Spring coming, Venus going

The spring or vernal equinox is coming, on Monday March 20, at 10:29 by Universal Time (4 to 7 hours earlier by clocks in contiguous U.S. time zones), and so is the inferior conjunction of Venus (on March 25).

As a reminder of what the equinoxes and solstices mean –

Equinoxes and solstices

At the vernal equinox, or March equinox as it is more neutrally called (because it is autumn equinox for our southern hemisphere), Earth traveling around its orbit reaches the point where its north pole is tipped most steeply backward.  North and south poles are equidistant from the Sun; the Sun is on the equator of the sky, and is overhead at noon on Earth’s equator.  Day and night are equal in length (at a first approximation, not taking into account the effects which make the Sun seem a little higher when it is close to the horizon).  And from now on, the Sun, for the northern hemisphere, is in the sky for more than 12 hours, and its daily journeys across the sky arch ever higher.

I’ve been silent in this space for a while, partly because on a trip and attending to other matters, partly because I’ve been working on Venus and will soon have more for you to see in its “Astronomical Calendar 2017” page.

I want to share an observation of the occultation of Aldebaran in the night of March 4/5, sent to me by Stephen DeMuth of Newport News, Virginia.  I think it communicates that grazing occultations by the Moon are observable with simple means and how exciting they are.  He writes:


In over 60 years of observing, I had never seen a Lunar event involving a bright, naked-eye star, with the Moon’s dark leading edge providing a nice touch spot.  It was BEAUTIFUL !!!!
2017-03-04  22:30 EST
Coastal Virginia, USA: 37deg 05min 34.9sec N  76deg 32min 09.2sec W
Temp: 35F/1.7C
Bright, clear, great seeing, unlimited visibility
The Moon was in the Hyades, one day prior to First Quarter.  At 22:30, the Moon was located approximately .5deg NNW of Aldebaran, and approximately equidistant from the North and South Limbs.  Over the next 30 minutes, the Moon slowly closed the distance while drifting slightly right-to-left.  As time passed, it became clear that the R-to-L drift rate might result in a missed opportunity.  By 23:00, naked-eye separation was not possible due to Lunar glare.  Using 7×50 binoculars, and masking about 90% of the illumination using my house roof-line, I was able to regain clear separation.  At approximately 23:02 EST, Alpha Tau [Aldebaran] “blinked out” VERY CLOSE to the North Limb Terminator (approx. 3min 45sec angular distance).  WOW!
I feel blessed to have seen this “near miss” event

2 thoughts on “Spring coming, Venus going”

  1. Stephen DeMuth’s observation of the occultation of Aldebaran resonated with me, but also provided a chuckle in comparison with my experiece. Ii was my original intent to be at a dark, remote location – but social commitments placed me at N40° 43′ 34.42″; W73° 43′ 1.59″ or in comprehensible terms, at the Triple Crown Diner off Jamaica Blvd in Queens, NY. Nearing event time, I slipped away from our party, and crossed the street – it was windy, in the low 20sF, with artificial light everywhere, but with clear and stable viewing, the Moon and Aldebaran were distinctly visible. I braced my binoculars against a utility pole and watched carefully, with no expectation of strong reactions, and some doubt as to whether this would be worth the effort – but as with DeMuth, the instant of occultation was a profound moment. In my awestruck state, I stood quietly pondering the experience for several minutes, and failed to record the time (it was close to 23:11 EST).

  2. Thanks Guy. I’ve been missing your posts. I hope you had a good trip and all is well, and I’m looking forward to the enhanced Venus info.

    Here in San Francisco on March 4, both the Moon and Aldebaran were occulted by clouds. Darn it.

    There have been enough breaks in the clouds to follow Venus’ thinning and lengthening crescent as she (sorry) approaches inferior conjunction. Probably my last peek was Friday March 17, through trees across the street. The crescent was clearly visible through hand-held 8×42 binoculars, and tilted slightly toward the right, showing that Venus is well north of the Sun.

    I’m hoping to get a sextant sight of the equinox noon Sun today and/or tomorrow, in part to see how well I can measure my latitude and longitude.

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