Posted on by David Dickinson

Here’s Your Sign: Are You an Ophiuchian?

Credit: Stellarium

It happens to all lovers of astronomy sooner or later.

I once had a friend who was excited about an upcoming conjunction of Saturn and Venus. They were passing closer than the apparent diameter of the Full Moon in the dawn sky, and you could fit ‘em both in the same telescopic field of view. I invited said friend to stop by at 5 AM the next morning to check this out. I was excited to see this conjunction as well, but not for the same reasons.

Said friend was into astrology, and I’m sure that the conjunction held a deep significance in their world view. Sure, I could have easily told them that ‘astrology is bunk,’ and the skies care not for our terrestrial woes… or I could carefully help guide this ‘at risk friend’ towards the true wonders of the cosmos if they were willing to listen.

We bring this up because this weekend, the Sun enters the constellation Ophiuchus, one of 13 modern constellations that it can appear in from our Earthly vantage point.

If you’re born from November 30th to December 18th, you could consider yourself an “Ophiuchian,” or being born under the sign of Ophiuchus the Serpent Bearer. But I’ll leave it up to you to decide what they might be like.

Photo by author.
Seen at the Albany Park Zoo: Herpetology, or a modern day “serpent bearer?” Photo by author.

You might remember how the “controversy” of the 13th sign made its news rounds a few years back. Hey, it was cool to at least see an obscure and hard to pronounce constellation trending on Twitter. Of course, this wasn’t news to space enthusiasts, and to modern astronomers, a ‘house’ is merely where you live, and a ‘sign’ is what you follow to get there.

The modern 88 constellations we use were formalized by the International Astronomical Union in 1922. Like political boundaries, they’re imaginary constructs we use to organize reality. Star patterns slowly change with time due to our solar system’s motion — and that of neighboring stars —about the galactic center.

Astrologers will, of course, counter that their craft follows a tropical scheme versus a sidereal cosmology. In the tropical system, ecliptic longitude 0 starts from the equinoctial point marking the beginning of spring in the northern hemisphere, and the zodiac is demarcated by 12 ‘houses’ 30 degrees on a side.

This neatly ignores the reality of our friend, the precession of the equinoxes. The Earth’s poles do a slow wobble like a top, taking about 26,000 years to make one turn. This means that in the sidereal scheme of things, our vantage point of the Sun’s position along the zodiac against the background stars if reference to our Gregorian calendar is slowly changing: live out a 72 year lifespan, and the constellations along the zodiac with respect to the Sun will have shifted about one degree due to precession.

Credit: Starry Night Education Software.
Our changing pole star. Credit: Starry Night Education Software.

Likewise, the direction of the North and South Pole is changing as well. Though Polaris makes a good pole star now, it’ll become increasingly less so as our north rotational pole begins to pull away from it after 2100 A.D. To the ancient Egyptians, Thuban (Alpha Draconis) was the pole star.

Credit: Wikimedia Commons
Precession over time. Credit: Tfr000 under Wikimedia Creative Commons 3.0 license.

Astrology and astronomy also have an intimate and hoary history, as many astronomers up until the time of Kepler financed their astronomical studies by casting royal horoscopes. And we still use terms such as appulse, conjunction and occultation, which have roots in astrology.

But the science of astronomy has matured beyond considering whether Mercury in retrograde has any connection with earthly woes. Perhaps you feel that you’re unlucky in love and have a vast untapped potential… sure, me too. We all do, and that just speaks to the universal state of the human condition. Astrology was an early attempt by humanity to find a coherent narrative, a place in the cosmos.

But the rise of the Ophiuchians isn’t nigh. Astrology relented to astronomy because of the latter’s true predictive power. “Look here, in the sky,” said mathematician Urbain Le Verrier, “and you’ll spy a new planet tugging on Uranus,” and blam, Neptune was discovered. If the planets had any true influence on us, why didn’t astrologers manage to predict the same?

Combating woo such as astrology is never simple. In the internet era, we often find tribes of the like-minded folks polarized around electronic camp fires. For example, writing ‘astrology is woo’ for an esteemed audience of science-minded readers such as Universe Today will no doubt find a largely agreeable reception. We have on occasion, however, written the same for a general audience to a much more hostile reception. Often, it’s just a matter of being that lone but patient voice of rationalism in the woods that ultimately sinks in.

Photo by author.
Zodiacal artwork seen at the Yerkes observatory. Photo by author.

So, what’s the harm? Folks can believe whatever they want, and astrology’s no different, right? Well, the harm comes when people base life decisions on astrology. The harm comes when world leaders make critical decisions after consulting astrologers. Remember, Nancy and President Ronald Reagan conferred with astrologers for world affairs. It’s an irony of the modern age that, while writing a take down on astrology, there will likely be ads promoting astrology running right next to this very page. And while professional astronomers spend years in grad school, you can get a “PhD in Astrology” of dubious value online for a pittance. And nearly every general news site has a astrology page. Think of the space missions that could be launched if we threw as much money at exploration as we do at astrology as a society. Or perhaps astronomers should revert back to the dark side and resume casting horoscopes once again?

But to quote Spiderman, “with great power comes great responsibility,” and we promise to only use our astronomical powers for good.

What astronomers want you to know is that we’re not separate from the universe above us, and that the cosmos does indeed influence our everyday lives. And we’re not talking about finding your car keys or selling your house. We’re thinking big. The Sun energizes and drives the drama of life on Earth. The atoms that make you the unique individual that you are were forged in the hearts of stars. The ice that chills our drink may well have been delivered here via comet. And speaking of which, a comet headed our way could spell a very bad day for the Earth.

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Don’t leave home without one… a travelling “pocket planetarium” circa 16th century seen at the Tampa Bay History Center. Photo by author.

All of these are real things that astronomy tells us about our place in the cosmos, whether you’re an Ophiuchian or a Capricorn. To paraphrase Shakespeare, the heavens may (seem to) blaze forth for the death of princes, but the fault lies not in the heavens, but ourselves. Don’t forget that, as James Randi says, “you’re a member of a proud species,” one loves to look skyward, and ultimately knows when to discard fantasy for reality.

 

Posted on by David Dickinson

Catch the Dramatic June 10th Occultation of Saturn by the Moon

The May 15th, 2014 occultation of Saturn by the Moon as seen from Australia. (Credit: Byuki/Silveryway).

Some terms in astronomy definitely have a PR problem, and are perhaps due for an overhaul.  One such awkward term is occultation, which simply means that one celestial body is passing in front of another from an observer’s vantage point, nothing more, and nothing less. I know, the word ‘occult’ is in there, raising many a non-astronomically minded eyebrow and evoking astronomy’s hoary astrological past. You can even use it as a verb in this sense, as in to ‘occult’ one body with another. A planet or asteroid can occult a star, your cat can occult your laptop’s screen, and the Moon can occult a star or planet, as occurs on Tuesday, June 10th when the waxing gibbous Moon occults the planet Saturn for observers across the southern Indian Ocean region.

Created using Occult 4.0
The occultation footprint for the June 10th event. The solid lines denote where the occultation occurs after sunset. Created using Occult 4.0.

Of course, most of us will see a near miss worldwide. This is parallax in motion, as differing vantage points on the surface of the planet Earth see the Moon against a different starry background.

And we’re currently in the midst of a cycle of occultations of the planet Saturn in 2014, as the Moon occults it 11 times this year, nearly once for every lunation. The Moon actually occults planets 22 times in 2014, 24 if you count the occultations of 1 Ceres and 4 Vesta on September 28th, with Saturn getting covered by the Moon once again on the same date! Saturn tops the list in the number of times it’s occulted by the Moon this year, as it’s the slowest moving of the planets and fails to hustle out of the Moon’s way until November, after which a series of occultations of the ringed planet won’t resume again until December 9th, 2018.

4x selected views of the occultation/conjunction of the Moon and Saturn on June 10th worldwide. (Credit: Stellarium).
Four selected views of the occultation/conjunction of the Moon and Saturn on June 10th worldwide. (Credit: Stellarium).

The shadow footprint of the June 10th occultation just makes landfall over southwestern Australia near Perth, a slice of Antarctica, and a scattering of southern Indian Ocean islands and the southern tip of South Africa in and around Cape Town. Note that the phase of the Moon is changing by about 30 degrees of ecliptic longitude as well during each successive occultation of Saturn. Next week’s event occurs as the Moon is at a 93% waxing gibbous illuminated phase this month and soon will occur when the Moon is a crescent. What’s especially interesting is the dark limb of the Moon is always the leading edge during waxing phases; this means that any stars or planets in its way get hidden (or ingress) under its shady nighttime edge.

Looking to the southeast from latitude 30 degrees north from the US east coast at 10PM EDT. Created using Starry Night Education software.
Looking to the southeast from latitude 30 degrees north from the US east coast at 10 PM EDT. Created using Starry Night Education software.

Central conjunction for Saturn and the Moon actually occurs at around 19:00 Universal Time on June 10th. The Moon rises at around 6:00 PM local on this date, and North American observers will see Saturn 4 degrees from the limb of the Moon and at an elevation of 28 degrees above the horizon at dusk. Unfortunately, the best occultation of Saturn by the Moon for North America in 2014 occurs in the daytime on August 31st, though you can indeed catch Saturn in the broad daylight through a telescope with good sky transparency if you know exactly where to look for it… a nearby daytime Moon certainly helps!

Unlike stellar occultations, blockages of planets by the Moon are leisurely events, and lend themselves to some pretty amazing video sequences. You can actually get a sense of the motion of the Moon as you watch it slowly cover the planet’s disk, in real time. It might also be fun to catch the occultation of Saturn’s brightest moon, +9th magnitude Titan. Hey, a moon occulting a moon, a sort of cosmic irony…

Saturn spends all of 2014 in the astronomical constellation of Libra. The Moon moves on to Full on Friday the 13th — triskaidekaphobics take note — at 4:13 UT/00:13 AM EDT. This is the closest Full Moon to the northward solstice which occurs on June 21st at 10:51 UT/6:51 AM EDT, meaning that while the Sun rides high in the sky during the day, the rising Full Moon transits low to the south at night. In the southern hemisphere, the reverse is true in June.

The June Full Moon is also known as per ye ole Farmer’s Almanac as the Strawberry or Rose Moon.

So there you have it, occultations were evoked no less than 21 times in the writing of this post. We need a modern, hip, internet ready meme to supplant the term occultation… y’know, like “ring of fire” for and annular eclipse or minimoon for an apogee moon, etc… blockage? Covering? Enveloping? Let us know what you think!