October’s Orionids Bring Meteor Showers To Central Mass.

Saturday, October 12, 2013

Dave Huestis, GoLocalWorcester Astronomy Expert

October is a month with a variety of interesting astonomical events, including the Orionid meteor shower, a Full Hunter's Moon and a penumbral lunar eclipse.

Hunter's Moon + eclipse

The Full Hunter’s Moon occurs on October 18, but more importantly that evening we will be treated to a penumbral lunar eclipse. For a lunar eclipse to occur the Sun, Earth and Moon must be nearly in a straight line with the Earth in the middle of this alignment. The reason why lunar eclipses do not occur monthly is because the Moon usually passes north or south of the Earth’s shadow in space.

Unfortunately we will not experience a partial or total lunar eclipse because the Moon will not move into the Earth’s darker umbral shadow. Instead, the Moon will slide into a pale portion of the shadow called the penumbra. You will need to watch it closely and carefully. Many people will not notice anything different about the Moon unless they have followed the eclipse's progress throughout the evening.

Though the eclipse will begin at 5:50pm (first contact), this event cannot be seen. The Moon is only then beginning to slip into the dim penumbral shadow. Besides, it will have just risen at 5:47pm and will be close to the horizon. Only as the eclipse progresses will an observer see a slight darkening of the lunar surface as the Earth's penumbral shadow sweeps across it from south (bottom) to north (top). Mid-eclipse, or maximum, will occur at 7:50pm when 76% of the lunar disk will be within the penumbral shadow. At that time an informed observer should notice the subtle shading of the southern portion of the moon. The northern 24% will remain unchanged.

After mid-eclipse the Moon will begin to move out of the penumbral shadow and the lunar surface will brighten from north to south, returning the Moon to its normal brightness at 9:49pm. This event, like first contact, will be unobservable. (The next total lunar eclipse visible from southern New England will occur in 2014 on April 15.)

Orionids over Central Massachusetts

Three days later on the evening of October 21st to the early morning of the 22nd the annual Orionid meteor shower will grace our skies. Unfortunately the still bright waning gibbous Moon will

interfere with observing the peak rate of 20 or so yellow and green meteors per hour. However, the Orionids are also noted for producing fireballs that create persistent dust trains high in the atmosphere, so it might still deserve a few hours of your time if clear skies prevail.

The meteors appear to radiate out of the sky just above Orion’s head (hence the name of the shower) and not far from the bright red super giant star Betelgeuse, which marks his right shoulder. While Orion is an easy star pattern to identify, at 3:30am this giant constellation will be due south of your location and about halfway up above the horizon. That pesky Moon, nestled among the V-shaped Hyades cluster of stars in Taurus, will be very close to the shower’s radiant point. Try to block the Moon from your vision to maximize your meteor count.

The best activity should occur between midnight and dawn. The particles we will see disintegrating in our atmosphere at around 41.6 miles per second are the remnants of Halley’s Comet.

Wishing you clear skies for all your astronomical endeavors.