Saturday, March 17, 2007

Crescent moon alerts

18 March 2007 @ 22:43 EDT, New Moon occurs. This means it time to chase the crescents. Earlier this year, I prepared a list crescent detection predictions on this post.

One day past New Moon, this month's young, waxing crescent should be easy to spot - provided the weather is agreeable - with a predicted sighting 19:10 ~ 19:15 EDT. The age of Moon at sunset on 19 March will be 20h23m after New Moon. Look for it with binoculars after sunset about 11° above where the horizon and slightly south in azimuth ~3°. The crescent should be oriented like a big smile.

I'll be somewhere along the eastern side of the Great Lawn on the perimeter sidewalk.

Get details at Crescent Moonwatch and then file a report with them of your experience.

I didn't list the waning crescent this month because it is very, very difficult at best. Given Moon's elongation from Sun and that it is relatively close to the ecliptic, within a degree, I would say we had a fighting chance. What makes this event so challenging is that the ecliptic rises very shallow relative to the horizon. (Contrast that with the angle of the ecliptic for the young crescent mentioned above.) That results in the Moon and Sun rising within minutes of one another and greatly diminishing any contrast the crescent could have with a twilight sky background. Simply it gets lost in the glare.

At magnitude 5.9, Uranus may be difficult to spot 3° WSW (celestial) in the civil twilight, but if I'm wrong it could serve as a landmark to help isolate the area where the crescent may be detected.

Nonetheless, if the weather permits, I'll give it a shot at Carl Schurz Park on Sunday morning. If I miss the crescent, I'm sure to catch a glorious sunrise and observe the city's pulse awaken along the promenade.