Post by Centaur on Oct 31, 2004 15:25:25 GMT -6
I've created a December astronomical calendar that can be downloaded as your computer's desktop background wallpaper or printed to paper. The Moon is the main feature. Information on planetary visibility is included.
To see it, click:
www.curtrenz.com/astronomical.html
For those interested in details, read on. Most of the information on the calendar is topocentric and assumes that the observer is located at the Adler Planetarium in Chicago. Although, it should well serve those in most northern hemisphere locations.
Each daily Moon image is depicted as it would appear on the night of the two dates it straddles. That includes the orientation of the illuminated portion. Specifically, 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. The effects of earthshine and the oppositional flash are also demonstrated.
The phases shown at the bottom of the page are calculated to conform to more intuitive definitions rather than the simplistic ones that were necessary in the age before computers. Dark Moon is the moment during the monthly cycle in which the apparent lunar disk is least illuminated. Full Moon is when the disk is most illuminated. Half Moon comes when the disk is 50% illuminated. The fraction illuminated is printed under each image.
Only the apogee and perigee data are geocentric: kilometers from center of Earth to center of Moon. Otherwise, this information might seem somewhat chaotic as the Earth's rotation causes a daily oscillation of the distance between a surface based observer and the Moon.
Here are the meanings of the planetary visibility tables. For this explanation the horizon has been divided into two halves, eastern and western. A Morning Star is a planet which at sunrise is either above the western horizon or at least 10 degrees above the eastern horizon. An Evening Star is a planet which at sunset is either above the eastern horizon or at least 10 degrees above the western horizon. A Midnight Star is a planet which is above the horizon at local midnight, the time midway between sunset and sunrise (the evening date is posted.) It is possible for a planet to be all of these during a particular night. Lost in Glare means the planet fails to meet any of the previous three criteria and is therefore too close to the Sun to be easily observed.
To see it, click:
www.curtrenz.com/astronomical.html
For those interested in details, read on. Most of the information on the calendar is topocentric and assumes that the observer is located at the Adler Planetarium in Chicago. Although, it should well serve those in most northern hemisphere locations.
Each daily Moon image is depicted as it would appear on the night of the two dates it straddles. That includes the orientation of the illuminated portion. Specifically, 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. The effects of earthshine and the oppositional flash are also demonstrated.
The phases shown at the bottom of the page are calculated to conform to more intuitive definitions rather than the simplistic ones that were necessary in the age before computers. Dark Moon is the moment during the monthly cycle in which the apparent lunar disk is least illuminated. Full Moon is when the disk is most illuminated. Half Moon comes when the disk is 50% illuminated. The fraction illuminated is printed under each image.
Only the apogee and perigee data are geocentric: kilometers from center of Earth to center of Moon. Otherwise, this information might seem somewhat chaotic as the Earth's rotation causes a daily oscillation of the distance between a surface based observer and the Moon.
Here are the meanings of the planetary visibility tables. For this explanation the horizon has been divided into two halves, eastern and western. A Morning Star is a planet which at sunrise is either above the western horizon or at least 10 degrees above the eastern horizon. An Evening Star is a planet which at sunset is either above the eastern horizon or at least 10 degrees above the western horizon. A Midnight Star is a planet which is above the horizon at local midnight, the time midway between sunset and sunrise (the evening date is posted.) It is possible for a planet to be all of these during a particular night. Lost in Glare means the planet fails to meet any of the previous three criteria and is therefore too close to the Sun to be easily observed.
