This highly regarded annual guide to the year’s sky events is back for 2023 in both print and ebook editions.
For many years, the Astronomical Calendar, authored and illustrated by Guy Ottewell and published under his Universal Workshop imprimatur, was a favorite annual purchase of amateur astronomers. The Calendar provided a well-illustrated guide to the year’s celestial events and the motions of solar system objects.
It was sad to see it disappear after 2016. But it is back! The Calendar returned in 2022 as an ebook-only edition. But for 2023 the Calendar is available once again both as an ebook and in print.
The hard copy version is a standard 8.5- by 11-inch print-on-demand book that can be ordered from your national Amazon outlet, where the cover price and shipping cost will vary. This is smaller than the big 11- by 15-inch tabloid format of earlier print editions. However, Amazon’s print-on-demand service, which makes a print edition possible, dictates the smaller letter size.
The Calendar can also be purchased from the book’s website as a downloadable PDF for viewing on any device with PDF reader software. As the Calendar’s introduction suggests, the ebook is best viewed on tablets as a two-page spread, allowing illustrations that cover two adjacent pages to be viewed at once. In Adobe’s free Acrobat Reader software for iOS under View settings I had to enable “Two Pages with Cover Page” for the spreads to break and display adjacent pages correctly when in landscape orientation. The free app, PDF Pro, also did a good job displaying the book properly on my iPad.
Either in print or digital versions, the 139-page Astronomical Calendar 2023 offers most of the features fans of the guidebook have come to know and love. I say “most,” as missing are some of the essays and departments written by guest authors in editions from the 1990s and early 2000s.
I reviewed the 2023 ebook edition, from which I’ve extracted the page images below.
The core content of the Calendar is the 72-page Months section, with each month allocated six pages. Each month’s opening two-page spread (I show January above) presents a basic all-sky star map and a plan view of the solar system showing the orbital location and motion of the planets. The all-sky map shows the sky for about 10 p.m. each night and plots the location of the planets, and the quarter and full Moons for that month.
A horizon chart shows a view of the dusk or dawn sky for a notable date that month showing the prominent planet(s) or the crescent Moon passing a planet. On all the charts, constellation outlines are drawn in Ottewell’s own style of curving lines, giving the charts a hand-crafted “organic” appearance.
The other two-page spreads for each month contain a detailed table of celestial events on the left and a set of horizon charts for both the dawn and dusk sky on the right, depicting a set of 10 dates, often consecutive, through the month. These illustrate the arrangement of morning and evening Moons, planets, bright stars, and conjunctions.
All the charts are drawn for 40° North latitude, so will be roughly applicable to any mid-northern location within 10 to 15 degrees of that latitude. However, there are no charts for Arctic or tropical latitudes, or (with the exception noted below) for the southern hemisphere. (For southern sky almanacs, I particularly like the annual guides by Wallace, Dawes and Northfield published in Australia by Quasar Publishing.)
In Ottewell’s Calendar, the event tables list one or more events per day — a lot! Many are simply milestones in some object’s orbital motion (i.e., “Moon at descending node”) and are not something one would actually observe.
To make it easier to pick out observable events, I would prefer to see the month’s best naked-eye sights highlighted in bold, and perhaps the main Moon phases indicated more graphically. There are no Moon phase calendars as such that show the phase for each day of the month. Those might be useful. On the other hand, I think we could do without any references to when the Sun enters astrological signs vs. the actual zodiac constellations.
The final 56 pages of the Calendar contain a number of sections with illustrations of sky motions and events for the year. You are not likely to find anything similar, or as informative, as these diagrams in other annual almanacs or handbooks.
For example, as shown above, a Zodiac map shows the path of the Moon in 2023 relative to the ecliptic. It illustrates how the Moon’s inclined orbit will take it well south of the ecliptic in summer 2023, and well above the ecliptic in winter at either end of the year. We will have unusually low summer Moons but high winter Moons in 2023.
Horizon charts depict the geometry of the waxing and waning crescent Moons for each month, and their ages, for those hunting for the youngest and oldest thin Moons. Again, these are for 40° North, and for an eastern North American longitude of 75° West, but are useful for other locations.
Other charts show the changing Earth-Moon distance for each new and full Moon, illustrating 2023’s “super blue” Moons in August, though Ottewell refrains from labeling them as such. You’ll also not find any references to the various Full Moon names that have become popular of late, wisely I think, as many are of dubious or at best only regional provenance.
Also unique are the plan views showing the geometry of the four eclipses in 2023 with the Earth, Moon, and their shadow cones drawn to scale.
Other maps show the path of the Moon’s shadow across the globe for the two solar eclipses in 2023, and the passage of the Moon through the Earth’s shadow for the two minor lunar eclipses in 2023, along with Earth globes showing what half of the world will see the eclipses of the Moon.
A section I particularly like is on occultations of bright planets by the Moon. In all other references to these events it can be hard to tell if the event is actually visible from your location and, if it is, if it occurs in a dark sky. Ottewell’s excellent maps make all that information graphically clear at a glance.
The brightest asteroids are covered, as are the main meteor showers, but there’s no information on any comets expected to be visible in 2023. There is no Mars map, and the corkscrew-style diagrams showing the positions of the main moons of Jupiter and Saturn cover only the few weeks on either side of each planet’s opposition.
2023 will be a good year for Venus, so horizon charts nicely illustrate the rise and fall of the planet and its phase and disk size change for both its evening and morning apparitions. In this case, charts are provided for both 40° N and 35° S latitudes. Similar charts show Mercury’s appearances at each of its elongations in 2023 for both latitudes.
The pages I show are samples of the Astronomical Calendar’s unique selling point — its excellent diagrams, many of a type you won’t find elsewhere. The book is presented at a level suitable for observers of all skill levels. Beginners will learn a lot about how the sky moves, while more experienced observers will benefit from the visualizations of concepts they might know but haven’t seen depicted as well as they are in the Calendar.
For an accessible yet detailed guide to the sky in 2023, I highly recommend Guy Ottewell’s Astronomical Calendar.
Unique visualizations of sky motion
Detailed tables of astronomical events
Less technical than some other annual almanacs
Main events and sights can be hard to pick out
Best for mid-northern latitudes
No information on comets
MSRP: $21 print edition; $12 for PDF eBook