MoonWatch
January 1999
The bay crater Le Monnier on the shore of Mare Serenitatis
7 October 1997 Peter Grego
After the chimes of Big Ben have ushered in the new year, and the hogmanay celebrations have wound up for the night, those stepping outside into the chill of winter will be greeted by a big near-full Moon high in the south, seemingly held in its lofty position on the celestial vault by the strong right arm of Orion. Even though the Moon is fully illuminated, make it your first astronomical port of call in 1999. While you make your new year's resolution, try spotting some lunar features that are rather appropriately named after good fortune and serendipity or connected to 1999 in some way.
Tonight the Moon's eastern limb is presented very favourably by virtue of a good libration, and using a pair of steadily held binoculars or a telescope, take a while to scan this region. Just on the northeastern border of Mare Fecunditatis (Sea of Fertility) there is the Sinus Successus (Bay of Success). Adjacent to Successus is Mare Spumans (Foaming Sea) which may well remind you of certain celebratory excesses you enjoyed earlier in the evening! A short distance to the north is the 56 km dark patch of the flooded crater Firmicus, named after a 4th century Sicilian astrologer. What you're doing tonight may be very loosely construed as a form of astrology - seeking to have some kind of control over daily affairs by divining heavenly signs - but remind yourself that the pursuit in which you're now engaged ranks as high science compared to the nonsense churned out by newspaper astrologers! However, nestling on Firmicus' northwestern flanks is the diminutive Lacus Perseverantiae (Lake of Persistence) - a reminder that astrology seems to be as popular as ever, despite all the solid scientific contraindications.
A bright spot near the northern sore of Fecunditatis marks the 12 km crater named in honour of the Japanese astronomer Goryu Asada, who died 200 years ago in 1799. The eastern shore of Mare Serenitatis (Sea of Serenity) is dented by the flooded crater le Monnier, a French astronomer and physicist who also died in 1799. In the same year the famous English astronomer William Rutter Dawes ("Eagle-eyed Dawes" as he was known) was born, and on the southeastern border of Serenitatis you will be able to see the 18 km crater named in his honour - a small light circle surrounded by a peculiar 50 km long grey rectangle on the marial plain. Astronomers still use Dawes' formula to calculate the resolving power of telescopes.
1999 marks the 150th anniversary of the birth of Jean Delambre (1749-1822), a French astronomer whose trigonometrical surveys led to the derivation of the metre as a standard unit of measurement. Delambre has a prominent 52 km diameter terraced crater named after him, a little distance to the southeast of Mare Tranquillitatis (Sea of Tranquillity). Delambre crater is an example of a lunar feature that, though obvious when near the terminator, completely vanishes under a high Sun. Tonight you can search for this crater in vain! Delambre could never have guessed that in the late 20th century the distance of the Moon could be known within metres - thanks to the laser reflectors left on the lunar surface by the Apollo astronauts. And, of course, 1999 marks the 30th anniversary of Apollo 11, the first manned lunar landing, which established the first scientific station and placed its passive laser retroreflector on the grey plain of Tranquillity base, just a hundred kilometres east of Delambre crater.
