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By Jupiter!

A blog about the stars, astronomy gifts, and other starry musings by the folks behind Indigo Night.

Evening Star

by Van Wymelenberg
November 17, 2009

Alfred Lord Tennyson, England’s late 19th century poet laureate, considered Crossing the Bar to be among his very best work. Collections of Tennyson’s poetry traditionally end with this short poem, this poem as elegy, written in the course of about 20 minutes while Tennyson was on a ferry crossing the Solent from mainland England to his home on the Isle of Wight, Farringford. He was in his early 80s at the time, and recently recovered from a serious illness.

Sunset and evening star,
And one clear call for me!
And may there be no moaning of the bar,
When I put out to sea,

But such a tide as moving seems asleep,
Too full for sound and foam,
When that which drew from out the boundless deep
Turns again home.

Twilight and evening bell,
And after that the dark!
And may there be no sadness of farewell,
When I embark;

For tho’ from out our bourne of Time and Place
The flood may bear me far,
I hope to see my Pilot face to face
When I have cross’d the bar.

I’ve always loved this poem, with its beautiful extended metaphor about dying. And I love the tides, too, the majestic, slow heartbeat of our planet.

I was curious about the sky over the Isle of Wight when Tennyson wrote this piece. We know it was written in October of 1889. Crossing the Solent would put him about 50° 45’05.33" North and 1° 09’07.29" West. Not too far off the Prime Meridian, so no time off-set for the calculations, and this was years before daylight savings, as well. Sunset and Evening Star. What was in the sky at evening twilight?

I’m not sure where the ferry ran… was it between Gosport and Ryde? Or over toward Yarmouth? Any Tennyson scholars out there? The ecliptic is fairly shallow this time of year, and at this location, so twilight would have lingered from late afternoon to early evening. I believe the ‘Evening Star’ that Tennyson saw was Jupiter, a bright prominence about 12° above the horizon, amid the stars of Sagittarius. A little west of south. In the gloaming, as the poets say. Venus was in it’s ‘Morning Star’ apparition, and not visible. (And all these years I thought it was Venus!) No other bright star or object was anywhere on the horizon, with the exception of Antares, clearly outshone by Jupiter.

Jupiter shone bright in the evening twilight. Antares, heart of Scorpius, shows below, at the horizon. Altair lights above, just visible, in Aquila.

Morning Star

by Van Wymelenberg
October 30, 2009

We live in a fairly dark site, about 10 miles from the nearest town, on a nice rise with a clear south view, surrounded by large working farms. The roads are gravel. When the moon is toward new and offers no friendly moonlight to help me find my way on a pre-dawn walk, I have to navigate by touch. It is literally pitch black out there. I wear my old, thin-soled boat shoes, and try to walk the smooth track, right or left, between the graveled crown and shoulder of the road, slowly making my way under a dense canopy of trees. When I get to the open fields it’s easy to find my way by starlight, or the faint bloom of Charlottesville. I follow the vague off-white blur of Hambone, our hound, too. Always up for a walk, even at 4 in the morning.

Venus has been the ‘Morning Star’ since early April. This is the object I’ve seen each clear morning, low in the east, when I round the bend on Foster’s Branch Road, and come out from under the Oaks and Poplars. Venus has risen steadily earlier since April (and was therefore higher in the sky at, say, 4:30 or 5 AM) and continued thus through about mid July, when in moved into Taurus from Aries. Since mid July it has steadily drifted back toward the east horizon, rising closer to dawn (later) each day, moving through Gemini, Cancer and Leo. Come December, it will disappear into the glare of the sun, in Virgo, and then appear again, late March / early next April, 2010 this time as the ‘Evening Star,’ at nightfall… again in Pisces, about where is was last April.

Venus and Mercury are ‘inner’ planets – they orbit the sun inside our orbit; their orbits are smaller than our orbit. Mars, Jupiter and Saturn are more distant from the sun; their orbits are larger than ours. The outer planets. From our perspective on the home planet that lets us see Mercury and Venus, the inner planets, on either side of the sun, depending on where they are in their orbits, in the morning or evening twilight — visible in the sky before sunrise, or after sunset.

So, Venus is both the ‘Morning Star’ and the ‘Evening Star.’ Technically the term refers to any exceptionally bright object, star or planet, that shows prominently in the morning or evening twilight. But in common usage the term almost always refers to Venus. Each apparition of Venus (the astronomy term that refers to its cycle of visibility) as the ‘Morning’ or ‘Evening’ Star lasts about six to seven months. When it passes behind the sun, its lost from view for several months, transitioning from ‘Morning’ to ‘Evening’ star. When it passes in front of the sun, it’s lost from view for several weeks, transitioning from ‘Evening’ back to ‘Morning’ star. This is for the casual, naked eye observer. If you’re looking hard, with binoculars or a telescope, the apparition will be somewhat longer. In fact, earlier this year, a keen observer could see Venus both in the morning and evening twilight, on the same day, because the offset of its orbit took it unusually far north of the sun. That doesn’t happen too often.

By the way, the upper graphic – the ‘overhead racetrack’ was based on the graphic done by Fred Schaaf in Sky&Telescope magazine. (OK, so I pretty much just re-drew exactly what he had done… but at least I re-drew it!) He does a monthly summary article (among other articles) on positional astronomy for S&T. This is my favorite sources of information, and Mr Schaaf’s arcticles, in particular, are the first I read. Thanks Fred!

Celestial Mechanics

by Van Wymelenberg
October 21, 2009

I thought I’d take some time over the next few posts to give you some sources and links I’ve found especially useful as introductions to the science of the night sky. When people call to place an order, I’m often asked, with some incredulity, how on earth (love that expression) we can figure out what the sky looked like way back in [insert date here]. Speculation often goes to "do you have a vast archives of photographs? (admittedly, our prints do look photo-realistic, so I suppose this is understandable on some level), or (the most interesting take, in my opinion) to “using Hubble to ‘look back in time.’” Interesting concepts both, but no.

Observational Astronomy is rooted in Celestial Mechanics – the branch of astronomy that explores the slow dance of our moon and planets wandering in procession against the vast canopy of night – those million, million fixed points of light, the stars in our night sky. ‘Planet’ actually comes to us from the Greek, planetai, literally wandering.

The science behind what we do here has been worked out for hundreds of years, though until recently it’s been the exclusive domain of the mathematician/astronomer. Formulas for calculating the orbits of planets go all the way back to Galileo and Kepler in the 1600s.

Let’s start here with that list of resources. Stellarium is free, open source planetarium software for the PC, MAC and LINUX operating system. Seriously cool.

Stellarium is like the software that we use here at Indigo Night. I can’t believe it’s free… it’s really a remarkable piece of work. This will put a virtual planetarium on your desktop. The controls are very simple and intuitive. Elegant. Pick a location, key in a date and time, and there’s the sky. It will give you a horizon line with illustration and compass point to orient yourself, unlike many internet astronomy references that bear no relation to what you see when you look to the sky… at least at first glance. Click and drag to rotate your view.

You can go back and look at the sky on the day you were born, or when your child was born. The night you fell in love. The night you married. And, of course, it’s predictive. That’s how most star-gazers use a program like this: to plan an observation session. What will be visible in the sky tonight? Will Saturn stand above the treetops at nightfall? For the naked eye observer new to the night sky, on the other hand, it tends to be used more as a real-time chart, or legend, of the sky. It answers the question “What’s that bright object low in the southeast at nightfall?” A UFO? Or perhaps Venus?

Play with the date. You’ll see that each year, on a given date at a given hour, the stars are, for all intents and purposes, in the same place. If you look out the window of your grandfather’s upstairs bedroom on say, November 4 of 2009 at 11 PM, you’ll see very nearly the same star filled sky that your grandfather saw at 11 PM on November 4th of 1939.

Now, the moon and planets will be different –– that’s the part I find so interesting. The great clockwork of our night sky. Each planet orbits the sun in it’s own sweet time – earth in one year, obviously. Saturn takes about 30 years. Jupiter about 12, moving through roughly one sign of the zodiac each year. Venus takes about 7 months, moving from ‘Morning Star’ to ‘Evening Star’ and back, as its orbit takes it behind (or in front of) the sun, lost from view to us for several months, then back out into the night sky.

These infinite variations in the pattern of the night sky, this regal dance in the heavens, slow, majestic, and absolutely, steadfastly, correct… that’s the beauty of it, to me, connecting all of us, across cultures and time. We all share a common frame of reference, our small blue-green planet, this island earth. Enjoy the view.

Blue Moon

by Van Wymelenberg
October 09, 2009

OK, Just a couple of more things on blue moon. “Once in a blue moon,” meaning rarely, has been a well known idiomatic expression since the mid to late 19th century. It’s original meaning of ‘never’ somehow morphed in ‘rarely.’ One possible explanation points to the natural philosopher. The 1800s were a time when science started to answer questions about the physical world, and that knowledge made its way to the public through increasingly easier access to newspaper and books. Common knowledge changes language.

One notable event that naturalists studied and reported on was the eruption of Krakatoa, an Indonesian volcano in the Sundra Straits, near Java. The cataclysmic eruption, late August of 1883, killed somewhere between 36,000 (official toll) and 120,000 people. A massive plume of ash was ejected into the atmosphere. Dark times, indeed. Average global temperatures fell 2.5° F the following year. There were widespread reports of ‘green’ sunsets and ‘blue’ moons over the next several years. And what’s that about? Particulate matter of about one micrometer (as from this eruption) suspended high in the atmosphere will filter out red light, and pass blue. Thus, the blue moon. The same effect has been observed following large forest fires.

I think I’ll let the blue moon thing rest for now, although I reserve the right to look at the 1934 Rogers and Hart lyrics to ‘Blue Moon.’ As well as the subsequent Elvis interpretation. And to report back on a certain Belgian Style beer.

Belewe Moon

by Van Wymelenberg
September 29, 2009

Two full moons will grace the December sky this year. This happens occasionally: most months have 30 or 31 days. The lunar month – the time it takes the moon to orbit the earth (also known as the lunation or its synodic cycle) – is 29 days, 12 hours, 44 minutes and 2.78 seconds. This time difference between the lunar month and the calendar month causes the two cycles to slowly weave in and out of sync. Every once in a while the synodic cycle of the moon falls completely within a calendar month, and two full moons appear in that given month. This happens about once every two or three years. The second full moon in a calendar month is commonly known as a ‘Blue Moon.’

This popular consensus on the astronomical meaning of a ‘Blue Moon’ is recent, only really finding it’s way into our language within the past 30 years or so.

The back story on the expression ‘Blue Moon’ is wonderfully complicated. Old English scholars point to the possible double meaning of ‘belewe’ in the earliest reference to ‘Blue Moon,’ which appeared in a short pamphlet entitled Rede Me and Be Not Wrothe. This short work was published in 1528. It was, to my understanding, a kind of critical essay mocking the English Clergy. The exact line is:

If they say the moon is blue / We must believe that it is true.

The word ‘belewe’ had a double meaning in Old English. It could have meant either the color blue, or ‘to betray.’

I think the writer was a man of wit, working ‘belewe’ here as a clever double-entendre, and perhaps introducing the idiomatic expression ‘blue moon’ for the first time. Although the meaning was clearly different then.

Here is the backstory. The church was the keeper of all arcane knowledge in those dark times, including the calculation for the date of Easter.

The date for Easter was (is) based on the date of a particular full moon. Easter must fall on the Sunday following the first full moon after the ecclesiastical vernal equinox, which always falls on March 21. (The Church divided the year neatly into 4 seasons, each of exactly 3 month, with the equinoxes and solstices always falling on the 21st. Astronomers, however, always define the change of seasons as when the sun crosses the celestial equator, or when it reaches it’s northernmost or southernmost extreme.)

Many important Christian days, such as Saint days, are fixed on the calendar, always on the same date, but Easter is variable because of the holy day’s origin during early Christianity’s Jewish Period. It referenced the Jewish lunisolar calendar, as did many other important events. The tradition of doing the calculation rather than fixing the date was kept by the Christians as its dogma evolved from Judaism.)

It’s a little too complicated, and off subject, to go into it here, but the calculations are kind of interesting and you can look at them here).

The short version of the story is that the church had to say which moon was the Lenten Moon, and which was the Paschal (Easter) Moon, because it wasn’t always obvious. Seven times over the course of every 19 years there would an extra moon somewhere in a season.

The three full moons across each “normal” season all had well established names that helped people organize their lives. The moons marked the change of seasons, and told them when to plant, reap, fast, celebrate, be hopeful. To everything there is a season as it is so beautifully written in the book of Ecclesiastes. But the ‘belewe’ moon betrayed this celestial almanac. Since there was no regular name for this moon, because it appeared in different seasons, those who kept the names and the knowledge would call this third full moon in a season of four moons the ‘belewe’ moon. The fist, second and last moon of a season kept their traditional names, and the rhythm of the seasons remained intact.

I’m no Old English scholar (or even student) but it seems to me that this early pamphlet confirms that the everyday use of the phrase ‘belewe moon’ was the liturgical reference to the third full moon in a season of four full moons. And that the ironic use of ‘belewe moon,’ meaning something that is absurd or impossible, was also indicated, perhaps for the first time, here in this same short work. Why else would the author speak thus? He was already being critical of the clergy, so there was obviously no fear involved, no need to cleverly mask the meaning in double-entendre. I call it wit. We’ll never know for sure.

This ecclisiastical definition of a ‘blue moon’ is followed by the Maine Farmer’s Almanac and is noted in publications as far back at 1817. This ‘rule’ is now generally referred to as the ‘Maine rule.’

And there’s more! Due to a misinterpretation of a 1943 Sky & Telescope article about the Maine Rule, a second definition of “blue moon” entered the vernacular. In an understandable mis-reading of this article an author simplified the rule to define a blue moon as the second full moon in any given month. One of the Stardate editors picked up on this definition from Sky&Telescope (hey, if you can’t trust S&T who can you trust?) and further popularized it in national radio broadcasts sometime in the late 1970s. The error has been noted by both Stardate and S&T, but the definition is so much a part of popular culture now it’s even made its way into Trivial Pursuit. But maybe not the genius edition.


Just Because

The night sky print which arrives for no particular reason, other than to celebrate the gift of love that is your beloved, is cherished like no other.


Each of us has a story that begins in a single moment. Poets and philosophers from Shakespeare to Tennyson, from Moore to Jung, share a common fascination with the night sky at the moment of birth, and the idea that the moon and stars stand in timeless, silent witness to this moment.

Wedding Anniversaries

The night sky print, showing the moon and stars just as they appeared on the night you met, the moment of your first kiss, or your wedding night, is an exceptional anniversary gift. Appropriate for any year, especially so for the 1st anniversary, the year of the ‘paper’ gift.

New Baby

The night sky print, showing the moon and stars just as they appeared on the child’s first starry night, with your words – funny, wise, sweet, hopeful, perhaps a favorite quote from a story or song – makes a beautiful keepsake.

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