will reveal more of the structure of our galactic neighbor. Telescopes at Seagrave and Frosty Drew observatories actually reveal the spiral arms and dust lanes. The view is quite impressive. If clear skies prevail during the open nights at the local observatories, ask one of the volunteer sky interpreters to show you the Great Andromeda Galaxy.

Keep your eyes to the skies.