Lyrid meteor shower will make you think big

A brilliant meteor flashes across the sky. Will this weekend's Lyrid meteor shower shower us with a few of these beauties? Lyrids are known for their occasional fireballs. Credit: John Chumack

The annual Lyrid meteor shower peaks tonight (Saturday) through Sunday morning April 21-22. While a minor shower, the Lyrids serve as a “season opener” to the bigger shows coming in mid-August and December.

Lyrid meteors originate from grains of dust shed by Comet Thatcher, which was discovered by A.E. Thatcher on April 5, 1861.

Every year in April Earth passes through the dust and debris left behind by past visits of Comet Thatcher. Illustration: Bob King

The comet takes 415 years to make a single trip around the sun, so there’s no hope of any of us seeing it in our lifetimes. But we can see little bits of it that were left behind long ago.

Each time a comet swings by the sun, it drops lots of dust, fluffy ice and pebbly pieces in its wake.  The third week of April every year Earth plows through debris ranging in size from sand grains to small pebbles left behind during Thatcher’s previous flybys. When a lucky mote strikes the atmosphere, it vaporizes in a flash of light called a meteor or shooting star.

When you’re out watching the show, consider that the average speed of a Lyrid meteor is 30 miles per second or 108,000 miles per hour. At that velocity, a bit of dust or small pebble burns to ash through friction. The luminous trail we call a meteor is mostly light given off by atoms in the upper atmosphere some 70 miles high. The fast-moving comet debris excites or ionizes the atoms; when they return to normal microseconds later they emit billions of photons of light we see as a bright streak or “falling star”.

In a flame test, sodium burns a brilliant yellow. Sodium is common in some meteorites. Credit: Soren Wedel Nielsen

A typical meteor trail is less than 3 feet in diameter but tens of miles long. Think of it as glowing tube overhead.

When the comet particle burns up, it can give off different colors depending on its composition. Sodium flares bright yellow; magnesium is blue-white and nickel a lovely emerald green to name a few. Speed also factors into color. The faster the meteor, the more energy it imparts to the air and the whiter and bluer the streak will be. Slower meteors blaze orange and red.

The Lyrids are named after Lyra the Harp, the constellation from which they appear to originate. The origination point is called the radiant, and you can see from the map it’s not far southwest of Lyra’s brightest star Vega, making it easy to pinpoint. The radiant is the direction Earth is moving toward as it slices through Comet Thatcher’s debris.

Snow appears to radiate from straight ahead as seen through your windshield when you drive into a storm. Meteor showers appear to radiate from one point in the sky because Earth is traveling "into the storm" just like your car. Photo: Bob King

Similar to seeing snow or rain appear to originate from a point ahead of you when you’re driving straight into it, the meteors stream out and away from the radiant. Lyrids closest to the radiant are short, slow stubs of light while those further off stretch into longer streaks.

News is all good for this year’s Lyrids. No moon to interfere and the shower maximum occurs Sunday morning, which for many of us is the weekend. From a dark sky expect to see 10-12 meteors per hour. If you have any doubt as to whether they’re Lyrids or just random meteors, trace their paths backwards and if they point toward Vega, you’ve caught one.

This map shows the sky early Sunday morning with Vega and the Lyrid radiant well up in the eastern sky. Face your lawn chair east or south for the best view. Created with Stellarium

To see the shower best Vega and the radiant should be well up in the northeastern sky. For observers in the U.S. and Canada, you can start watching around 12:30-1 a.m. Sunday.      Numbers should pick up as the radiant rises higher and higher until dawn.

I like to flop out in a folding chair under a warm blanket. Don’t get too comfortable though – you might fall asleep! Having a friend join you is a great way to stay alert. It also puts the conversation in a larger, more cosmic context. I’ve found that almost everyone thinks bigger thoughts under a starry sky than when seated inside a building.

In a related story, this weekend, NASA scientists, amateur astronomers, and astronaut Don Pettit on board the International Space Station will attempt the first-ever 3D photography of meteors from Earth and space. Read about it HERE.

Gemini twins still shine in shimmer of Venus

The sky around 9:30 p.m. local time as you face west. Orion is setting but Gemini and Auriga are easy to spot above the planet Venus. Maps created with Stellarium

It may seem silly to talk about winter constellations with spring so far along, but I have my reasons. Gemini the Twins is associated more with the bitter cold of January, when it holds sway in the southern sky along with Orion the Hunter. It’s just possible you missed it back then because you didn’t feel like freezing the tip of your nose off. Let me introduce the boys a second time now that nighttime temperatures are more bearable.

Gemini dominates the western sky during early evening hours in April along with the pentagon-shaped Auriga the Charioteer. Both constellations make their last stand before fading away in mid-May twilight.

We start with blazing Venus, located in Taurus below Auriga in the northwestern sky after twilight. If you can take your eyes off the planet and look upward about two fists held against the sky, you’ll bump into Capella, Auriga’s brightest star. Using Capella as your anchor, it’s easy to “connect the dots” of the 5-sided constellation Auriga.

The mythological figures of the Gemini twins will help you better visualize them among the stars. The two brothers are from ancient Greek mythology. Castor was mortal (son of the King of Sparta) while Pollux was a son of Zeus and immortal.

From the top of Auriga we swing another “two fists” to the upper left and land at Pollux and Castor, the twin brothers of ancient Greek mythology. Despite being so closely related, you’ll notice that Pollux shines more brightly than his sibling. Both stars form a short line parallel to the western horizon.

A trickle of fainter stars below Pollux and Castor form the twins’ stick-like bodies, outstretched arms (you can picture them in a shoulder hug) and feet that point out in either direction. Under rural skies, you can see the complete set of legs for each twin; those under more typical skies will see only a single leg per brother. That’s enough to get the picture.

Have a telescope? Point it at Castor, a close and beautiful double star. And if binoculars are your thing, see if you can find the rich star cluster M35 a little above Castor’s foot. Look for a fuzzy patch peppered with tiny stars. I know Venus is a powerful attractor but there’s more in the west these froggy nights. Give Gemini a try.

Venus is so bright it created an aureole of light in passing clouds last night. At lower left are Aldebaran (bright star) and the Hyades star cluster. Photo: Bob King

Tomorrow I’ll have a guide and tips for watching this weekend’s Lyrid meteor shower. See you then.

Air Canada pilot dodges Venus; new aurora video simply spectacular

Is it a plane, a UFO, a sign? No, it's just Venus being its brilliant self. The planet looks so much bigger than the rest of the stars because it's so much brighter. Its nearest rival, Sirius, shines 15 times fainter. Photo: Bob King

Bright as a sapphire in the western evening sky, Venus grabs our attention this month. News came yesterday of an Air Canada pilot who mistook Venus for an approaching plane on Jan. 14 this year. While it’s not unusual to mistake the beacon-like planet for an aircraft or even a UFO, the pilot took the unusual step of putting the plane into a steep 400-foot dive to avoid the planetary menace. Passengers flew out their seats and hit their heads on the ceiling as a result of the maneuver. Worse, the dive brought the plane within 1,000 feet of hitting a U.S. Air Force cargo plane.

If only the officer had taken a community ed astronomy class, the incident could have been avoided. Any one of my students could have calmly explained that the bright light ahead was Venus. Read the full story HERE.

Mercury and the moon are a challenging catch for observers in the northern U.S. (left) 45 minutes before sunrise tomorrow. Southerners will have an easier time of it (right). The moon returns as an evening crescent early next week. Created with Stellarium

Our class looked at Venus through a telescope last night before the clouds rolled in. The overbright planet is currently in its buttery croissant phase. Truly adventurous skywatchers can attempt to spot the solar system’s other inner planet in the morning sky. Mercury and a very thin crescent moon will lie just a few degrees above the eastern horizon 40-45 minutes in the east before sunrise. Bring binoculars! I find that if I don’t see something first with my naked eye, a scan with binoculars will show it and help me know exactly where to look. If you live in the northern states, this will be a challenge. Southerners have the advantage since the pair will be higher up in a slightly darker, less hazy sky.

A single frame from Ole Salomonsen's new Celestial Lights video. Click the image to watch it. Credit: Ole Salomonsen

Aurora photographer Ole Salomonsen just released a new online video called Celestial Lights created from 150,000 pictures he’s taken of some of the most spectacular northern lights of his life. All the photos were shot between September 2011 and April 2012 with Canon 5D Mark II and 5D Mark III cameras and a variety of wide-angle lenses.

Another of the 150,000 images Salomonsen shot of the northern lights from Norway. Credit: Ole Salomonsen

Salomonsen lives in northern Norway not far from the auroral oval, a permanent cap of auroral centered on Earth’s north magnetic pole.  Auroras there are frequent and often spectacular. Judging from the variety of scenes in the video, Salomonsen hasn’t wasted a single clear night. You’ll love the variety of scenes, and the high-def image quality imparts a very visceral “you’re there” feeling. Click the link, hit the full screen button, turn up the volume and enjoy!

Starts as starlight, becomes something wonderful

Tiny reflections of the sun created by the contact points of legs and water between two mating water striders. Photo: Bob King

Sunlight and starlight are transformed in wonderful ways by our environment. For a half hour this weekend I sat by a creek and watched water striders, those spidery-looking insects with long legs that scoot across a creek or pond in search of food. The tiny points of contact between their legs and water dimpled the surface without breaking it. They also focused the sun into minute images that reflected back to my eyes. When several striders by chance came together, the “sun spots” looked like a constellation of stars.

Time exposure of a flare from the Iridium 31 satellite last night from Duluth, Minn. The flare started at left and faded to the right. At far right is the star Arcturus. Photo: Bob King

Last night you might have seen a flare from an Iridium satellite similar to what we saw in Duluth just after 10 o’clock. Since satellites aren’t equipped with lights like airplanes, we see them only by the sunlight that reflects from their shiny parts. It’s the same reason the moon and planets are visible. A portion of the sunlight they receive is reflected back to our eyes.

Brilliant Vega and a host of neighboring stars rise through tree branches last night around 11 p.m. Photo: Bob King

Later yesterday evening the bright star Vega and a rich entourage of stars appeared in the northeastern sky. They glittery crew hung from bare branches like tiny flickering Christmas tree lights. The sight of stars mingled with trees has always been one of my favorites. They can transform a thicket of weed trees into a wonder of the night.

Frost crystals refract or bend sunlight into its many colors this morning. The picture was intentionally shot slightly out of focus to emphasize the colors, which show well to the eye but not when shot in focus with a digital camera. Photo: Bob King

This morning a heavy frost splintered sunlight into every color of the rainbow on my front lawn. Ice crystals took the sunlight and refracted it into its component colors. Moving my head this way and that, the colors continually shifted as the angle between my eyes, the crystals and sun changed. It was Isaac Newton who first demonstrated that a prism could refract or spread light into its component colors, but frost has been at it all along.

Forrest Overby of Duluth fishes for trout as sunlight glints off waves coming to shore on Lake Superior this morning at the mouth of the Sucker River. Photo: Bob King

While on assignment today for the newspaper, I came across a man fishing in Lake Superior for trout. He was enveloped in pure sunlight glinting off the waves as they crashed ashore. I love how moving water profoundly affects the light that travels to our eyes. Glass shards, perfect reflections, writhing underwater snake-streaks, millions of tiny suns – it’s all there and more in one of the most familiar substances on Earth.

I’ve heard that when we die we see a bright light at the end of a tunnel. I hope so. Light in its many forms has been a source of wonder all my life. How appropriate for it be there at the final train stop.

Iridium satellites show their flare – see one tonight!

The night lights of Ireland (left) and the United Kingdom stand in contrast to the bright arc of sunrise and the pastel hues of the aurora borealis in the farther distance in this photo taken from the International Space Station last month. Credit: NASA

We’re in for another week of evening space station watching. You’ll find times and descriptions for passes over the Duluth, Minn. region below. As always, click over to Spaceweather’s Satellite flyby link and pop in your zip code or log in to Heavens Above to find viewing times for your town.

* Monday April 16 starting at 9:05 p.m. passing from west to east across the northern sky.
* Tuesday April 17 at 9:46 p.m. ”     ”
* Wednesday April 18 at 8:49 p.m. in twilight across the north. Second pass in the north at 10:26 p.m. The station will enter Earth’s shadow and disappear only a few minutes later.
* Thursday April 19 at 9:30 p.m. across the north
* Friday April 20 at 8:33 p.m. ”    ” in bright twilight. Second very bright pass at 10:09 p.m. to the top of the sky. Enters Earth’s shadow below Big Dipper
* Saturday April 21 at 9:13 p.m. across the north

Iridium satellite with reflective Teflon-coated antenna. Credit: Seesat-L

This week also features some spectacular flares from the Iridiums, a group of some 66 satellites orbiting the Earth like that old picture of electrons whizzing around the nucleus of an atom. They form a global ‘constellation’ 485 miles high used for relaying voice and data communications. The name ‘Iridium’ comes from the element iridium which is number 77 on the periodic table. The constellation was originally expected to number 77 satellites.

Normally Iridiums are too faint to see except in binoculars, but they have silver-coated Teflon antenna arrays that reflect sunlight like a mirror. When the angle between satellite and observer is right, a brilliant reflection of the sun from the antennas causes an Iridium to suddenly and spectacularly brighten for 5 to 20 seconds.

Unlike a meteor, the satellite doesn’t dash across the sky as it flares but moves slowly because it’s far away. At 485 miles up, Iridiums are nearly twice as high as the space station.

Time exposure of an Iridium 75 flare from 2010. The flare began at right end of the trail, peaked in the middle and faded. Photo: Bob King

Flares range in brightness from equal to the brightest stars all the way up to -8 or about 20 times brighter than Venus! I’ve seen a few -8 magnitude flares, and they’re so intense, you think the satellite’s going to explode. Nearly as quickly as they flare, Iridiums fade back to invisibility.

Watching for Iridium flares is like going out to see a space station pass with two differences.

First, make sure you’re on time. Flares last seconds compared to minutes for a typical satellite. Also flares are only visible within a limited range. The flares at my house will be brighter or fainter than what someone in the next town will see.

These maps will help you look for three upcoming Iridium flares in the next few nights. All are visible from the Duluth-Superior area below the Big Dipper's handle and to the left of Arcturus. Created with Stellarium

The best resource for Iridium flare times and locations is the Heavens Above website. Once there, login and select your location. Under the Satellites heading on the left side of the page, look for Iridium flares and click on the Next 7 days link. You’ll be taken to a page that shows a table of dates, times, intensities (the higher the negative number, the brighter the flare), the satellite’s number and its altitude and azimuth.

Altitude tells you how high to look. If it’s 90 degrees, that’s overhead. If 45 degrees, that’s halfway between the horizon (0 degrees) and overhead. Azimuth tells you what direction to look. Due north is 0 degrees azimuth, east is 90, south is 180 and west 270.

I hope you give the Iridiums a try. I promise you’ll be amazed at how suddenly they appear and disappear. And if you catch a really bright one, well, you just have to see it to believe it.

Saturn best and brightest of the year; Mars stands still

Saturn and Earth line up at opposition on the same side of the sun today when they're closest for the year. In October, when Earth is on the opposite side of the sun, the two planets will be 190 million miles farther apart. Illustration: Bob King

Once a year Saturn and Earth line up on the same side of the sun. The event is called opposition, when the two planets are the closest together. From our perspective on Earth, Saturn will be opposite the sun in the sky. If you face south this evening with the setting sun on your right, Saturn will rise directly opposite in the east at sunset and remain visible all night.

As Saturn revolves around the sun in its 29.5-year-long orbit, we see the rings fan open, shut and fan open again. They're currently tipped almost 14 degrees or halfway to maximum. Credit: Tom Ruen

Last year’s opposition date was April 3; this year it’s April 15. Saturn oppositions occur about two weeks later each year because in the time it takes the Earth to return to another lineup, Saturn has also along traveled further along its orbit. We need about two weeks to “catch up” with the ringed planet and re-align for another opposition.

Since Saturn is the brightest and biggest it will be this year, the coming weeks are an ideal time to train your telescope on the planet for a satisfying look at its rings and satellites. At low power in a small scope you’ll see one ring and Saturn’s brightest moon Titan, the only satellite in the solar system with a significant atmosphere. Observers with larger telescopes will spy Titan’s orange-red color caused by hydrocarbon smog. I’ve easily seen the moon’s hue through my 10-inch reflector when it’s off to one side of Saturn.

Saturn and its brightest moons visible in small and medium-sized telescopes. Iapetus will be bright through early May. The view shows south up - typical orientation in most scopes. Illustration created with Chris Marriott's SkyMap

Larger scopes and calm air also reveal that the single ring is split in two by a narrow dark gap called Cassin’s Division. And if you’re patient, you’ll also see a third, semi-transparent inner ring called Ring C or the Crepe Ring. A thick, gray band – the North Equatorial Belt – crosses the planet between the ring plane and its north pole.

As for Saturn’s family of moons, I mentioned that Titan was visible in a small scope. The moon Iapetus (eye-AP-it-tuss) is almost as easy to spot when it’s far to the west of the planet (western elongation) and showing off its icy hemisphere.

When the moon swings east of Saturn, we see its much less reflective darker hemisphere, causing the moon to dim by nearly two magnitudes from 10.2 to 11.9. As fortune would have it, Iapetus is at western elongation and bright right now. The smaller, fainter moons Dione (dye-OH-nee), Rhea (REE-uh), Tethys (TEE-thiss) and Enceladus (En-SELL-uh-duss) are also visible in larger scopes.

Mars does a loop-de-loop in Leo. It's now about 4 1/2 degrees from Regulus at the stationary point. Beginning tomorrow, it will depart from the star's vicinity and loop back east. Created with Chris Marriott's SkyMap

The Mars event is far less dramatic than Saturn’s opposition. For some months now, the Red Planet has been moving west in retrograde motion, closing in on Leo’s brightest star Regulus. Today it stands still – briefly – and then resumes its normal eastward motion.

Astronomers say that Mars reaches its “stationary” point before resuming “direct” motion. What it means for us is that the planet will now slowly depart from its bright companion Regulus.

The Earth passing Mars causes the planet to appear to move backward in retrograde motion for a time in the sky before resuming its normal eastward path. Credit: NASA

Mars, like all the planets outside Earth’s orbit, appears to travel backwards for a time as the faster-orbiting Earth catches up and passes the planet around the time of opposition. It’s similar to passing a car on the freeway. As you approach the car you plan to pass, it appears to slow down and go “backwards” as you drive by and watch it disappear in your rear view mirror.

Since planets orbit in ellipses and not straightaways like freeways, they soon resume their normal motion a month or so after Earth passes them.

Keep an eye on Mars over the next month and you’ll see it pick up speed as it cruises through Leo and into Virgo where it meets Saturn for a nice conjunction in mid-August.

Just in case you’re still now familiar with where to look for Mars and Saturn, use the map below, which is drawn for 9:30 p.m. local time. Wishing you all clear skies and great Saturn viewing!

Face south to see Mars in Leo and Saturn in Virgo around 9:30 p.m. local time (and later) this week. Created with Stellarium

Weird Uranus auroras seen first time from Earth

Wild leeks push through the dried leaves of the forest floor each April in Duluth's Hawk Ridge nature reserve. Photo: Bob King

The ground is snapping and popping. Ever hear this? On quiet evenings in the country in mid-spring, you can walk up to a roadside ditch along the edge of the forest and listen to green plants pushing up through last year’s leaves and grasses. It sounds like fire consuming tiny twigs. Green fire.

I used to think it was insects but I’ve looked with a flashlight and heard it for so many years I’m certain the sound is from plants on their way up and out. Not even night can hold back the call of the sun.

The sun reached out to Earth this week in the form of the aurora borealis. Uranus also displays auroras but as dots instead of arcs and curtains. Auroras were seen by the Voyager 2 spacecraft during it 1986 flyby of the planet, but this is the first time they’ve been spotted from Earth.

Uranus' northern lights have an unusual form and different location compared to Earth's due to the planet's unusually large tilt and offset magnetic field. Uranus faint ring system is also seen. Credit: Laurent Lamy

Using the Hubble Space Telescope, astronomers photographed dim dots of aurora glowing above Uranus’ pale blue cloudtops. The Uranian lights last only a few minutes at a time before fading away, making them even trickier to catch than the earthly variety.

Auroras on both Earth and Uranus are produced when charged particles (electrons and protons) from the sun enter a planet’s magnetosphere or protective magnetic envelope, and are guided into the polar atmosphere by the planet’s magnetic field.

Uranus' axis is tilted almost 98 degrees. During its 84-year orbit, first the north pole and then the south pole points toward the sun. In between, one side or another faces the sun. Credit: Smithsonian

Earth’s magnetic field is tipped just 11 degrees relative to the our axis of rotation. When the solar wind hits, the particles travel toward the north and south polar regions, which is why auroras are visible in Earth’s more northern and southern locations than nearer the equator.

Uranus is another place altogether. Its rotational axis is tilted 98 degrees compared to Earth’s modest 23.5. This means the planet literally rotates on its side like a bowling ball rolling down a lane. Its magnetic axis is way out of whack too – not only offset from the planet’s core but tilted 60 degrees relative to the rotation axis. Back during the Voyager 2 flyby, the planet’s south pole was pointed toward the sun with the magnetic poles far off to the sides. Voyager observed auroras on Uranus’ nightside resembling those on Earth.

The Earth, with its modestly-tipped rotation axis (blue arrowed line) and nearly north-pointing magnetic field axis, is a far cry from the extremes of Uranus.

Uranus has since moved along its orbit so that now its side faces the sun instead of a geographic pole. This happy circumstance means that one of the magnetic poles points directly at the sun.

When a big blast of solar wind left the sun in September 2011, the particles sped past Earth in 2-3 days, blew by Jupiter two weeks later and arrived at Uranus in mid-November, creating the odd dots of aurora that seem to lie near the equator. They’re really near the planet’s magnetic poles!

Uranus, you’re a mixed up planet, but we love you anyway. To read more about the new aurora discovery, click HERE.

More aurora pix plus the contrail vs. “chemtrail” controversy

The International Space Station leaves a trail of light in this 30-second time exposure as it cruises below the Big Dipper last night. Photo: Bob King

At 9:40 last night the International Space Station flew by while I was taking pictures of the aurora. Because it passed almost overhead, the station was especially bright, outdoing Jupiter for sure. Its orbit is currently about 250 miles high, so if you’re lucky enough to get an overhead pass, the ISS will be as close to you as it can – 250 miles away.

A pass off to the north or south or when the station is off in the eastern or western sky is generally not as bright. because you have to add in the extra “horizontal” distance plus the altitude.

The clouds gobbled up what was left of the northern sky and northern lights late last night from my town. Hopefully, you had clear skies. Judging by the index of magnetic activity (Kp), the aurora continued well into the night. Tonight space weather forecasters are calling for another chance of aurora. Quiet conditions return Saturday and Sunday. More aurora pix are included at the end of this article.

The trail the ISS made in the photo reminds me of an airplane condensation trail or contrail. It’s fatter than usual because sunlight reflecting from the spacecraft lit up a high, thin cloud layer at my location. Earlier Thursday I was witness to real contrails as four separate transcontinental jets crossed the sky within the span of 10 minutes.

A jet trailing a contrail flies over another contrail left by a lower-flying aircraft. Water vapor condenses into a cloud behind the plane as it chilled by -40 F temperatures and colder experienced at 26,000 feet and higher. You create your own "mouth contrails" when you see your breath on a cold morning. Photo: Bob King

Contrails are created when warm water vapor created during the burning of jet fuel condenses into strings of artificial clouds in the wake of a high-flying aircraft. Real clouds form in a similar way – water evaporated from land and lakes by sunlight rises upward; when it reaches colder air aloft, it condenses into the visible form of a cloud.

Two jets with contrails yesterday over Duluth flying in opposite directions. Photo: Bob King

Both contrails and clouds require tiny nuclei – dust, soot, etc. – to serve as sites for water to condense upon. For contrails, the exhaust particles from fuel combustion are right at hand, which is why contrails form so quickly behind an airplane.

Sadly, there’s a massive hoax and disinformation campaign online and elsewhere characterizing contrails as “chemtrails”. Supposedly our government is enlisting pilots to “aerial spray” the U.S. with virus and strange chemicals to study their effects on humans. Really?

There’s no scientific evidence to support this idea, just mistaken impressions and the usual fear-mongering. Many contrails disappear quickly because the air at altitudes of 26,000 feet and up is extremely dry. Sometimes however temperature, higher humidity or an approaching weather front conspire to not only prolong the trails but cause them to balloon into large rafts of cirrus clouds. These are the ones a few people are calling “chemtrails”. We’ve all seen these, and they’re perfectly normal. No chemicals needed – just the right atmospheric conditions.

Satellite image of jet contrails over the southern U.S. on January 29, 2004. Credit: Langley Research Center

If you’re still looking to point the blame finger at contrails, there may be a real scientific reason to do so. They appear to contribute to global warming. When they fan into clouds, they act like real clouds and trap heat rising from the Earth causing surface temperatures to rise. Weather service data reveal that the temperature of the surface and lower atmosphere rose by almost 0.5°F per decade between 1975 and 1994 because of contrails. So yes, they may affect our climate in a small way, but that’s a far cry from the bogus claims of chemical spraying.

Aurora (green-yellow) and clouds colored by sodium vapor light pollution photographed last night from Boulder Lake north of Duluth. Thanks and credit to Brett Grandson

Part of a thick auroral arc seen from Rice Lake Township north of Duluth last night. Photo: Bob King

Aurora out tonight April 12 in Duluth, Minn.

Active aurora spreads across the lower half of the northern sky about 10 p.m. CDT tonight from Rice Lake Township north of Duluth. Photo: Bob King

Just a heads up from Duluth, Minn. The Kp index hit “5″ at 9 o’clock tonight and the northern lights are putting on a modest show as of 10 p.m. CDT. We have high clouds moving in, but a chunky green arc with a few active rays are sliding around low in the northern sky. The ray tops are reaching about 20 degrees (two fists held at arm’s length); the arc’s about 10 degrees up. There’s a fair amount of movement, but you’ll need to get out of town to a place with a good northern horizon to appreciate it.

The auroral oval is expanding southward tonight. We can see its edge as active auroral arcs low in the north from the northern U.S. The red line is the approximate edge of visibility. Credit: NOAA

Chance for auroras, North Korea’s shining star and Comet Garradd

The green glow of geomagnetic goodness painted the bottom of the northern sky early this morning. Minor auroras are forecast for tonight for northern regions. Photo: Bob King

The aurora crept up in the north very, very late last night. Just a green glow, not too much. I noticed the light around 11:30 p.m. and watched it slowly intensify into a bright arc speared by occasional faint rays just before 1 a.m. A half hour later, a promising display that almost sent me to the computer to post an alert, collapsed into a faint arc at the bottom of the northern sky. Who let the air of the tires?

The northern lights have much in common with the trickster character of many American Indian myths. He’s the prankster and rule breaker. When we think life is predictable, the trickster keeps us on our toes.

Thanks to a big hole in the sun’s corona (outer atmosphere) a stream of high speed particles is buffeting Earth’s protective magnetic bubble, giving us a chance of auroras. No big storms are expected, but you might want to scan the northern sky around midnight the next couple nights. In the photo above, both the green glow, which was visible with the naked eye, and the much fainter pink, were caused by excitation of oxygen atoms high in Earth’s atmosphere.

A North Korean soldier keeps an eye on things at Sohae Satellite Launch Station. The Unha-3 rocket (background) will carry the Bright Shining Star satellite into space. Credit: AP

Satellite watchers are sitting on pins and needles waiting for the imminent launch of North Korea’s  Kwangmyongsong-3 satellite. Billed as an Earth-observation spacecraft, it would be used to gather weather data and photograph the country’s forest and farmland during its two-year lifetime in orbit. You’re probably more familiar with the backstory that the launch is really about testing ballistic missiles.

The satellite’s name means “Bright Shining Star” and it’s the third in a series that began with Kwangmyongsong-1 in 1998. Although North Korea says the first two launches were successful, no independent observer ever saw them in orbit.

Kwangmyongsong-3 will mark the 100th anniversary of founding of the Democratic People’s Republic of Korea by its founder Kim Il Sung. Once in orbit, the satellite will broadcast two patriotic tunes -  ”The Song of General Kim Il Sung” and “The Song of General Kim Jong Il.” If the launch succeeds, I’ll post times when it might be visible from your town. UPDATE 7 p.m. CDT: The satellite was launched at 7:39 a.m. Korean time but failed to reach orbit. Story HERE.

Comet Garradd passes through the toes (Theta, Kappa, Iota stars) of one of the Dipper's paws the next few nights. The comet's path is marked every five days. Stars shown to 6.5 magnitude. Created with Chris Marriott's SkyMap software

If you have a 6-inch or larger telescope, the next couple nights are ideal for finding the comet observers have been going steady with since last summer –  Comet Garradd. It’s passing through ones of the “paws” of the Great Bear a.k.a the Ursa Major a.k.a. the Big Dipper. It’s faded to 7.5-8 magnitude but I still spotted it last night from a dark sky in 10 x 40 binoculars as a faint, fuzzy glow. The map above is drawn for 9:30 p.m. local time as you face north. Through the telescope, the comet is a fuzzy ball with a brighter center or nucleus. A faint dust tail 1/2 degree long pointing northeast is visible in 10-inch and larger scopes.