What's up with Vernon

Cheap Astronomy proudly hosts Vernon Whetstone’s weekly update on the night sky—and he sent in this photo to indicate he gets the whole Southern Sky context too.

What's Up by Vernon Whetstone (thestargeezer@gmail.com) 21 July 2010

For those of you who love a parade, there is a grand one still going on in the early evening hours in the west just after sunset. There is even a new addition to the other stalwart three that have been holding forth these last few weeks. Venus, Saturn, and Mars have been making their presence known for a while now, and fleet-footed Mercury has joined the group in the early evening sky.

If you want to see this newcomer be outside looking west an hour or so after sunset. Find a place with an absolutely clear, unobstructed view of the western sky. Mercury is the tiny dot about six degrees above the horizon. Binoculars will be helpful because being that low on the horizon it could get lost in the cloudy soup that lines the area. If you are having a hard time finding it wait until Tuesday and Wednesday, 27 and 28 July, when Mercury will be very close to Regulus, the brightest star in Leo the Lion. They both will be closer to the horizon so again, use binoculars.

As for the rest of the parade, Venus, the brightest object you will see in the west is about halfway between Regulus and the Saturn/Mars duo. The latter two being about five degrees apart. That is about the width of your binocular field of view which will put both of them in your view at the same time.

The ecliptic, the path the Sun follows through the sky is inclined very steeply to the horizon now and the planetary path goes almost straight up with a slight lean to the north. If you have been watching these three wanderers—which is what the ancient astronomers called them—for the last few weeks you have noticed how far they all have traveled. They still have more traveling to do, so keep watching and mark their positions each evening. A waxing Moon is already well up just after sunset, almost overhead, which will make observing in the later evening difficult.

How about a viewing challenge? Double stars are always a wonder to look at. I have two of them for you. The first is Albireo, the beak, or nose star of Cygnus the Swan. It is on the opposite end of Cygnus from Deneb, one of the stars making up the Summer Triangle. It can be located in the northern sky about 20 degrees above the horizon, best time to look is at about 11pm Canberra time. A telescope will be needed for this one. Albireo is a magnificent double, one of the pair is yellow and the other is blue.

The second double star challenge is even better, at least to my way of thinking. It is Epsilon Lyrae, the Double-Double star. To find it first locate Vega, the highest, and brightest of the stars in the Summer Triangle just below and left of Cygnus. Look about one degree (the width of your pinkie finger held at arms length) down and left of Vega. If you are watching from a dark sky place you might even be able to see it is a double without any optical aid. In binoculars you will certainly be able to. But with a telescope, even a small one, you will see that each of the doubles is a double—a total of four stars, hence the Double-Double name.

SKY WATCH: Full Moon, Sunday, 25 July. Four of the easily visible planets can be found in the early evening hours in the western sky. The fifth, Jupiter, will rise in the east and be visible by midnight, Canberra time. Jupiter will continue to move westward against the background stars until December when it will be an early evening object again. Fellow gas giant, Uranus, is still within five degrees up and left of Jupiter and can be seen in the same field of binocular view as Jupiter. There is one star that is slightly dimmer than Uranus between the pair. If you want to make sure you are seeing Uranus, it will be the bright dot that is the furthest of the two.

What’s up with Vernon