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Partial Lunar Eclipse, 17th August 2008
Submitted: Tuesday, 8th July 2008 by Mike Salway
The Partial Lunar Eclipse on August 17th 2008 will be visible at Moonset for all of Australia, Asia and New Zealand, though New Zealanders will only see the Penumbral stage. Africa and most of Europe will see the Partial Eclipse in it entirety, and South Americans will see the eclipse at Moonrise. North America and Canada won't see this eclipse. The below map shows visually where the eclipse can be seen from (large version here). Read on below for more information, local timings, hints and tips for viewing and photographing the eclipse. We'd love you to register at the IceInSpace Forums and don't be afraid to ask if you have any questions. To see images and read reports after the event (and to post yours too!), check regularly in the Observational Astronomy and Solar System sections.
Use the links below to find the information you're after:
What is a Lunar Eclipse?The diagram below shows the basic geometry of a Lunar Eclipse. The Earth's shadow has two parts - the Umbra, which is the darker inner shadow, and the Penumbra, which is the fainter outer shadow. Please contact me if you'd like a larger version of the diagram below.
A Lunar Eclipse occurs when part or all of the Moon passes into Earth's shadow. This doesn't happen every Full Moon though, because the Moon's orbit is actually tipped about 5° with respect to Earth's orbit around the Sun. This means that during most Full Moon's, the Moon is actually above or below the Earth's plane and therefore not in the shadow of the Earth. However two to four times per year, the Moon passes through some or all of Earth's penumbral and umbral shadow, causing one of the three types of Lunar Eclipse: Penumbral Lunar EclipseA Penumbral Lunar Eclipse is when the Moon passes into the Earth's penumbral shadow. This type of eclipse accounts for 35% of all Lunar Eclipses. The difference in visibility of the moon during this phase is very subtle and difficult to observe. Partial Lunar EclipseA Partial Lunar Eclipse is when only a part of the Moon passes into the Earth's umbral shadow. This type of eclipse accounts for 30% of all Lunar Eclipses. During this phase, a "chunk" or portion of the moon goes into shadow. Total Lunar EclipseA Total Lunar Eclipse is when the Moon passes completely into the Earth's umbral shadow, described as "Totality". Total Lunar Eclipses account for the other 35% of all lunar eclipse. These are the most spectacular type of Lunar Eclipse, as during totality the moon can take on a range of striking colours. Scattered sunlight passes deep through the Earth's atmopshere which filters out most of the blue light. The remaining light renders the Moon in shades of red, orange, yellow and brown - depending on the amount of dust and volcanic ash in the Earth's atmosphere. All Total Lunar Eclipses start with a Penumbral, followed by a Partial and then the Total Lunar Eclipse. Finally, a Partial followed by a Penumbral completes the event. All types of Lunar Eclispe are completely safe to observe with the unfiltered and unaided eye. The images below show what each of the types of Lunar Eclipse can look like.
When and Where Can I See it?The Partial Lunar Eclipse on August 17th 2008 will be visible at Moonset for all of Australia, Asia and New Zealand, though New Zealanders will only see the Penumbral stage. Africa and most of Europe will see the Partial Eclipse in it entirety, and South Americans will see the eclipse at Moonrise. North America and Canada won't see this eclipse. The table below shows the timings for the points of contact during the Partial Eclipse. The times are given in local time for that city. The altitude column is the altitude of the Moon at that point. If it's red, it means it's below the horizon and not visible for you. At greatest partial eclipse, approx 70% of the Moon will be covered by Earth's shadow.
Viewing GuideLunar Eclipses (unlike Solar Eclipses) are completely safe to observe with the unfiltered and unaided eye - no special equipment is needed. Telescope observations can be done, however at full moon the lack of contrast due to absence of shadow regions means that visible features are limited. Binoculars can help improve the view, giving you more magnification and intensifying the colouration. A pair of 7x50 or 10x50's are best - any larger than that and you'll need a steady tripod to mount them on. Sometimes a Total Lunar Eclipse is best viewed without any optical aid, and just lying under the stars watching the change as the Moon first gets slightly darker (penumbral phase), then starts to get eaten away (partial phase), finally turning deep red as it enters totality. For something different, try predicting the Danjon Brightness Scale - a measure of the colour and brightness during totality. However you choose to view the Eclipse, we'd love to hear about your experiences! Please register and post your observing reports in the Observational Astronomy section. Photography / Imaging GuidePhotographing a Lunar Eclipse is quite easy, and doesn't need any special equipment or filters. The whole event can last quite a while as well, so you've got time on your hands. The penumbral phase lasts about 50 minutes, while the whole Partial phase (for this eclipse) lasts 3 hours (although the Moon will set for most of Australia before the Partial phase completes). If you're using digital, this gives you time to preview your images and make sure your composition and exposure is correct, and to re-shoot if needed. Much of this photography guide is aimed at photographing a Total Lunar Eclipse, but the techniques will work exactly the same for the Partial Lunar Eclipse in August 2008. There are many ways to photographically present a Total Eclipse of the Moon. Following are a few ideas. These ideas will be focused on digital imaging - if you still use film then the techniques will be similar, but you lose the ability to preview your shots and re-shoot if needed! 1) Short Focal Length Telescope ViewAs mentioned before, high-resolution high-magnification views through a telescope are likely to be quite disappointing due to the lack of contrast during a full moon. The same applies if you're trying to image the Eclipse using normal high-resolution imaging techniques. If you're using a telescope, the best results will be obtained where you can fit the whole Moon in the Field Of View (FOV) of your telescope and imaging device. Some examples of this could include:
You can take images during various stages of the eclipse to present a final composite showing all phases on the same image, or you could simply use a single totality image (for example) to present the Moon during a Total Lunar Eclipse. An example of both of these methods is seen in the images above. You could also take a sequence of images over the entire eclipse (for example, every 10 minutes), resize them down and present an animated gif showing a "movie" of the Moon diving into shadow, entering Totality and then coming out again. An example showing an animated gif like this, is one from Fred Espanek in January 2000. 2) Long Focal Length Camera ViewUsing a normal digital camera sitting on a tripod, choose your longest zoom setting or longest focal length lens (using a DSLR) and frame the Moon. Take test shots to check your composition and exposure. Make sure you use the histogram function on your camera to ensure that you're not clipping either end of the histogram (not overexposing or underexposing). Zoom in on the preview screen to check that your focus is sharp. Most cameras should be able to get an autofocus lock on a bright object like the Moon, so focus shouldn't be too much of an issue. If your camera is able, once you've got a focus lock, change the focus to Manual so that it doesn't change between shots. As the weather gets colder and the Moon increases in altitude, the focal point may change so it may be worth re-checking focus once every hour or two. For a normal digital camera (not a SLR/DSLR) change the focus to the "infinity" setting and leave it there. The exposure will need to change during the phases of the eclipse as the Moon dives into shadow. During totality, a longer exposure such as a few seconds may be needed while a fraction of a second is all that's needed when the Moon is not in shadow. Keep your ISO setting low (eg: ISO100) to minimise the noise. It's also worth bracketing your shots or simply check the image afterwards and re-shoot if necessary. During haze, fog or high cloud you will need to increase the exposure. You can take images during various stages of the eclipse to present a final composite showing all phases on the same image, or you could simply use a single totality image (for example) to present the Moon during a Total Lunar Eclipse. An example of both of these methods is seen in the images above. You could also take a sequence of images over the entire eclipse (for example, every 10 minutes), resize them down and present an animated gif showing a "movie" of the Moon diving into shadow, entering Totality and then coming out again. An example showing an animated gif like this, is one from Fred Espanek in January 2000. 3) Widefield Camera ViewThis technique involves a digital camera with a wife field of view or short focal length lens, and would give the most natural "eyeball view" of the Eclipse. Simply sit the camera on a tripod and take an image of the Moon in it's natural environment. The challenge is to present it with beautiful foreground interest - so put some thought into where you're going to photography from. A view of the Moon above some houses and trees might not be as spectacular as the Eclipsed Moon rising above the ocean or interesting architecture or structure. Be creative. Visit the location beforehand and take some test landscape shots so you can be sure the image will look aesthetically pleasing. Landscape photography is an art in itself, so practising will help! Use a slow focal ratio (stop down the lens), for example f/9 or higher, to ensure that both the foreground and the Moon are captured in sharp focus. Another interesting and beautiful way to present widefield images of the Eclipse is to take a sequence of images over the duration of the Eclipse (every 5-10 minutes) and make a composite of the Moon images over the foreground. It's important to keep the camera steady and make sure the tripod doesn't move throughout the night so you can ensure accurate position of the Moon when making the composite. Fred Espanek has used this technique with great success by taking multiple exposures on the same piece of film. Some of his examples of this technique are here and here. You can see his full gallery on his website to get some more ideas. I also used this technique during the August 28th 2007 Total Lunar Eclipse; you can see my result here. My Lunar Eclipse Gallery is here.
However you choose to photograph the Eclipse, we'd love to see your results posted on IceInSpace so please register and post your images to the Solar System section. Further Reading and Resources
Article by Mike Salway (iceman). Discuss this Article on the IceInSpace Forum.
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