Ring of Fire

Among those celestial events observable by humans, solar eclipses have an unmistakable allure, so much so they’ve spawned an exclusive community of people called “eclipse chasers.” These adventurers research, plan, schedule, scheme, and ultimately travel anywhere in the world to be in the right place at the right time for eclipse events, especially rare total solar eclipses.

A solar eclipse occurs when the Moon passes in front of the Sun, as seen from Earth. Oftentimes the alignment is imperfect, resulting in a partial solar eclipse. However, if the Moon completely covers the Sun from our perspective, a total solar eclipse ensues. And if the alignment is good, but the Moon is at a point in its orbit where it’s too far from Earth to completely cover the Sun, an exposed ring of sunlight surrounds the dark lunar disk. This third type of solar eclipse is called an annular eclipse, from “annulus,” Latin for “ring.”

On May 20, 2012, an annular eclipse was visible from Asia to western North America, stretching across the Pacific. Fortuitously, the path of annularity, a 200-mile-wide swathe where the “ring of fire” was visible, crossed New Mexico and was centered on Albuquerque. Although at this locale the eclipse began around 6:30 p.m. and was still in progress at sunset, most of it was observable. The impending event created lots of buzz in the local amateur astronomy community, not to mention among the general public and photographers at all skill levels. Albuquerque became a destination for astronomy enthusiasts from across the country.

 

 

World map of the May 2012 solar eclipse

Line of red circles = path of annularity

Figure by Fred Espenak, NASA

http://eclipse.gsfc.nasa.gov/eclipse.html

 

My email inbox lit up with discussions of eclipse-related timings, techniques, equipment, locations, phenomena, and media misinformation. We fretted over how cloudy the western sky had been lately. We verified the next annular eclipse visible in our area would occur in 2023. We identified an upcoming (2017) total solar eclipse visible from the U.S. (rare!) and evaluated both Kentucky and Wyoming as prospective viewing destinations (Wyoming won).

My experience of the May 2012 annular eclipse, which I’ve recounted below, was a highlight of my observing life thus far. And best of all, it came right to my doorstep. If you’ve not seen one, I recommend you put it on your bucket list immediately!

*****

Eschewing the designated public viewing site in Albuquerque where a crowd of 10,000 would gather, we were seven strong at my astronomy club’s remote observing site. I was joined by club members Jeff, Bill, and Carl, as well as two visiting amateur astronomers from the Kansas City Club and one from Florida.

The Kansas City folks were particularly thankful to be there. Arriving in Albuquerque, they had tried contacting our astronomy club through its website without success, somehow found (unpublished) coordinates for the observing site, entered them into their GPS, and started driving.

They got lost. They had no idea where they’d ended up: “in the middle of nowhere,” as they put it. After a while, a young man came along in his car. They told him they were trying to get to the astronomy club’s site. He led them through the wilderness, deposited them at the gate, and vanished in a cloud of dust. Ah, the kindness of mysterious strangers.

Like an eating-contest contender training for gluttonous excess, I had methodically prepared to cram as many experiences as I could into the hour-and-a-half-long event. It was, after all, my first solar eclipse observation, and I wanted to make it count. So I had with me four pieces of welder’s glass of varying densities, 10x50 binoculars equipped with black polymer solar filters, an 80mm refractor telescope equipped with glass solar filter and 25mm eyepiece, and a piece of plywood drilled with several 7/64-inch holes—for making pinhole projections during annularity, the fleeting Ring of Fire phase.

 

Welder’s glass and curious beetle

 

My observing colleagues also came prepared for observing or imaging the event safely, with properly filtered equipment. We scattered along the full length of the observing field, extravagant in our use of the flat, graveled expanse and its big-sky vista to the west.

Carl set up to image with a Canon DSLR, shooting through our club’s vintage 6-inch Astrophysics refractor. Brent from Florida was also imaging, with one DSLR shooting through his refractor and a second piggybacked on his mount. The Kansas City duo was observing with a 10-inch Dobsonian reflector telescope. Jeff was packing eclipse glasses and a refractor. Bill busied himself with fine-tuning the club’s new astrophotography equipment.

In my haste to get to the site, I’d forgotten one critical piece of equipment:  a hat. The bright, hot, cloudless afternoon boded well for eclipse visibility, but my deficit in headwear quickly became uncomfortable. Fortunately I was able to borrow a ball cap.

DeAnna and Leonard, a couple from the nearest town, arrived unexpectedly and parked their big truck precisely between our equipment and the Sun. Oops. At our urging, they hurriedly and abashedly moved their vehicle to a better spot. Although outfitted with their own eclipse glasses, they were nevertheless curious to see what was happening at our observing site.

And then there were nine.

 

Eclipse watchers

Image by DeAnna

 

I’d brought an atomic clock from home so I could call out countdown times to each event milestone—called “contacts.” Thirty seconds to 1st contact—the beginning of the eclipse—I single-mindedly plastered my eye to my refractor, because it would present the most magnified view.

Before I actually saw the Moon’s silhouetted disk slide into view, I noticed that something was happening on the Sun’s outer edge, a sort of subtle bubbling effect. Then the Moon took its first visible nibble, accompanied by a sudden frenzy of drumming from the crowd of New Agers who’d gathered at their ceremonial site half a mile away.

It had begun.

 

First nibble by the Moon - lower right, at 4 o'clock position

 

Throughout the eclipse, I was moving continually among my color and magnification options—thrilled alike by the unmagnified lime green view through #12 welder’s glass, the magnified-10-times deep orange view through the binoculars, and the magnified-16-times yellow gold view through the refractor. Of course, we all shared views with one another through our array of equipment, even taking turns looking through Jeff’s vintage eclipse glasses, a souvenir from the 2001 total solar eclipse he’d traveled to Africa to see. Together we witnessed the usually benign Moon relentlessly devour each of three large sunspot groups on our freckle-faced star.

 

  Hungry Moon advances on a sunspot

 

At one point, Bill said, “Hey, turn around and look at our shadows.” We twirled in unison. Replacing our familiar shadows was a menacing band of gangly creatures with hideously misshapen heads and curiously deformed fingers, rendered otherworldly by the lunar cutout.

About an hour into the eclipse, the Moon was almost entirely inside the Sun’s disk. At 2nd contact, it pulled away from the Sun’s limb (outer edge), and we had our first exhilarating look at the Ring of Fire. I moved, mesmerized, from view to view to view of that impossible ring suspended in the evening sky:  blazing, bodacious, biblical.

 

 

Ring of Fire, as seen in refractor eyepiece

Image by DeAnna

 

Overhead, powder blue deepened to cornflower. DeAnna held her smart phone to the refractor eyepiece, snapped an image of the ring, and crowed, “Got it!” A nearby mockingbird took a deep breath and launched into a coloratura passage of trills, whistles, and high notes. At 30 seconds to mid-eclipse, I sprinted—with perforated plywood and camera—to the sunlit side of a white travel-trailer for my first-ever experiment with pinhole projection.

 

 

With the Sun behind me, I shoot my shadow and my board's shadow on a white background.

Rings of sunlight stream through the small holes, showing the Sun in mid-eclipse.

So easy, and so fun!

 

A mere four minutes and nine seconds after 2^nd contact, the unstoppable Moon kissed the opposite limb of the Sun for 3^rd contact, the end of annularity. Planted at my refractor during both 2^nd and 3^rd contacts, I observed dainty Baily’s beads, one of the items on my eclipse wish list. More commonly seen during total solar eclipses, these are discrete beads of sunlight briefly shining through the valleys and other irregularities along the Moon’s outer edge, just before it pulls away from or connects with the Sun’s limb. Truly exciting to witness!

 

The end of annularity: 3^rd contact

 

After the high drama of annularity, there was time for more leisurely pursuits. We looked for and spotted Venus high above the eclipse, waiting in the wings for her star turn: a very rare and much ballyhooed transit across the Sun in early June.

The Moon continued to move eastward in its orbit, slowly unmasking the Sun. Clouds drifted across the crescent Sun, flirting with the re-emerging sunspot groups. Sunset approached, and the partially-eclipsed Sun descended into atmospheric haze near the horizon. Needing less protective darkening as a result, I switched to the #11 welder’s glass, and it was just right.

 

 

Moon leaving Sun’s disk, as clouds drift by

 

The serrated western horizon began to gnaw on the abbreviated Sun. We knew we wouldn’t see the end of the eclipse, 4^th contact, when the Moon’s disk completely leaves the Sun, because sunset would occur first.

As I drank in another long, satisfying look through the telescope, a fissure suddenly opened on the Sun’s surface. What the ???!  Realization dawned. “Jet trail on the Sun! Shoot! Shoot!” I yelled, and the imagers began clicking furiously. Big orange jack-o’-lantern grin. Shark fin. Glowing ember. Gone baby gone, ushered out with another flurry of drumbeats.

 

 

Partially eclipsed Sun with jet trail

 

 

 

 

Shark fin:  the still-eclipsed Sun sets

 

 

Do it again. Oh, do it again. Please? Finally I understand the compulsion, the addiction, the fever that grips eclipse chasers. Must. Find. The. Antidote. I hear it’s in Wyoming.

Hunting Himalia - Part Two

For Part One, click here.

My observing circle is filled with people with far more observing experience than I, people who have been amateur astronomers since adolescence, people who have forgotten more about astronomy than I’ll ever know. Q: What can I possibly bring to the table? A: Enthusiasm!

When I read or hear about an object that intrigues me, and I then find out it’s accessible to amateurs, suddenly I have to see it. I’m on fire to see it—and make sure others see it too. I do like to instigate.

I’ll mention the object casually to observing pals, talk it up, drop hints. In the process, I’ll sometimes discover that, amazingly, few to none of the seasoned veterans have seen it. That’s all I need to hear to put that object firmly in my crosshairs. In the case of Himalia, even the über-observers of my club hadn’t seen it. Here was an irresistible challenge: pursue an object even they hadn’t seen!

I knew the Fall 2011-Spring 2012 apparition of Jupiter would be ripe for a Himalia quest. Jupiter was rising around 10 p.m. in September, and so would be high enough to begin Himalia hunting around midnight. It’s always a plus when you don’t have to stay up bleary-eyed until 4 a.m. to acquire your target. Another big plus would be the warm late-September night; no clothing layers required. Yup, this was gonna be great.

Final Prep Step #1: Assemble the Equipment

With the promise of good weather and clear skies as the appointed evening approached, the mate decided to retrieve his 24-inch reflector from storage, where it had been safely stowed since our move to the mesa. Although that may sound like mosquito hunting with an elephant gun, all that glass can help tremendously when trying to recover a 14.8 magnitude speck.

Since it’s not a tracking telescope—a motorized telescope that keeps acquired targets in the field of view by compensating for Earth’s rotation—we decided to place it on an equatorial platform, which turns a non-tracking scope into a tracking one. Although the platform is heavy and must be manually re-set every half hour or so, not having to worry about constantly nudging the scope to keep your target centered is a huge plus when you need all your concentration just to spot it.

Equipment Checklist

• 24-inch f3.9 home-made reflector (aka “The Cannon”)
• Osypowski equatorial platform
• 13mm Nagler eyepiece
• 4.5-inch Starblast with 24mm eyepiece (used as a finder scope on the 24-inch)
• Ladder
• Jellybeans

"The Cannon"

Equatorial Platform

  

Final Prep Step #2: Assemble the Experts

With the mate—a more seasoned observer—at my side, I had substantially increased my odds of success. While setting up at our astronomy club’s observing site, we pooled resources by reeling in Kevin, a very accomplished observer who also had Himalia on his life list and was keen to try for it. Kevin was familiar with the motions of Jupiter and its moons, which proved extremely valuable in our shared quest.

  

The Main Event

At the appointed hour, the mate re-set the equatorial platform to get a full 30 minutes of accurate tracking, and then aligned his telescope using his NGC-MAX (a computer controller that aids in locating objects). I read off the RA and DEC coordinates for Himalia from my ephemeris (see Part One) and he tapped them into the NGC-MAX. He inserted a 13mm eyepiece in the focuser, as we had determined that the field of view produced would be a good match to the field shown in the DSS image.

After pushing the cannon-like scope to the coordinates, he climbed the ladder to the eyepiece clutching the piece of paper with the DSS star field image. After rotating the paper once to the right, the image matched what was in the eyepiece. A few bright stars in a triangle pattern and a three-star arc within the target field helped. Piece of pie!

He then set out comparing the DSS image to the eyepiece view, star by star. Finally, he was left with one star in the center of the field of view that was not represented on the DSS image. It had to be Himalia, didn’t it?

I climbed the ladder next, and using the DSS image, was easily able to tick off the brighter stars in the field, including the triangle. I made my way incrementally to each dimmer star in the field, but was only able to see the top star of the three-star arc. I couldn’t see the two dimmer stars below it. I waited to let more light integrate on my retinas. And then using averted vision, I saw the central speck that wasn’t on the DSS image. The mate confirmed that it was dimmer than the top arc star but brighter than the two lower arc stars, which explained why I could see Himalia, but not the lower arc stars.

Himalia was seen at tip of arrow

We huddled to confer. It couldn’t be just another star in the field that was too dim to be represented on the DSS image, because it was brighter than the two lower arc stars, which were on the image. It had to be Himalia, didn’t it?

Kevin mounted the ladder next. He easily spotted the “interloper” star in the field. We discussed whether we could see it move that night. Observed movement against the background stars would be verification that it was no star. Based on how much the RA & DEC coordinates on my ephemeris changed over time, it seemed likely. In fact, Kevin predicted that, if we waited about an hour, we would be able to see motion. With his knowledge of the current motions of Jupiter & Company, he also predicted in which direction we would see the Himalia candidate move.

I kept thinking: can it really be this easy? Rick Scott’s article (see Part One) had made this target sound so daunting. As it turned out, what we had—that the author didn’t—was aperture, 24 inches compared to his 10 inches. It made all the difference.

We waited about an hour to see if the suspected moon moved against the background stars. Sure enough, it had shifted westward, moving in the direction Kevin had predicted. Eureka! Himalia was ours!

I was only able to see Himalia with averted vision, that is, by using my peripheral vision and looking at a spot in the black sky right above it, rather than directly at it. My two observing partners were able to see it with direct vision, the second time they looked at it. This is because  1) Himalia was then a little higher in the sky and less obscured by Earth’s atmosphere, and  2) their eyes are annoyingly better than mine. Given Himalia’s faintness, I was suitably impressed with Rick Scott’s accomplishment, spotting it with far less aperture. How did he do it?

Although it was exciting to observe such a tiny fleck of reflected light, one of the best views of the night, for me, was when I looked at Himalia and couldn’t see it. Let me explain.

Starblast (little blue scope) riding piggyback as a finder scope

We were using a 4.5-inch Starblast, a nice little telescope in its own right, as a finder scope (targeting tool), riding piggyback on the 24-inch scope and aligned with it. The view through the finder provided a much wider field of view and much less magnification than the big scope. I could therefore see Jupiter and all four Galilean moons, with a lot of black space around them. Himalia was centered in the big scope—and staying centered because it was tracking. So when I looked through the finder, I knew that Himalia, although I couldn’t see it with such low magnification, was dead center in the field of view. That allowed me to see the big picture, where Himalia was in relation to its host planet.

I knew Himalia was considered a “far-ranging” moon; indeed, most moons in Jupiter’s large harem have far-ranging orbits. Himalia floats through space about seven million miles from Jupiter. Compare that to the orbit of Earth’s Moon, a mere quarter of a million miles from its parent planet. The view through the finder confirmed Himalia’s lonely orbit: it was more than one degree from Jupiter, far from the mother ship and its four famous satellites. A degree in the sky is two times the width of a Full Moon as observed from Earth.

  

Four other seasoned observers on the field that night—Dave, Bob, Ed, and Vance—came over for their first look at Himalia. This is what I call “giving back”: for all the fabulous views of remarkable objects offered to me over the years and for the unfailing generosity of the amateur astronomy community.

Hunting Himalia was team astronomy at its best, and we seven could now say we had “been to Himalia”!

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.

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 spiny 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 spadefoot toads, harmonizing. How long had those intrepid 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.

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.

Jumpin' Geminids!

In the wee hours of Tuesday morning, December 14, the Geminid meteor shower will peak. This is a great opportunity to view one of the more reliable meteor showers of the year, if you're an early riser or if you don't have to work on Tuesday.

I fall into the latter category, which is a good thing, since I'm far more adept at staying up than at getting up. I plan to begin viewing after midnight, since a big old waxing (growing) gibbous Moon will light up the sky until around 12:45 a.m. Bright moonlight is a meteor watcher's nemesis, as its glare washes out many of the fainter meteors.

This shower's radiant--the point in the sky from which the meteors appear to emanate--lies in the constellation Gemini, which will be at its highest point in the sky between 1 a.m. and 2 a.m. local time. Geminids can appear anywhere in the sky; if you spot a meteor during this hour and can trace its trajectory back to a spot overhead, chances are it was a Geminid.

Geminids usually appear white or yellow, and we'll have a chance to spot some really bright fireballs. There should be around 120 meteors per hour "jumping" at the shower's peak.

The best viewing position for meteor watching is lying down, so you can see the largest amount of sky at once. You have a better chance of spotting the most meteors this way. I plan to lie on a comfy chaise lounge inside a down sleeping bag. Yes, the Geminids are a great shower but do they have to fly during the coldest month of the year in my area?? A thermos of hot chocolate within reach is also on my must-have winter meteor watching list.

Here's hoping for clear skies on Tuesday morning in your area. Good luck, and be sure to post your Geminid-watching experience here.

Honk If You Love the Heliosphere

I’ve heard that there’s a point, marked by turbulence, that marks the edge of the solar system as a satellite passes out of it. What causes the turbulence? What is out there to be turbulent? ~Matt


Racing from the Sun in all directions at about a million miles per hour, the solar wind is a stream of electrically charged particles. The solar wind, carrying with it the Sun’s magnetic field, forms an enormous magnetic “bubble” called the heliosphere that encases the solar system. This protective bubble shields our solar system and planet from (some but not all) harmful cosmic rays, high-energy particles traveling through space. We heart the heliosphere!

The transition zone where the solar wind meets the interstellar medium, the thin gas and dust that exists between stars, is called the heliopause. Here at the outer edges of the heliosphere, the solar wind mixes with the interstellar medium; this interaction between two different densities and pressures creates turbulence.

The Heliosphere and the Voyager Spacecrafts
Courtesy NASA/JPL-Caltech

When the solar wind approaches the heliopause, it slows very abruptly, causing a shock wave to form. The shock wave is called the termination shock, and this boundary is marked by dramatic changes in magnetism and temperature.

NASA’s Voyager 2 spacecraft crossed the termination shock in 2007; Voyager 1 had crossed it three years earlier in 2004. And here’s a funny twist: Voyager 1 only had to cross the termination shock once; Voyager 2 had to cross it five times! This occurred because the heliosphere bubble flexes in response to solar flares and other ejections of material from the Sun. In this case, the termination shock became a moving finish line.

Voyager 1, launched in 1977 and now ten-billion-plus miles from Earth, is the most distant of all active spacecraft. Voyager 2, which launched a few weeks earlier than Voyager 1, is only eight-billion-plus miles from Earth. This lag exists because Voyager 2 took a little planetary side tour. It began heading out of the solar system nine years later than Voyager 1, after becoming the first spacecraft to observe Uranus and Neptune.

In about five years, Voyager 1 will leave the heliosphere behind and enter interstellar space; Voyager 2 a few years after that, each spacecraft heading in a different direction. What new wonders will these stalwart space voyagers encounter, in the realm beyond the Sun? Stay tuned.

How Far Can We See? (part two)

Now for the exciting conclusion--and the second answer--to Matt's question of last week, which you may recall was:

"Is there a specific star that represents the farthest a person can see with the naked eye?"

Although the Andromeda Galaxy is the farthest object the average person can see with the naked eye, there is a star that is reportedly the most distant that can be seen naked-eye. It's a variable star in the constellation Cassiopeia the Queen, and it has the unromantic name of V762 Cas.

A variable star is a star that periodically brightens and dims. In the case of V762 Cas, it's most likely doing that because it's in a red supergiant phase, and it's begun to swell and shrink. A red supergiant is approaching the end of its life. It has burned up all its hydrogen fuel, and has begun burning other elements in a specific sequence. This causes rather dramatic changes in the star's size, temperature, and "behavior."

Image from Palomar Observatory Sky Survey

V762 Cas lies about 15,000 light years away. As we learned last week, one light year is nearly six trillion miles. Now multiply that by 15,000, take two aspirin, and go lie down.

V762 Cas must be a big honkin' supergiant, if it's that far away and we can still see it, yes? Unfortunately, I have not yet been able to spot V762. It is right on the outer limits of naked-eye accessibility, so I need to try again at a really dark site. Acquiring this sort of faint target, along with a faint target like the Andromeda Galaxy, benefit greatly from an effort to properly dark adapt (see last week's post).

To give it a try yourself, face north and locate the Lazy W asterism of Cassiopeia, which looks like a W or an M, depending on its orientation when you look. Download a free sky map for the month at http://www.skymaps.com/, if you don't know how to locate Cassiopeia.

Now draw an imaginary line between the star at the roof peak of the House asterism of Cepheus--it looks like a child's drawing of a house--and the leftmost star of the Lazy W, if it were oriented as a right-side-up W. V762 lies on that line. The star map below will help you pinpoint its location.

Looking north toward Cassiopeia and Cepheus

If you have success spotting it, please post your results in the Comments. Also, if you can spot it with binoculars or a telescope, let us know that also; I'm curious to know if anyone sees any color in the magnified image. Sometimes color is significantly enhanced with a little magnification.

Good luck to us all!

How Far Can We See? (part one)

Astronomy enthusiast Matt, whose favorite celestial object is the three-star asterism (recognizable star pattern) Orion’s Belt, dropped quite a few questions into the Ask An Astronomer box. We’ll start with this one, since it’s perfectly timed for autumn stargazing:

“Is there a specific star that represents the farthest a person can see with the naked eye?”

I love this question, because it has two answers. First, the most distant object that a person with average eyesight can see with the naked eye is…
...not a star! It’s a galaxy, specifically, the Andromeda Galaxy.

Originally called the Great Andromeda Nebula, it became known as the Andromeda Galaxy after the famous astronomer Edwin Hubble confirmed its galactic nature in the 1920s. At an estimated 2.5 million light years away, it’s the nearest spiral galaxy to our Milky Way. The Andromeda Galaxy is more or less comparable to our home galaxy in size and mass, but astronomers believe it has a significantly higher star count.

Keep in mind that one light year is nearly six trillion miles, so the distance to the Andromeda Galaxy is pretty hard for us to wrap our heads around. But amazingly, with a little bit of effort, we can see it! Let’s gaze.

1) You’ll need a dark site, away from city lights, to see this “faint fuzzy.” Before beginning your hunt, be sure to dark adapt to maximize the acuity of your night vision. To dark adapt, simply avoid all white light for 20 minutes before stargazing. Then use a red flashlight during your stargazing session, to maintain your dark adaptation.

2) About one hour after sunset, face east. Look well above the eastern horizon for a large, four-star square. Each side of the square is about two fists wide, if you hold your fist at arm’s length against the sky and measure across the knuckles. This is the asterism called the Great Square of Pegasus.

Star maps created with Your Sky

3) Next, find the Chains of Andromeda, the two strands of stars that arc to the left (north) of the star that marks the Square’s lower left corner. Now look above the middle star of the upper chain for a faint, fuzzy patch. A Persian astronomer of the 10th century called it the “little cloud,” an apt description. If you spot it, you’re gazing upon a collection of about one trillion gravitationally-bound stars, what the farsighted philosopher Immanuel Kant called an island universe.

If you can’t see it, you may need to try again at a darker site with less light pollution. Additionally, your sky transparency, or atmospheric clarity, may be negatively impacted by the presence of clouds, haze, dust, or humidity. If this is the case, try again when conditions are improved.

When you look up at the night sky, every star you see is in the Milky Way. The exciting thing about spotting the Andromeda Galaxy—in addition to it being the farthest object you can see naked eye—is that you’re seeing a world beyond your galactic neighborhood. That’s right, it ain’t local.

For the second answer to Matt’s fine question, tune in next week. And until then, happy hunting.

Opposition - It's a Good Thing

In everyday use, the word “opposition” has a somewhat negative connotation. But in observational astronomy, opposition is a good thing.

Each planet beyond Earth in the solar system—Mars, Jupiter, Saturn, Uranus, and Neptune—is said to be at opposition when it is opposite the Sun as seen from Earth. In other words, Sun, Earth, and outer planet are in a line, with Earth in the middle.

This happens because, moving outward from the Sun, each planet’s orbit is larger than the one before, and each planet travels slower in its orbit than the one before. Therefore, each planet takes longer to complete its orbit than any of the planets closer to the Sun.

For example, Jupiter was at opposition this past September. Since Jupiter takes longer to chug around the Sun (4,332 days) than Earth does (365 days), Earth catches up to and passes Jupiter about every 13 months, slipping between Jupiter and the Sun.

The significance of opposition to hobby astronomers is three-fold:
1) When a planet is at or near opposition, it is closer to Earth than at other points in its orbit;
2) A planet at opposition is fully illuminated by the Sun, from our vantage point on Earth; and
3) A planet at opposition is visible all night long, rising at sunset and reaching its highest point in the sky around midnight.

In short, a planet at or near opposition is close, bright, and up all night. This combination presents planetary observers with optimal viewing conditions and the opportunity to see detail on the planet’s surface they might not otherwise spot. Not to mention an excellent excuse to stay up all night, no matter what the neighbors think.

Here’s a related question recently dropped into my Ask An Astronomer box at a local science center’s evening event; it was submitted by Tara:

“Jupiter just went into its closest opposition since 1963. A site I found on the internet said it wouldn’t be this close again until 2022. Why the uneven time difference if this is true?”

Wonderful question and observation, Tara. And you need know but one thing to understand why: the orbits of the planets are not perfect circles. Instead, planetary orbits are elliptical, or oval. The eccentricity of each planet’s elliptical orbit differs, that is, the degree to which the oval is stretched out from the circular. In addition, the planets’ orbits are inclined, or tilted, with respect to the plane of Earth’s orbit around the Sun. These variables inserted into the distance-at-opposition equation mean the possible distances separating Earth and another planet when they rendezvous at opposition are, well, astronomical.

The Kids Are Far Out - part three

The final set of questions from the kids of Cosmic Carnival may be last, but they’re certainly not least. In fact, I think these three budding scientists asked questions which we should all consider. To do so is to begin to have some understanding of our place in the universe.

Ryan from Albuquerque, age 9, pondered this:

“I was wondering how thick the atmosphere is on Earth.”

A real brain teaser of a question, Ryan! There is no straightforward answer to this question because our atmosphere does not have clearly defined borders. As we go up in altitude, Earth’s atmosphere very gradually becomes thinner and thinner until it merges with outer space. So we could say the answer is 800 miles thick if we include the outermost layer, the exosphere, where the air is extremely thin.

Or we could use the altitude where space is officially considered to begin: 62 miles (100 kilometers) above sea level. So, the answer could also be 62 miles thick, since around 99% of the mass of our atmosphere is found below this point. You can read more about Earth’s atmosphere here.

The layers of Earth's atmosphere, bottom to top:
Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere

Image source: NOAA/National Weather Service

Scott from Rio Rancho, age 8, posed this question:

“How does the Earth spin around the Sun?”

Scott, we generally say that Earth spins (or rotates) on its axis, the way a top spins. We also say it orbits (or revolves) around the Sun. 24 hours a day, 7 days a week, our home planet is spinning like a top and traveling in an orbit around the Sun, at the same time.

Whenever you look east (the direction of the rising Sun), you are looking in the direction toward which the Earth is spinning, as well as the direction in which Earth is traveling as it circles the Sun.


Sophie from Albuquerque, age 9, was looking way beyond the solar system when she asked:

“If we’re in the Milky Way, how do we have pictures of the Milky Way?”

It’s a puzzle, isn’t it, Sophie? It’s true: we do reside in the Milky Way galaxy. In fact, every star you see in the night sky is in the Milky Way galaxy.

If you go stargazing out in the country, away from city lights, you will probably see what looks like a long, glowing cloud arching overhead from horizon to horizon. It’s actually a collection of billions of stars too numerous and faint to be resolved (separated into distinct points of light) with the naked eye, so we see it as a hazy band of light. We call this object the “Milky Way” too, even though it’s just part of our home galaxy. This is probably what you have seen in photographs, as it’s a popular target for astrophotographers.

The glowing “cloud” is an edge-wise view of the star-packed spiral arms of our platter-shaped galaxy. Even though we are in one of those arms (the Orion Arm), we can look across space at neighboring arms. The diagram below will give you a better picture of your place in space.

Diagram of the spiral arms of the Milky Way

Image source: Richard Powell

In conclusion, I have to admit that I seriously doubt I could have formulated any of these questions at the tender age of 8 or 9. I was a science ignoramus for my entire childhood and, indeed, much of my adult life. So, I am awed and inspired by the far-out kids I met at Cosmic Carnival, who are already looking up and wondering about the universe in which they live. I hope they never lose that sense of wonder.

Have you looked?

The Kids Are Far Out - part two

As a rule, kids like planets, and the kids at the recent Cosmic Carnival event were no exception.

Phillip from Albuquerque, age 8, commented on his favorite planet:

“I like Neptune because I think there might be life there.”

Phillip, that’s as good a reason to like a planet as I’ve ever heard! Wouldn’t it be exciting to discover evidence of extraterrestrial life in our own solar system?

Neptune
Image source: NASA

Along with Jupiter, Saturn, and Uranus, Neptune is one of the gas giant planets, which means it has no solid surface on which we could walk. Its thick atmosphere has 1,000-mile-an-hour winds and a bone-chilling temperature of minus 350 degrees Fahrenheit. Brrrrr! Beneath the harsh atmosphere is a hot “ocean” of water, ammonia, and methane, and perhaps a small core of rock and ice.

It’s safe to say any life form that can survive on Neptune is pretty darn tough.

Julia from Rio Rancho, age 9, asked:

“Why did Jupiter become a moon?”

Thanks for your question, Julia. Jupiter is actually a planet, not a moon. In fact, Jupiter is the biggest planet in our solar system!

The planets to scale
Left to right: Outer edge of Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Image source: NASA

A planet is a celestial body with a nearly round shape that orbits the Sun. A moon, on the other hand, is a celestial body that orbits a planet. Jupiter has over 60 moons going around it! The four largest ones were discovered by the famous Italian astronomer Galileo. You can read more about Jupiter here.

Melissa from Albuquerque, age 12, wondered:

“How long does a day last on Pluto? How long does it take for it to orbit around the Sun?”

A great pair of questions, Melissa! Although distant Pluto has been reclassified by professional astronomers as a dwarf planet, we still love it, don’t we?

A day on Pluto, that is, the time it takes for Pluto to complete one rotation around its axis, is a little more than 6 Earth days. A year on Pluto, that is, the time it takes for Pluto to complete one orbit around the Sun, is 248 Earth years.

Life on Pluto is life is the slow lane.

The Kids Are Far Out - part one

To turn kids on to science and astronomy was the reason we all gathered at the annual Cosmic Carnival outreach event held at the Albuquerque International Balloon Museum this past Sunday, September 5.

The joint was jumping!

Dave Dooling of the National Solar Observatory deflates the Sun.

Len Duda of Sandia National Labs inspires a future engineer.

I met some “far out” kids (and adults) who like astronomy and stargazing, and invited them to write a comment or pose a question to be published on my blog. Liam from Albuquerque, age 10, had this to say:

“My favorite constellation is ‘o-Ryann.’ My stepsister’s name is Ryann. She is three months younger than me. Sometimes we get into arguments, but most of the time I like her. I find Orion easy to recognize.”

Ditto, Liam! That distinctive hourglass shape, along with the three diagonal Belt stars in the middle, makes Orion the Hunter quite easy to spot in the winter sky, even if you’re a beginner. Read more here.

Wow, how lucky are the kids who call Dara from Albuquerque, age 40, “Mom.” She shared this story:

“Each time we take our sons camping, they are a little older and can pick out more things in the night sky. This summer our 5 year old spent hours looking for his favorite constellation, but never found it (must be the wrong time of year for Delphinus). But we had a great time counting shooting stars and naming our own constellations.”

Right you are, Dara. The delightful little constellation of Delphinus the Dolphin leaps its way into our hearts in autumn. Starting in late September, look for it after sunset, just west of the Great Square of Pegasus. Read more here.

Finally, a young lady named Vaidehi from Lone Tree, Colorado, age 8, posed this question:

“Why do the stars change over a year?”

Excellent question, Vaidehi! Many adults don’t know the answer to that question either. So, why do we say that Orion is a “winter constellation” and Delphinus is an “autumn constellation?” And why can we see Scorpius the Scorpion in the summer, but not in the winter? In other words, why are the stars seasonal?

The Earth is in orbit around the Sun 365 days a year, right? Because we’re always moving along this path around the Sun, each night when we spin around to face the night sky, we don’t have exactly the same view we had the night before. Although it won’t be obvious to you, the night sky and its star patterns have shifted slightly to the west, or right. This is because the Earth has moved slightly eastward in its orbit, or toward the left.

This continuous westward shifting of the stars will become more noticeable to you as the months pass and seasons change. For example, you might notice that the constellations you enjoyed in summer are moving farther and farther to the west in autumn, until finally they are below the western horizon after sunset and no longer visible.

The diagram below shows an example of this, using the constellations of the zodiac. If we were standing on the Earth shown in the diagram (the black circle), at night we would look out at the constellation Pisces the Fishes. But six months later in its orbit, when Earth was on the other side of the Sun, we would look out at the constellation Virgo the Maiden at night.

Diagram by Dr. Guy Worthey

Because we’re always in motion, we’re always looking out at different “slices” of the night sky.