Eclipse safety

The multiple warnings about not looking directly at the sun seem peculiar.

I mean, really? “Don’t look at the sun” is akin to “don’t hold your hand over a flame” or any other dangerous and painful act that would be ludicrous to do and impossible to sustain. Common sense dictates against such a practice (but judging from recent events in our culture, common sense is at a premium).

I couldn’t help but wonder (Carrie Bradshaw style)…is this really a problem? Turns out it is. According to LiveScience.com, total blindness is rare, but you might be in danger of contracting “solar retinopathy”—aka photic retinopathy, foveomacular retinitis, solar retinitis, and eclipse retinopathy—resulting in temporary to permanent blurriness or a blind spot at the center of your vision.

“Eclipse blindness” is caused when ultraviolet light overwhelms your retina, located at the back of your eye where the photosensing cells that allow you to see are located. During the deep partial phases of the eclipse when sunlight dims it can be tempting to sneak a peek, and the damage at that point is delivered without pain and when protective reflexes (like blinking and pupil contraction) are slacking off.

Solar retinopathy can occur at any point during the partial phase—including the final seconds before totality—and the most important reason to shield your eyes occurs in the very last two or three seconds before blackout: looking directly at the sun during this time can cause temporary vision distortion that can bork your enjoyment of the scant, precious minutes of totality.

Many people don’t understand that you must look at the sun with the naked eye after Second Contact, and the trick for a first time eclipse viewer is to know when to whip those eclipse shades off in time to see the entry phenomenon like Bailey’s beads and the diamond ring. Stay calm, and keep your glasses on until you’re sure it’s safe. (The sound effects coming from those around you will alert you that totality has occurred.) Rest assured that you’ll get a good long look at the ring and the beads in reverse order at Third Contact. Don’t risk blurry eyesight during the big event by removing your shades too soon.

It’s optimal if there’s a coach in the area to let you know what to do. This video is an example of the phenomena countdown by Jay Anderson, meteorologist aboard the expedition ship Orion in the Great Barrier Reef with (TravelQuest, Nov. 13, 2012). Some find spoken words distracting, but I think it adds to the thrill.

I love looking at the eclipse safety posters and flyers that local governments distribute—like the ones at the end of this post.

Your options

The only safe way to look directly at the partially eclipsed sun is through special purpose filters such as “eclipse glasses” or my uber-dorky #14 welder’s goggles.

The popular paper eclipse glasses you’ve seen are made with optical density 5 “black polymer” material that filters out harmful ultra-violet, infrared, and intense visible light. Look for brands made in the USA (beware of overseas knock-offs) and that state they are CE certified and meet ISO standards. I recommend Rainbow Symphony, manufacturer of our custom Blackout Rally shades. I’m told American Paper Optics and Thousand Oaks Optical are two other reliable manufacturers.

What’s true for your eyeballs is true for the devices you look through. Do not look at the uneclipsed or partially eclipsed sun through an unprotected camera, telescope, or binoculars—and don’t use these things while wearing your eclipse shades, either. The intensified solar rays will damage the filter and enter your eye. (Gad, this is getting scarier and scarier, isn’t it? You’’ll be happy to know that your own prescription eyeglasses are safe to use with eclipse shades or a solar-filtered telescope.) Both your eyes and your optical device need their own filter. Pointing an unprotected telescope directly at the sun can also result in the unfortunate melting of the plastic parts that hold the internal instruments together.

Oh, and don’t make your own filter like some hillbilly. Black plastic trash bags, balloons, camera film (WTF is that), or three pairs of sunglasses worn together won’t bar ultraviolet light.

Eclipse shades make a great souvenir of the experience; I have a small collection and the ones from Egypt are my favorite.

You’ll be able to put your hands on a pair of eclipse shades pretty easily before August 21, but order online soon. Alternatives to the standard style include hand-held viewers, magnification viewers (like the Celestron EclipSmart™ power viewer) and even wacky ones that let you look like an astronaut or an alien.

The weakest technique of all is the pinhole projection, but it’s fun to do to pass the time during the boring partial phases before and after totality. Here’s how:

  • Use two sheets of cardboard (stiff white paper, even two paper plates)
  • Make a tiny, round, smooth hole in the middle of one sheet using a thumbtack, a sharp pin, or a needle
  • Stand with your back to the sun, and hold up the paper with the hole.
  • The second sheet of paper serves as a screen for the projected image. Do you see a little crescent shadow? That’s the inverted image of the sun coming through the pinhole.
  • Experiment: make the image of the sun larger by moving the pinhole paper closer to the sun.
  • Anything with “holes” can be a pinhole projector: a straw hat, your loosely crossed hands, etc. Find a nearby tree and look at the ground below: the leaves will create hundreds of crescent projections.

Check out this excellent 4+ minute video courtesy of the American Astronomical Society (AAS) Solar Eclipse Task Force and the American Institute of Physics. It will tell you everything you need to know about eclipse safety.

Above: #14 welder’s glasses. Below: Blackout Rally shades; Egypt souvenir (what does that hieroglyphic say, “scram, tourist”?); handheld viewer, solarscope (I have no idea what this does); PowerViewer; alien shades; pinhole hands.

 

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First-timers guide to looking at the sun with the Celestron 8SE

Big filterIf you own a nice telescope outfitted with solar filters, you’re probably an advanced enough user not to need these dumbed-down, step-by-step instructions. If, improbably, you share my situation—an absolute noob with a big, complex scope on her hands—I offer the following easy, lowest-tech way to align and track to the sun.

All thanks and kudos go to Grant Tandy, Astronomical Interpreter at the Oregon Observatory at Sunriver. During a practice session with Grant I learned that the alignment process—contrary to the marketing prose at Celestron.com—is more finesse than precision. One of the most valuable and consoling takeaways during the guided viewing with Grant was discovering that “close enough,” “keep trying, it’s hard,” “just turn it on and off and start over,” “it takes practice,” and “you’ll get used to it” are all acceptable stargazing concepts.

Do I need a solar filter?

Oh hell yes. Unequivocally. Without it, you’ll destroy the corneas of your eyes, and the plastic gizmos inside the telescope will melt. The solar filter reduces sunlight to the optics—both yours and the telescope’s.

What kind of filter should I get?

There are two main types: “white light” and hydrogen-alpha (“H-alpha”). Without going into detail, a white light filter allows you to see sunspots and some textures in the photosphere. They’re great for the safe viewing of partial solar eclipses, and the transits of Venus and Mercury. You’ll see a white image of the sun (or sometimes a yellow-orange color).

With an H-alpha filter you’ll observe all of the above, plus solar flares and prominences. Thusly, they cost a lot more; expect to pay up to a grand for a high quality system. The H-alpha filter transmits only one wavelength of light in a deep red color, and that’s how you’ll see the image of the sun.

I selected the two-part H-alpha system from Thousand Oaks Optical for use with my 8SE. It includes the energy rejection filter (ERF) that fits over the business end of the telescope, covering the aperture, and the H-Alpha filter unit (HAU), which acts like an eyepiece. The HAU and ERF are always used together, and the following steps include installation of both. (“Installation” is strong. They just pop into place.)

Where do the filters attach on the scope?

It’s safest for your telescope to be indoors, in the shade, or at the very least pointing well away from the sun when you’re changing solar filters. Just remove the plastic protective cover from the front of your telescope, and replace it with the big solar filter cap/energy rejection filter (ERF). Position the circle cutout at the top, at 12 o’clock. Then remove whatever eyepiece you were last using for nighttime viewing, and insert the solar eyepiece/H-Alpha filter unit (HAU). It works in tandem with a regular viewing eyepiece.

Select the right eyepiece.

Splurge on the the Celestron accessory kit, a nice assortment of five eyepieces, a Barlow lens, and a bunch of fun filters in a sharp little metal case. (We experimented with the Barlow for X2 magnification, but settled on the 32 millimeter for solar viewing.) All right! Let’s look at the sun!

Bring the telescope outside where it’s sunny.

Do this on a clear day, of course. Carry the scope (it’s heavy) from the base, where the battery compartment is. Bring along your eyepieces and the PowerTank if your extension cord won’t reach from the source of the shore power. Turn the telescope on. (The power switch is at the base of the fork arm.)

How do I align the telescope directly to the sun without risking my eyesight?

Good question. You could stare right up at the sun to see exactly where it is in the sky, but that’s not a good idea, is it? Use the shadow of the telescope on the ground as your guide.

controllerBut first, you’ll be using the computer in a minute, so check the settings. You’ve probably already used your NexStar hand controller to key in the date, time and location. Run through the setup procedures again to make sure the correct data was stored; you might have to update the time.

Press “Enter” to begin alignment.

Use the scrolling arrows on the hand controller (the small arrows, not the big PlayStation-style ones that move the telescope) to find “Solar System Align”. Press enter. (It may ask for the time. If it displays as correct, press enter.)

“Select Object”. Scroll to find “The Sun”. Enter.

See an ominous warning: “Do not look at the sun without the proper filter.” We’re good. Right? Better doublecheck. (I wonder how many people per year fry their eyes this way. Probably during a solar eclipse it’s chronic.) Press enter.

Now use the big direction key arrows to tilt the scope up toward the sun. Watch the shadow of the telescope on the ground; angle it around, looking at the different shadows made by the optical tube. If it’s a sausage-shape, you’re not quite there. An oval? Closer. Stop when the shadow is as perfectly round as you can get it.

Scope shadow

Now set the telescope to track the sun.

Look into the solar eyepiece. If you’ve nailed the shadow, you’ll see a small-ish, spot-on, perfectly centered image of the sun. (It’s fine if it’s off to the side a little).

Don’t panic if you see a cookie bite in the sun at first. There isn’t an eclipse in progress, that’s just the solar filter. That bite will go away when you get everything aligned and are using the right eyepiece. (Make sure the mirror circle of the big solar filter is toward the top.)

If you don’t see the sun, do you at least see a shadowy, ambiguous patch of red? Good. That means the sun is just off to the edge of the filter, and you’re very close to where you want to be. Slowly tap the arrows in each direction until the sun appears. If you see more red coming into view, keep going in that direction.

Insert the viewing eyepiece.

EyepiecesAgain, we recommend the 32mm. “It gives you a bigger view,” advised Grant. Indeed, the ball of the sun nearly completely fills the eyepiece with the 32.

Dock it on top of/behind the solar eyepiece. You can’t screw this up— they only fit together one way: solar first, viewer second. Secure them both by tightening the little silver knobs. (Not the white plastic knob. That’s a focus adjustment. More on that later.)

Look into the eyepiece: now you’ll see a big image of the sun. As it’s so large, you’ll have to align it perfectly to keep it in the middle. Use the right/left/up/down direction key arrows to zoom the view around until the sun is centered. The controls seem counterintuitive at first, due to the diagonal of the mirror that flips the image of the sun. You’ll get the hang of it. At any time you can slow down the motor speed as needed. (Press the motor speed/rate button, then a number on the keypad, like 4, or 6. No need to press enter.)

As soon as the sun is centered—doublecheck one last time that the full image of the sun appears centered in the eyepiece and hasn’t wandered away—press “Enter”, “Enter”, then “Align”.

“Align success”! If you went through the process correctly, and the sun was pretty well centered in the eyepiece, the clock drive will take over and the telescope will now track the sun to keep it centered. From here, you can fiddle around looking for sunspots and flares at the edge. You can fine-focus even while the telescope is tracking.

What if it’s not tracking?

The sun was probably not perfectly centered when you selected the final alignment buttons. Just go through the process again. Or swap eyepieces and try again. The alignment may never be perfect, and you might have to re-center the sun every five or ten minutes. If you’re actively observing, minor tweaks will keep it in alignment.

Lost the sun? Remove and pocket your viewing eyepiece and look back through the solar eyepiece to locate the red area again. Completely lost? Turn off the telescope for ten seconds to reset the computer.

If you go in for a sandwich you can always come back and start over. Just keep trying. A person I’m close to—I won’t say who, but it rhymes with my smushband—will always default to “this thing is broken!” after about two minutes of failure. “This equipment is very technical,” assured Grant. “You have to play around with it.”

Note that you don’t NEED to set the scope to track. You can make continual minor swiveling adjustments with the direction keys to keep the sun from floating out of view if you’re not using the clock drive. Don’t forget that you can change the swivel speed.

I’m having trouble seeing.

“It’s tough,” said Grant. “With the way the eyepieces are angled, and especially during the day, it’s tough to get your eye on it.” You might be seeing a floating red ball, a blob like mercury in a thermometer, your own eye, your eyelashes. Sunscreen may be running into your eyes. A sun shade might help but I don’t think Celestron sells one for the 8SE. Just relax and keep at it. If you wear prescription eyeglasses or sunglasses, look into the eyepieces without them on. I cup my hand over my non-viewing (left) eye to avoid squinting and distortion.

Damn it’s hot out here in the driveway.

Yes, it is. Hydrate. Don’t worry about your scope so much. It can take the heat as long as you’re out there with it.

What are those black discolorations on the surface of the sun?

Sunspots! You’ll see them alone or in a cluster or sunspot grouping, caused by the magnetic field of the sun. To put their size into perspective, envision that the diameter of the sun is about 110 Earths, side by side across. A nice visible sunspot is about the size of Earth. On an “active” day you’ll see more.

Now look for prominences.

Scan around the edge of the solar disk. If you see a misty, foggy rising, turn the little plastic white knob this way and that to bring the prominences in and out of focus. Use it in tandem with the big black focuser knob at the base of the optical tube…whatever works. This won’t disturb the tracking.

If you’re well-focused on prominences, you’ll be in a good position to clearly see any sunspots. Both are related to the erratic magnetic field on the sun, which causes random jets of hydrogen to come out (as a prominence), or, less commonly, as a big flare or loop.

“Most prominences are not very prominent,” observed Grant. Don’t see any? Maybe there’s just not a lot of activity today. Try again some other time.

Fun fact: When you see a prominence, you’re seeing it eight minutes ago. That’s how long it takes the light from 93 million miles away to reach us.

Adjust your expectations. 

Though a prominence is actually moving like a flame or a geyser, you won’t see it that way “because it’s on such a large scale,” explained Grant. “If you think about a prominence—an average, kind of medium-sized prominence—it’s about 40,000 miles across. If it’s moving 2000 miles an hour, you’re looking at it moving 1/20th of its total distance in one hour. So you see just a small fraction of it move in an hour. If you were to come back six hours later, you’d see more of it has moved.”

There are so many filter-enhanced and computer generated astrophotos in Discover magazine and on Instagram and elsewhere online that you might be disappointed in the actual view through your eyepiece. Try to maintain perspective—you’re a speck standing 93 million miles away, looking at flames on the sun. That’s pretty cool.

I still can’t get this frickin telescope to work.

You are not alone. Try the Beginner’s Forum on Cloudy Nights online or the recently added Cloudy Cities list to find other astro-geeks in your neighborhood.

Sky provides an easy way to find your local astronomy club. “Astronomy is fun,” states their website, “but it can be even more fun when you do it with other people. Sky & Telescope encourages you to contact your local astronomy club, where you’ll find like-minded enthusiasts eager to share their knowledge and love of the sky with you. Club meetings offer opportunities to try out new equipment, learn new techniques, and make new friends. They are one of the best resources around for developing your skills and passion for astronomy. In addition to clubs, you’ll find planetariums, observatories, museums, and other great resources, all of which appear in our directory of clubs and organizations.” Slick!

Plan ahead to look for specific phenomenon, like sunspot groupings. SpaceWeather.com lets you know “what’s up in space” on a daily basis, or subscribe to NASA’s various social media channels.

Want to feel connected to the universe? View the daily solar photo from the SOHO space telescope, then point your own little scope on Earth at the sun. You’ll see the exact same image.

How I Learned to Stop Worrying and Love My Telescope

Solar scope GrantI do love my Celestron scope. The NexStar 8SE wasn’t too hard to assemble. It really makes a statement as a decor focal point in the dining room. And it would pull in most of the go-to night sky objects, up close and personal—from the cool lunar craters, to Cassini’s Division in Saturn’s rings and the Great Red Spot, even the M13 cluster—if I could figure out how operate the damn thing for maximum enjoyment.

Likely due to the price tag (it was gifted to me by a very generous father-in-law), that level of telescope assumes a basic operator knowledge that I frankly don’t/ever will have. I never passed through the kiddie-stages of owning smaller, less complex scopes. I haven’t yet read Astronomy For Dummies. I can’t point to Polaris. As dense as it is, the paper documentation that comes with the 8SE still reads a little like the Monty Python “How To Do It” sketch. How to play the flute? “Well, you blow there and you move your fingers up and down here.” How to use an 8-inch altazimuth Schmidt-Cassegrain telescope with a SkyAlign’d clock drive, Barlow lens, assorted Plossl eyepieces, filters, power tank, and energy rejection/H-alpha solar filter system? “Well, you point it there, and you push this button here, and then you start looking at the Solar System.”

Well, there are few more steps. My husband, neighbor, and I all flailed around on multiple occasions, late at night, trying to properly align to the stars and planets. The only ones we’re sure of are Saturn and the moon. There’s more to see, I think.

There are one billion—no wait, TWO billion resources on the internet to teach me how to operate my telescope. But who has time to wade through all of that, most of it over my head anyway? I set out to find a tutor, and a wonderful one I did find.

Meet Grant Tandy, Astronomical Interpreter at the Oregon Observatory at Sunriver. He agreed to help me set up my scope for solar viewing (a function I’ll need to master within two years, before TSE2017) and teach me to find and appreciate nighttime objects as well.

Quick and dirty glossary of eclipse jargon

Alt-Azimuth – “Altitude and Azimuth”. This is about spherical coordinates in degrees and something to do with your telescope. EGGHEADS, ANGRILY COMMENT NOW. (Seriously, please use the comment section to weigh in and correct or explain anything that I’ve gotten wrong or am just making a flip joke about. Thanks. I’d love to hear from you.)

AnnularAnnular eclipse—A type of partial eclipse where the disk of the moon is JUUUST a little too small to blot out the sun, causing a way cool “ring of fire” effect. Not safe for direct viewing without protective eyewear. Also referred to as a hybrid eclipse.

Aphelion—The point in Earth’s orbit when we’re furthest from the sun. Eclipses that occur near aphelion are total because the size of the sun in the sky is smaller, and the same size as the moon is near perigee.

Apogee—The further possible point the moon can orbit around the earth. The closer to apogee, the shorter the eclipse.

Baily’s beads—Ready to have your mind blown? Baily’s beads are the dots of light in a ring you see with the naked eye immediately before totality caused by SUNLIGHT SHINING THROUGH THE MOUNTAINS ON THE MOON.

Centerline—The position running through the middle of the path of totality where the eclipse is at maximum duration. Most chasers fight to be closest to the centerline; others interested in specific observations of the chromosphere, shadow bands and other associated phenomenon might set themselves up closer to the edge of the path.

Chaser— AKA umbraphile; one who uses valuable vacation time and travel dollars to stand in the shadow of a total solar eclipse, usually on multiple occasions. (Why aren’t we called lunatics?) A bizarre niche market for the travel industry. (I recommend hooking up with TravelQuest for this purpose.)

Chromosphere—The layer of the sun’s atmosphere just above the photosphere, visible as a red rim around the black disk during a total solar eclipse.

Contact—Points at which the disk of the moon touches the edges of the solar disk. A total solar eclipse can be described by four contact points: First, when the moon touches the edge of the sun. Second, totality, when the disk of the moon makes it all the way across the sun initiating the Diamond Ring. Third, the “outtro” Diamond Ring, ending totality. And fourth, when the tiniest final sliver of moon no longer bites into the disk of the sun.

Cookie biteCookie bite—Description of the solar disk during the early partial phases. (Not to be confused with “orange peel”, the image of the sliver of sun close to totality when viewed through an orange solar filter.)

Corona—Meaning “crown”, the wispy plasma that appears as a white glow with long streamers reaching away from the surface of the sun. The solar corona can be seen with the naked eye only during a total eclipse. The coronal shape is unique to each eclipse, and varies due to sunspot activity.

Diamond ringDiamond Ring—The phenomenon visible at Second and Third Contact when the last point of light from the sun is blocked by the moon, creating an enormous, shiny diamond ring in the sky, just like you see in cartoons. Looks exactly as it sounds.

Duration—Though eclipses can drag on for two or so hours after First Contact (the beginning) to Fourth Contact (the end), duration usually refers to totality, the period between Second and Third Contact. The shortest duration can be seconds; the longest possible is slightly more than seven and a half minutes.

Eclipse—In general, when any heavenly body is visibly darkened when it falls into the shadow of another heavenly body. Eclipses can be annular, partial, total and lunar (an eclipse of the moon occurs when the shadow of the earth falls on the moon).

Eclipse glasses—Solar filters fashioned into lenses and set into (usually) inexpensive cardboard frames or sometimes more substantial eyewear. Often made of Mylar. Make sure they’re labeled as “CE” compliant, or choose welder’s goggles fitted with a #14 lens for safe, long term exposure and a fetching, sexy look.

Edge effects —A ground phenomenon that occurs when the sun is more than halfway obscured, causing tall shadows to appear crisp on one edge and indistinct on the other. I’ve never seen this.

Edging—Observing at the edge of the path of totality to prolong Diamond Ring viewing (but sacrificing duration).

First Contact—The official beginning of the eclipse—the first partial phase—when the moon begins to obscure the sun.

Fourth Contact—The official end of the eclipse; the final moment of the last partial phase when the moon ceases to block any part of the sun.

Horizon effect—AKA twilight glow. The 360° sunrise (or sunset, if you’re an Enneagram 4) occurring during totality as the moon’s shadow commingles with the atmosphere at the horizon.

Hydrogen alpha filter or “H-Alpha”—a solar filter for your telescope that allows safe viewing of the sun (and sunspots) during the partial phases due to something about nanometers.

Partial  solar eclipse—A relatively common occurrence, when the sun is partly obscured by the moon to any percent that isn’t 100% total. Was once fun to observe until you saw your first total. Now like kissing your sister.types of eclipses

Path—The track of the lunar shadow as it passes across earth during an eclipse; usually meaning the path of totality, in the umbra, where the total eclipse can be observed. “The path” varies in width up to only 100 to 150 miles wide at its widest point. The closer one stands to the center of the path, the longer the eclipse will last.

Penumbra—The outer part of the lunar shadow when the sun is only partially blocked. Those standing in the penumbra see a partial eclipse.

Perigee—The closest distance between Earth and a body in orbit around us. The disk of the moon appears largest in the sky—and a total eclipse is possible—when the moon is at perigee.

Perihelion—When the orbit distance between the sun and Earth is as close as possible. Eclipses during perihelion are shorter in duration.

Photosphere—The layer of the sun’s atmosphere just below the chromosphere that causes “sunlight”. It’s very hot.

Pin hole projection—A fun way to ground-observe the partial phases of a solar eclipse. Poke a small hole into a piece of paper and angle it so that it casts a tiny shadow on the ground in the image of the “cookie bite”.

Prominence—The bright red flames that erupt from the edge of the sun’s photosphere into the corona, visible during totality. Solar magnetic fields may form a “prominence loop”.

Saros cycle —The ancient, still-used repeating cycle to calculate the occurrence of eclipses. Specifically? Every 18 years, 11 days, and 8 hours per cycle. A 56-year “exeligmos cycle” is comprised of three saros cycles (with four eclipses in the same saros). Related: the metonic cycle, a period of 19 years, 6,932.4 days, during which it’s possible for a series of up to five eclipses to occur on the same date 19 years apart. And so forth. I was told there would be no math.

Totality ArubaSecond Contact—The moment the moon fully obscures the sun, creating totality.

Shadow bands—A weird, not-always-observed (and not-fully-explained) ground phenomenon during the last moments before totality and directly after caused by “shimmers” in the atmosphere. Some describe shadow bands as similar to the undulating patterns on the bottom of a swimming pool. Best seen on a flat, light colored surface, like a concrete patio or wide area of beach.

Sunspots—Dark blemishes on the sun where the photosphere is cooler. Observable through a telescope with a solar filter. Tracking sun spot activity can help predict of the quality and shape of the corona and prominences.

Streamers—The long white projections of the corona typically at the sun’s equator…but length, placement, and shape of the corona will be a glorious surprise (see sunspots, above).

Telescope—You know what this is. A telescope is not necessary to enjoy a total eclipse. But it’s fun if there’s a good one nearby (owned by an seasoned operator) that you can peek through.

Third Contact—Sadly, the moment when totality ends and the sun reemerges from behind the moon.

Total eclipse—When the sun is completely covered by the moon…or is it?  Here’s a question I’ve never found an answer to. Is “total eclipse” synonymous with totality, or does the term refer to the entire event from First to Fourth Contact, with the payoff of totality in the middle?

Totality—The period of time—up to 7 minutes, 32 seconds—when the sun is completely blocked by the moon.

Transit—An underwhelming phenomenon to observe during the off years when there’s no total eclipse on the calendar. Just kidding. Sort of. A celestial body is “in transit” when it passes in front of the sun and can be observed as a tiny speck from Earth as it crosses. Catch the Transit of Mercury in May of 2016—but it’s a long wait until the next Transit of Venus in 2117. (My profile picture was taken during the TofV in 2012.)

Umbra—The darkest part of any shadow where the light source is completely obscured. A small light, like a flashlight, forms only an umbra; a giant source (like the sun) forms both a penumbra and an umbra. Only in the umbra during a solar eclipse can you experience the astonishing awe of totality.

Umbraphile—One who loves eclipses. (You too? I’d love to hear from you—drop me a line in the comments. Clear skies!)

The stages of a total solar eclipse

There are technically six phases, but First, Second, Third and Fourth Contact are the important ones to know. Second Contact is the money shot—and the final seconds before it are exhilarating.

First Contact

When the edge of the moon touches the sun.* Hooray! The eclipse has officially begun, and you’ll notice zero difference from the moment before. Keep your eclipse glasses or other protective eyewear on while looking at the sun. Go get a beer; you have about an hour to tinker with your telescope and chat up the other chasers before the real action begins.

Partial Phase One

The moon moves slowly to pass in front of the sun and the sky remains bright until the final ten or so minutes before totality. Clouds may form and disappear, causing widespread panic below. In the final few minutes before totality, daylight will eerily gray; watch for shadow bands on the ground and notice the drop in temperature, often up to twenty degrees. Confused night birds and insects may emerge. You may feel a vague, uncontrollable dread—you’re experiencing your home planet in a way you’ve never felt before. It’s not like twilight. Your beloved sun is growing faint, losing strength. (Reflect upon the way ancient man must have reacted.) Keep your eye filter in place until the last seconds, then whip it off just in time to see Baily’s Beads and everyone’s favorite phenomenon, the self-explanatory Diamond Ring.

Espenak no creditSecond Contact

This is it! TOTALITY. Our moon is now blocking our sun, and you’re standing in the umbra. Wispy white coronal streamers materialize and flow from the blackest, black hole in the sky. Red prominences (yes, you can actually see FLAMES ON THE SUN) are visible at the edge of the black disk. It’s okay, scream and clap; try not to be the “woo guy”. No shame if you cry—at least one person near you will be openly sobbing. Some say it’s like looking into the eye of God. Wrench your eyes away for a few moments to observe the colorful 360° twilight on the horizon and the constellations that are always up there during the day but you never get to see. Don’t forget to kiss your sweetie (it’s good luck). Take pictures if you must, but don’t try too hard unless you’re a pro. Photos never capture the full phenomenon or represent what you felt.

Third Contact

Did you miss the Diamond Ring on the way in? No worries—you’ll get a good long look during Third Contact when the moon hits the sun’s other edge before it’s time to re-don your filter glasses. The sky brightens quickly. Earth returns to normal, but you do not.

Partial Phase Two

For most, the eclipse is now OVER; folding chairs collapse and chasers beat feet to whatever conveyance brought them to the centerline. Nerds like me—the same sort of people who watch the final movie credits until the union logo—continue to drink and observe all the way to Fourth Contact.

Fourth Contact

The last tiny sliver of moon passes…passes…wait, no…okay, yes, passes finally away and bids adieu to the sun until next time. Smattering of applause.

*Note to the truly clueless: You know the moon is not actually touching the sun, right? Only the disks of the Sun and Moon as they appear in the sky are touching. Just wanted to make that clear.

Photo credit Fred Espenak

Total eclipses: the basics

Eraserhead memeIf you think you’ve seen a total solar eclipse, but aren’t sure—you haven’t.

A total solar eclipse of the Sun occurs on Earth when, during a New Moon phase, the orbit of the Moon sends it into direct alignment between the Sun and the Earth, completely blotting the disk of the Sun and casting a shadow that falls onto Earth. Those standing in that shadow witness an eclipse.

Not every New Moon produces a solar eclipse; the tilt of the Moon must be oriented exactly so with respect to Earth’s orbit around the Sun.

The width of the shadow—the path of totality—will be about 100 to 180 miles wide, and will vary based on how close the Moon happens to be from the Earth. The closer an observer stands to the center of that path, the longer the eclipse will be. The maximum length of totality is a little over seven minutes; usually they are much, much shorter. (As my husband noted after the four-minute eclipse in Egypt: “That cost a thousand dollars a minute.”)

A total solar eclipse occurs somewhere on Terra (fun fact! that’s the real name of our planet. And our moon is Luna, and the sun is Sol—no relation to the Hebrew baby name) every 18 months or so. Not all are reasonable to travel to see; many last only a few seconds and occur over a remote body of water or an inaccessible wilderness.

As far as we know, Earth (okay, I’m over it, back to the common name) is the only planet where a total solar eclipse occurs; it’s made possible because our Sun and Moon appear nearly the same size in the sky as seen from Earth. Why? The Sun’s diameter is approximately 400 times larger than the moon’s—but the Sun is also 400 times farther away.

(Think about it: Earth has one sun, one moon, and it’s possible we’re the only planet with sentient beings on it who can appreciate an eclipse. Coincidence? I think not—and that’s the subject for different blog entirely.)

Civilizations of yore had colorful, regionalized explanations for what caused an eclipse. The Chinese believed that a celestial dragon devoured the sun; Viking cultures blamed wolves. In Vietnam they believed it was a giant frog. Incan natives thought a puma god was responsible. Ancient man! So stupid.

JUST KIDDING. Superstitions continue today, though. No joke: Many 21st century citizens still consider eclipses to be an evil omen. A popular misconception in some cultures is that they’re dangerous to children and pregnant women, who hide indoors to shield themselves from totality. In India, some people fast, believing that food cooked during an eclipse will be tainted.

In a couple of countries I’ve traveled to, small children were concealed during the days surrounding the eclipse; a rumor circulated that white North American women were there to kidnap babies to take home—that was the insidious purpose of our oversized backpacks.

Some superstitions are pleasant and positive. Leave it to the Italians to plant flowers during an eclipse; everyone knows that they’ll grow to be the most colorful in the garden.