- September 22, 2015 - Planétarium : Astronomical News
On the evening of September 27, the full moon will be completely engulfed by the Earth’s shadow, marking the last in a series of four total lunar eclipses to occur since April 2014. Of the four, only the April eclipse and this one have been or will be seen from beginning to end throughout Québec. Unfortunately, the April 2014 eclipse was clouded out… Will this one be?
Some background facts
Total lunar eclipses occur during the full moon (when the Earth is between the Sun and the Moon) – but only when the Earth, the Moon and the Sun are aligned. During these alignments the Moon’s orbit carries it completely through the Earth’s shadow. Though the Moon orbits Earth at about 1 km/sec, the Earth’s shadow is so large that totality can last up to 100 minutes. On average, one total lunar eclipse is visible in its entirety from southern Québec every three and a half years. But the weather cuts that figure roughly in half: statistically, weather patterns for southern Québec at the end of September indicate a 50 percent chance of overcast skies, and 50 percent clear to partly cloudy.
The eclipse in detail
The event gets under way in the east-southeast at 8:11 p.m., as the left side of the Moon enters the Earth’s penumbra – the lighter, outer part of our planet’s shadow cone. The effect is subtle at first, but becomes more apparent as time passes. By 9:07 the Moon enters the dark, central umbra, and a distinct “bite” begins to disappear from our satellite. These partial phases continue until 10:11, when the Moon becomes entirely immersed in the Earth’s shadow: This is the beginning of totality.
Throughout totality, which will last 72 minutes, the Moon assumes a characteristic coppery-red colour due to sunlight refracting through the Earth’s atmosphere and illuminating the lunar surface. In effect, these are the colours of sunset being cast onto the Moon.
At 11:23 p.m. the Moon begins moving out of the Earth’s umbra, and totality ends. The final partial phases of the eclipse ensue until 00:27 a.m., at which point our satellite will have left the umbra entirely. The final penumbral stages of the eclipse end at 1:22 a.m.
How to shoot the eclipse
Lunar eclipses are completely safe to observe with the naked eye or binoculars…and because they occur slowly, they are also easy to photograph. Begin by setting your camera to ISO 400 and your aperture to f/8. Next, zoom in as far as possible: a focal length between 300 and 500 mm is ideal. During the partial phases, try varying shutter speeds between 1/500 and 1/60 of a second. As totality approaches, vary your exposure times between 1 and 15 seconds. Of course, a tripod will be necessary for these slower shutter speeds. Don’t be afraid to experiment. With digital cameras you can see your results instantly and make adjustments accordingly. And then you can post your photos on our Facebook page.
