What's Up in the Night Sky

October 2024 - Vol. 28, No. 10

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

Although the Summer Triangle is still visible in the W, the "Great Square of Pegasus" is now prominent high in the S. Far below, lonely Fomalhaut [FOE-ma-lot] of Piscis Austrinus still glitters near the S horizon. Between Pegasus and the N pole star, Polaris (Ursa Minor), find the familiar "W" shaped asterism of Cassiopeia. If you are fortunate to be viewing from a dark site, you will also see the constellations, Perseus and Auriga, with its bright star, Capella, embedded in a starry band stretching across the night sky from East to West. You are looking at the Milky Way, one of the spiral arms of our galaxy. In the East the constellations, Gemini, with its bright twin stars, Castor and Pollux, and Orion, with its distinctive hour glass asterism, rise above the Eastern horizon. Now the Big Dipper (Ursa Major) dips low in the North.

MERCURY emerges slowly into the evening sky this month, favoring southern observers. VENUS in the evening sky, also favoring the southern hemisphere. MARS moves from Gemini into Cancer on the 30th, shining at magnitude 0.3 by month's end. JUPITER reaches its first stationary point on October 9, hovering between the horns of the Bull. SATURN after its September 8th opposition, remains in the sky most of the night, obscured again this month by the Moon on the night of the 14th. URANUS, in retrograde motion, continues toward its opposition on November 17. NEPTUNE is in Pisces, just past opposition.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
01	The Zodiacal Light or "false dawn" is visible in the E about 2 hours before sunrise. This pyramidal glow is caused by meteoroids, dust particles spawned by passing comets, etc., that have settled into the ecliptic plane (path followed by the Sun, Moon and planets), reflecting the Sun’s light before it rises here. This phenomenon will be visible until about October 14th although the Moon may interfere.
02	Annular solar eclipse visible from Chile and Argentina. The moon will cover 93% of the Sun's disk for 7 min 25 seconds at greatest eclipse far away from land in the south Pacific Ocean. Moon at apogee.
05	Venus 3 deg. N. of Moon.
07	Alpha Scorpii, Antares, 0.2 deg. S. of Moon, occultation from Galapagos Is., Easter Is., S. half of S. America, SW edge of Africa.
09	Jupiter stationary.
14	Mars at western quadrature. Saturn 0.1 deg. S. of the Moon, occultation from parts of Ascension Is., S and E Africa, Madagascar, SE Arabian Peninsula, most of Asia, China and Mongolia.
15	Neptune 0.6 deg. S. of Moon, occultation from parts of Africa, Middle East, NW India, NW half of China, C. Russia, and N. Japan.
17	October's full moon is often called the "Hunter's Moon" because it is the time of year that native Americans hunted and stored meat for winter. Because the Moon is at perigee, it will be called a "supermoon" by the media. Moon at perigee, expect large tides.
19	Uranus 4 deg. S. of the Moon. Moon 0.2 deg. N. of the Pleiades star cluster (M-45).
21	Orionids meteor shower peak. This shower produces up to 20 meteors per hour. Meteors in this shower are generated by Halley's comet. The orbit of this periodic comet leaves a trail of dust particles on its way to the Sun. This trail of particles remains in this area of space until they encounter the Earth's orbit. This produces the annual shower. Jupiter 6 deg. S. of Moon.
23	Mercury at aphelion. Mars 4 deg. S. of Moon. Alpha Geminorum, Pollux, 1.7 deg. N. of Moon.
29	Moon at apogee.
30	Venus at aphelion.
31	Alpha Virginis, Spica, 0.5 deg. S. of Moon.

Lunar Almanac for September 2024

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 02	Deep Space Objects
	1st. Qtr 10	Planets & Moon
	Full 17	Moon
	Last Qtr 24	Deep Space & Planets

Topic of the month: The Winged Horse, Pegasus

The evening sky welcomes the northern hemisphere to longer nights and views of the celestial vault; while in the south, night is shrinking and Spring has arrived. Soon after darkness falls, the Great Square of Pegasus is now fully risen above the eastern horizon. An ancient constellation fairly easily recognized as four stars trace out the shape of a square. These are Markab, Sheat, Algenib and a fourth star, officially attributed to the adjoining constellation of Andromeda, the star Alpheratz. This "great square" has been a valuable guide for navigators and astronomer's alike. Another prominent star in the constellation is the Epsilan Pegasi, Enif that is said to represent the "nose" of the horse. Pegasus, like many other constellations, only represents the front half of the horse including the wings. Pegasus is also notable as it lies on the 0 hour of right ascension. Each side of the square covers 15 degrees of the sky, lying in a north-south direction.

The constellation of Pegasus against a celestial grid

Two stars, Alpheratz and Algenib point to the position of Spring equinox, the position of the Sun on the first day of Spring, about as far below them as the distance of their separation. There is no special star to mark this position, but it may help to understand how the stars appear to rotate around the Earth on the celestial sphere. Markab is considered to be the alpha star of the constellation, its magnitude is 2.5, consequently there are no first magnitude stars in the constellation. The star 1 Peg at magnitude 4.1 is a nice double, a yellow star with a mag 9 companion visible in small telescopes.

There are some wonderful objects in the constellation of Pegasus, including the bright globular cluster M-15. It is one of the most beautiful clusters in the northern sky, about 4 deg N. of Enif. The core of this cluster is very bright, occupied by a host of 13th magnitude stars, that may be seen in a larger instrument at 175x. Another favorite galaxy in the constellation is NGC 7331, a 10th magnitude spiral galaxy about 40 million light years away. This galaxy is often used to illustrate how the Milky Way would appear from a distance. It is a type Sb spiral, tipped about 20 degrees toward us. It has 4 known companion galaxies that also have NGC numbers.

The Great Square of Pegasus is also used to find the closest large galaxy to the Milky Way in the nearby Andromeda constellation. The spiral galaxy M-31 also known as the Andromeda Galaxy is so bright that it can appear to the naked eye as a fuzzy patch, broader than the Moon.

--See You Under the Stars!
Astra for Astra's Almanac

The star chart above was generated by Stellarium, a free open source planetarium program. The above image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. Editing was done for educational purposes only. Stellarium offers much more to amateur astronomers and is being used in planetariums and to guide telescopes in the field. Simple charts like the one above can be used on the internet for non-profit, illustration purposes. Proper credit is due of course! Thank you to the makers of this fine program from Astra's Star Gate.

--See You Under the Stars!
Astra for Astra's Almanac