Astronomers from casual to the pros know of “deep-sky objects.” These objects, clearly neither stars nor comets nor planets, began to get notice in telescopes in the 17th to 18th centuries. At first, scientists struggled to explain them. Today, we have them figured out pretty well.
Charles Messier, left, assigned numbers to dozens. Many amateur astronomers keep them on a checklist for observation. Note this visual catalog made by one observer.
I don’t have a telescope these days, so I guess I’ll be satisfied with a series of brief essays on the objects and if they have any connections in religion, fiction, or some other area of personal interest.
With the customary Dog Days having ended on the 13th, I decided to annotate my daily-annual astronomical-climate spreadsheet I created a generation ago to include the local heliacal risings and settings of both Sirius and Orion’s Belt. Locally, they set roughly around the same time of year (~May 7th), though at different azimuths, but they rise 47 days apart (~July 19th for Orion’s Belt, ~Sept 3d for Sirius) and their middle-of-the-night (not clock midnight, but local midnight) zeniths are a few weeks apart (second week of December for Orion’s Belt and first week of January for Sirius).
I gather that the precession of equinoxes has moved the heliacal rising of Sirius weeks later in our current calendar year compared to when it was first charted in ancient Egypt at the dawn of the Second Millennium BC as synchronous with beginning of the arrival of the floods in the Nile in Egyptian lands after the monsoonal rain dump on the roof of east Africa made its way down the watershed – or the calamitous lack of monsoonal rain and consequent absence of the floods. Of course, with the Nile now being dammed, there are no more such annual floods that formerly defined Egyptian civilization for millennia.