October 2005 Skies

October marks the first full month of Autumn (Fall).
Mars will be seen to rise earlier each evening and to dominate the nighttime sky in October.
A partial lunar eclipse occurs the morning of October 17th.
Many of Summer’s spectacular stars and constellations remain visible most of the night, while some prominent Winter stars are also good stargazing targets during October.

The summer and winter Milky Way presents especially good opportunities for binocular and small telescope viewing.

The SUN now resides south of the Celestial Equator until the 1st day of Spring next March. This means the Sun rises South of East and sets South of West until springtime and rides lower in the sky than during Spring & Summer. Also, our nights are longer than the days.
The Sun begins October already in the constellation VIRGO and remains there nearly all month. It does not enter the next zodiac constellation, LIBRA, until October 31st.

The Moon:
October’s NEW MOON occurs on the morning of the 3rd in Virgo.
The 1st QUARTER MOON is seen on October 10th in SAGITTARIUS.
October’s FULL MOON occurs the morning of October 17th in PISCES. We will see it rise shortly before sunset the previous evening and shortly after sunset the evening of the 17th.

The 3rd QUARTER Moon occurs on October 24th on the GEMINI-CANCER border.

October’s Full Moon on the 17th is somewhat unusual in that it is accompanied by a partial LUNAR ECLIPSE.  This event occurs in the constellation PISCES before dawn the morning of the 17th (see below: The Morning Sky).

In October the Moon can be seen to pass near all five naked-eye planets:
MERCURY & JUPITER: in VIRGO VERY low and a bit South of West about 6:25p.m. the evening of October 4th. Jupiter will appear like a bright star. The Moon is found left of Jupiter; Mercury is fainter, below Jupiter and closer to the horizon.
VENUS: in LIBRA low in the Southwest the evening of October 6th.
MARS: in  ARIES overnight the 18th – 19th.
SATURN: in CANCER before dawn on the mornings of the 25th & 26th.

The Moon also passes near these prominent stars:
Crescent Moon near Antares in SCORPIO the evening of the 7th.
Waning Gibbous Moon near the Pleiades star cluster overnight the 19th-20th.
3rd Quarter Moon near Pollux in Gemini the morning of October 24th
Very thin crescent Moon near the bright star SPICA in Virgo at dawn on the 31st.

The Evening Sky:
The Sun: Sunset on the 1st in Central Arizona occurs about 6:05p.m..  As winter approaches, we should notice our Autumn evenings lengthening and our sunsets occurring a bit later each day.  By month end the Sun will set at 5:30p.m.

Evening Planets.  Mercury, Venus, Mars, and Jupiter.:
Mercury remains an evening planet all month, but stays very near the Sun in the sky.  Mercury starts October in VIRGO, moves into LIBRA on October 13th, and further East into SCORPIO on October 29th. Although Mercury will not be seen in a dark sky (just in a darkening on), try to glimpse it with binoculars low in the Southwest after sunset.  Mercury begins the month only 10 degrees from the Sun and widens that gap all month.  So, each evening in October Mercury will set a bit later than the Sun and should be a bit easier to view.
A good time to spot Mercury will be when it passes the 2nd magnitude star Delta Scorpii on Oct. 31st and Nov. 1st.

Jupiter begins the month low in the West only 15-degrees from the Sun. On the 1st, it is still bright enough to be seen very low above the horizon about 20-30 minutes after sunset. Each day thereafter, Jupiter moves closer to the Sun before passing the Sun and entering the morning sky on October 22nd. For the rest of the month, Jupiter is too close to the Sun to be observed.

Observers with good binoculars and a CLEAR VIEW TO THE HORIZON should look for Jupiter, Mercury & Spica in a vertical line and the day-old Moon to the left (South) of Jupiter on October 4th about 20 minutes after sunset.

Venus, the brightest object in the night sky after the Moon, begins the month low in the Southwest in Libra. It moves quickly Eastward across Libra and into Scorpio on October 8th, then on into OPHIUCHUS on the 23rd. Through a telescope, one can see brilliant white Venus is not round, but appears only about 65% illuminated early in the month. By October 31st, Venus has shrunk to 50% illuminated (like a 1st Quarter Moon).
Look for the Moon below and to the right of Venus on the evening of October 6th.

Venus passes about the width of the Full Moon away from 2nd magnitude Delta Scorpii on the evenings of October 8th, 9th, and 10th.

Venus slowly passes the bright star ANTARES in Scorpio over several evenings in mid-month. The star and planet are closest on the 15th & 16th.

Mars and Earth continue to approach as Mars nears opposition in early November. On October 1st, Mars is about 49 million miles from Earth and appears 93% illuminated; by month end, Mars is only 43 million miles away and is 99% illuminated. On October 1st Mars begins Retrograde (or Westward) motion vs. the stars. On the 9th Mars moves westward from Taurus into Aries, where it remains for the rest of the month.
Dark nights in October will provide excellent opportunities for telescopic viewing of Mars.

The Morning Sky:
Early October sunrises occur shortly after 6:25a.m. but, by the 31st, the sun will not rise until 6:50a.m. Look for the waning crescent MOON on October 1st low in the East before dawn.  The next morning it will be lost in the Sun’s glare.

A VERY Partial Lunar Eclipse will be visible from Arizona before sunrise on the morning of October 17th. At the middle of this eclipse (about 5:00a.m.), only about 5%-6% of the Moon will be covered by the Earth’s shadow.  If you miss it, however, you must wait until 2007 for the next lunar eclipse to be visible from Arizona!

The eclipse starts at about 4:36a.m. when the Moon is 24-degrees above the Western horizon, and it ends at about 5:26a.m., 70 minutes before sunrise.

Partial lunar eclipses are also of limited astronomical interest, but this eclipse will probably be broadcast over the Internet.

Morning Planet.  Saturn.
Saturn remains in CANCER the Zodiac crab all month. It rises about 1:40a.m. on the 1st and at 10 minutes before midnight on the 31st.
Telescopic observers can watch Saturn slowly pass by the 7th magnitude star SAO 98161 on the mornings of the 15th – 18th.

What Else to See?  An Annular (Ring) Eclipse of the Sun occurs before dawn on October 3rd, so it will not be visible from Arizona. However, observers in Europe and North Africa will see either a partial or total annular eclipse. An annular eclipse shows a complete ring of sunlight around the dark Moon, and happens because the Moon is too far away from Earth to completely cover up the Sun.  Although this type of solar eclipse is of limited astronomical interest, the event may be broadcast over the Internet.  Try using an Internet search engine on the 16th to locate web sites with live eclipse broadcasts or real-time posting of digital photos to the Internet.

Several close positionings of the Moon and a planet or star are listed above.  However, observers with small telescopes can watch the Moon occult (pass in front of) several stars of 6th magnitude or brighter near mid-month.  These occur as the Moon moves through the constellations of Capricornus, Aquarius, Pisces, Aries & Taurus on October 12, 14, 16, 17, 19, 20 & 21st.  See the list, along with disappearance & reappearance times here.

Early October will be the last opportunity of the season to view the constellations SCORPIO and SAGITTARIUS in the heart of the summer Milky Way.  Several impressive stars, star clusters, and nebulae set earlier each evening until they are too low in the Southwest to be observed by month-end.  However, the Moon complicates the picture, and prevents observing faint Milky Way objects from the 7th through the 16th.
The rest of the summer Milky Way is found higher in the sky in October.  Since the Moon rises later each evening (after 10p.m. on the 22nd), there should be several of dark late-October evenings to continue viewing late-Summer sky objects.

Binoculars or a small telescope will also help you observe many interesting WINTER Milky Way objects, as they start to become visible in the Eastern sky this month.  Look for the Pleiades star cluster to rise at about 8:30p.m. in the Northeast on the 1st (and about 2 hours earlier on the 31st).  Also of interest are the star-rich Winter Milky Way Constellations of CASSIOPEIA, PERSEUS, AURIGA and GEMINI.  Look for the famous “Double Cluster” of two adjacent star clusters midway between Perseus and Cassiopeia low in the East at 8:p.m. on October 1st. Auriga rises by 10:30p.m. and Gemini rises by 12:30a.m.

Good Luck Observing!