StarWatch for the greater Lehigh Valley

MAY  2007


Print Large Sky Charts For 10 p.m. EDT:   NORTH | EAST | SOUTH | WEST | ZENITH

[Moon Phases]
Solar X-rays:  
Geomagnetic Field:  
Status Current Moon Phase

559    MAY 6, 2007:   Moon, Mercury to Create Kodak Moment
If I were “Master of the Universe,” I would guarantee that Thursday, May 17, would be spectacularly clear everywhere. On that evening as twilight deepens, a thin, crescent moon, only 29-hours old, will emerge low in the WNW, just three degrees to the right of the planet Mercury. It will truly be a Kodak moment, a wonderful opportunity for anyone with a camera to capture an earthshine-drenched moon along with the most difficult of the naked eye planets to view. About 15-45 minutes after sundown between 8:30 p.m. and 9:00 p.m. EDT, you’ll probably only have to point and shoot, letting the camera’s automation take care of the task of calculating the correct exposure. After 9:00 p.m., you might have to switch to a manual setting and attach your camera to a tripod for longer one-to-six second exposures. With sensor sensitivity set to ASA 400, you’ll easily be able to capture the moon’s earthshine, sunlight first reflected from the Earth, and then reflected back to us from the moon. If you have a built-in telephoto lens or interchangeable lens system, use them to make your lunar images large enough to capture detail in the earthshine-lit portion of the moon. At six power the moon will appear as if it is being viewed through binoculars, allowing the darker seas and brighter highlands to be seen. One of my favorite earthshine images is posted with the web version of this article at the URL below. Click on this week’s StarWatch when the page loads. If you’re out on May 17, you’ll notice exceptionally bright Venus above and to the moon’s left. Luna will lie between Mercury and Venus on the following evening and be positioned just three of its diameters to Venus’s right on May 19, creating more photo prospects. A nearly first quarter moon is above and to the left of Saturn on Tuesday, May 22.

[Young Moon, March 20, 2007]
This 45 hour old moon shows a wealth of earthshine, light reflected from a nearly full Earth, back to the moon, and then back to us. Sky conditions were exceptionally clear on March 20, 2007 when this digital image was taken several minutes after the start of spring. Gary A. Becker photo...

560    MAY 13, 2007:   Tracking Mercury
Nicolas Copernicus, the great Polish astronomer who reintroduced the heliocentric theory that the Earth revolved around the sun, was said to have lamented on his deathbed that he had never observed the planet Mercury. Maybe that is why Mercury has fascinated me so much. Every time I see it, I’m one-upping the great Nicolas. “Ha, ha, Nick, I did something that you never did.” Truthfully, I believe that my desire to see Mercury stems from the reality that my vision has always been slightly below par. I had detached retinas in my early 20’s and nearly went blind. I live by the mantra that if I can see it, anyone can, so I keep hyping this little world as perhaps my own personal adaptation of an eye chart. The challenge to seeing Mercury successfully is its closeness to the sun. Even at its best from mid-latitudes, Mercury is almost never viewed in a completely dark sky. Add buildings and trees, clouds or haze, and anything else that obscures or lights up the horizon, and problems are compounded. Currently, and similarly to this past February, Mercury is located on the eastern side of the sun, meaning that under favorable sky conditions, it should become visible low in the WNW about 30 minutes after sundown. Mercury will be just a little fainter than it was in February, but often May and early June evenings can be equally clear. More importantly, they are warmer. If you’re going to be tracking Mercury, start this Thursday, when the moon will be just to the Messenger God’s right (see last week’s StarWatch). Start viewing low in the WNW about 30 minutes after sundown, and use binoculars for the initial confirmation. As darkness envelops your surroundings, Mercury will become visible to the unaided eye. Mercury should stay visible through the first week of June. Clear skies!

The moon plays in a rich planetary field this week, passing Mercury on May 17, Venus on May 19, and Saturn on May 22. Start observing about 8:50 p.m. Gary A. Becker graphics...

561    MAY 20, 2007:   Parade of the Planets
For the next two weeks observers have the opportunity of viewing four of the five naked eye planets in the evening sky plus the moon. Get out early, perhaps about 30 minutes after sundown, and look WNW to see the planet Mercury low to the horizon. Initially use binoculars to locate its position, and then wait as darkness settles to see the most elusive of the naked eye planets without any optical aid. If you miss brilliant Venus about 30 degrees above the western horizon at 9 p.m., consult your ophthalmologist immediately. Your vision is definitely failing. The Goddess of Beauty is just over 30 times more luminous than Mercury which is currently the fifth brightest object in the heavens—sun, moon, Venus, Jupiter, Mercury. Above Venus and farther to the left, about mid-sky in the WSW, is ringed Saturn, God of the Harvest. Continue just a little farther along, and you’ll see the star Regulus of Leo the Lion. Over 60 times fainter than Venus, Saturn is tied for seventh place, along with white Vega, low in the east. The only other star brighter is creamy Arcturus of Bootes the Herdsman, high in the NE during the early evening hours. Follow the arc of the Big Dipper’s handle to Arcturus, and then continue to spike blue, supergiant Spica in Virgo. Arcturus and Spica are the two luminaries which define the spring sky. As the week progresses, the moon brightens and gallops towards Spica. By Sunday their separation from each other is only two degrees. View with binoculars or hide the moon with your thumb to reveal Spica. Late in the week, Venus, Saturn, and the moon will be strung across the sky like pearls defining the ecliptic, Earth’s orbital plane projected into space, and the eventual location of the sun in the months ahead. Jupiter, low in the SE by 10:00 p.m., will be the topic of next week’s StarWatch discussion.

[Mercury and the Moon]
The moon looks down upon Mercury, near the horizon just right of center in this late twilight image taken on May 18 from Coopersburg, PA. Unfortunately, it was cloudy the night before, when the moon and Mercury would have stood side by side. Gary A. Becker photo...

[Mercury Takes Center Stage]
Mercury graces a moist spring sky on a day when it was cloudy, beautiful, rainy, and finally clear at sunset. The star above Mercury is first magnitude Elnath, one of the horns of Taurus the Bull. Mercury was nearly five times brighter than Elnath on this May 20 evening. Gary A. Becker photo...

562    MAY 27, 2007:   Mercury at Best, Jupiter Rises
This week Mercury puts on the best sky show possible from our latitude, setting an unprecedented one hour, 45 minutes after sundown. By 9:10 p.m., 45 minutes after sunset, look for Mercury in the WNW almost 11 degrees above the horizon. At the same time Venus shines brilliantly in the west above and to Mercury’s left. About mid-sky in the WSW is Saturn. For this week, Mercury and Saturn are approximately equidistant from Venus as darkness deepens. But wait! There is a new player on the field this week, Jupiter, rising in the southeast about 20 minutes after sunset. Unless your eastern horizon is flawless, I wouldn’t pursue Jove until you’ve had a chance to glimpse Mercury, Venus, and Saturn in the west. Try looking in the SE about 10 p.m. when the largest planet within our solar system and the fourth brightest sky object gains enough altitude to become readily visible. On Friday the full moon and Jupiter rise nearly at the same time creating additional dazzle in the SE as well. Observe with binoculars, and you’ll see red, supergiant Antares to the moon’s right. By Saturday evening, the moon has moved far enough away to allow Jupiter and Antares to rise as an easily seen pair in a darker sky. Keep in mind that Jupiter will be about 30 times brighter than Antares, but the reddish color of this star will contrast nicely with the almost pure white color of Jupiter. Use binoculars to enhance the crimson hue of Antares. If you follow Jupiter this summer, you’ll notice that it will always be low in the sky. Jupiter is currently positioned in that portion of the heavens where the winter sun can be found. During the winter months, Sol is always close to the horizon and rises far to the south of east and sets far to the south of west. Likewise, Jupiter will be doing the same for another couple of years.

[May Star Map]

[May Moon Phase Calendar]