Around and Around

Why a half-full moon equals three-quarters

The waning gibbous moon rises in the southeast early Friday around 12:30am and sets in the southwest some nine hours later around 9:20. By Monday, the last-quarter moon rises close to 2:30am and sets after 12:30pm.

Looking at half the moon’s face, you may wonder why it’s called the last- or third-quarter moon. Whether waning or waxing, quarter-moon refers to the moon’s cycle in orbit rather than the wholeness of its face. So Monday, the last-quarter moon is three-fourths of the way through its orbit around Earth.

The moon shines amid the summer constellation Sagittarius in the wee hours before dawn Saturday, with Jupiter trailing behind about a dozen degrees. Early Sunday morning the two are paired tight, with Jupiter now a few degrees higher.

In the evening, sunset reveals Mars high in the east and Saturn high in the south. Now just a month past equinox, the sun sets well north of due east. This week’s sunset is a few minutes before 8:30, with old Sol inching ever so slowly northward each passing night until summer solstice, when it sets at its farthest point north, pretty close to true northeast.

Mars, which has shined amid Gemini all month, this week forms a distinct triangle with the twins Pollux and Castor. Saturday Mars nears within five degrees of golden Pollux, the brighter of the two stars.

Saturn has kept company with the constellation Leo for months, but now the ringed planet is practically glued to the lion’s blazing heart, Regulus.

Tidelog®

Illustration: © Copyright 1925 M.C. Escher/Cordon Art-Baarn-Holland; Graphics: © Copyright 2007 Pacific Publishers. Reprinted by permission from the Tidelog graphic almanac. Bound copies of the annual Tidelog for Chesapeake Bay are $14.95 ppd. from Pacific Publishers, Box 480, Bolinas, CA 94924. Phone 415-868-2909. Weather affects tides. This information is believed to be reliable but no guarantee of accuracy is made by Bay Weekly or Pacific Publishers. The actual layout of Tidelog differs from that used in Bay Weekly. Tidelog graphics are repositioned to reflect Bay Weekly’s distribution cycle.Tides are based on National Oceanic and Atmospheric Administration and are positioned to coincide with high and low tides of Tidelog.