September 21, 2017

Astro-Event: Ushering in Spring 2012.

The Double Shadow transit at 3UT on March 23rd.

(Graphic created by Author in Starry Night).

Residents of the northern hemisphere take heart; the spring or Vernal Equinox occurs this week on March 20th. This is the moment that the Sun crosses the celestial equator as seen from our Earthly vantage point and begins its march north into positive declinations. The exact moment occurs at 05:14UT/01:14 EDT early Tuesday morning, the earliest its occurred since 1896 and the earliest until 2016 when it slides back another 44 minutes. Our orbit (or one sidereal year) isn’t exactly 365 days long, nor is the pesky remainder exactly a quarter day long. Hence, you can see those 6 hours add up every year in the solstice and equinox times until we add a leap year (as we did this year) and reset the time back 24 hours… though not precisely. A slight cumulative deficit of about 10 minutes & 48 seconds causes the equinox and the solstices to slide back ever so slightly; already, this week’s spring equinox occurs on the 19th as reckoned in the western US, and it will start falling on the 19th with greater frequency as reckoned in Universal Time this century beginning in 2044! However, the year 2100 A.D. evokes a secondary rule of our Gregorian calendar, skipping a century leap year for the first time since 1900. This rule of “removing a leap year on century years not dividable by 400” (or think of it another way, we have 97 leap years every 400 years) very nearly brings our calendar back in line with physical reality. Vernal equinoxes falling on the 19th occur with less frequency (5 times) in the 22nd century, and cease altogether in the 23rd. Play with the dates a bit with this handy online calculator and you’ll see what I mean.

Happy Spring/Fall equinox to your respective hemisphere, celebrate with the Wheel of the Year or favorite equinox tie-in holiday, and be sure to watch for those local Stonehenge-style alignments coming to a neighborhood near you as the Sun rises due east and sets due west!

This week’s New Moon occurs on Thursday, March 22nd, and heralds the optimal time of year this week to conduct a Messier Marathon. Can you catch all 110 deep sky objects in one dusk ‘til dawn sprint? Give her a try!

…And speaking of calendars and their accompanying idiosyncrasies, the United Kingdom and the European Union states follow suit and join back up with the United States in springing forward one hour on March 25th to ye ‘ole Daylight Savings time. Just think, if you live in the UK, you won’t be able to consider local time and Universal as one in the same again ‘til this coming Fall!

Live in northern Quebec or along the southwest corner of the Iberian Peninsula or North Africa? The +9.3 magnitude asteroid 5 Astraea occults an +8.3 magnitude star in the constellation Leo on March 21st 00:22 to 00:47 UT. This one should be interesting even if you’re not “on the path” because unlike most occultations, owners with even a small telescope should see both the asteroid and the star masquerading as a close pseudo-binary. 5 Astraea just passed opposition on the 12th of this month. Don’t forget to check out Mars also in Leo, now receding from us but well placed for evening observation in the eastern sky.

An interesting double shadow transit occurs over the cloud tops of Jupiter on March 22nd with both Ganymede & Io casting simultaneous shadows from 2:30AM UT (on the 23rd) until 3:30AM UT. Jupiter currently sets around 10:30 PM local, and thus some or all of the double shadow transit is visible from the Mississippi River westward on the night of the 22nd. This is a unique event that only takes place a few times a year.

In the department of the strange and curious, the asteroid 2883 Barabashov transits the tiny disk of Uranus as seen from Earth on March 23rd… both however, are lost in the Sun’s glare as Uranus reaches superior conjunction just a day later on the 24th!

Finally, March 19th marks the anniversary of a total solar eclipse that has been one of a handful linked to the crucifixion of Christ. It would be tough to see how this could have been possible, however, as the path of totality crossed the Indian Ocean and wasn’t even partial from the Holy Lands… plus, another strike against a crucifixion solar eclipse was that the event occurred around Passover during the Full Moon. If there’s any linkage between the March 19th 33 AD solar eclipse and the stories of the New Testament, it’s that this eclipse set up the skies over Jerusalem for a 58% partial lunar eclipse visible at moonrise on April 3rd of the same year over the Middle East. Eclipses generally occur in pairs like this, as the Moon is near the opposite node where its path intersected the ecliptic two weeks prior. Thus a solar eclipse is usually paired with a lunar one. Is there a possible celestial connection to the darkness mentioned in the Gospels of Matthew, Mark and Luke? It’s interesting to speculate on what might have been this Lenten season as we approach Easter on April 8th!



  1. [...] 21st: Asteroid 5 Astraea occults an +8.3 magnitude star, visible across Africa, Portugal, and Eastern [...]

  2. [...] double in the eyepiece of a telescope. This is one of the closer planet-star conjunctions of 2012. Uranus will appear as it always does, with a tiny blue-green disk 3.7” across. Uranus reaches [...]

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