Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into four sections: what you can see with the naked eye, with binoculars, with a small refracting telescope and with a Dobsonian reflector. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on August 2nd. For August, your best viewing nights will be from August 1st to the 8th and the 22nd to the 31st. The Star chart below is set for Florence, SC on August 15th at 9 pm. Note: A table of contents for earlier columns is located in the February 2016 column.
The Perseids Meteor Shower:
A meteor shower is when a large number of meteors can be seen during one or two nights. There are three good meteor showers each year, each occurring around mid-month in August, November and December. Over the last several years, in my opinion, the December Geminids yielded the best shower. The favorite shower for most amateurs, however, is the Perseids which occur this month. This shower is favored because it occurs when the weather is warm, and during summer vacation time. I agree that these are good reasons to stay up past midnight and look to the heavens from a lawn chair. My personal observed maximum for this shower was 60 meteors per hour.
A detailed description of meteor showers and various observation methods is found in my August 2015 column; just scan down in this blog to read it. In that description, you will find that the best time to view a meteor shower for maximum rate of meteors is after midnight; even better would be about 3 am. If you have trouble staying up that late, you may be able to see a notable amount of meteors before midnight. Another major factor in viewing a meteor shower is the Moon. If astronomers predict a meteor shower of ~100 per hour, this is based on a dark sky site, with no interference from the Moon. A full or nearly full Moon will wash out the vast majority of meteors. If the shower occurs during a favorable new Moon, viewing from a neighborhood back yard can also wash out the majority of meteors.
The Perseids meteor shower this month will peak on the morning of August 12th. The lunar phase on the evening of August 11th will be about a nine-day-old Moon heading toward a full Moon on August 18th. (Allow me to digress: For clarity, amateur astronomers like to discuss lunar phases by the age of the lunar cycle. Therefore, a first quarter Moon is about a seven day Moon, and a full Moon is about a fourteen day Moon. So by knowing it is a nine-day Moon, you can have a clearer image of lunar cycle, and when the Moon will set.) Returning to the 11th and 12th. The nine-day-old Moon will set at 1 am. Therefore, 1 am forward should offer excellent viewing of the meteor shower, and as I mentioned before, this coincides with the best viewing times for most meteors showers. For the people who can’t stay up this late, try this. Go to bed early, and have a designated meteor watcher who stays up. If it is a great meteor shower, he or she can wake up the other family members.
One final comment about this Perseids shower. It is quite difficult for astronomers to give accurate predictions of the meteor rate per hour for any meteor shower. This year, two astronomers noted that the stream of comet debris responsible for the Perseids shower passed quite close to Jupiter this year, which they predict moved the debris field closer to the Earth’s orbit. With this in mind, they are predicting a meteor rate of 100 to 150 per hour. Personally I am quite skeptical about that rate, but I will check it out and hope.
So go out late at night on August 11th into early August 12th. If the predictions are wrong, then it can be fun just sitting out in the backyard on a warm night hoping to see some meteors; at least for the designated meteor watcher.
The three planets of this summer have now been reduced to two as Jupiter finally sets in the west this month. However, Saturn and Mars remain, both near or in the constellation Scorpius. For amateurs who like attention to detail, Saturn is actually in the constellation Ophiuchus all month. Mars begins in Libra, moving through Scorpius, and into Ophiuchus by month’s end. Saturn being much farther away appears stationary, but you will easily see the daily movement of Mars through Scorpius.
You can see the rings of Saturn with a simple 60-100 mm refractor, starting at 25power, but better viewed at about 50 power or above. A 6-8 inch Dob should give you even better views of the ringed planet. Whichever way you choose to view the ringed planet, your views may suffer due to the high temperatures and humidity this summer.
Mars is best viewed through high end (expensive) refractors. If you can find a clear night in the summer heat, the larger Dobs should give you a nice view of the Red Planet.
Naked Eye Sights: The Perseids meteor shower on the morning of August 12th. The Summer Milky Way.
Binocular Sights (7 to 10 power): Scan the southern skies between Scorpius and Sagittarius and upward following the Milky Way picking out the several clusters and nebulae.
Telescope Sights (60-100mm): Saturn is the best target. Also the crescent Moon the 6th through the 9th.
Dobsonian telescope (6 -8 inch): Saturn and Mars. Some of the clusters and nebulae in the Milky Way. First find them with your binoculars and then aim your Dob at the targets.
See you next month!