This Week’s Sky at a Glance, 2019 January 19 – 26 ~by Curt Nason
At the mercy of the weather, night-owl stargazers could be treated to a lunar eclipse beginning late Sunday evening. This is our first lunar eclipse since the Harvest Moon eclipse in September 2015, and we won’t get another until a deep partial eclipse in November 2021 and a total one in May 2022.
Although the Moon starts slipping into Earth’s dark shadow at 11:34 pm, look for subtle gray shading on the lunar surface beginning a half hour sooner. This is the penumbra, a lesser shadow created when Earth partly covers the Sun as seen from the Moon. From 11:34 pm to 12:41am the dark umbra will creep across the lunar surface toward totality. Note that the umbra appears on the left side, which indicates the Moon is moving eastward in its orbit rather than the westward motion we see as our planet rotates. Also, note the curvature of the shadow. Aristotle noticed this in the fourth century BC and correctly assumed it was because the Earth is spherical. Watch for more stars to appear as totality approaches and the sky darkens. The Beehive star cluster, also called the Praesepe and M44, will be just to the east of the Moon.
Totality lasts for 62 minutes, ending at 1:43 am. The Moon could take on a red or orange hue during totality, caused by our atmosphere acting like a lens and bending the red part of the sunlight moonward. Blue light is scattered more, right across our sky, which is why we see that colour on a clear day. You might also note that the top of the Moon is brighter than the bottom. The Moon passes above the centre of Earth’s shadow during this eclipse, so the top portion is farther from the deepest and darkest part of the umbra. From 1:43 you get to watch the partial phase play out in reverse over 67 minutes, followed by the fading of the penumbra.
Weather permitting, telescopes will be set up at Saints Rest Beach in Saint John and a live feed of the eclipse through a telescope will be broadcast via the Facebook page Astronomy by the Bay. The Physics and Astronomy Department at the Université de Moncton plans to host a talk and eclipse observing. Attendance is limited but the tickets are free.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 7:54 am and sunset will occur at 5:05 pm, giving 9 hours, 11 minutes of daylight (7:57 am and 5:12 pm in Saint John). Next Saturday the Sun will rise at 7:48 am and set at 5:15 pm, giving 9 hours, 27 minutes of daylight (7:51 am and 5:22 pm in Saint John).
The Moon is full and somewhat brick-coloured very early on Monday morning, the traditional Wolf Moon and the Mi’gmaw Tom Cod Moon. The two brightest planets make a striking pair in the morning sky; with Venus being a binocular width above Jupiter on Saturday and about the same distance to the left of Jupiter by next Saturday. Saturn might be spotted in twilight a hand span to their lower left. Mars resembles a first magnitude red star in the southwest during the evening.
RASC NB, the provincial astronomy club, meets in the Rockwood Park Interpretation Centre on January 19 at 1 pm. All are welcome.
Questions? Contact Curt Nason.