In the Transient Sky – October 2012

October 2012 Highlights
* Orionid meteor shower peaks on the night of October 20-21
* Venus and Regulus pair up on the morning of the 3rd
* Mars and Antares pair up on the evening of the 20th

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Mercury – For northern hemisphere observers, Mercury spends the month in a very poor evening apparition. The best time to try and spot Mercury will be on the 16th when a very young, day old Moon is just to the lower right of Mercury. South of the equator, the show is much better as this is one of Mercury’s best evening apparitions of the year.

Mars - Continuing its slow descent towards the Sun in the evening, Mars glows at a rather meager +1.2 magnitude. On the 20th and for a few days on either side of that date, Mars pairs up with its nemesis, Antares (in ancient Greek, ‘the anti-Mars’). Antares is just a bit brighter than Mars at magnitude +1.1 and both objects are red. You can spot the two low in the SW at the end of evening twilight. The Moon joins the show on the evenings of the 17th and 18th.

Morning Planets

Jupiter – Jupiter rises around 10-11 pm at the start of the month and around 8-9 pm at the end of the month. Still it is considered a morning object because it reaches its highest point in the sky after midnight. Shining between magnitude -2.5 to -2.7, it is the brightest object in the night sky after the Moon and Venus. This month Jupiter is slowly traveling among the picturesque stars of the winter Milky Way constellation of Taurus as it heads towards opposition on December 3rd. The Moon passes nearby on the nights of Oct. 5th and 6th.

Venus – Venus rises about 3.5 hours before the Sun this month. In a telescope the planet will appear more than half-illuminated (about 70-80%). At magnitude – 4.1, Venus is by far the brightest ‘star’ in the morning sky. October sees Venus make a tight pair (0.2°) with Regulus, the brightest star in Leo, on the 3rd. The Moon also passes to the south of Venus on the morning of the 12th.

Saturn – The ringed planet is too close to the Sun to be easily seen this month.

Meteors

The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. Meteor activity is at an annual peak this month.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During October mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Orionids (ORI) [Max Date = Oct 21, Max ZHR = ~35-45 per hour]

The Orionids are one of the most reliable and productive showers of the year. Another point in their favor is their high level of activity over the course of ~5 nights or so. This gives ample opportunity to catch a few Orionid meteors. This year the waxing Moon will set before midnight making for nice dark skies during the prime Orionid-watching early morning hours.

The meteors that make up the Orionid shower were originally released by the one comet everyone has heard of, Comet Halley. Computer simulations of the past movements of Halley and its dust suggest that many of this year’s Orionid meteors were released by Halley between 1265 BC and 910 BC (for some points of reference, the Trojan War took place around 1200 BC and King David ruled around 1000 BC).

The Orionids are usually active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. During their peak, rates can be as high as 20-70 meteors per hour. During the last two years ZHRs reached 35-45 meteors per hour which is nearly half the rate observed in 2007 (70 per hour). This year’s activity should be similar to the last few years.

The Orionids appear to come from an area in northern Orion. This area, called the radiant, rises around 10pm local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 1am). The radiant is highest around 3:30am which is the best time to look. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month.

Binocular Comets (V = 6.0 – 8.0)

None this month

Small Telescope Comets (V = 8.0 – 10.0)

None this month

Meteor Activity Outlook for September 1-7, 2012

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

September offers longer nights in the northern hemisphere that tend to be less hazy than those experienced in mid-summer. In the sky, no major showers are visible from either hemisphere but the northern hemisphere enjoys the advantage of higher sporadic rates. Most of the shower activity this month is produced from the Perseus-Aurigid complex active this time of year. These showers rarely produce more than five meteors per hour but still manage to produce most of the shower activity seen this month. Unfortunately the Perseus-Aurigid complex lies too low in the northern sky for southern hemisphere observers to view very well. Video studies have shown that the Southern Taurids are visible as early as September 7th, therefore after this date the Antihelion radiant will no longer be listed until the Taurid showers end in December. The Antihelion meteors are still active but their radiant is superimposed upon that of the more numerous Taurids, therefore it is impossible to properly separate these meteors. Observers in the southern hemisphere suffer from some of their lowest rates of the year this month. The Southern Taurid radiant is not too badly placed so observers south can expect to see a little of this activity this month.

During this period the moon wanes from its full phase to nearly last quarter. These are the worst circumstances possible for meteor watchers as the moon will interfere with observing all week long as it will be present in the morning sky when meteor rates are at their best. The bright glare of the moonlight will obscure all but the brightest meteors reducing rates significantly. The estimated total hourly meteor rates for evening observers this week is near three for observers located at mid-northern latitudes and two for observers in mid-southern latitudes. For morning observers the estimated total hourly rates should be near eight from the mid-northern hemisphere and four from the mid-southern hemisphere. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Rates are reduced during this period due to the intense moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning September 1/2. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiants are expected to be active this week. Detailed descriptions of each source will continue next week when moonlight will not be such a problem.

Antihelions (ANT) – 23:28 (352) -02   Velocity 30km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

September Epsilon Perseids (SPE)  03:52 (043) +41  Velocity 61km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – <1 per hour

IMO #149  04:52 (073) +45   Velocity 70km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Aurigids (AUR) – 06:16 (094) +40   Velocity 67km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

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