Fall is rapidly approaching! The days become noticably shorter, the air becomes far less humid, and avid skywatchers notice that different constellations are appearing in the sky. As the Earth moves around the sun, the spring and summer constellations are becoming hidden by the daylight. A new batch of stellar objects are becoming visible, and since the days are shortening, there is ample time for stellar-viewing!
Among the easiest fall objects to see is the Pleiades open star cluster. Located a mere 500 light years from Earth, these young stars appear as a small kite with a tail. On a clear night, six stars are readily visible to the naked eye, albeit somewhat dim. When viewed with binoculars or a telescope, dozens of stars appear in a wider field of view. Without the aid of long-exposure photography, the nebulosity is not easily viewed. However, the Pleiades is one of the easiest star clusters to view with the naked eye, thanks to its proximity to Earth. The real treat is viewing this cluster with optical aid, which is worth the time. Look for the Pleiades shortly after midnight in the east in September. It begins climbing higher in the sky earlier in the evening in October and November.
Next in our tour of the autumn night sky is the constellation Orion, the hunter. One of the brightest constellations in the night sky, Orion is visible even in heavy light pollution. To the top left is the massive red giant Betelgeuse. Betelgeuse’s red color is apparent in a dark sky. To the bottom right is the blue supergiant Rigel. Rigel is actually a triple-star when viewed through a telescope. Ancient peoples used this constellation to denote the beginning of hunting and harvest seasons as winter is inevitably approaching. Orion can be found in the southern half of the sky. The 3 horizontal stars denote Orion’s belt, and the 3 vertical stars are his sword. There’s something special about the center star in Orion’s sword…
In the center of Orion’s sword is the Orion Nebula. In light-polluted skies, it appears as just another star. In dark skies, it appears as a fuzzy star, making it one of the few nebulae visible with the naked eye, though no significant detail can be distinguished. With binoculars, it appears as a very small cloudy star. A telescope reveals it as a star factory, similar to the Lagoon Nebula in Sagittarius during the summer. See if you can make out the Orion Nebula!
Slightly above and to the left of the farthest left star in Orion’s belt is another nebula, Messier 78. M78 is known as a reflection nebula because it reflects the light of the blue supergiant stars that inhabit it. Its a tough find with binoculars, but possible to spot. A telescope makes it easier to find. It will appear as two small clouds, as the finer details are difficult to make out as our eyes aren’t sensitive enough. Be sure to check out this forgotten nebula in Orion!
Below and to the left (southeast) of Orion lies the constellation Canis Major, Orion’s hunting dog. The brightest star in the sky (that is not a planet) is found here. It’s a blue star names Sirius, also known as the Dog Star. In fact, the term “dog days of summer” came from Sirius becoming visible in the morning late in the summer. Sirius is a binary star, with it’s companion becoming visible in a telescope. To the left of the point where the two “hind legs” of the dog come together lies VY Canis Majoris, one of the largest known stars. It is too dim to see with the naked eye, but a star chart and binoculars will get you a glimpse of this red hypergiant. How large is VY Canis Majoris? If it were located where the Sun is, the surface of VY Canis Majoris would extend beyond the orbit of Jupiter! Now that’s one huge star! Try to find this hypergiant, located approximately 3,600 light years away!
Below the “W” that makes up the constellation Cassiopeia is the constellation Perseus, origin point for the acclaimed Perseid meteor shower in August. Both Cassiopeia and Perseus lie in the northern half of the sky. Contained near the top of Perseus and just slightly below Cassiopeia is a special double star cluster. Just barely visible to the naked eye, it’s the jeweled-handle of Perseus’ raised sword. Binoculars and a telescope will provide you with a very unique and breathtaking view of two globular clusters very close together, with hundreds of visible stars between them. A definite must-see for anyone interested in viewing the heavens!
Also easily viewed in a dark sky in the fall is the closest galaxy to the Milky Way, the Andromeda Galaxy. Located between the bottom right point of the “W” and the Great Square of Pegasus, you can view this galaxy with your naked eye on a dark night. It appears as a cloudy smuge in the sky. Binoculars will show it as a larger blur, but a telescope reveals astonishing details! A 6 or 8 inch scope will allow you to see the dust lanes towards the front of the galaxy. The real treat is when its satellite galaxies are visible! M32, the brightest of the two is located above and to the left of the Andromeda Galaxy. It will appear as a bright, fuzzy star as the point of a triangluar formation of stars nearby. M110 is harder to spot, requiring darker skies. It will appear as a faint smudge below and slightly to the right of Andromeda. This triple-galactic treat is sure to amaze! Keep in mind as your viewing that Andromeda is one of the most distant objects you can see with your naked eyes, as it lies about 3 million light years away. Andromeda is speeding towards the Milky Way, and will “collide” and merge with us in a few billion years’ time.
Another galactic treat to view in the fall months is the Triangulum Galaxy, or Messier 33. M33 is a face-on spiral galaxy, also known as the Pinwheel galaxy due to its shape. It’s visible to the naked eye in the very darkest of skies. Look for it straight below the Andromeda Galaxy, as it’s not too far below it. It lies above the right point of the dim triangular constellation Triangulum. It’s somewhat dim, and very easily affected by light pollution, so look for this galaxy on a dark, moonless night. Again, human eyes aren’t sensitive enough to see a great deal of the nebulosity of this galaxy. Instead, what you’ll see with binoculars and a telescope is a group of stars in a pinwheel shape. With a wide-field eyepiece and lower magnification, such as 30-40x, M33 will completely fill your lens.
Last, but not least on our tour is Albireo. Albireo is a double star located in the constellation Cygnus, the giant cross that appears overhead at dusk. Albireo is the foot of the cross. When viewed with the naked eye, Albireo is a dim, unimpressive star. But when it’s viewed with a telescope, it resolves into a binary, with a larger golden-color star and a smaller bluish colored star. It’s a very pretty color combination to see! Try to spot it soon though, as Cygnus is part of the “Summer Triangle”, and sets a few hours after dark. By October and November, it will be too low in the west to see.
The night sky in the fall is full of interesting and amazing objects to view, from naked eye viewing on a dark, cool night, to using a telescope to examine the grandeur of the nearby universe. With the days shortening, there is a lot more time to view the night sky, so be sure to take advantage! You won’t be disappointed with the sights contained in the skies of fall, and you’ll definitely be amazed with a telescope with so many wonderous sights!
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