Each Moon image depicts the fraction of the lunar disk illuminated, apparent tilt, angular size and brightness of both the sunlit and dark side of the Moon, during the night between the dates which it straddles. A waxing Moon is shown as it would appear midway between sunset and moonset. A waning Moon is shown as it would appear midway between moonrise and sunrise. Although best for Chicagoland, the images should well suit all North Americans.
The posts of the Moon’s perigee and apogee times with distances in megameters are geocentric to avoid gyrations due to the Earth’s rotation. However, the times of the Moon’s four primary phases are posted for topocentric (Chicagoland) observers. They are based on the fraction of the apparent lunar disk that is illuminated, rather than the simplistic geocentric angular separations delimiting the four lunation quarters that are commonly printed on calendars. The Moon’s topocentric angular width in arcminutes is shown for the time of each Full Moon. The topocentric phase data should appear fairly accurate throughout North America.
Apparent separations of less than 5° among bright planets and stars are posted, if greater than 10° from the Sun. The planets’ solar oppositions and conjunctions are shown, as are the greatest eastern and western elongations from the Sun for Mercury and Venus.
The posted solar and lunar eclipses, may or may not be visible in Chicagoland. All lunar occultations at least 10° from the Sun of bright planets and first magnitude stars are posted. Those for which at least the immersion or emersion is visible during nighttime from Chicagoland are tagged with the letters Chgo, even for stars as dim as magnitude +4.00.
The rising and setting times for the Sun, Moon and planets are ideally for northwest suburban Chicago, but should remain correct within a minute or two for all of Chicagoland. For each planet, only its rising or setting occurs at night, and that is the one listed. The planetary risings and settings are shown for odd numbered dates; averaging the times on either side should be sufficient for even numbered dates.
The peak dates for major meteor showers are posted. Each month a graphic appears in the calendar’s lower right featuring an upcoming astronomical event.
© Curt Renz
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