Saturday, December 10, 2011

Hunting Himalia - Part One

It was a super autumn here in the wild west, restorative you might say.

After the brutal spring winds that started unseasonably early in February and finished unseasonably late in May—accompanied by drifts of choking smoke from the catastrophic Wallow fire in Arizona—I was fall-to-my-knees grateful for clean, fresh fall air, accompanied only by fragrant drifts of roasting New Mexico green chile. After the blistering heat of our first summer on the mesa—and the challenges of trying to stay cool in a minimally insulated outbuilding masquerading as a residence—the crisp, cool autumn air was invigorating. After more than a few dark days of doubt, I am again filled with hope for my homesteading adventure.


Bolstering my restored optimism are systems that are finally beginning to work as envisioned. We sorted out the problems with our photovoltaic system and are now powered 24/7 by our nearest and dearest star, the Sun. We acquired a full-size propane refrigerator, so no more cooler runs to the ice machine in town, a 30-mile roundtrip. Even the cell phone service at our homestead miraculously and mysteriously returned this fall, after going AWOL for four months.

Our propane generator has been repaired and works like a top; we use it for our occasional heavy power loads. Such as, tada, pumping water! That’s right, we’ve fired up the well pump and filled our water tank. After having our H2O tested for E coli and nitrates (it passed with flying colors), we drank deep from the aquifer deep.


Water flows for the first time at the homestead



Nope, no flush toilet yet, but we’re almost there. The holes were dug, the tank acquired, the permit signed off on, and then the John Deere tractor broke down. Machines rule. We need it both to set the tank in the hole and to fill the leach field with river rock. We acquired the tractor second-hand, and although nothing runs like a Deere, the previous owner did only the minimum maintenance required to keep it running. It’s been in the shop for a month as the mechanics give it a complete overhaul, disassemble each system, revise and re-revise the initial estimate, and order in more parts. My foot is tapping compulsively. Can’t they work any faster? Don’t they know they’re standing between me and the realization of my flush toilet pipe dream?

*****

Speaking of dreams realized, this enchanted autumn I fulfilled 50% of my 2011 New Year’s Stargazing Resolutions. Okay fine, there are only two items on the list, but they’re tough ones.

My first resolution was to observe Himalia, the so-called “fifth moon of Jupiter.” Anyone who’s looked at Jupiter with even a decent pair of binoculars has seen the four Galilean moons, the moons discovered by Galileo in the early 1600s: Ganymede, Io, Callisto, and Europa. The bright, star-like dots are easily apparent as they orbit the planet, arranging and re-arranging themselves in different configurations.

Well, Himalia is Number Five, reportedly the only other of Jupiter’s 60-plus moons that can be observed by amateur astronomers. It’s tiny, and recovering the faint speck would be a challenge requiring a bit of preparation and a substantial telescope. No one I knew, even veteran observers, had seen it, which made it irresistible as an observing target.

Like the Galilean moons, Himalia is named for one of the mythological Zeus’s (Jupiter’s) romantic conquests; the nymph Himalia, seduced by Zeus when he visited her native island of Rhodes, bore him three sons. The moon Himalia is about 100 miles in diameter; compare that to the smallest of the Galilean moons, Europa, which is 975 miles in diameter. I didn’t know if I had the observing chops to spot a 15th-magnitude (really really faint) flea-speck 400 million miles away in outer space, but I was on fire to try.


The highest resolution image available of Himalia
Image source: NASA, New Horizons mission to Pluto




When the stormy summer skies gave way to azure days and inky black nights, and Jupiter returned to the eastern sky after sunset, I knew my window of opportunity had arrived. I began my quest by reading amateur astronomer Rick Scott’s invaluable how-to article.

His six-step approach was a bit daunting, however, and involved the purchase of a couple software aps, so I only did Steps #1 and #2 in preparation. I figured I would see how far I could get, and re-group if unsuccessful.

Step #1
I went to the JPL Horizons site to generate an ephemeris. An ephemeris is a table showing the position of a celestial body for regular intervals. This data would tell me precisely where in the sky Himalia would be at specific times so I could target the telescope correctly. On the input screen, I changed Target Body to Himalia, and Observer Location to the closest town to my location.




For Time Span, I first had to determine what time I wanted to start looking for Himalia. I wanted Jupiter to be fairly high in the sky because observing conditions are generally best when an object is high in your sky (you’re looking through less of Earth’s murky atmosphere overhead). So for that night, I settled on midnight. Since all astronomical events are expressed in Universal Time (UT), you need to be familiar with how your time zone converts into UT, so you can interpret the ephemeris when it spits out.

I inputted the following day’s date for Start Time, and the next day’s date for Stop Time, and selected “1 hour” for Step Size. This would give me a 24-hour ephemeris at 1-hour increments, more than what I needed, but spanning my planned observing time. A click on the “Generate Ephemeris” button, and Bob’s your uncle. Here’s what it looked like:




Step #2
Next, off to the Digitized Sky Survey (DSS) site to pull an image of the piece of sky I’d be looking at. This would tell me what stars lie in the field of view where I’d be looking for Himalia. Since the moon would be in motion and just passing through the star field, I could expect to see a “star” that shouldn’t be in that field, once I began observing.





Astronomers use a celestial coordinate system—a sky-grid, if you will—to pinpoint the location of celestial objects, as seen from Earth. Each object has a Right Ascension (RA) coordinate and a Declination (DEC) coordinate. I had the RA and DEC for Himalia listed on my ephemeris, for each hour. I knew that 12 midnight in my local time converted to 6:00 UT, so I transferred the RA and DEC coordinates listed for the 6:00 time slot into the DSS search form. I selected HST Phase 2 (GSC 1) in the Retrieve From field. For File Format, I selected GIF. For Height and Width, I retained the default setting, to generate an image 15 arcminutes by 15 arcminutes. The image would be oriented with the RA and DEC for Himalia dead center. A click of the "Retrieve Image" button, and I was able to view and print this image of my hunting ground.


The starfield where I would hunt for Himalia


I had secured my two key pieces of supporting documentation to take to the observing field. Just two more important preparation tasks remained before lift-off. Stay tuned for the exciting conclusion, in my next post.






Sunday, August 14, 2011

Heavenly Waters

At the off-the-grid DIY homestead where I have staked my corner of paradise, all things proceed at the breakneck pace of a banana slug, and any piece of equipment may break or blow up at any given time.

Five months after turning my back on civilization, I take stock and find myself living in a 200-square-foot building with a spousal unit, four rescue cats, a part-time jury-rigged power system, a postage-stamp-sized RV fridge that reliably spoils milk, a cell phone that can’t pick up a signal unless I drive a mile away (and which is “supported” by technicians who can’t even find our property), and no running water. Think Beverly Hillbillies, before the oil strike.

Why (you may ask in a horrified tone of voice) would any sane woman choose to live this way? Simply put, my mate and I are stargazers, avid amateur astronomers who need dark skies to pursue our passion. We have staked our claim at the side of the road-less-travelled because that’s where we can escape the light pollution that has taken over the night sky above cities, suburbs, and even semi-rural areas. It’s a straightforward equation really:


No neighbors = No line-of-sight lights



At the drop of a hat, we can go outside, throw up a telescope or grab a pair of binoculars, and be ready to visit the bright lights of our home galaxy, the Milky Way: planets, globular clusters, nebulas, and brilliantly colored stars. Not to mention entire other galaxies far far away.

Living in the high desert—with its reliably transparent, steady skies—is how we ensure maximum access to our celestial playground. If skies are cloudy and don’t clear up until after midnight, no problem. There are no cars to load with equipment and no middle-of-the-night expeditions to get to an acceptably dark site. We simply wait it out like patient game hunters, and pounce when the stars emerge. We don’t even have to change from our camouflage-print pajamas if we don’t want to.

*****

Desert dwellers understand better than most what it means to do without. (Have I mentioned we have no running water?) When you choose to live among arid grasslands atop a windswept mesa in middle-of-nowhere New Mexico, water is a luxury and becomes more precious to you than the Hope Diamond, the Koh-i-Noor, and the Great Star of Africa combined. A girl’s best friend, as it turns out, is a flush toilet.

In this poverty of creature comforts, water seems like something from the realm of myth and magic: something that surely could be conjured if only I knew the right incantation. It flows unseen beneath my feet at a depth equivalent to the height of a 52-story skyscraper. In our well casing—or Big Drinking Straw, as I like to think of it—hangs a three-horsepower pump and enough copper wire to send ripples through the commodities markets. Sadly, can’t start a fire without a spark. The propane generator—a.k.a. Big Spark-Maker—sits silent, broken by a careless contractor and waiting for a replacement part that surely must be coming by stagecoach.

Water gathers unseen above, also. After a brutally dry and windy spring and early summer, the monsoons have finally arrived. Spectacular thunderheads, laden with moisture from the Gulf of Mexico and the eastern Pacific Ocean, travel northward from Mexico, bringing the summer rains that represent up to 70% of New Mexico’s annual precipitation.

We watch the storms’ northward progress with equal measures of hope and cynicism. Often they simply break apart on the southern prow of our ship-like mesa, dumping their juicy payloads in the river valleys on either side. Our skin cracks like the tessellated adobe soil lying just under the blow sand. We grow as leathery as the resident collared lizards.

Occasionally, though, the rain clouds sail straight overhead and we receive a direct hit. Recently, like tears of joy, a half-inch pelted the parched earth, the thirsty mesquites and junipers, the dusty cattle, and all the enduring creatures of land and air.

That night, a strange sound came to me in the dark from across the mesa. It took me a few minutes to pin it down: a chorus of frogs, harmonizing. Frogs in the desert! How long had those recondite amphibians burrowed in the desert floor, waiting for the elixir of rain? How many generations ago had their ancestors shipwrecked on this desert island, when the inland ocean receded?

*****

Any good Southwestern stargazer knows that a freshly-scrubbed, transparent sky follows monsoon rain. Freshly-scrubbed. Gee, that sounds good. Did I mention we have no running water? But I digress.

Tonight I looked for omens of water in the sky. The Moon rose shortly after sunset, and its nearly full face was filled with large dark splotches called maria (MAH-ree-yuh) or seas, easily seen with the naked eye. Their watery name derives from an early belief that they were bodies of water, lunar oceans. We now know they’re craters that filled with lava when the Moon was volcanically active. I tick off their names like charms: Sea of Serenity, Sea of Tranquility, Sea of Fertility, and my new favorite, Sea of Rains.




I find that when the Moon is close to full (in this case, one day after) with most of its face illuminated, it’s easier on the naked eyes to look at it before the sky gets dark. I can see more surface features when its brightness is muted against the blue sky of twilight. But when the sky grows dark, whammo, the Moon becomes as blinding as a searchlight and hard to look at. Check this out for yourself on or near any Full Moon that rises when the sky is still light.

Is it an especially good omen that tonight the Moon was in the constellation Aquarius the Water Bearer? While I take a moment to imagine myself standing in the endless stream of water flowing from his jar, enjoy this portrayal of Aquarius from John Flamsteed’s 1729 star atlas:



Courtesy of Linda Hall Library of Science, Engineering and Technology


A few hours after sunset, I spy the star Fomalhaut (FOAM-uh-lott) in the southeastern sky. The brightest star in the constellation Piscis Austrinus the Southern Fish, Fomalhaut shines through even in a sky washed out by moonlight. From the Arabic for mouth of the fish, Fomalhaut marks the open mouth of the rather thirsty fish, into which pours the cool stream from the Water Bearer’s jar. Heavenly.

Saturday, March 19, 2011

March Madness

Greetings, sky-watchers! Please forgive my multi-month absence, but I had the best of reasons. I was moving to a locale with significantly darker skies--an observer's dream come true.

This year, my blogging focus will be on "current events," that is, to inform you of neat celestial events happening in the present or the very near future, as well as to recommend objects for you to look at in your current sky.

It's an eventful time in the sky right now--starting tonight!

1) Just after sunset tonight, look west. As the sunset glow recedes, the first objects you'll see pop out low in the western sky will be two planets. The brighter one is Jupiter. It will be about one fist-width above the horizon. Make a fist and hold it at arm's length against the sky. Measure across the knuckles to approximate a fist-width. About half a fist-width above Jupiter is Mercury, not nearly as bright as Jupiter and pinkish in color. NASA's Messenger spacecraft just this week entered orbit around Mercury--a first in space exploration. We can expect to learn a lot more about this sun-drenched planet in the next year.

You can see the planetary pair for the next few days, after which Jupiter will disappear below the western horizon. Mercury will be do-able for a few more nights, but as we head towards month's end, you'll probably need binoculars to pick Mercury out of the twilight.

2) Tonight about a half hour after sunset, look east to watch the Full Moon rise. This is the "super-perigee moon," the biggest Full Moon in nearly 20 years. It will be in the sky all night, so you'll have plenty of time to gaze upon it.

Why is it so big? The Moon’s orbit around Earth is oval-shaped, with one narrow part of the oval about 30,000 miles closer to Earth. At its closest to Earth, the Moon is said to be at perigee; at its farthest, at apogee. Full Moons that occur near perigee are the biggest and brightest, about 14% bigger and 30% brighter than “apogee moons.” Tonight, the Full Moon occurs a mere one hour from perigee!

Note: the Moon is not closer than it's been in 20 years. I've been hearing this a lot on TV and other media, and hearing people repeating it. The Moon draws close to Earth every perigee, and perigee occurs once every 28 days. It would, however, be correct to say that the Full Moon is closer than it's been in nearly 20 years, because normally the Full Moon does not coincide so closely with perigee.

3) Tomorrow, Sunday, March 20, at 5:21 pm Mountain Time (adjust for your time zone), we celebrate the moment of the Spring Equinox or Vernal Equinox. By convention, this event marks the beginning of the season we call "spring" in the Northern Hemisphere. The Spring Equinox is when the Sun crosses the celestial equator (where the plane of Earth’s equator would intersect the sky), heading north. On the Equinox, the Sun rises due east and sets due west, so you can use this opportunity to mark west and east at your location, using natural or man-made markers on your horizons. (Caution: To protect your eyesight, never look directly at the Sun!)

Until next time, happy star trails to you.