Lunation’s End

Waning Moon in conjunction with Venus over Illinois

And so another month of waxing and waning, known as a lunation, draws to a spectacular close.  I got up early to catch a last look at the waning Moon before it disappears into the pre-dawn glare.  We’ll see the Moon again with the Sun “backlighting” it in the middle of the day on Monday.  And from our vantage point under the moon’s shadow as it races by us at 2,700 km/hour we may also see Venus, Mars peeking out from behind scattered cloud. If it is totally cloudy and raining, we’ll just see the ground getting very dark indeed. Estimates of the probability of the Sun/Moon being hidden by cloud at our chosen location vary from 20% to 40%.  So that’s a 60%-80% chance of seeing the Sun’s ethereal atmosphere, known as the “corona” which is good enough for me.  Obviously weather is the show-stopper now.

When I saw the total eclipse of 1979 from Kennewick, Washington on a crisp February morning, there was scattered cloud covering about 40% of the sky.  When the shadow passed, the Sun/Moon remained behind a solitary cloud the whole time, but this did not diminish the awe of the eerie darkness: stars and planets all around and lights in the valley below my hilltop vantage point on the side of a road.

Depending on the likely partial cloud cover, we may see 4 planets (M,V,M,J) and two bright stars (Sirus and Arcturus) peeking out in the sky and several less bright stars especially in the darkest part of the sky near the Moon/Sun.

Computer simulation of a cloudless sky over Nebraska during the eclipse


The return of daylight will mark the start of a new lunation where we may observe the waxing of the moon from evening crescent to Full Moon over two weeks, then rising later and later in the night until is is once again a waning crescent in the September sky next month.



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