September 16, 2014

Astro Event: A South Pacific Eclipse.

Animation of the July 11th Solar Eclipse. (Credit: A.T. Sinclair/NASA).

Path of the solar eclipse…click for animation. (Credit: A.T. Sinclair/NASA).

   This year’s big ticket astronomical event occurs over a sparsely populated but beautiful track of our planet; we’re talking about July 11th’s total solar eclipse. Of course, it isn’t often that an eclipse doesn’t occur over the windswept Arctic or a war-torn banana republic… the Sun and sand of an island eclipse may just be the perfect combo. If you haven’t already made plans to catch one of the numerous cruises headed that way you may have to enjoy it vicariously with the rest of us via the Internet; this eclipse graces only a smattering of islands before making a brief landfall in South America across the Chilean-Argentine border at sunset. The path of solar totality will not grace our planet again until November 2012 in another South Pacific eclipse that intersects this month’s path! Its maximum length of 5 minutes and 20 seconds occurs over open ocean. Two very interesting sites for viewing include Easter Island and just off of the coast of French Polynesia and Tahiti; the more adventurous may want to head for the Cook Islands site of Mangaia, which lies right along the centerline. Weather prospects may favor the northern hump of the path, with a mean cloudiness of less than 50%… but for sheer beauty and landscape photo ops, Easter island will be your best bet. No doubt most of humanity will experience this one vicariously via the web; follow @Astroguyz via Twitter, as we’ll post where online to watch this extra-ordinary event in the days leading up to the eclipse!     

The Astro-term for this week is Metonic Series. A metonic series of eclipses arises from the fact that the period of 19 tropical solar years is very nearly equal to 235 synodic months. This was first recognized by the astronomer Meton of Athens in the year 432 B.C. The error of difference is 2 hours per 19 years, and this accumulates to a full calendar day every 219 years. A metonic cycle of eclipses will share the same calendar date in groupings of 4 to 5 per series… for example, the first eclipse related to this month’s was on July 11th, 1953 and the last will be 19 years from now, on July 11, 2029. Do not confuse metonic series with saros cycle, which is independent of the solar calendar and based on a period of 223 synodic months. So what, you say? Well, metonic series not only factor into eclipses landing on the same date, but also play a role in calculating when the Moon will appear at the same phase in the same position again… metonic series even play in to trajectory calculations for lunar bound spacecraft, as well as serving as a basis for the Hebrew calendar and the computation of Easter!

Review: The Age of Wonder by Richard Holmes.

Out now from Pantheon Books!

Out now from Pantheon Books!

 

 Every once in a while, a book crosses our nightstand that just makes us say “Wow…” We then have to ration out this discovered gem, lest we burn the midnight oil and consume it in one lost weekend…

Such a discovery came to us in the form of recent book The Age of Wonder by Richard Holmes. Out by Pantheon Books, this huge opus does nothing short of charting the course of science through the early 1800’s. From Joseph Banks to William Herschel to Humphrey Davies, many a fascinating untold tale is contained in this book. I explicitly saved this book for reading during our Ecuador trek late last year, as adventure travel deserves good reading to go along with it. Each of these tales are an engaging read, and cover such diverse fields as astronomy, chemistry, anthropology, and botany. Of course, since this is an astronomically based blog, the chapters on William Herschel came first. [Read more...]

Top Astronomy Events for 2010.

(Photo credit: Art Explosion).

(Photo credit: Art Explosion).

Ah, it’s that most hallowed time of year yet again; a time to look ahead at what astro- wonders await in 2010. Here’s a quick month-by-month rundown of the curious, unique and bizarre coming to a sky near you. Like last year, rather than bore you with a laundry list of every obscure wide conjunction and moon phase, we distilled ‘em down to the best of the best. [Read more...]