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FORT McMURRAY — Skywatchers in Fort McMurray will have a chance to watch most of the moon darken to a faint reddish glow Thursday evening as a deep partial lunar eclipse crosses the night sky.
The eclipse will already be underway when the moon rises at 8:24 p.m., with the visible partial phase beginning just nine minutes later at 8:33 p.m.
Maximum eclipse is expected at 10:12 p.m., when about 93 per cent of the moon will be immersed in Earth’s shadow.
Royal Astronomical Society of Canada member and published astrophotographer Richard Covey says the eclipse should provide a dramatic show without requiring any specialized equipment.
“At maximum, more than 90 per cent of the moon will be in Earth’s shadow, so this should be a very dramatic partial eclipse,” Covey said. “Most of the moon could take on a copper or reddish colour, with a small bright portion remaining outside the darkest part of the shadow.”
A partial lunar eclipse occurs when the sun, Earth and moon align closely enough for part of the moon to pass through the Earth’s umbra, the darkest central portion of its shadow.
As the moon moves deeper into the umbra, Earth’s shadow will appear to gradually spread across the lunar surface before receding later in the evening.
The reddish or copper colour sometimes seen during an eclipse is caused by sunlight passing through Earth’s atmosphere before reaching the moon. Much of the shorter-wavelength light is scattered, while redder light passing through the atmosphere can illuminate the portion of the moon inside Earth’s shadow.
For Fort McMurray viewers hoping to catch the eclipse from its earliest visible stages, location will matter.
The moon will be extremely low when it rises in the east-southeast, sitting less than one degree above the horizon when the partial phase begins.
“The biggest challenge early in the evening will simply be finding a clear horizon,” Covey said. “The moon rises while the eclipse is already underway, so anyone hoping to watch from the beginning should find somewhere with a good unobstructed view toward the east and southeast.”
By the time the eclipse reaches its maximum at 10:12 p.m., the moon will have climbed to about 12 degrees above the southeastern horizon.
The partial phase will continue until 11:51 p.m., when the moon completely leaves Earth’s darker umbral shadow.
A more subtle penumbral phase will continue until 1:01 a.m. Friday as the moon passes through the lighter outer portion of Earth’s shadow.
Unlike a solar eclipse, no protective eyewear is needed to watch a lunar eclipse.
“The nice thing about a lunar eclipse is you don’t need any special equipment,” Covey said. “You can watch the entire thing with your eyes, and unlike a solar eclipse, there’s no need for protective eyewear.”
Binoculars can provide a closer look at the boundary between the illuminated and shadowed portions of the moon, while a telescope can reveal changes in colour and detail across the lunar surface.
People also don’t need to leave Fort McMurray to see the eclipse. The moon is bright enough for the event to remain readily visible despite urban light pollution, provided clouds don’t interfere.
For photographers, a tripod or other stable support can help keep images sharp as the eclipsed portion of the moon becomes darker. Smartphone users can also improve their chances by turning off the flash, stabilizing the phone and reducing the exposure on the moon rather than relying heavily on digital zoom.
Saturn will provide another target for skywatchers during the evening, appearing as a steady, golden point of light in the same broad region of the sky, although the planet and moon will not be particularly close together.
The eclipse comes just before the full Sturgeon Moon and will unfold gradually over several hours, giving viewers plenty of time to watch Earth’s shadow move across the lunar surface.
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