Posts Made By: Curt Renz

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:
http://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.

During the early morning hours of 2004 Dec 07, the Moon will occult (cover up) Jupiter during nighttime for observers in much of the US east of the Rockies. I have created graphics with data that preview the event as it will be seen from three different cities.

To see a graphic, click:
http://www.curtrenz.com/astronomical.html

Then click the small blue button for the occultation as seen from the city nearest you.

The central image depicts Jupiter as seen through the Moon by X-ray vision. In reality, of course, you won't see Jupiter at that moment of closest approach between centers. The left and right images show the pair of objects at the moments of immersion and emersion, defined by when the center of Jupiter appears on the Moon's limb. In the graphics, straight up is the direction toward the local zenith, not celestial north.

The graphics may be removed soon after the event occurs.

Who will be first to spot the New Moon by naked-eye after its conjunction with the Sun on 2004 Dec 12 @ 01:29 UT?

This slender young crescent Moon was traditionally referred to as the New Moon. On the day of conjunction it was called the Dark Moon. Most modern calendar makers, however, label the conjunction day as that of the New Moon.

Since I began this series in March within several astronomical message boards, the overall champion is DanielO in Michigan with a March sighting at 25:37 after conjunction. Our November winner was Christine Canelos Welsh of Palatine, Illinois with a time of 32:24.

Please report your December observation within this thread, including location and time with zone. Even negative results would be interesting. Photos would be especially nice. No prizes, just bragging rights.

I've created graphics previewing the western sky soon after sunset on December 12 & 13 as seen from Chicago, although they should be useful for most North American observers. To see them, click:

http://www.curtrenz.com/astronomical.html

Then click the blue buttons for the December New Moon Contest.

The graphics may be removed soon after December 13.

Here is a link to a warning from the New York City Department of Consumer Affairs regarding a firm that accepts payments for naming stars:
http://www.ras.ucalgary.ca/~gibson/starnames/isr_news.html

I've created a January 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:
http://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.

Who will be first to spot the New Moon by naked-eye after its conjunction with the Sun on 2005 Jan 10 @ 12:03 UT? Sky and Telescope magazine has a fine article describing such attempts in its February issue.

This slender young crescent Moon was traditionally referred to as the New Moon. On the day of conjunction it was called the Dark Moon. Most modern calendar makers, however, label the conjunction day as that of the New Moon.

Since I began this series in March within several astronomical message boards, the overall champion is DanielO in Michigan with a March sighting at 25:37 after conjunction.

Please report your January observation within this thread, including location and time with zone. Even negative results would be interesting. Photos would be especially nice. No prizes, just bragging rights.

I've created a graphic previewing the western sky 25 minutes after sunset on January 11 as seen from Chicago, although it should be useful for most North American observers. To see it, click:

http://www.curtrenz.com/astronomical.html

Then click the blue button for the January New Moon Contest.

The graphics may be removed soon after January 11.

On the morning of 2005 JAN 13, Mercury will pass to the celestial south of Venus by only 19 arcminutes.

I have created a graphic previewing the event as viewed from Chicago before dawn on January 13, although it should well serve observers at other locations. To see it, click:

http://www.curtrenz.com/astronomical.html

Then click the small blue button indicating Mercury Conjuncts Venus.

On Wednesday evening, January 19, the waxing gibbous Moon will pass near the Pleiades star cluster. Geocentrically, the Moon's center will be 1.3 degrees from Alcyone, the Pleiades brightest star. Beginning next month the Moon will initiate a series of occultations of Alcyone that will last nearly six years. This repeats in a cycle of 18.6 years.

I've created a graphic that depicts the sky an hour after sunset on the 19th as viewed from Chicago where the minimum separation between the Moon and Alcyone will be 1.9 degrees. Although the chart should well serve viewers at most locations. To see it click:

http://www.curtrenz.com/astronomical.html

Then click the small blue button for Moon Conjuncts Pleiades.

The International Astronomical Union is the only organization recognized by astronomers as the official registry for the names of celestial objects. They charge no fees. The many who do are charlatans. Warn your friends and avoid the embarrassment of having such foolishness presented to you, the knowledgeable astronomer.

For more info, click the links below:

http://www.space.com/spacewatch/mystery_monday_030915.html

http://www.wired.com/news/business/0,1367,49345,00.html

http://www.iau.org/IAU/FAQ/starnames.html

http://home.carolina.rr.com/nirgal/buyastar.html

http://www.nmm.ac.uk/server/show/conWebDoc.309

http://www.ras.ucalgary.ca/~gibson/starnames/isr_news.html

During the early morning of January 31, the Moon will conjunct (appear to pass nearby) the bright planet Jupiter. For the few observers who may be in Antarctica and the southeast Pacific, this will actually be an occultation (covering by Moon). The minimum geocentric separation between centers will be 0.8 degrees on 2005 JAN 31 @ 10:00 UT.

I have created a graphic previewing the event has seen from Chicago, although it should well serve most observers. From that location the separation will narrow to 1.3 degrees at 02:20 CST. The first magnitude star Spica will appear only 6 degrees beneath the pair. It should be a pretty sight.

Click below to link to the graphic:

http://www.curtrenz.com/astronomical.html

Then click the small blue button for Moon Conjuncts Jupiter.

The graphic will be removed soon after January 31.