Bob King, Author at Universe Today

July 8, 2013April 26, 2016 by Bob King

Faces And Animals On Mars? Pure Pareidolia!

Seeing familiar shapes in clouds is easy especially when you've got a handy reference. Credit: Andrew Kirk

As kids, my friends and I would stare at clouds on lazy summer afternoons and point out faces and animals we saw in their folds and domes. When the light was right, some of them looked as detailed and real as if chiseled by a meteorological Michelangelo. Later, with kids of our own, we often revisit this simple pleasure.

image of the "Virgin Mary" appears in the glass of a Tampa, Florida office building on Christmas Day 1996. Credit: Wikipedia — *image of the “Virgin Mary” appears in the glass of a Tampa, Florida office building on Christmas Day 1996. Credit: Wikipedia*

Patterns can materialize anywhere – old men with scraggly beards in carpeting, blocky visages in road cuts and even Jesus on toast. Here are 50 more fun examples. Our instinctive ability to find patterns in the often random mish-mash of nature is called pareidolia (pair-eye-DOLE-ya).

The late planetary scientist and astronomy popularizer Carl Sagan believed pattern-recognition was part of our evolutionary heritage:

“As soon as the infant can see, it recognizes faces, and we now know that this skill is hardwired in our brains,” wrote Sagan. “Those infants who a million years ago were unable to recognize a face smiled back less, were less likely to win the hearts of their parents, and less likely to prosper.”

Maybe it’s simpler than that. Face-recognition is critical because we ultimately need each other for survival not to mention keeping track of the kids in the grocery store. Pattern recognition also helped us find food back in the days of hunting and gathering. The ability to distinguish a particular plant or animal against the background noise meant the difference between a full belly or starvation.

*The infamous Mars Face (left) photographed in comparatively low resolution by the Viking orbiter in 1976 and a much higher resolution view made by current Mars Reconnaissance Orbiter. Credit: NASA*

Pareidolia also works its magic across the cosmos. To narrow the scope, I’ve selected images taken of Mars, the most fertile planet for imaginary faces around. Who doesn’t remember all the hubbub over the “Face of Mars”? Old Viking spacecraft images from the mid-1970s taken at low resolution in slanted lighting seemed to show a face carved of rock staring back at Earth.

Since pareidolia works best when the stimulus is vague or the object unclear the “face” was perfect. Our brains are more than happy to fill in fictional details. Later photos taken at much lower altitude with higher resolution cameras made the face disappear; in its place we clearly see an eroded mesa. Then there’s the so-called “Bigfoot on Mars,” (an extremely very tiny Bigfoot) and later someone zoomed in on a small rock and said there was a gorilla on Mars. Information equals identity, lack of detail opens the door to anything we might imagine.

Here are 10 examples of imaginary faces and creatures on Mars. The inspiration to write about the topic came from a series of recent “art” images taken with the THEMIS camera on board the Mars Odyssey spacecraft. The probe orbits Mars every 2 hours and carries three science instruments; the camera combines images shot in 5 wavelengths or colors of visual light and 9 in the infrared or heat-emitting part of the spectrum. Others were snapped by the Mars Reconnaissance Orbiter. All are NASA images, and I’ve taken the liberty to colorize several of the black and whites to approximate the appearance of the color images.

Enjoy!

1. My Happy Martian

Those Martians obviously have a sense of humor. This 2-mile-wide (3 km) unnamed crater was photographed in 2008 by the Mars Reconnaissance Orbiter. — *Martians obviously have a sense of humor. This 2-mile-wide (3 km) unnamed crater was photographed in 2008 by the Mars Reconnaissance Orbiter.*

2. That Buzzing Sound

This crater chain with its wispy "wings" of impact debris resembles a wasp. The feature was most likely created when a meteorite coming it at a very low angle broke into pieces just before impact. — This crater chain with its wispy “wings” of impact debris resembles a wasp. The feature was most likely created when a meteorite arriving it at a very low angle broke into pieces just before impact.

3. The Mammoth Still Lives

Lava flows in Mars' Elysium Planitia region have left a rather good likeness of a woolly mammoth or elephant. The region is known for some of the planet's youngest lavas - this one may formed in the past 100 million years. — Lava flows in Mars’ Elysium Planitia region have left a rather good likeness of a woolly mammoth or elephant. The region is known for some of the planet’s youngest lavas – this one may have formed as recently as the past 100 million years.

4. Have A Heart (or two)

I love these two little hearts. The one on the left is a mesa top outlined by frost about the size of a football stadium. On the right, a small impact crater near the tip of the heart blew away dark surface material exposing lighter soil beneath. Some of the material appears to have flowed downslope to create the heart.

5. Rare Sighting Of A Dust-Covered Hummingbird

5. Rare sighting of the dust-coated hummingbird — *The head and long beak of a hummingbird is easy to imagine in this scene. I can’t say for sure how these features formed but wind and erosion no doubt played a part.*

6. Hitchcockian Horror

A Martian bird of prey? Watch out, that beak looks sharp! — *Martian bird of prey or just another wayward pigeon?*

7. Get It In Gear

*The eroded blankets of ejecta blasted out when these craters formed look like a series of interlocking gears.*

8. Lone Wolf On The Martian Prairie

*Dark sand dune deposits look eerily like a howling wolf.*

9. Thumbs Up!

*These dunes remind me of a Minnesota “Thank you” for jump starting your car on a cold winter morning.*

10. To A “T”

*Tectonic stretching of the Martian crust created this unusual right-angle fracture. I wonder how many other letters of the alphabet we might find on the Red Planet?*

July 3, 2013December 23, 2015 by Bob King

What You Can See in the Sky While Waiting for Fireworks on The 4th Of July

A thin lunar crescent rises beneath the Pleiades star cluster tomorrow morning at dawn. This map shows the sky facing northeast about 4 a.m. local time. Maps created with Stellarium

The sky can be a showy stage with big-time events like eclipses, meteor showers and the occasional bright comet, but most nights have a quiet beauty that whispers instead of shouts. The contrast between hype and hush is no more apparent than on the 4th of July – American independence day celebration – when we gather at a park or hilltop to watch the fireworks boom and flash across the heavens.

But there are other interesting things — some quiet fireworks — you can see in the sky to see while you are waiting for the holiday fireworks.

You can watch a less flashy but equally satisfying July 4th event as soon as tomorrow morning about the time the first bird lifts its voice at dawn. Look northeast to find a thin crescent moon dangling below the Seven Sisters star cluster. Also called the Pleiades, the cluster is a highlight of the winter evening sky. Though it seems out of place now at the height of summer, the Sisters remind us that nothing stands still. With the solstice behind us, winter’s already buckling his boots.

As you relax before the fireworks begin, look for two bright stars and two bright planets in the west and southwest skies. You can fit about three fists held at arm's length between Saturn and Arcturus. — As you relax before the fireworks begin, look for two bright stars and two bright planets in the west and southwest skies. You can fit about three fists held at arm’s length between Saturn and Arcturus.

While you’re waiting for the show to begin tomorrow night, take a look around the twilight sky and see how many celestial luminaries you can spot. If you’ve got kids in tow, share the view with them, too.

The brightest natural object in the sky will be Venus, glimmering low above the western horizon. Much further up in the southwest, look for a tall, skinny triangle outlined by orangy Arcturus, highest of the three, along with Saturn and Spica.

*Facing east brings the three bright stars of the Summer Triangle in to view.*

Twist around to face east to find another triangle, this one named after the summer season. Halfway up is Vega, the 5th brightest star in the sky, shining white and bright as burning magnesium. Below it you’ll spot the other Summer Triangle members, Altair in Aquila the Eagle and Deneb in Cygnus the Swan better known as the Northern Cross.

These bright stars and two planets coalesced from gas and dust millions to billions of years ago. Much has happened beneath their gaze, from the first stirrings of humankind to the crackle and boom of fireworks on a starry evening.

July 2, 2013April 26, 2016 by Bob King

Dark Skies – Good For Fireflies And People Alike

Fireflies make green trails of light during a time exposure on a July night. Jupiter is at upper left. Credit: Bob King

Bioluminescent stars flash across the night landscape these July nights. Fireflies or lightning bugs provide a source of wonder for many of us living in the eastern half U.S. and Canada. Did you know dark skies may be as important to them as they are to you and I?

To stoke their yellow-green fires, the bugs – they’re really beetles – cook up light through a series of chemical reactions within their abdomens.

Adult Photurus firefly. Fireflies produce a cool light by combining oxygen in the air with the chemical luciferin. Credit: Bruce Marlin

Oxygen from the air combines with a chemical fittingly named luciferin. Luciferin next hooks up with the energy molecule ATP to form another molecule that when combined with oxygen yields a flash of green, yellow or amber light, depending upon the firefly species.

Fireflies June 30 2013 C — Fireflies compete with the stars from a dark location near Duluth, Minn. two nights ago. Each species has its own specific flash pattern. Credit: Bob King

The males perform the flash-dance moves, wiggling and zigging about to attract the females, who typically remain on the ground hidden among blades of grass. Each species has its own flashing pattern. When a female finds a male’s flashes suitably alluring, she winks a flash back. Back and forth communications soon bring the two together to make more fireflies.

Firefly light emits no heat, making it one of the most efficient light sources known. A standard incandescent light bulb converts electricity into 10% light and the rest as heat; fireflies transform 100% of their chemical energy into light. These insects do not waste photons.

One of my favorite memories from childhood was running around on summer nights collecting fireflies in a glass jar. Credit: Bob King

Every night I’m out under the July stars at least one firefly manages to land within the telescope tube and create a surprise supernova. If I inadvertently switch my LED flashlight on and off at the right rate, more than a few of them will land right on top of the device in a futile attempt to mate.

Urban sprawl and accompanying light pollution is an issue for both astronomers and fireflies. This view shows the light dome from the city of Duluth, Minn. 20 miles north of town. Credit: Bob King

One thing fireflies and skywatchers have in common is love of the night. To appreciate the twinkling heavens, we either escape to the countryside or do our best to contend with the lights in town. Firefly numbers are declining across the U.S. and the world, and though no one’s certain yet why, there’s both anecdotal and scientific evidence suggesting that loss of habitat and light pollution are to blame.

Example showing poorly shielded light fixtures. With nothing to contain or direct the light, it shines where it's not needed - straight up! Credit: Bob King — Example showing poorly shielded light fixtures. With nothing to contain or direct the light, it shines where it’s not needed – straight up! Credit: Bob King

Urban sprawl has comprised the habitats of many wild creatures not just fireflies. Sprawl also brings increased lighting, much of it poorly shielded and on all night. Fireflies avoid heavily lit areas for obvious reasons – light pollution interferes with their ability to see each others’ flashes. Even car headlights can throw them off rhythm. According to a 2008 story in the Boston Globe, controlled experiments have shown that brighter lighting levels cause fireflies to mate less often.

Full cutoff lighting fixtures like these put light where it's needed - on the road - and not out to the sides or up in the sky. Credit: Bob King — Full cutoff lighting fixtures like these put light where it’s needed – on the road – and not out to the sides or up in the sky. Credit: Bob King

We all can help ensure our favorite bioluminescent buddies remain around for a long time. Turning off your own yard light not only helps you to see more stars but makes it easier for fireflies to find their mates. If you absolutely need illumination, consider one of these efficient shielded light fixtures that puts light where you want it while eliminating the glare that frustrates fireflies and stargazers alike. To learn more about good lighting and keeping the sky dark, check out the International Dark Sky Association.

June 25, 2013December 23, 2015 by Bob King

Gesundheit! Hairy And Sneeze-worthy Rings Snare Summer Sun

Billions of aspen seeds float by the sun on tiny hairs creating a multicolored corona around the sun yesterday. To see and photograph the rings, I used a power pole to block the sun. Credit: Bob King

For the past two weeks puffy clumps of seeds have been riding the air in my town. You can’t avoid them. Open a door and they’ll breeze right in. Take a deep breath and you’d better be careful you don’t take a few down the windpipe.

Every June the many aspen trees that call northern Minnesota home release their booty of tiny seeds that parachute through the air on tiny clusters of hairs. And while they all have no particular place to go, their combined and unintentional effect is to create a series of beautiful colored rings about the Sun called a corona.

A single aspen seed (left) only about 1 mm across embedded in a cottony fluff of tiny hairs. At right is a spider web. Both show colors caused by bending and interference of light, a phenomenon called diffraction. Credit: Bob King (left) and Andrew Kirk

Reach your hand up to block the Sun and if your eyes can stand the glare of blue-white sky, you’ll see bazillions of tiny flecks a-flying. If you were to capture one and study it up close, you’d see it diffract light in tiny glimmers of chrome green and purple.

When light from the sun or moon strikes a tiny water droplet, speck of pollen or aspen seed hairs, it's scattered in different directions. Some of the scattered waves reinforce each other to make a bright ring of light in the sky while other waves cancel each other out to create a dimmer ring. A series of alternating rings around the sun is called a diffraction pattern or corona. Credit and copyright: Les Cowley www.atoptics.co.uk — When light from the sun or moon strikes a tiny water droplet, speck of pollen or aspen seed hairs, it’s scattered in different directions. Some of the scattered waves reinforce each other to make a bright ring of light in the sky while other waves cancel each other out to create a dimmer ring. A series of alternating rings around the sun is called a diffraction pattern or corona. Credit and copyright: Les Cowley www.atoptics.co.uk

Light is always getting messed with by tiny things. When it comes to aspen seeds, as rays of light – made of every color of the rainbow – bend around the hairy obstacles they interfere with one another like overlapping, expanding wave circles in a pond. Some of the waves reinforce each another and others cancel out. Our eyes see a series of colored fringes that flash about the tiny hairs.

*Most halos are circular but pollen halos like this one around the moon often have unusual shapes like this oval with bulging sides and top. Credit: Bob King*

The exact same thing happens when light has to step around minute water droplets, pollen grains and our hairy aspen fluffs when they’re drift through the air overhead. Overlapping wavelets of light “interfere” with one another to form a series of colorful concentric circles called a solar corona. While the same in name, this corona is an earthly one unrelated to the huge, hot coronal atmosphere that surrounds our star.

Oil-coated water droplets show beautiful diffraction colors for the same reason soap bubbles do. Light reflecting from the bottom surface of the oil film interferes light reflecting from the top of the layer creating fringes of color. Credit: Bob King — Oil-coated water droplets also show beautiful diffraction colors for a similar reason as clouds and pollen do . Light reflecting from the bottom surface of the oil film interferes with light reflecting off the top of the layer to create shifting patterns of color. Credit: Bob King

The ones created by seed hairs and pollen require clear skies and a safe way to block the Sun’s overwhelming light. My filter of choice is the power pole mostly because they’re handy. Sunglasses help to reduce the glare and eye-watering wincing.

While I can’t be 100% certain the chromatic bullseye was painted by poplar hair deflections – there’s always a chance pollen played a part – I’ve seen similar displays when the seeds have passed this way before.

*Iridescent clouds are another form of a corona formed by minute water droplets diffracting light. Credit: Bob King*

Coronas created by water droplets in mid-level clouds are much more common, and the familiar “ring around the sun” or solar halo is an entirely different creature. Here, light is bent or refracted through billions of microscopic six-sided ice crystals.

I figure that if the night is cloudy, the play of light and clouds in the daytime sky often makes for an enjoyable substitute.

June 10, 2013December 23, 2015 by Bob King

Observing Alert: Rare Meteor Shower May ‘Outburst’ on June 11

The rare and rarely heard of meteor shower called the Gamma Delphinids will appear to radiate from the constellation Delphinus (del-FINE-us) the Dolphin high in the southern sky shortly before dawn tomorrow morning June 11. This map shows the sky facing south at 3:30 a.m. local time. Delphinus is near the bottom of the bright 3-star figure the Summer Triangle. Stellarium

Back on June 11, 1930 three members of the American Meteor Society (AMS) in Maryland saw a half-hour-long bright outburst of meteors from the little constellation Delphinus the Dolphin. No one had predicted the shower, but it came out of nowhere and hasn’t been seen since. Attempts to catch a repeat performance in subsequent years met with no success.

That may change tomorrow morning, June 11, 2013. Peter Jenniskins, research scientist with the SETI Institute and NASA Ames Research Center, has examined dust outbursts from long-period comets and suggests the Gamma Delphinids may return for a brief moment of splendor, as Earth passes through this stream of cometary debris not seen since 1930.

Bright meteors photographed in Ohio during the Eta Aquarid meteor shower in 2012. The Gamma Delphinids may send similar bright meteors our way tomorrow morning. Credit: John Chumack

The expected time of maximum activity is 4:30 a.m. Eastern Daylight Time, 3:30 a.m. Central, 2:30 a.m. Mountain and 1:30 a.m. Pacific. These times are ideal for the Americas where Delphinus is high in southern sky at the peak time. Robert Lunsford of the AMS recommends starting your Gamma Delphinid vigil 2 hours ahead of time in case the shower’s early. If these meteors really do happen, you’ll see them anywhere in the sky, but they’ll all trace back to a point near the star Gamma Delphini in the dolphin’s nose.

The map above shows the worldwide possible visibility for the gamma Delphinid shower. Visibility will be best in the bright green areas, which have the highest radiant elevation. Unshaded areas on the map will not have a view of the shower. Credit: Geert Barentsen, International Meteor Organization

No one knows how strong the shower might be or even the duration though it’s likely to be brief. Time estimate range from one hour to 15 minutes. Lunsford expects bright meteors to appear a minute or two apart. If you’re game, split the difference and set up in a comfy lawn chair facing south an hour before the expected maximum. Should you see any of these rare dolphin tears, consider e-mailing a report to: [email protected]

Tonight June 10-11 from 10 p.m. – 2 a.m. CDT, Dr. Bill Cooke of NASA’s Meteoroid Environment Office will take your questions via live web chat. He’ll offer viewing tips about the shower and include a live Ustream telescope view of the skies over Huntsville, Ala.

If you shoot video or images and want to help improve our understanding of this elusive meteor shower, you can upload them to the Office’s Flickr group and also to Universe Today’s Flickr group. We’ll post images if this meteor shower proves to show up!

June 6, 2013December 23, 2015 by Bob King

June Arietids – The Invisible Meteor Shower You Just Might See

You might just see a few meteors from the combined Arietids and Zeta Perseid showers that peak Friday and Saturday mornings. This map shows the sky facing northeast at dawn for the mid-section of the U.S. Created with Stellarium

I’ve never seen an Arietid meteor and chances are you haven’t either. Peaking on June 7-8, the Arietid (AIR-ee-uh-tid) meteor shower is one of the strongest of the year with a maximum rate of 50-80 per hour. But there’s a rub. The shower radiant, the point in the sky from which the meteors appear to radiate, is near the sun and best seen during daylight hours. When was the last time you saw meteors in daylight?

Early scientific exploration of the sky in radio waves at Jodrell Bank Observatory in 1945. Credit: Jodrell Bank, University of Manchester

If you’re wondering how anyone could discover a meteor shower when the sun is out, it’s impossible unless your eyes can see radio waves. The Arietids were first “seen” in 1947 by operators of radio equipment at Jodrell Bank Observatory in England. Meteors leave trails of ionized gases when they rip through our upper atmosphere at tens of thousands of miles per hour and briefly make ideal reflectors of radio waves.

You can even hear them yourself by tuning to a “blank” spot between stations on an FM radio and listening for sudden bursts of talk or music when the meteor trail boosts a neighboring station into audibility. Click HERE for simple instructions if you’d like to give it a try.

The Arietids are joined by a second daytime shower at the same time by the Zeta Perseids, a smaller shower, to guarantee a couple busy days of meteor-listening — and potential meteor-watching — on and around June 7-8. Most meteor showers are tied to a particular comet, since they’re swarms of dusty detritus left behind in a comet’s wake as it travels ’round the sun. When Earth intersects the stream, tiny comet bits slam into the atmosphere, heat up to 3,000 F or more and self-immolate in glowing streaks we call meteors. Occasionally a shower’s parent can be an asteroid as in the case of the January Quadrantid meteor shower. It’s suspected that the asteroid 2003 EH1 may be a extinct comet.

Most meteors are comet dust striking at the atmosphere at speeds so high, they vaporiz in a blaze of light. This is a meteor from the Leonid shower in 2001. Credit: Bob King

No one’s certain of the Arietids’ parentage. Likely candidates include the near-Earth asteroid 1566 Icarus and Comet 96P/Machholz, both of which have orbits that resemble the shower’s.

After ignoring May’s Eta Aquarid meteor shower for years because of its very low radiant at dawn, I was pleasantly surprised by the many meteors I saw when I happened to catch the shower at maximum on May 6 this year. Circumstances are only slightly worse for the Arietids. That’s why I think it’s worth your while to check out this shower tomorrow (Friday) and Saturday morning(June 7-8). Face east and start watching an hour or two before the start of dawn and continue your vigil until the sky brightens in the east.

The lesser Zeta Perseids are also active, adding to the fun. Since the two shower radiants are close to each other in the sky, it may be hard to tell which you’re seeing. No matter. Any fiery streaks you can trace back toward the east-northeast horizon will likely be one or the other.

Earth-grazing meteor photographed by Manuel Conde of Barcelona, Spain.

Whenever a radiant is near the horizon, many of the meteors approaching us do so at a very shallow angle almost horizontal to the Earth’s atmosphere. From our perspective they travel slowly and last a much longer time than do meteors striking the air at a steeper angle, typical for radiants that are higher in the sky.

Astronomers use the poetic “Earth-grazers” to describe them. Having seen a handful of these unique beauties during the May Aquarid shower, I’m hungry for more. Since the Arietids / Zeta Perseids also originate low in the sky, we should expect similar sights Friday and Saturday mornings.

May 31, 2013April 26, 2016 by Bob King

Noctilucent Clouds – Electric-Blue Visitors From The Twilight Zone

Noctilucent cloud display taken around midnight May 30 near Kendal Castle in northern England by Stuart Atkinson. "Beautiful display, better than all last year's pathetic displays combined - and the season has just started!" said Atkinson

Every year at this time I add a new item to my list of what to watch for in the night sky. Oddly enough, it’s clouds. I must be nuts, right? What astronomer needs more clouds? But these are different. Called noctilucent clouds (NLCs), these skittish objects are visible now and again low in the northern sky during morning and evening twilight. Late May through August is the best time to see them.

What are these wispy, sometimes eerie clouds? And how can you see them?

First a caveat. If you live in Mississippi your chances of spotting them are slimmer than a string bean. Uncommon to begin with, NLCs are typically visible at higher latitudes; the northern U.S., Canada and Europe are prime outposts for an NLC vigil.

Noctilucent clouds, which form about 50 miles high in the chilly mesophere, lie high above the common clouds that form in the troposphere. photographed from the International Space Station. Credit: NASA — Noctilucent clouds, which form about 50 miles (80 km) high in the chilly mesosphere, lie high far above the troposphere, home to the more familiar clouds. Photo taken from the International Space Station. Credit: NASA

NLCs hole up in Earth’s mesosphere, a rarefied blanket of air extending from 30 to 53 miles (48-85 km) high. Most of the meteors we see burn up in this layer. It’s also extremely cold up there with temperatures at the top dropping to a teeth-rattling -130 F (-90 C). Because of their great height, noctilucent clouds reflect sunlight long after sunset when other clouds have gone gray and colorless. Their color is imparted by the ozone layer located 12-19 miles (19-30 km) overhead. The reds and oranges of reflected sunlight are absorbed by ozone on their way down to our eyes, tinting the clouds blue.

Cirrus clouds often look like fine streaks compared to the pleated, wavy appearance of NLCs. Credit: Bob King — Cirrus clouds often look like fine streaks compared to the pleated, wavy appearance of NLCs. This photo also demonstrates the difference in their altitudes during a typical display across the northern U.S. Credit: Bob King

For any cloud to take shape and grow, water needs to stick to something. In day-to-day clouds, dust from wind storms – especially from the world’s deserts – supplies the necessary “nuclei” for the formation of water droplets and ice crystals.

Cirrus clouds, the ones that look like feathers wafting across the daytime sky, are typically about 10 miles high. Composed of ice crystals, they float near the top of the lowest, thickest layer of air called the troposphere. Noctilucent clouds share the realm of the Greek gods, basking in sunlight well into the night at an altitude of some 50 miles. That’s nearly as high as the aurora borealis, which can shimmy down to a scant 60 miles.

We see noctilucent clouds well after sunset when other clouds have gone dark because they're much higher up and can still catch sunlight and reflect it back to Earth. Credit: NASA — *We see noctilucent clouds well after sunset when other clouds have gone dark because they’re much higher up and still able to catch sunlight and reflect it back to Earth. Credit: NASA*

Since it’s next to impossible to get dust up high enough to provide nuclei for noctilucent cloud formation, scientists suspect outer space dust from meteoroids and comets provide some of the necessary material. As Earth travels around the sun, it sweeps up some 40,000 tons of interplanetary dust a year, plenty to get the job done. Other sources include volcanic dust and even chemical residues from rocket exhaust from the once-frequent launches of the space shuttle.

Winds from summer storms carry the water vapor into the mesosphere from the lower atmosphere which condenses on terrestrial and extraterrestrial dust nuclei. That’s why NLC displays are most frequent in summer.

*Waves of NLCs on June 12, 2012 seen from Duluth, Minn. Credit: Bob King*

Here in Duluth, Minn. at 47 degrees north I’ve seen probably half a dozen displays in years of sky watching, but to be honest, I only started looking for them in a dedicated way in the last 5 years. As late May approaches and twilight stretches deep into the evening hours, I scan the sky hoping for their return. The key to spotting NLCs is to find a place with a wide-open view of the northern horizon.

In the north, the sun retires around 9 p.m. and twilight ends more than two hours later. Watch for NLCs starting about an hour after sunset when cirrus clouds have turned pale gray and the stars begin to come out. From my home, they typically hover between 5 and 10 degrees (about a fist held at arm’s length or less) high above the northern horizon. The clouds make their first appearance at the upper end of that range, but as dusk deepens, they shrink back toward the horizon.

Video of NLCs from the Science Photo Library

NLCs look WEIRD. It’s not only their telltale eerie, plasma-blue coloration but their form that gives them away. Stripes, undulations, curls, streaks are mixed together in a way that seems alien. You might expect these on Mars maybe, but Earth? Binoculars are a huge help in appreciating the clouds’ peculiar textures and color. I say this because I’ve forgotten mine on several occasions. Two other dead giveaways – NLCs will grow brighter for a time as the sky grows darker. Regular clouds behave the opposite. NLCs also move and change shape very slowly because they’re so high up and far away.

Looking down from above, AIM captured this composite image of the noctilucent cloud cover above the Southern Pole on December 31, 2009. Credit: NASA/HU/VT/CU LASP — Looking down from above, the Aeronomy of Ice in the Mesosphere (AIM) Mission captured this composite image of noctilucent cloud cover above the South Pole on December 31, 2009. Click to read more about AIM. Credit: NASA/HU/VT/CU LASP

Night-shining clouds remain aglow until nearly twilight’s end. The cut-off viewing time for the northern U.S. is about 2 hours after sunset or earlier if the mosquitos have their way. By then the sun drops too far below the horizon to provide the light to sustain them. Those living farther north in Canada, northern Ireland, England and Finland, where the sky is never truly dark during the early summer months, can enjoy NLC viewing all night.

Dawn display of electric NLCs on June 13, 2012. Credit: Bob King — *Dawn display with stars of electric-blue NLCs on June 13, 2012. Credit: Bob King*

There are indications that NLC displays are becoming more common, even pushing into lower latitudes in the past 20-30 years. It might have to do with increased levels of carbon dioxide in Earth’s atmosphere. While CO2 helps to warm the lower air layers, it can can cause the upper atmosphere to grow chillier, creating the cold conditions necessary for accelerated noctilucent cloud formation. You can dig deeper into the topic HERE.

For more about Earth’s most unusual clouds, stop by the Noctilucent Cloud Observers’ Homepage. Like the northern lights, a thrilling noctilucent cloud display is a quest worth a trip to the north country.

May 22, 2013April 26, 2016 by Bob King

Bright Planetary Conjunctions Liven Up This Week’s Evening Sky

Three bright planets gather in the northwestern sky this week. This map shows the sky 30 minutes after sunset from the middle latitudes. Stellarium

Planning a barbecue this weekend? You may want to top it off with a look at three bright planets shuttling about the western sky at dusk. Jupiter, Venus and Mercury gather for nearly a week of delightful alignments including three separate conjunctions staring right now. Mercury and Venus pair up on Friday; Mercury and Jupiter on Sunday and Venus and Jupiter on Monday. All three form a series of ever-changing triangular arrangements as the nights go by.

Three bright planets will highlight the northwestern sky this week and early next. Mercury is shown in pink and Jupiter in yellow. Stellarium — Three bright planets will highlight the northwestern sky this week and early next. Mercury is shown in pink and Jupiter in yellow. Time is 30 minutes after sunset facing northwest. They’ll be closest together – less than 3 degrees apart – on the night of the 26th. Stellarium

Brightest of the bunch is Venus followed by Jupiter and then Mercury. The key to seeing them all is a clear sky and unobstructed view of the west-northwest horizon. Best time for viewing is a half hour to 45 minutes after sunset. Although the diagrams make the planets look like largish disks, difference in size is a device to show their brightness. Bigger means brighter.

Mercury gradually climbs higher in the coming days, Venus will remain in nearly the same spot and Jupiter slowly drops off toward the horizon. Seeing three planets bunch up isn’t rare, but it is unusual – all the more reason to go for a look if your skies are clear. Alignments like this occur because all 8 planets lie in essentially the same flat plane. As we look across the solar system, sometimes near planets and far planets lie along the same line of sight and appear side-by-side in the sky. They may look close to each other but of course they’re millions of miles apart.

Positions of the planets on May 27. The arrow shows our point of view from Earth. Notice that the line of sight through all three takes our gaze near the sun. That's why they're only visible shortly after sunset in a bright sky. Click image to see a cool, interaction planet display. Credit: dd.dynamicdiagrams.com — Positions of the planets on May 27. The arrow shows the point of view from Earth. Notice that the line of sight through all three takes our gaze near the sun. That’s why they’re only visible shortly after sunset in a bright sky. Click image to see a cool, interactive planet display. Credit: dd.dynamicdiagrams.com

This week Venus is 154 million miles (248 million km) from Earth, Mercury 113 million (182 million km) and Jupiter a distant 562 million (904 million km). The planet position diagram above will give you a sense of their current arrangement in space.

Whenever you go planet-seeking in bright twilight, I always recommend bringing along a pair of binoculars. They penetrate haze and make finding these bright little dots much easier. Enjoy the show!

May 22, 2013April 26, 2016 by Bob King

What Do Comet PANSTARRS And Pinocchio Have In Common?

Comet C/2011 L4 PANSTARRS on May 21, 2013, when its anti-tail had grown to more than 12 full moons in length. The original main tail of the comet - to the right of the head - has faded and shortened. Credit: Damian Peach

While comets can’t tell lies, they do sometimes grow long noses. As the weeks click by and our perspective on Comet L4 PANSTARRS changes, its original plume-like dust tail has shrunk and faded while a second tail just won’t stop growing.

Comet PANSTARRS' orbital plane slices (marked by gray lines) slices right through the plane of the planets. Earth crosses that orbital plane on May 27. As we look up into space at the comet (blue arrow), all the dust it shed along its path - including a fine sheet of particles - stacks up to create a narrow, streak-like tail pointing toward the sun. The shorter, active dust tail sticks up and away (top). Credit: NASA with my own additions — Comet PANSTARRS’ orbital plane slices (marked by gray lines) slices right through the plane of the planets. Earth crosses that orbital plane on May 27. As we look up into space at the comet (blue arrow), all the dust it shed along its path – including a fine sheet of particles – stacks up to create a narrow, streak-like tail pointing toward the sun. The shorter, active dust tail sticks up and away (top). Credit: NASA with my own additions

I’m talking about the anti-tail, so called because it points toward the sun instead of away. Like the normal dust tail, an anti-tail is formed from fresh dust blown back from the comet’s head by the pressure of sunlight. As the comet continues along its orbital path, last week’s dust lingers behind, forming a “trail of breadcrumbs” in its wake. Right now those breadcrumbs look like a light saber straight out of Star Wars. Time exposure photographs show a striking sunward-pointing appendage more than 6 degrees (12 full moons) long. I’ve been keeping an eye on Comet PANSTARRS here at home and can report that the anti-tail is plainly visible with a telescope under dark skies. Watching it grow from a short nub to the most dominant feature of this remarkable object has been the highlight of many a clear night.

Our current "edge on" view of Comet PANSTARRS is similar to seeing from high above the Earth's north pole, where the dust stacks up to create a bright, streak-like tail. Credit: NASA/JPL/my own additions — Our current “edge on” view of Comet PANSTARRS is similar to looking down on it from high above the Earth’s north pole, where the dust stacks up to create a bright, streak-like tail. Credit: NASA/JPL/my own additions

Nothing stands still in our solar system. Earth’s moving, the comet’s moving. Later this week on May 26-27, Earth will pass directly through the comet’s orbital plane, which slices through the plane of the planets at a very steep angle. As the Earth approaches this intersection, we look up (from the northern hemisphere) and stare squarely into the long trail of dusty debris deposited by PANSTARRS during its recent swing around the sun in March. It gets better.

If we step back in time to May 9, we see that the anti-tail was neither as long or as pronounced because the Earth was further from the comet's orbital plane. Credit: Michael Jaeger — If we step back in time to May 9, we see that the anti-tail was neither as long nor as pronounced because the Earth was further from the comet’s orbital plane. Because we were more broadside to the comet then, the dust sheet is much more obvious. It extends millions of miles into space but is only 5,000-10,000 miles thick. Credit: Michael Jaeger

Sunlight pushes the smaller particles into a vast, thin sheet or fan extending millions of miles into space well beyond the path traveled by the comet’s nucleus. Since we now see PANSTARRS almost “edge-on”, all that dust overlaps from our perspective to form a thick, bright line sticking out of the comet’s head. It’s as if we’re seeing the ghost of PANSTARRS from the recent past still lingering in space. If we could somehow see the whole works broadside, the comet would appear fainter, spread out and much more diffuse.

Simulated view of looking at the dust shed in PANSTARRS' tail edge-on vs. broadside. Dust piles up in the edge-on view to create a skinny, saber-like tail. Illustration: Bob King — Simulated views of dust shed by PANSTARRS’ in its orbit around the sun. Dust piles up in the edge-on view to create a skinny, saber-like tail vs. a faint, broad tail (right). Illustration: Bob King

The Milky Way stands out as a band of light distinct from the thin scree of stars for the very same reason; our gaze cuts edge-on through our galaxy’s flattened disk where stars are most concentrated. Like comet dust, they pile atop one other to create a distinct ribbon of fuzzy light slicing across the night sky.

Back on April 10 the anti-tail (short stub to left) was just getting its start. It's completely dwarfed by the comet's main dust tail and fan of tinier dust particles. Credit: Michael Jaeger — Going back even further to April 10, the anti-tail (short stub to left of bright head) was just getting started. It’s completely dwarfed by the comet’s main dust tail and fan of tinier dust particles. Compare this photo to the current view. Click to enlarge. Credit: Michael Jaeger

In the next few days the tail could grow considerably longer and intensify in brightness as we move closer to the comet’s orbital plane. Unfortunately the moon will be at or near full at the same time, making it tougher to fully appreciate this amazing apparition at least with binoculars and telescopes. Cameras will have better luck. Will that stop you from looking? I hope not. Either way, you can use this map to help you find Comet PANSTARRS and check it out yourself.

Map showing Comet C/2011 L4 PANSTARRS' location tonight through June 21. Positions are marked off every three nights. Stars are shown to about magnitude 8. Credit: created with Chris Marriott's SkyMap software — Map showing Comet C/2011 L4 PANSTARRS’ location tonight through June 21. Positions are marked off every three nights with stars are shown to about 8th magnitude. Credit: created with Chris Marriott’s SkyMap software

When you do spot the anti-tail, don’t be fooled. It may appear to be pointing at the sun, but it’s only dust spread along a path once tread.

A magnificent view of the very thin anti tail of Comet PANSTARRS, as seen on May 22, 2013 from near Payson, Arizona. Credit and copyright: Chris Schur.

A negative image showing Comet PANSTARRS and its very thin anti tail, as seen on May 22, 2013 from near Payson, Arizona. Credit and copyright: Chris Schur.

May 20, 2013April 26, 2016 by Bob King

Put The Aurora Borealis In Your Ear

A rural location is ideal for listening to the subtle sounds of the aurora with a VLF radio. Just turn it on and hold it up to the sky.This photo was taken early Saturday morning when green auroras were still visible through breaks in the clouds. Photo: Bob King

Do the aurorae makes sounds? That’s been a subject of discussion — and contention — among people who watch the sky. While most of us will never hear the aurora borealis directly, there’s help out there in the form of a little handheld radio. It’s called a VLF receiver and guarantees you an earful the next time the aurora erupts.

High-speed electrons and protons buzzing along Earth's magnetic fields lines emit very low frequency radio waves that human ears can here with a VLF receiver. Credit: Bob King — High-speed electrons and protons buzzing along Earth’s magnetic fields lines emit very low frequency radio waves that human ears can here with a VLF receiver. Credit: Bob King

Despite seeing hundreds of northern light displays ranging from mild to wild, I’ve yet to actually hear what some describe as crackles and hissing noises. There is some evidence that electrophonic transduction can convert otherwise very low frequency (VLF) radio waves given off by the aurora into sound waves through nearby conductors. Wire-framed eyeglasses, grass and even hair can act as transducers to convert radio energy into low-frequency electric currents that can vibrate an object into producing sound. Similar ‘fizzing’ sounds have been recorded by meteor watchers that may happen the same way.

Laboratory tests reveal that a surprising variety of substances, including frizzy hair and vegetable matter, can act as radio-to-audio VLF transducers. Credit: NASA

Imagination may be another reason some folks people hear auroras. Things that move often make sounds. A spectacular display of moving lights overhead can trick your brain into serving up an appropriate soundtrack. Given that the aurora is never closer to the ground than 50 miles, the air is far too thin at this altitude to transmit any weak sound waves that might be produced down to your ears.

If you’re like me and hard of auroral hearing, a small VLF (very low frequency) radio receiver will do the job nicely. This handheld device converts very low frequency radio waves produced from the interaction of the solar electrons and protons with the Earth’s magnetic field into sounds you can listen to with a pair of headphones.

The battery-operated WR-3 VLF (Very Low Frequency) receiver with headphones for tuning in on sounds bouncing around Earth's magnetic field. Credit: Bob King — The battery-operated WR-3 VLF (Very Low Frequency) receiver with headphones for tuning into sounds “natural” radio broadcast by planet Earth. Credit: Bob King

We’re used to waves of light which are very, very short, measuring in the millionths of an inch long. The pigments in our retinas convert these waves into visible images of the world around us. Radio waves given off by auroras and other forms of natural ‘Earth energy’ like lightning range from 19 to 1,800 miles long or longer. To bring them within range of human hearing we need a radio receiver. I fire up a little unit called a WR-3 I purchased back in the mid-1990s. The components are housed in a small metal box with a whip antenna and powered by a 9-volt battery. The on-off switch also controls the volume. Plug in a set of headphones and you’re ready to listen. That’s all there is to it.

olar wind heading into space and impacting Earth's protective magnetic shield, its magnetosphere. The particles are seen heading out in all directions, but with some of them hitting our magnetosphere. Earth's magnetic field lines are shown in concentric purple ovals, pushed on by pressure from the Sun and elongated on the side facing sway from the Sun. Credit: NASA — The magnetosphere of the Earth is enormous bubble of magnetism that surrounds our planet. It’s created through the interaction of the solar wind (yellow lines) and Earth’s magnetic field. The magnetosphere acts as a shield to protect us from dangerous radiation in space. Earth’s magnetic field lines are shown in concentric purple ovals, pushed on by pressure from the Sun and elongated on the side facing sway from the Sun. Credit: NASA

The receiver picks up lots of things besides aurora including a big ‘unnatural’ hum from alternating or AC current in power lines and home appliances. Turn one on in your house and you’ll immediately hear a loud, continuous buzz in the headphones. You’ll need to be at least a quarter mile from any of those sources in order to hear the more subtle music of the planet.

Lightning produces a great variety of radio sounds - sferics, tweeks and whistlers - you can hear with the right receiver. Credit: Bob King — Lightning produces a great variety of natural radio sounds – sferics, tweeks and whistlers – you can hear with a VLF radio receiver. Credit: Bob King

I drive out to a open ‘radio quiet’ rural area, turn on the switch and raise the antenna to the sky. Don’t stand under any trees either. They’re great absorbers of the low frequency radio energy you’re trying to detect. What will you hear? Read on and click the links to hear the sound files.

* Sferics. The first thing will be the pops, crackles and sizzles of distant lightning called sferics which are similar to the crackles on an AM car radio during a thunderstorm.

* Tweeks. Lightning gives off lots of energy in the long end of the radio spectrum. When that energy gets ducted through the upper layers of Earth’s atmosphere called the ionosphere over distances of several thousand miles, it emits another type of sound called ‘tweeks‘. These remind me of Star Wars lasers or dripping water. Flurries of tweeks have an almost musical quality like someone plucking the strings of a piano.

* Whistlers and Whistler Clusters. When those same lightning radio waves enter Earth’s magnetosphere and interact with the particles there, they can cycle back and forth between the north and south geomagnetic poles traveling tens of thousands of miles to create whistlers. Talk about an eerie, futuristic sound. After their long journey, the higher frequency waves arrive before those of lower frequency causing the sound to spread out in a series of long, descending tones. The sound may also take you back to those old World War II movies when bombs whistled through the air after dropping from the hatch of a B-17. Tweeks are very brief; whistlers last anywhere from 1/2 to 4 seconds or longer.

* Dawn Chorus. Sometimes you’ll hear dozens of whistlers, one after the other. When conditions are right, a VLF receiver can pick up disturbances in Earth’s magnetic bubble spawned by auroras called ‘chorus‘ or ‘dawn chorus’. Talk about strange. Who would have guessed that solar electrons spiraling along Earth’s magnetic field lines would intone the ardor of frogs or a chorus of birds at dawn? And yet, there you have it.

* More Dawn Chorus: On a good night, and especially when the northern lights are out, it’s a magnetospheric symphony. Thunderstorms thousands of miles away provide a bounty of crackles and tweeks with occasional whistlers. Listen closely and you might even hear the froggy voice of the aurora rising and falling with a rhythm reminiscent of breathing.

The crescent moon, Jupiter and Venus accompanied a spectacular aurora over Lake Superior in Duluth, Minn. last July. Credit: Bob King — The crescent moon, Jupiter and Venus accompanied a spectacular aurora over Lake Superior in Duluth, Minn. last July. With solar activity on the upswing and solar maximum predicted for the fall, auroras are more likely than ever in 2013. Credit: Bob King

If you’re interested in listening to VLF and in particular the aurora, basic receivers are available through the two online sites below. I’ve only used the WR-3 and can’t speak for the others, but they all run between $110-135. One word of warning if you purchase – don’t use one when there’s a lightning storm nearby. Holding a metal aerial under a thundercloud is not recommended!

* WR-3 VLF receiver from Stephen McGreevy
* North Country Radio ELF Earth Receiver

More on natural radio can be found HERE. Things to keep in mind when considering a purchase are whether you have access to an open area 1/2 mile from a power line and away from homes. You’ll also need patience. Many nights you’ll only hear lightning crackles from distant storms thousands of miles away peppered by the occasional ping of a tweet. Whistlers may not appear for weeks at a time and then one night, you’ll hear them by the hundreds. But if you regularly watch the sky, it’s so easy to take the radio along and ‘give a listen’ for some of the most curious sounds you’ll ever hear. How astonishing it is to sense our planet’s magnetosphere through sound. Consider it one more way to be in touch with the home planet.

For more on natural radio including additional sound files I invite you to check out Stephen P. McGreevy’s site.