Posts Made By: Curt Renz

Two of the Galilean satellites will be transiting Jupiter simultaneously for many North American observers during the evening of 2007 OCT 28. Later their two shadows will transit simultaneously. First Europa (#2) will begin a transit followed by its shadow. Then Io (#1) will begin a transit followed by its shadow.

Between 22:37:37 UT and 23:13:16 UT at least portions of two satellites will appear on the face of Jupiter. Between 23:30:21 UT and 00:56:56 UT at least portions of two shadows will appear on the face of Jupiter. Below are my predictions for the event timings.

Photos or descriptions of the event would be welcome additions to this thread.

I’ve prepared two graphics previewing the event. One is a view from above Jupiter’s north pole and the other is a view from Earth. To see them, click: http://www.curtrenz.com/astronomical.html

20:29:52 UT #2 Partial Transit Begins
20:34:06 UT #2 Total Transit Begins
22:19:07 UT #2 Partial Shadow Transit Begins
22:23:21 UT #2 Total Shadow Transit Begins
22:37:37 UT #1 Partial Transit Begins
22:41:17 UT #1 Total Transit Begins
23:09:02 UT #2 Total Transit Ends
23:13:16 UT #2 Partial Transit Ends
23:30:21 UT #1 Partial Shadow Transit Begins
23:34:00 UT #1 Total Shadow Transit Begins
00:50:11 UT #1 Total Transit Ends
00:51:34 UT #2 Total Shadow Transit Ends
00:53:51 UT #1 Partial Transit Ends
00:56:56 UT #2 Partial Shadow Transit Ends
01:39:18 UT #1 Total Shadow Transit Ends
01:44:53 UT #1 Partial Shadow Transit Ends

Mercury has begun an apparition as a morning star following its inferior conjunction between Earth and Sun on 2007 OCT 23. It should reach its greatest western elongation of 19.0° on NOV 08 before descending to superior conjunction behind the Sun on DEC 17. This should present a far better opportunity for northern hemisphere observers than the planet’s recent evening apparition. To see my panorama for this apparition, click: http://www.curtrenz.com/astronomical.html

Photos or descriptions of Mercury would be welcome additions to this thread.

I’ve created a sky map for Comet Holmes in horizontal coordinates (altitude & azimuth) as it will be seen from Arlington Heights, IL from 2007 OCT 31 through 2008 MAR 14 at 21:00 CST or 22:00 CDT. Although it should well serve most observers at mid-northern latitudes.

What appears on the map to be big leaps by the comet during December is actually an effect of the map projection: near the zenith the azimuth lines actually become much closer than they appear in the map.

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

The holiday season will soon be upon us and a friendly sounding person will again slyly invite us to send him money to have our chosen name for a star placed in a "copyrighted" book. Wow - that must surely make it official. Who needs the astronomers' International Astronomical Union when there are slick operators like him who choose similar sounding names for their dubious enterprises.

Of course folks here are not fooled by the star naming scammers. But if you still feel compelled to provide a similar but more legitimate gift for a friend, try this instead: http://home.columbus.rr.com/realnumbers/

Another lunation will soon be upon us, meaning a fresh opportunity to spot the New Moon. The Moon will be in geocentric longitudinal conjunction with the Sun on 2007 NOV 09 at 23:03 UT. However, we are still in that period of the year in which spotting a very young Moon after sunset is virtually impossible for those of us north of the tropics. The position of the ecliptic works against us during the months around the autumnal equinox. Added to that, the Moon will be well south of the ecliptic due an effect of the lunar 18.6-year nodal cycle. And being near apogee means a Moon that progresses slowly each day.

So forget spotting a one-day-old Moon this month, if you’re north of the tropics. At my location near Chicago on NOV 10, both the Sun and Moon will set at 16:36 CST, despite the Moon being 24 hours old. The Moon at that time will be nearly 6° south of the ecliptic, while the ecliptic slants well to the left of the Sun.

That means for most of us our first opportunity will come with the two-day-old Moon on NOV 11. For North Americans shortly after sunset on that day the Moon will be a degree or two to the lower left of the bright star Antares in Scorpius. Also the Moon will be about 13° to the lower right of Jupiter.

I’ve created a graphic that may help you locate the Moon after sunset on NOV 11. It’s specific for Arlington Heights, IL 25 minutes after sunset, but should well serve most North Americans. It can be seen by clicking: http://www.curtrenz.com/astronomical.html

Photos and descriptions of the young Moon would be welcome additions to this thread.

The Full Moon will occult stars of the Pleiades cluster (M45) during the pre-dawn hours of 2007 NOV 24 for many North American observers. The Moon will be close to perigee and appear almost as large as the Full Moon in October. It should be noted that a Full Moon presents a challenge to occultation enthusiasts, since there is no dark limb.

For Chicagoland observers, the following 5 among the 21 brightest Pleiads will be occulted:

#4 Mag 3.9 Maia
#6 Mag 4.3 Taygete
#10 Mag 5.4 Celaeno
#12 Mag 5.8 Asterope
#19 Mag 6.4 22 Tauri

I’ve created a North American graze map for #3 Electra along with Maia and Taygete. Observers north of a star’s southern graze path will see a full occultation. Those on a graze path will witness a star winking on and off as lunar hills and valley’s pass by. I also made a preview graphic for 06:20 CST when five Pleiads will be occulted from the view of Chicagoland observers. To see the images, click: http://www.curtrenz.com/astronomical.html

Photos or descriptions of the event would be welcome additions to this thread.

Saturn will soon be returning to our evening skies. It will begin rising before local midnight (the time midway between sunset and sunrise) for Chicagoland observers on 2007 NOV 24, making it both a midnight star and a morning star. That will be essentially true for most observers at mid-northern latitudes. In standard time Saturn began rising before midnight for Chicagoland on NOV 19.

Saturn will reach its western quadrature (90° from Sun) on NOV 30. It will begin apparent retrograde motion on DEC 19. Its greatest brilliance for this opposition should be achieved around 2008 FEB 16 at magnitude +0.2. Its closest approach of 8.2914 AU and its oppositions in longitude, right ascension and elongation will all occur on FEB 24 CST.

At the time of opposition the apparent tilt of Saturn’s rings (technically, the saturnocentric latitude of Earth) will be -8.4°. Its angular equatorial diameter will be 20.0 arcseconds. At a declination of N 11.3° Saturn remains well positioned in the sky for northern hemisphere observers.

Retrograde motion will end on MAR 02. Eastern quadrature will be achieved on MAY 22. Then on SEP 03 Saturn will be in conjunction with the Sun.

The southern side of Saturn’s rings was maximally exposed for us on 2003 APR 07 at 27.0°. The Sun will pass through the ring plane on 2009 AUG 10, then the Earth will do so on SEP 04. Between those dates the dark side of the rings will be presented to us, and they will be essentially invisible. Although that will be at a time when Saturn is nearing conjunction with the Sun.

Saturn's ring plane is not actually wobbling. It is the direction toward which we view Saturn that changes as both the Earth and Saturn orbit the Sun.

At my website you will find a couple of graphics I've created related to Saturn: http://www.curtrenz.com/astronomical.html

Your photos and descriptions of Saturn would be welcome additions to this thread.

The red planet Mars is now prominent in our evening eastern sky. It reached its western quadrature 90° from the Sun on 2007 SEP 17 and will rise this evening (NOV 24) at 18:46 CST for Chicagoland observers. Today it is at a distance of 0.644 AU with a diameter of 14.5 arcseconds and 96% of its apparent disk illuminated at magnitude -1.2. It’s currently brighter than all stars visible from mid-northern latitudes except for Sirius.

On NOV 15 Mars started its apparent retrograde motion as Earth began sweeping past it. The loop that will be formed is demonstrated in my graphic of the current Mars apparition. To see it, click:

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

Mars closest approach for this apparition will occur on DEC 18 at 0.58933 AU, which is considerably further than the extremely favorable approach in 2003 of 0.37272 AU. Its angular diameter on DEC 18 will be 15.9 arcseconds compared with 25.1 in 2003. Mars’ opposition from the Sun will occur on DEC 24 in longitude, right ascension and elongation. It will then be rising around sunset and setting around sunrise. Its magnitude during the period around opposition will be -1.6, which is slightly brighter than Sirius.

Mars will end its retrograde movement on 2008 JAN 30 and reach eastern quadrature on MAR 30. Eventually it will move into conjunction behind the Sun on 2008 DEC 05.

This year Mars may approach further than in 2003, but its declination of N 26.8° at opposition will be much more favorable for northern hemisphere observers. My diagram illustrating the positions of Mars, Earth and Sun at oppositions from 2003 to 2018 can be seen at the same link given above. Enjoy your hunt for Martians!

Below is my photo of the Full Moon rising over Arlington Heights, Illinois tonight (2007 NOV 24) at 16:27 CST. That was 19 minutes after moonrise and 3 minutes after sunset. It was taken with my Sony Cyber-shot DSC-F717 at full 5x zoom, ISO 100, F/2.4 and 1/125 sec. The original 2560x1920 pixels were cropped to 1280x960 then reduced to 640x480.

During the night of 2007 DEC 23/24, the Full Moon will occult Mars which will be near its opposition. The event will be visible in portions of northwestern North America and eastern Europe. The southern graze path will extend from Oregon, across Canada, through Greenland, into central Europe, before ending in Saudi Arabia. There will be no northern graze path since that would be in outer space above the North Pole.

Observers on the graze path will be able to watch hills and valleys of the Moon’s south polar region pass across the disk of Mars. Those north of the path will witness a full occultation. Since the Moon will be full, there really won’t be much of a dark limb for either the immersion or emersion.

I’ve created two graze maps, one for North America and one for Europe and the Near East. They can be seen by clicking:

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

Also on that webpage can be found my graphics related to the opposition of Mars and my December astronomical calendar for your computer’s desktop background wallpaper.

Photos and descriptions of the occultation of Mars would be welcome additions to this thread.