Harvest Moon Arrives in October
The signs of autumn are now upon us. When I look out the window, before sunrise and after a clear night, I notice heavy frost has made its appearance on the roofs of houses in the neighbourhood. Trees are losing their coloured leaves. Many of the flowers planted for the summer season have succumbed to the cold night air and frost attacks. What I have noticed over the past few weeks is that the days are shorter and the darkness of night falls earlier.
An interesting phenomenon is when the moon passes in front of brighter stars in its course through the sky as it orbits the earth. Due to the position of the moon’s orbit at this time the moon will pass in front (occult) of many bright stars in the Pleiades star cluster (M45). This event happened three times earlier this year but the moon and cluster has either been too low to the horizon to be easily seen or occurred during the daytime as seen from Thunder Bay. On the night of October 9-10 the waning gibbous moon will occult stars in the Pleiades. The event will begin just before midnight on October 9 as the illuminated edge of the moon enters the star cluster. The moon will be around 30 degrees above the eastern horizon at that time. With the moon 86 percent lit, a small telescope will be needed to follow the stars through the moonlight glare up to the moon’s illuminated edge. The stars will blink out instantaneously as they pass behind the lunar disk. The stars will be much easier to see when they pop out from behind the moon’s trailing dark limb. It will take the moon about two hours to make its way in front of the stars in the Pleiades cluster.
The brightest star in the Pleiades is Alcyone at a magnitude of 2.86 and is located close to the centre of the star cluster. From Thunder Bay it disappears at 1:10 a.m. EDT and reappears at 2:08 a.m. EDT. Be prepared for these events before the predicted times as they will vary earlier or later depending on the observer’s location.
Meteor watchers will get a break from the bright moonlight for the Orionid meteor shower this year. The Orionids will peak on the night of October 21, a day before new moon. These meteors are some of the fastest of any of the meteor showers. They enter the Earth’s atmosphere at a speed of around 66 kilometers per second leaving persistent trains (glowing trails of ionized gas created by the dust particles burning up). This meteor shower can produce hourly rates of around 20 meteors per hour and appears to radiate from a point near the “Club” asterism in the northeastern area of the constellation of Orion where it borders the neighbouring constellation of Gemini. The Orionid meteors are residual particles and dust left by the passage of Comet 1P/Halley (Halley’s Comet) through the inner solar system over the years. The Earth passes through this debris trail to produce two fine meteor showers (the Orionids in October and the Eta Aquarids in May). The best time to view the meteors is between midnight and dawn when the sky is darkest. A dark site away from the lights of the city will make meteor spotting easier as well. The temperature this time of year on a clear night is not very cold but meteor observing is not a vigorous activity so becoming chilled will cut short observing time. I will generally dress for winter conditions to be comfortable during meteor observing. It is easier to remove a sweater than to wish that I had one on.
At the beginning of October Jupiter can be found low in the southwest an hour after sunset. For early morning observers Saturn can be spotted about 30 degrees above the eastern horizon an hour before sunrise. Saturn is located in the constellation of Leo near the head of the Lion.
The full moon in September is usually designated as the Harvest Moon. The Harvest Moon is defined as the full moon nearest the autumnal equinox. Since the equinox occurred on September 23 this year the closest full moon to it occurs on October 6. The full moon in September was on Sept. 7, 16 days before the equinox. The full moon of October will be on Oct. 6, only 13 days from equinox. These facts place the Harvest Moon in October in 2006. This is almost the latest that a Harvest Moon can happen in any year.
Finally, Daylight Savings Time ends and Standard Time begins on Sunday, October 29 so remember to set your clocks back one hour before bedtime Saturday night.
Clear Skies
Ted Bronson