Lunar eclipse and occultation of Mercury

Ah! November… Typically known for its grey and dreary weather that fluctuates between rain and snow, it is also the month when night prevails again, to the great delight of astronomers. November is when amateurs can tune in at reasonable hours, and more experienced and professional stargazers can stay up late to indulge their passion and fully enjoy the celestial sphere.

The night of November 6-7—the eve of the Quebec municipal elections—is when the clocks fall back: At 2 a.m. Eastern Daylight Time it will officially be 1 a.m. Eastern Standard Time. This means we all get to enjoy an extra hour of sleep or skywatching and still be in top form to do our civic duty. But this year, our municipal candidates will be upstaged by Mercury and the Moon.

In fact, on the afternoon of November 3, we’ll be treated to a rare occultation of Mercury as the Moon briefly passes in front of the tiny planet. As seen from Montreal, the illuminated edge of the very thin lunar crescent (almost in a new Moon phase) will hide Mercury at around 3:35 p.m.; in just under an hour, the lunar disc will glide in front of the planet until the latter emerges around 4:32 p.m. from behind our satellite’s dark limb. The phenomenon will take place in broad daylight, very low in the sky and only about 15 degrees from the Sun, making it very difficult to observe. Experienced astronomers will likely be the only ones out there observing this occultation, especially since it’s extremely important not to look directly at the Sun with the naked eye, much less accidentally point an optical instrument (telescope or binoculars) in its direction.

Mercury’s excellent morning apparition that began in October continues in early November: The tiny planet is visible until around November 10, low on the east-southeastern horizon, 30-45 minutes before sunrise. After that date, the planet quickly loses altitude and disappears in the glare of the rising Sun. The conditions for spotting Mercury are best around November 1, in the glow of dawn, between 6:30 and 7 a.m.

Spotlight on the Moon

The Moon will also guide us through the November sky and point us to other planets. For example, on the evening of November 7, the thin crescent Moon lies 5 degrees to the right of dazzling Venus: Admire the pair low in the southwest some 30-60 minutes after sunset. On the evening of November 10, the crescent Moon appears thicker and can be found to the lower left of Saturn at twilight; the gap between the two celestial bodies gradually widens over the course of the evening. The next evening, on November 11, the first quarter Moon shines to the lower left of Jupiter at twilight, but it too will pull away over the following hours.

The Moon will be full at 3:57 a.m. EST on the night of November 18-19, when we’ll also be treated to a partial lunar eclipse that will be fully visible from North America, the Pacific and the Far East. (During the eclipse, the Moon sets in South America and the Caribbean, and it rises in Southeast Asia, China, Mongolia, Australia and New Zealand.) However, this partial eclipse is actually very deep because, at its maximum, 97.4% of the Moon’s diameter will plunge into the Earth’s umbral shadow: The Moon will thus take on the characteristic reddish hue of a total eclipse, leaving only a thin border still lit by direct sunlight.

The partial eclipse will begin at 2:18 a.m. and end at 5:47 a.m. In Montreal, when the eclipse reaches its maximum, around 4:03 a.m., the Moon will be 29 degrees high in the west, beneath the Pleiades and Hyades star clusters. Let’s hope the weather is kind to all the brave souls who will take the time to observe this spectacular natural phenomenon.

Clear skies!