ALCON skies, and coming eclipses

ALCON 2018 is coming, and so is a three-eclipse season.  Here’s the western evening sky for the first night of ALCON:

And the eastern sky at the same time:

What’s ALCON?  It’s the conference of the Astronomical League, and fills July 11 to 14 (Wednesday to Saturday).  See https://www.astroleague.org/content/alcon-2018

Its central activities are at the Hilton Minneapolis / St. Paul Airport Mall of America (an expression I find impossible to punctuate according to classical rules; English seems to be becoming an agglutinative language).  So our pictures are as seen from Minneapolis.

They show the post-sunset sky for the first day of ALCON.  On the succeeding evenings the scene will scarcely change; the arrows through the planets show how they move over a span of 5 days against the starry background.  And for some of the planets the arrow is too small to see because they happen to be moving hardly at all in relation to Earth.

Over the western horizon, Mercury and Venus are following the Sun down.  Venus shows plenty of movement: it is continuing to circle outward toward its Aug. 17 maximum elongation from the Sun.  It passed slightly less than a degree north of Regulus early on July 10.  Mercury is reaching its maximum elongation (26°, on July 12).  Because of the angle of the ecliptic at this season, this is, for northern latitudes, a favorable chance to see Mercury, the second highest of the year.

Jupiter is arching over the southern horizon, not so high as it can be, because in these years it is traveling the southern part of the ecliptic.  It was at opposition on May 9, seeming to move back westward as we overtook it, and is just now ending that phase: at its second stationary moment among the stars, about to resume eastward motion, becoming more distant as we leave it behind.

In the east, Saturn is still seeming to move slowly westward after its June 27 opposition.  And Pluto, dimmer than thousands of stars, takes its turn to be at opposition (July 12, at 3 Universal Time).  You can see in the picture that it’s at the “anti-Sun” point, but you won’t be able to see it – or maybe you will, if you’re an accomplished Astronomical League telescopist and ALCON attendant.  At any rate you can imagine its “painted deserts” that have now been revealed by the New Horizons space mission and are described in our new book.

Mars will rise about 1 hour 25 minutes after sunset, well to the south in Capricornus.      And the Moon is out of the way, being New on July 13.

Space view of the planets’ travels in July, with sightlines to them from the Earth at July 11.  The dashed line shows the vernal equinox direction, from which positions in space are measured.

As for the eclipses, the fact that three of them, instead of the more usual two, fit into an eclipse season has to mean that the outer two are marginal: partial solar eclipses seen from the Antarctic on July 13 and the Arctic on August 11.  The middle one is nearly central, a total eclipse of the Moon on July 18, visible from the Pacific and much of America.  But it (in the kind of words with which many of the “overflowing” chapters of Don Quixote delightfully end) “deserves a chapter of its own.”

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Correction:  The July 27 (not 18) lunar eclipse will be visible from the Indian Ocean and its surroundings, including most of Africa; not from Earth’s Pacific-and-American face.  Thanks to Anthony Barreiro for saving me from a result of some momentary weariness.

Hitherto I have abstained from retrospectively correcting blog posts (except for minor improvements of wording), because doing so could make comments seem unintelligible.  But I realize that it can be done in this way; an advantage over printed magazines.