December 13, 2017

The Strange Realms of 70 Ophiuchi.

In early 2011, astronomers “discovered”¯ a constellation. Well, not exactly; but if you were to believe the media, the “13th sign”¯ of the zodiac was a new one, at least to them. Hey, non-event it may be, but it was fun to see Ophiuchus trend, as folks pondered the realm of the serpent bearer and wondered exactly what the horoscope of a person born under such an arcane sign could be. The truth is that the Sun has been known to past through 13 constellations since the boundaries of the 88 modern constellations were formalized by the International Astronomical Union in 1922, and the Moon can appear in 18 of them! (Can you name the 6 non-zodiacal signs?) [Read more...]

Astro-Event: On the Path of Comet Garradd.

We had great skies at our recent local Star Party this past weekend. Hot on the heels of the NecronomiCon, we zipped out to the relative darkness that is Starkey Park in Pasco county and set up for what turned out to be our third star party in 24 hours. Amidst Jupiter approaching opposition, a final ROSAT pass, and various deep sky wonders was a special treat; comet 2009 P1 Garradd lying at +7.9 magnitude on the Ophiuchus/Hercules border. [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: Can You Spy the Zodiacal Light?

This week’s astronomy challenge is seasonal for mid-latitude observers. Around the time of the equinox, the ecliptic meets the horizon at a favorable angle and a unique phenomenon may become apparent: the zodiacal light. This diffuse band of light can be briefly seen after sunset or before sunrise from a moderately dark location.

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18.01.11: The Signs They Are a Changin’

Sextans…the 14th sign? (Created by the Author in Starry night).

OK. By now, you know that your astrological sign isn’t what you were always told it was. Last week, (non-) news broke that according to astronomy, not only were the zodiacal signs wrong, but the Sun actually passes through a 13th sign, that of Ophiuchus. The astrology-minded scrambled, desperately trying to conceive not only what a ‘serpent bearer’ should be like, but how to pronounce it. [Read more...]

Astro-Event: An Asteroid Occults a Bright Star.

One of the best occultations of a bright star occurs this week for observers along a line from western Canada down the U.S. west coast. At around 10:00 UT, on the morning of April 6th, 14th magnitude asteroid 824 Anastasia will occult, or pass in front of, the bright +2.5 magnitude star Zeta Ophiuchi for up to 8.6 seconds. This is a rare event in that the occulted star will be visible with the naked eye! Stellar occultations give us the rare opportunity to profile the shape of an asteroid; if enough folks are lined up along the graze line and make and submit accurate observations, a chord map of the “shadow” of the asteroid can be plotted. Binary asteroids have even been discovered by amateur astronomers using this method! Anyway, if you’re located anywhere along the predicted path and the sky is clear, don’t miss this rare event!

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Astro Event of the Week: December 15th-21st: The Winter Solstice.

Take heart, those based in chilly northern climes; the Winter Solstice is on the way. This is the point at which the Sun reaches its most southerly declination as seen from the tilted Earth and begins its long migration northward.

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Astro-Event of the Week: July 22nd-28th 2008:Spot Pluto!

Now, for the telescopic challenge of a lifetime; a chance to spot the elusive and controversial Pluto. Even experienced amateur astronomers have yet to accomplish this feat, and I’ve only done it once with the 14″ Schmitt-Cassegrain at the Flandreau Observatory.

[Read more...]

Astrology: An Astronomical Perspective

Astronomy may well be man’s oldest scientific endeavour. When we weren’t busy eking out an existence, we were looking to the stars. The sky to our ancestors must have seemed enigmatic and mysterious. Removed from terrestrial affairs, the heavens seemed aloof. [Read more...]