The Sky in November 2017
by Dee Sharples –
November is here. Daylight saving time ends and clocks will be set back one hour to standard time on the 5th of the month. Looking up at the night sky will become more convenient since it will get dark earlier and earlier as the month progresses.
Pegasus, the winged horse, is a prominent constellation in the fall. After November 5th around 8:00 to 9:00 p.m. look high in the south for four fairly bright stars of similar magnitude (2.1, 2.4, 2.5, and 2.8) which will resemble a large square, an asterism (group of stars) called the Great Square of Pegasus. Many fainter stars complete the constellation which in Greek mythology was a horse with wings.
If you’d like a challenge, you can use this asterism to star-hop to Andromeda, a beautiful spiral galaxy, which is the most distant object that can be seen with the naked eye. Star-hopping is like using a road map and will help you reach your destination in the night sky. I use it to locate astronomical objects through my telescope. Although many telescopes today are computerized and will do the work for you, mine is manual. With computerized telescopes, observers only need to enter the name of the object they’re searching for and the telescope will automatically point to the exact location in the sky.
To star-hop to Andromeda with your unaided eye, start at the brightest star in the Great Square of Pegasus. It’s the star that forms the upper left corner of the square (Alpheratz – magnitude 2.1). Move up and to the left about l5 degrees (1 ½ fist widths) and you’ll see a star of similar brightest (Mirach – magnitude 2.0). Then star-hop about 8 degrees (less than 1 fist width) higher up and toward the right. Halfway there you’ll pass a dimmer star and then reach a spot in the sky where there doesn’t appear to be any visible stars. Let your eyes slowly scan this small area looking for a faint smudge of light. When you catch sight of it, don’t look directly at it but look slightly away with what astronomers call your “averted vision” or peripheral vision. Each person may be different but the sweet spot of my averted vision for seeing a dim object in the night sky is when I look slightly above that object. If you have binoculars, you can also use them to find this galaxy. The magnification will reveal a larger oval shape, but it will still look like a hazy patch of light.
The Andromeda galaxy is slightly more than twice as big as our own Milky Way galaxy and is about 2.5 million light years from Earth. A light year is the distance light travels in one year and is a simpler way to express the enormous distances in space. One light year is almost 6 trillion miles which makes Andromeda about 15 quintillion miles (15,000,000,000,000,000,000 miles) from Earth. The light from this galaxy has traveled 2.5 million years to reach our eyes today.
The sky in the Finger Lakes area is much darker than the light-polluted sky near the city of Rochester so if you pick a clear moonless night, you’ll have a good chance of seeing this distant galaxy with your own eyes. Pegasus and Andromeda will be in our night sky for a few months, rising in the east about 30 minutes earlier each week so if you can’t spot it the first time, there’ll be other opportunities.
The Leonid meteor shower is active from November 6-30, but it peaks in the early morning hours of Friday, November 17th. The best views will be from 3:00 to 5:00 a.m. when the constellation Leo the Lion will be high in the southeastern sky. Leo’s brightest stars form the outline of a backwards question mark. There won’t be a bright Moon in the sky to wash out the fainter meteors so people in a dark sky area can expect to see about 10 meteors per hour at the peak.
These meteors are actually particles of dust and debris left by Comet Temple-Tuttle as it passes through our solar system every 33 years. As the Earth orbits the Sun, once a year it travels through this stream of debris. The particles enter our atmosphere traveling at speeds of 44 miles per second and burn up creating meteors. This is the fastest speed of any meteor shower and also the reason why the Leonid shower produces many fireballs, extremely bright meteors that blaze across the sky.
Be sure to dress very warm, make yourself comfortable in a chair facing southeast, and leisurely scan the sky with your naked eye. When viewing meteor showers, binoculars won’t help. The meteors can be seen anywhere in the sky but they will appear to originate from the constellation Leo the Lion.
Early morning risers will see the bright planet Venus rising in the southeast one hour before the Sun, shining at a dazzling magnitude -3.9. On November 13th, Venus and the planet Jupiter will meet in a close conjunction 30 minutes before sunrise. Venus will be just one-third of a degree to the left of dimmer Jupiter which will shine at only magnitude 1.7. One-third of a degree is less than your little finger held out at arm’s length against the sky.
On November 16th a beautiful sight awaits you in the pre-dawn sky. Before the Sun rises, Jupiter will appear 3 degrees above Venus with a slender crescent Moon joining them 6 degrees above Jupiter.
Whether early morning or night, take a few minutes to look up at the sky.
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Magnitude:
Measures the apparent brightness of a celestial object and is expressed by a decimal. The larger the number, the dimmer the object.
Sun: -26.7
Full Mon: -12.6
Venus at its brightest: -4.4
Bright star: 0.0
Dimmest star visible with the unaided eye: 6.0
How to measure degrees in the sky: A simple “ruler” is to hold your arm straight out and make a fist. The area of the sky covered by your fist measures roughly 10 degrees. By moving your fist and counting how many “fist widths” it takes to reach an object in the sky, you’ll have an approximation of degrees.
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Dee Sharples is an amateur astronomer who enjoys observing planets, star clusters and the Moon through her telescope. She is a member of ASRAS (Astronomy Section of the Rochester Academy of Science) and records “Dee’s Sky This Month”, describing what can be seen in the sky, on the ASRAS website at rochesterastronomy.org. Watch for her monthly Owl Light News feature to learn more about the night sky.