August 1998

by Steve Stefanik

The planets Pluto, Neptune, Uranus, Jupiter, and Saturn will adorn August’s nightsky. Although you can’t directly observe Pluto without a large telescope and a camera, the pint-sized planet is in the constellation Ophiucus high overhead at dusk. Later this year it will once again be the farthest planet from the sun because its eccentric orbit crosses that of Neptune as it did back in 1979. You may be able to spot the +7.8 magnitude blue planet Neptune and the +5.7 magnitude greenish-blue planet Uranus away from city lights among the stars of the constellation Capricorn in the southeast at nightfall with just your eyes because they are as bright as they are going to get. Neptune just reached opposition from the sun 10 days ago and Uranus will be at opposition tonight. You may be able to make out five of Uranus’ largest moons through a 10 inch telescope or larger.

The next planet to rise is Jupiter. You can’t miss it! At a blazing magnitude -2.8 it clears the treetops in the southeast by 11:00 p.m. Its the brightest thing in the nightsky except for the moon of course. It will dominate the night-time sky in the weeks and months ahead as it approaches opposition in September. Its atmosphere of bright bands and dark shadows contrasted by white festoons and eddies, not to mention the GRS (Great Red Spot) and its four Gallilean moons gayly gliding in front of and behind the planet and each other are enough to captive one for hours.

The planet Saturn rises in the southeast amidst the stars of the constellation Aries about 90 minutes later than Jupiter. Although not nearly as bright as Jupiter, at magnitude 0 its still bright enough to rival the brightest star in the summertime sky, Vega in the constellation Lyra high overhead. Even though Saturn takes a second seat to Jupiter with regard to brightness and size, its rings are fascinating enough to capture anyone’s attention. They will be tipped 17 degrees towards us during this year’s apparition.

Three more planets appear in the morning sky at daybreak. Vibrant Venus at -3.9 magnitude is low in the northeast followed by the relatively dim +1.7 magnitude Mars. Look for the pair about 2 degrees from each other the first week of the month but they begin to separate after that as Mars makes its way toward us and Venus is heading away from us toward the sun. They will be the closest (0.9 degree) on the mornings of the 4th and 5th. Both can be seen near the open star cluster M44 the "beehive" in the constellation Cancer.

Mercury joins the pair making it a threesome on the morning of the 13th but you are not likely to spot the -0.1 magnitude planet until the mornings of the 27th and 28th when it will be about 2 degrees to the right of Venus. From then on it will remain within 3 degrees of Venus until mid-September.

The full "green-corn" moon will undergo a partial penumbral eclipse on the night of August 7th but you probably won’t notice a thing because less than one eighth of the moon will dip into the lighter part of Earth’s shadow.