May 25, 2017

April 2014- Life in the Astro-Blogosphere: Tales of Lunar Totality

A time exposure of lunar totality shot on ye ole film.

(Photo by Author).

Eclipse season is neigh for 2014 this coming week, with the first of two total lunar eclipses for 2014. Lunar eclipses are always the big ticket astronomical events for any year, and the total lunar eclipse occurring on the night of April 14/15th 2014 is sure not to disappoint. [Read more...]

Astro-Event: A Fine Total Lunar Eclipse.

Our photo of last December’s total eclipse.

Mark your calendars; this Saturday, December 10th a total lunar eclipse graces our fair planet, and a good swath of humanity will get to see it. This particular eclipse occurs at sunset/moonrise for observers in central Europe, the UK, and north-eastern Africa westward, and just before sunrise/moonset for all of North America except the U.S. eastern seaboard and the Maritimes. [Read more...]

AstroEvent: Will Anyone Welcome the New Saros?

A Remote partial for the hardcore…(Credit: Eclipse Predictions by Fred Espenak, NASA/GSFC).

This week, we’d like to turn your attention to a unique event that no one but a few penguins may witness. July 1st kicks off the month with a partial eclipse of the Sun, the second solar in the past month and the third eclipse overall. The penumbra of the Moon will barely kiss the Earth from 07:53 to 9:22UT and greatest eclipse is a paltry 9.7% around 8:39UT. [Read more...]

AstroEvent: A Loooong Central Eclipse!

Last December’s colorful lunar eclipse… (Photo by Author).

One of nature’s finest spectacles is on tap this week for observers stationed from Europe to the Far East. A total lunar eclipse of a particularly long duration is in the offing spanning the night of June 15th-16th. The duration of totality is 100 minutes, nearly the maximum 107 minutes possible. A question we frequently receive as of late is “how often does such a long eclipse occur?” Well, keep in mind that the umbra or the dark inner core of the Earth’s shadow is about 3 times the apparent diameter of the Moon as seen from Earth. For an eclipse to occur, the Moon has to be very near the ascending or descending node of the ecliptic; its orbit is canted about 5 degrees to our own and thus usually passes to either side of our 1.5 degree wide shadow. For an ideal eclipse to occur, the Moon would have to occupy that node while its smack dab in the center of the Earth’s shadow… this current eclipse will be the longest in duration until July 27th, 2018 with a duration of 103 minutes. In fact, a quick perusal of NASA’s eclipse website reveals that although this week’s eclipse is the longest this century thus far, & eclipses on 2029, 2047, and 2094 also beat it out for duration, making it the fifth longest of the century.  This could as prove to be an especially dark eclipse, as the Moon passes through the central part of the Earth’s shadow… be sure to note the Danjon number of the eclipse, as well as use our tried and true method of magnitude estimation via the reverse binocular method. Particulars of the eclipse are as follows;

Penumbral 1st contact: 17:25 UT

Umbral 1st contact: 18:23 UT

Totality Begins: 19:23 UT

Totality Ends: 21:03 UT

Umbral last contact: 22:02 UT

Penumbral last contact: 23:01 UT

The penumbral phases will only appear as a diffuse shading, while entry into the umbra will be more distinct. Also, there has been plenty of volcanic activity worldwide in hot spots such as Chile and Iceland, so the eclipse may prove to be quite colorful. And yes, this eclipse occurs in the constellation Ophiuchus, the bad boy “13th constellation” of the zodiac! (Shhh… don’t tell astrologers!) This is also the 68th eclipse of saros 118.

Photographing the eclipse with even a moderate (i.e. 200mm or larger) zoom is relatively easy; just remember that the Moon will be much darker during totality than partial phases and thus you’ll need longer exposure settings… I’ve even lost telescopic acquisition of the Moon during particularly dark eclipses!  Finally, some interesting occultations of background stars will occur during totality, the brightest of which is the +4.8 magnitude star 51 Ophiuchi as seen from the Far East… speaking of which, folks around the periphery of the eclipse (i.e. Japan, U.K. and Australia) should be vigilant for the possibility of a Selenelion, or the chance to catch totality while the Sun is still above the horizon!

Well, it looks like us folks in North America will just have to sit this one out, or at least watch it through broadcast via the Net… will tweet links (@Astroguyz) if live… We’ll just have to console ourselves with a rising pre-eclipse Honey (or do you say Strawberry or Rose) Full Moon as we eagerly await the next Total Lunar Eclipse of December 21st that occurs for North American observers at moonset/sunrise!

The Astro-word for this week is Lunation. This is simply the period of time that it takes the Moon to return to the same phase (i.e., New to New, Full to Full, etc). This is the same as our friend, the synodic month, and is on average 29 days, 12 hours, 44 minutes and 3 seconds long. This period can however, vary by up to 15 hours due to the elliptical nature of the Moon’s orbit about the Earth the period for which is getting ever so slightly longer as the Moon recedes from us by about 38mm per year. This means that eventually, total solar eclipses will no longer occur as the Moon of millions of years in the future will be visually tinier than the Sun, even at perigee. We will, however continue to enjoy total lunar eclipses during that far off epoch!

AstroEvent: Would the REAL Blue Moon Please Rise?



A Heavily Photoshoped Blue Moon...(Photo by Author).

   This week, we here at Astroguyz seek to re-ignite the controversy (or do you say non-troversy?) That swirls in some of the more obsessive astronomical circles; just what is a Blue Moon? Modern vernacular states this as simply the “second Full Moon of a calendar month,” but as researchers first point pointed out in a Sky & Telescope article in the March 1999 edition, the history behind the term is much more convoluted. [Read more...]

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!

Event of the Week: A “Blue Moon” Eclipse!

A setting partial eclipse in 2007 much like this month's New Year's eve partial...(photo by author).

A setting partial eclipse in 2007 much like this month's New Year's Eve partial...(photo by author).

This New Year’s Eve rounds off the calendar with an especially rare treat, although its one that not everyone will get to witness; a partial eclipse of the full “blue” moon. The second full moon of December, the first occurred on December 2nd of this month. This eclipse, however, is extremely shallow; at maximum, the moon will only be 7.63% immersed in the dark umbra of the earth’s shadow. [Read more...]

Event of the Week: 20.07.09: A VERY long solar eclipse!!!

Total Solar Eclipse Path. (Credit: NASA/Fred Espenak).

Total Solar Eclipse Path. (Credit: NASA/Fred Espenak).

The astronomical event of the year is about to take center stage this Wednesday. A total eclipse of the Sun, the longest possible for a VERY long time! Those lucky enough to have secured a ticket or live along the Pacific/Southeast Asia corridor will see an eclipse of a duration of up to 6 minutes and 39 seconds, near the maximum 7 minutes and 31 seconds possible. This is a consequence of the Earth passing aphelion a few weeks ago (read: a visually small Sun) and the a large New Moon very near perihelion (remember the year’s smallest Full Moon a few weeks back?) [Read more...]

AstroEvent of the Week: 6.7.09: Can you spot the Penumbral?

A 2002 Sunrise/Penumbral as seen from Vail, Arizona. (Photo by Author).

A 2002 Sunrise/Penumbral as seen from Vail, Arizona. (Photo by Author).

This week, I give you what is surely the meekest of all eclipses; a very shallow penumbral eclipse. At about 5:38 Eastern Standard time on the morning of Tuesday, July 7th, the northern edge of the Moon will find itself not quite a quarter submerged in the Earth’s penumbra, the light outer part of the planet’s shadow. The geometry for most of the continental United States is not good, as the Moon will be setting in the brightening dawn twilight. So why should you care to wake up early for an almost non-eclipse? [Read more...]