A friendly observing reminder: this week marks a good opportunity to catch a glimpse of elusive Mercury in the morning as it shares the stage with neighboring Venus. On the Thursday the 10th and Friday the 11th, Mercury will hover just below its brighter counterpart as the two reach roughly 2° of separation. (Map, courtesy of Spaceweather.)

Mercury will reappear in the evening sky beginning in late September, and subsequently return for a stint of morning visits starting in late November. Venus, however, will be absent on both occasions — so if you’d like to see them together, now is your last chance for 2006.

Mercury (L) and Venus (R) keep company in the evening twilight. Taken June 30th 2005, Spicewood, TX.

On a related note, speaking of messengers: August 3rd marked the second anniversary of the Messenger mission’s launch. Destined for a 2011 rendezvous with our solar system’s innermost planet, the spacecraft has already logged a staggering 1.2 billion miles. Read through Messenger’s itinerary if you have a chance — it’s completing a most remarkable journey in advance of its orbital insertion.