Posts Made By: Curt Renz

I've created a May astronomical calendar that can be downloaded as your computer's desktop background wallpaper or printed to paper. It includes information on the naked-eye planets, Moon and eclipses.

To see the calendar, click:
http://www.curtrenz.com/astronomical.html

For those interested in details, read on:

The lunar images and planetary visibility tables are topocentric and assume the observer is located at the Adler Planetarium in Chicago. Although, the calendar should well serve those in most northern hemisphere locations.

Each daily lunar image is depicted as it would appear on the night of the two dates it straddles. That includes the orientation of the Moon’s illuminated portion and its relative apparent size. 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 described at the bottom of the page are calculated for more classical and intuitive definitions, rather than the simplistic ones necessarily employed in more recent times but before the advent of 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 percentage illuminated is printed under each image.

The apogee and perigee data are geocentric: megameters (thousands of 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.

In the planetary tables, a morning star is a planet appearing before sunrise, an evening star is a planet seen after sunset, and a midnight star is a planet visible at local midnight.

Here's the latest news: http://www.theonion.com/content/node/47977

During the coming weeks Mother Nature will present northern hemisphere observers with an especially good early evening apparition of Mercury. The often elusive little sun-hugger passed behind the Sun in Superior Conjunction on 2006 May 18. It will reach Greatest Eastern Elongation of 24.9° on June 20.

As viewed from Chicago at 30 minutes after sunset, the planet will reach its greatest altitude of 12.0° in the west-northwest sky on June 14, which is also the date it will appear as a 50% illuminated “Half Mercury”. Before that date it will be seen as gibbous – afterward as a crescent.

The period of visibility will be especially long: late May through early July. Mercury will be dimming throughout the period from a stellar magnitude of –1.7 to +2.4. It will then pass between the Earth and the Sun in Inferior Conjunction on July 18.

I’ve created a graphic demonstrating the evening appearance of Mercury and the Moon 30 minutes after sunset during the period from May 23 through July 7. It’s customized for the location of the Adler Planetarium in Chicago, but should well serve most northern hemisphere observers. To see it, click:
http://www.curtrenz.com/astronomical.html

Who will be first ground based observer to spot the New Moon after sunset by naked-eye following its conjunction with the Sun on 2006 MAY 27 at 05:26 UT (00:26 CDT)?

The slender crescent Moon, a day or two old, was traditionally referred to as the New Moon. On the day of conjunction our ancestors called it the Dark of the Moon (or Change of the Moon.) However, most modern calendar makers insist on labeling the conjunction day as that of the New Moon.

The springtime celestial geometry is still favorable for North American observers who may be able to sight a Moon aged only about 20 hours on the 27th. During that evening the thin lunar crescent will appear about 3° to the right of Mercury which will be at Mag -1.3. If you fail to spot the Moon on the 27th, a sighting the next evening should be less challenging but still an accomplishment.

Please report your May 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 representing the western sky 30 minutes after sunset on May 27 & 28 as seen from Chicago's Adler Planetarium. Nevertheless, the diagrams should be useful for most North American observers. To see them, click:

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

The graphics may be removed soon after May 28.

The planetary gods are always orchestrating a show for us. Jupiter may be the “star” right now while we anticipate the apparition of Mercury. But let’s not forget our old friends Mars and Saturn who have been inhabiting our evening sky for a while now. They will be performing a dance together and with the Beehive cluster (Praesepe, M44 in Cancer) over the coming weeks. I calculate that Saturn will complete its triple conjunction with the cluster on 2006 JUN 03 at 10:57 UT when it makes it closest approach for the cycle to Epsilon Cancri (Beehive’s brightest star) by passing 48’ south. Then Mars will pass 14’ south of the same star on JUN 15 at 19:43 UT. Finally, Mars will pass 33’ north of Saturn on JUN 18 at 06:25 UT. 8)

I have created graphics demonstrating the movements of Mars and Saturn that can be seen by going to http://www.curtrenz.com/astronomical.html

Who will be first ground based observer to spot the New Moon after sunset by naked-eye following its conjunction with the Sun on 2006 JUN 25 at 16:05 UT (11:05 CDT)?

The slender crescent Moon, a day or two old, was traditionally referred to as the New Moon. On the day of conjunction our ancestors called it the Dark of the Moon (or Change of the Moon.) However, most modern calendar makers insist on labeling the conjunction day as that of the New Moon.

The celestial geometry has become less favorable for North American observers following the Summer Solstice. However, there will be a number of guideposts for locating the young Moon on the 26th shortly after sunset. Mercury will be about 9° to the left of the Moon. Bright Pollux will be about 3° above the Moon with Castor about 5° to the Moon’s upper right. Saturn and Mars will be in the neighborhood, respectively about 20-24° to the upper left.

Please report your June 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 representing the western sky 30 minutes after sunset on June 26th as seen from Chicago's Adler Planetarium. Nevertheless, the diagram should be useful for most North American observers. To see it, click:

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

The graphic may be removed soon after June 26th.

Pluto has a mass that is 1/500 of the Earth and 1/6 of the Moon, even though in 1930 it was thought to be 10 Earth masses. There are many trans-Neptunian objects besides Pluto, and it is not the largest one.

Its orbit is far more eccentric than any planet (occasionally bringing it closer to the Sun than Neptune.) Its orbit is far more inclined to the ecliptic than any planet. Its orbit is not stable enough to allow for the development of a long-term theory of Pluto’s position. It shares all of these orbital anomalies with asteroids and not planets.

All asteroids orbit the Sun and have regular rotation periods. Some asteroids are round, and some have satellites. For nearly 50 years after the first asteroids were discovered they were referred to as planets. Considering their small sizes and similar orbital characteristics, astronomers realized that it would make more sense to create a separate class for them. A rational classification system helps scientists as they seek to determine the origin, characteristics and future of natural objects and systems. Hence, it may make more sense to place all Kuiper Belt Objects, including Pluto, into a separate class from either the major planets or asteroids.

If the high school graduate who was assigned in 1930 the arduous task of comparing sky photographs and his mentors had not been so eager to discover a planet, they may have stopped to realize that they were seeing an example of a new class of objects that demanded further scientific investigation. The Kuiper Belt might then have been called the Tombaugh Belt - a far more impressive scientific accolade then having been the first to see a particular celestial body in a photograph.

Just because our third grade teachers had us learn by rote the multiplication tables and the names of the planets, does not imply that both accomplishments were equally valid. We’ll just have to accept that our teachers and their sources may have occasionally dispensed imperfect information. Acceptance of change and errors is an important aspect of living.

For those viewing from the Americas, many of the stars of the Pleiades cluster will be occulted by the Moon during the early morning (nighttime) hours of 2006 JUL 20. The waning crescent Moon will appear 23% illuminated.

Below is seen occultation data that I’ve calculated for observers at Chicago’s Adler Planetarium. From that location the brightest of the Pleiades, Mag +2.9 Alcyone, will be missed by the Moon’s northern limb by 1/45 of a lunar diameter at 02:50 CDT. Several others will also narrowly escape occultation.

The times of immersion (disappearance) and emersion (reappearance) are given in CDT. The zenith angle is shown for the position of the star measured counter-clockwise from the zenith along the lunar limb. The name or each star and its magnitude also appear. Immersions will occur on the Moon’s bright limb and emersions on the dark limb.

02:58:46 -- 101.2° -- Atlas
03:53:09 -- 317.5° -- +3.6

02:05:42 -- 056.6° -- Merope
02:31:53 -- 358.2° -- +4.2

03:06:37 -- 083.3° -- Pleione
03:53:20 -- 335.7° -- +5.0

02:46:28 -- 136.7° -- 26 Tauri
03:39:19 -- 281.5° -- +6.5

I’ve created a graphic depicting the Moon amidst the Pleiades at the moment that it makes its closest approach to Alcyone as viewed from Chicago. I’ve made another one that maps the graze paths for Alcyone. To see them, go to http://www.curtrenz.com/astronomical.html

The graphics may be removed soon after the event occurs.

Have you never seen Mercury? Here's your chance. It's about to commence a fine apparition as a morning star from late July through late August. This follows its Inferior Conjunction between Earth and Sun on July 18.

The elusive little planet will reach its Greatest Western Elongation of 19.2° on August 7. As viewed from Chicago, its greatest altitude at 30 minutes before sunrise will be 10.2° on August 9.

Mercury will be brightening in stellar magnitude from +2.6 to –1.6 throughout the period of visibility. Do not confuse it with far brighter Venus, which will be a little higher in the sky. Mercury will reach Superior Conjunction on the other side of the Sun on September 1.

I’ve created a panoramic graphic that previews the entire apparition. It displays the east-northeastern sky as seen from Chicago 30 minutes before sunrise from July 25 to August 26, although it should well serve most northern hemisphere observers. To see it, click:

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

The graphic may be removed late in August.

International Atom Registry Allows Customers To Name Atom After Loved One

July 19, 2006 | Issue 42•29

HOT SPRINGS, AR—For only $26.75, customers worldwide can now honor their loved ones by naming an individual atom after them, executives at the International Atom Registry, Inc. announced Monday. "Every time that special someone looks at the matter containing their special individual atom, they'll think of you and your lasting tribute," said Guy Warriner, IAR president and chief archivist. "But hurry—the universe's 1x10(^78) atoms won't last forever!" Special packages are available for those who wish to name very special atoms, such as those that make up the Vietnam War Memorial, the turf of Lambeau Field, or the sweater Lisa Kudrow wore for the final episode of Friends.

http://www.theonion.com/content/node/50645