Spotting a planetary pair

Clouds ... again. Only these were not the all-over-cover-the sky kind; rather, they blocked a strip of sky right along the western horizon -- right where I wanted to look; of course.

The clouds partly hid the conjunction of Venus and Mercury on Wednesday, Aug. 20, and eliminated any chance of a glimpse of fading Saturn. Venus, as bright as it is, punched through the muck with no problem, but Mercury couldn't make the trip; even in binoculars and through a telescope the tiny planet was nowhere to be seen.

The planetary pair will remain close together for the rest of August as they travel up and to the left towards an Aug. 31 meeting with very faint Mars. This will be the second planetary trio of the month.

Mars, if visible, will be about six degrees to the upper left of Mercury and Venus with the two innermost planets of our solar system being about three degrees apart. Six degrees is a little more the the width of your clenched fist held at arm's length. Mercury will be slightly below Venus.

The evening viewing session was not a total loss however. Bright Jupiter was hanging in the southwest just above the handle of the teapot asterism of Sagittarius and made a wonderful sight in the telescope. The four bright dots of its Galilean moons made for nice viewing with three on one side and one on the other. You can see the moons for yourselves in binoculars -- try it.

There was a nice surprise for the evening too, an Iridium flare blossomed just above and slightly to the left of Jupiter. This particular flare was about as bright as Jupiter.

An Iridium flare is the reflection of sunlight off of one of the face panels of an Iridium communication satellite. They are extremely transitory events lasting no longer than three to seven seconds. So if you are going to look for one, you have to know exactly where and when to look.

That information can be found on the web site www.heavens-above.com and clicking on the Iridium flare link which will give you the time, direction, altitude and brightness of the flares. I enjoy looking for them; you might get hooked too.

I would have stayed longer to view other objects but the transparency -- a measure of sky clarity -- was terrible; only three of the seven stars of the Little Dipper were visible. That is one way astronomers use to measure transparency, in a clear sky all seven stars are visible. Alas, maybe next time.

SKY WATCH: New moon on Aug. 30, the second one of the month, with a very, very slender crescent moon possibly appearing the next night joining the Mercury-Venus-Mars group. Try looking low on the horizon in the west about a half hour after sunset, use Venus for a guide. Binoculars will be essential. A much fatter moon will join Antares, the bright red star at the heart of Scorpius, the scorpion on Saturday, Sept. 6.

NEXT TIME: More astronomical blathering.

PS: The next night, Thursday, was a better viewing opportunity. There were some clouds but they were very thin and not nearly as opaque as on Wednesday. Venus was there and so was Mercury and I was able to get glass on both of them. It was working out to be a good viewing evening, then the mosquitoes showed up.