On Tuesday 4 May 2004 (Wednesday 5 May in Australia and Asia), the full Moon passed through the Earth's shadow, producing a total lunar eclipse for skywatchers throughout Asia, Australia, Europe, Africa and South America. In The Netherlands and Belgium Astronet and Kennislink ("Knowledge Link") in cooperation with the Dutch Copernicus Public Observatory and Belgian Mira Public Observatory organized a live webcast of the event.
Archive image of webcast by
Copernicus Public Obervatory, Netherlands
Archive images by
Mira Public Obervatory, Belgium
The Moon encounters the penumbra, the Earth's outermost shadow zone, at 17:51 Universal Time (UT). About thirty minutes later a slight dusky shading can be noticed on the leading edge of the Moon.
At 18:48 UT the Moon begins its entry into the innermost shadow zone, or umbra. For more than an hour a circular shadow creeps across the Moon's face. At 19:52 UT, the Moon will lie completely within Earth's dark shadow. It will then take on an eerie coppery tint that has often been compared with blood.
During a total eclipse the Moon shines with a orange reddish glow
Photograph: Robert Smallegange (Leeuwarden, The Netherlands)
Without Earth's atmosphere, the Moon would disappear completely once immersed in the umbra. Longer wavelengths of light penetrate Earth's atmosphere better than shorter wavelengths, which is why the rising or setting sun looks reddish. In essence, the ruddy tint of a totally eclipsed moon comes from the ring of atmosphere around Earth's limb that scatters a sunset-like glow into the umbra.
During totality a ring of reddish sunlight surrounds the Earth
Courtesy: Francis Reddy.
The hue actually changes from one eclipse to another, ranging from a bright coppery orange to brownish. The Moon may darken so much that it becomes all but invisible to the unaided eye. These very dark lunar eclipses often occur after exceptional volcanic eruptions.
Totality will end at 21:08 UT, when the moon's leading edge exits the umbra. The moon will leave the umbra completely at 22:12 UT, and the eclipse will end at 23:10 UT when the moon makes its last contact with the penumbra.
Path of the Moon through Earth's umbral
and penumbral shadows during the Total
Lunar Eclipse of May 4, 2004.
Courtesy: Fred Espenak
Here can be found predictions for the immersions and emersions of craters, mountains and a small mare on the Moon.
David Dunham communicates:
"Occultations of two 6th-mag. stars will be visible from most of Europe, with grazes of both near the Pyrenees Mountains. Eberhard Riedel has prepared a map that shows the paths of all grazing occultations of stars brighter than mag. 9.3 that will occur against the umbra during the partial or total phases of the eclipse. It can be found in an item at the top of my Web site at http://iota.jhuapl.edu , or more directly, http://iota.jhuapl.edu/leg04504.htm. You can use Occult or LOW to calculate predictions of the total occultations for your location, or of graze paths for individual events, or Eberhard Riedel at E_Riedel@msn.com can supply predictions of the graze paths.
The southern-limit graze paths for both ZC 2111 (mag. 6.9) and ZC 2119 (mag. 6.5) cross the southernmost part of France, near Pic du Midi Observatory, and the paths seem to intersect just north of Andorra; it would be interesting to travel to the intersection place to observe both grazes without having to move. In northeastern Spain, Carles Schnabel of the Agupacio Astronomica de Sabadell, (e-mail firstname.lastname@example.org), writes:
"We are preparing an expedition to observe the grazing occultation of ZC 2119 on the [Mediterranean] coast, between Girona and Barcelona, exactly between Malgrat and Calella. This event occurs during the totality of the lunar eclipse, so it may be an extraordinary phenomenon. You are invited to join our expedition."
Most remarkable will be the occultation during totality of the 2.8-mag. star alpha 2 Librae = ZC 2118 = Zubenelgenubi for observers in southern Africa, as noted on pages 104 and 106 of my article in this January issue of Sky and Telescope (with northern limit shown on the map on p. 103). Alfons Gabel is leading an expedition to the deserts of Namibia to observe this rare event, and there will be efforts to observe it in South Africa, as well - for details of this event, maps, and plans, see http://www.lunar-occultations.com/iota/2004alibrae/2004alibrae.htm
I hope that someone can record this year's event with one of the sensitive video cameras that are available now (and much cheaper than the Ultricon I used in 1985; see below), possibly one in color, to show the eclipsed part of the Moon much better.
I think Alfons Gabel has already left to travel to Namibia, so I don't know if he will be able to receive e-mail or not at email@example.com. Observers in South Africa can get information about efforts to observe the graze there from Brian Fraser at firstname.lastname@example.org.
The last time a star this bright was occulted during a total lunar eclipse was on May 4, 1985, a 19-year Meton cycle earlier, when the same star was occulted across most of Africa. In that case, the southern limit passed over South Africa, where dozens of observers organized by the late Danie Overbeek observed the graze, some without optical aid. The northern limit passed from Algeria to Somalia; at that time, the only country crossed by that path with friendly relations with the U.S.A. was Sudan, so Paul Maley, a few other observers from Houston, TX, and I made arrangements to go there to observe the event; we had valuable help from the physics department of Khartoum University and use of a transit satellite navigation receiver from a local oil company. I managed to video record the occultation with a cluncky Ultricon camera attached to a C5; you can see parts of that recording that are in large .avi files that my wife, Joan, digitized from a time-inserted copy of the orginal tape. They can be downloaded from my Web site at http://iota.jhuapl.edu/leg04504.htm but you need a fast connection.
Several years ago, Jean Meeus wrote an article about lunar eclipse occultations, examining all possibilities up to 2050. He and G. P. Konnen published it as "Occultations of Bright Stars by the Eclipsed Moon" in Journal of the British Astronomical Association, Vol. 85, No. 1, pp. 17-24 (1974). After May 4th this year, there will not be another chance to observe an occultation of a 3rd-mag. or brighter star until May 6, 2050 (I incorrectly said 2049 on the Web site; I'll correct that Monday), when Zubenelgenubi will again be occulted by the totally eclipsed Moon. Unfortunately, that event will be visible only from Antarctica, and at low altitude from the Falkland Islands and Tierra del Fuego; the northern limit passes entirely south of South Africa. Konnen and Meeus' article also mentions an occultation of Zubenelgenubi by the totally eclipsed Moon a Meton cycle later, on 2069 May 6, but I could not find that event with Occult. Occult predicted many occultations during that eclipse for a location in eastern Antarctica, including a nearly central occultation of 8th-mag. ZC 2122, but Zubenelgenubi is about 40' south of that star, so maybe the 2069 event is a mistake? The next Zubenelgenubi event after that with a totally eclipsed Moon is on 2134 May 8."
June 8, 2004: Venus transit