Night Sky Highlights for October-December 2017
Orionid Meteor Shower
This moderate meteor shower peaks around October 21. Under ideal conditions, perhaps 15-20 meteors per hour can be observed in the early morning hours, when Orion is high in the sky. The Moon is new and will not be a problem, so this is a good year to observe the Orionid shower.
For a week or two during late November, Mercury will be low in the western sky after sunset. It will be farthest from the Sun on November 23, but even then a good view toward the western horizon will be need to see it. Mercury will also be visible in the eastern sky before dawn at the end of December.
Brilliant Venus can be seen in the eastern sky before dawn during October and much of November, but it will be approaching the Sun, and by December it will be too close to the Sun to be visible.
Mars will be visible in the pre-dawn sky throughout the fall, moving from Virgo in October to Libra in December. Although it will be about magnitude 1.5, it will be very far from Earth and will therefore appear very small through a telescope. Its angular size will be only about 4 to 5 arcseconds, about the same as Uranus! On October 5, Mars will be about 0.2 degrees from Venus, so they will easily fit in the same telescopic field.
In October, Jupiter will be too close to the Sun to observe. It then enters the morning sky, and can be seen low in the east before dawn. A good viewing opportunity occurs in the pre-dawn hours of November 13, when Jupiter will be just 0.3 degrees away from brighter Venus.
Bright Saturn will be in the southwestern sky (in Scorpius and Sagittarius) early in the evenings in October and November. Each night it will be getting closer to the Sun, and by the beginning of December it will be very difficult to observe.
Uranus is in Pisces,and it will be well placed for observing in the evenings throughout the fall. If you try to spot it with a telescope, this article from the Sky & Telescope website includes finder charts for both Uranus and Neptune:
Neptune is in Aquarius this year, and like Uranus it will be conveniently placed for telescopic observing throughout the fall.
Deep Sky Objects
The fall sky offers some favorite targets such as the Andromeda Galaxy and the Pleiades, but it also contains a wealth of lesser-known objects that are not hard to find. The 10 objects listed here are either (1) visible to the naked eye, or (2) within a few degrees of a star that is visible to the naked eye. All you need to find them with your telescope are a star chart that lists the Greek letter designations of the stars and the willingness to do a short star-hop.
Mu Cepheus, Herschel’s Garnet Star
Red variable star in Cepheus
This is one of the most colorful stars as seen through binoculars or a telescope. If you think of the constellation Cepheus as forming the shape of a house with a very pointy roof, Mu is in the basement, about halfway between and below the two stars that form the bottom of the house. Its magnitude varies irregularly from 3.6 to 5.0, and at its brightest it is easy to see with the naked eye.
Double star in Aries
The two components of this double star are a matched pair of blue-white stars of magnitudes 4.6 and 4.7, 7.8 arcseconds apart.
Double star in Cassiopeia
You can see Eta with the naked eye as the “sixth star” of the W shape of Cassiopeia. It is 1.8 degrees northeast of Alpha Cassiopeia, the bright star that forms the second angle in the W shape. The two components are magnitudes 3.4 and 7.5, and their colors have been described as gold and purple. They make a very attractive pair.
Open cluster in Cassiopeia
M103 is a small and pretty open cluster with a triangular shape. It is less than 1 degree northeast of Delta Cassiopeia, the star that forms the first angle of Cassiopeia’s W shape. After observing M103, you can move your scope another degree or so to the northeast and search for three other open clusters of varying sizes and brightness, NGC 654, 659, and 666.
Open cluster in Perseus
This is a nice open cluster about the size of the full Moon, with stars that seem to form a pinwheel shape. It can be found about 1.6 degrees northeast of Lambda Perseus.
Messier 1, the Crab Nebula
Supernova remnant in Taurus
This fuzzy irregular patch is what remains of the bright supernova that appeared in the sky in 1054. Through a telescope it appears pretty dim, but it is not hard to locate, about 1 degree northwest of Zeta Tauri, the tip of the southern “horn” of Tauris’s bull-head shape.
Open cluster in Taurus
Use low power for this is a nice open cluster of about 50 stars that spans an area about the size of the full Moon. It is just to the east of the naked-eye Hyades cluster, about 3 degrees northeast of bright red Aldebaran.
Globular cluster in Pegasus
At magnitude 6.3, M15 is one of the brightest globular clusters in the sky. This is a superb object to observe at high magnification. It is very condensed and has a bright center. It can be found about 4 degrees to the northwest of Epsilon Pegasi.
NGC 404, Mirach’s Ghost
Galaxy in Andromeda
Mirach, or Beta Andromeda, is a magnitude 2 star that is very easy to spot with the naked eye. Get Mirach in the center of your eyepiece, and then look just 7 arcminutes (about 0.1 degree) to the northwest and see if you can spot a small circular fuzzy ball. This is the elliptical galaxy NGC 404, about 10 million light years away. Despite the proximity of bright Mirach, NGC 404 is not very hard to see with a medium-sized telescope.
Galaxy in Pisces
This face-on spiral galaxy is about magnitude 9, but its low surface brightness makes it one of the hardest Messier objects to observe. Start by pointing at Eta Pisces, magnitude 3.6, then move about 1.3 degrees to the east and a little north to find Messier 74. This galaxy is about 33 million light years away.