Lively discussion at the breakfast table this morning (August 31) with Ted Pellman, Jon Dannehy, Eric Norland and Bob Greene. How do people on so little sleep continue to talk astronomy nonstop? Three things: passion, coffee and … lack of sleep.  Photo: Bob King

I know, I know. I promised you the Andromeda galaxy and Cepheids but I hope you won’t mind if we make a stop near Webster, Wisconsin for a look at the annual Furtman Farm Star Party. It’s still going on as I write this. Earlier this afternoon, over pasta and salsa, we tackled subjects from how to cook corn in the microwave to what the universe would look if you could travel at the speed of light. Let’s just say the corn turned out well.

Paula Meier (left) of Duluth zeroes in on the planet Jupiter during twilight last night. Photo: Bob King

The star party is an easygoing, friendly gathering of amateur astronomers and their families hosted by the genial Greg and Laura Furtman. We set up our telescopes on a grassy clearing near an old grain silo, and shared the sky with one another till 3 this morning. I knew I was in the right place at the right time when I overheard a young boy named Murphy react to seeing the Milky Way: "It looks like powder spread across the sky," he called out.

During a 30-second time exposure of the Milky Way early this morning, Jim Schaff of Hermantown used a green laser pointer to "paint" the silo with the name of the Furtman Star Party. Photo : Jim Schaff

As you who read this well know, it’s very energizing to share our passion with those of like mind. We form a bond with them that sustains and nurtures our spirit. A gathering under the stars is one of the most enjoyable ways to achieve this.

After the midnight snack and a discussion of why the main deflector (whatever that is) always seemed to get the cast of TV’s Star Trek out trouble, we returned to plumbing the sky until the body wasn’t able. I went to the barn just before 3 a.m. to unroll my sleeping bag. The moving beam of my flashlight lit upon an odd assortment of computer keyboards and bales of hay. We live in constant transition. Even as I lay my head to pillow, I thought of the sleepless stars beyond the window. While they run their incessant cycles, the good people of Earth join together to find purpose in it all. 

Gracious party hosts Greg and Laura Furtman. Photo: Bob King

Fiery colors illuminate the western sky a half hour after sunset last night (August 29) over Rice Lake Township. Volcanic dust and gas high in the atmosphere have deepened the colors of twilight the past week or two. Photo: Bob King / News Tribune

I hope some of you found our featured variable star Eta Aquilae under last night’s clear sky. Look again in a few nights and it will have noticeably faded. Maybe you’ve been keeping an eye on sunsets as well. Have you noticed that the twilight sky in the west has looked more colorful lately? Clouds of volcanic dust and sulfur dioxide sent sky high from the July and August eruptions of three volcanoes in Alaska’s Aleutian Islands are the reason why. The most recent, Kasatochi, shot plumes of ash and gas 45,000 feet high into the stratosphere.

The Okmok volcano (pictured above) erupted in July in the Aleutians launching dust into the atmosphere. Dust and gas from this eruption and those of the Cleveland and Kasatochi volcanoes have been responsible for our more intense twilight colors. Photo: Jessica Larson, AVO/UAF-GI

This abundance of volcanic aerosols gives the setting sun new material for flaunting its colors, like a kid with a new set of markers and fresh pad of paper. In addition to color, I’ve also noticed subtle, grey bands and streaks of dust low in the west after sunset. While the intensity of the twilight hues doesn’t come close to those we experienced during the 1991 Mt. Pinatubo eruption, that could change depending on further activity and upper level winds. To find out more, check out the updates from the Alaska Volcano Observatory. And if you’re out around 8:15-8:30 p.m. and have a good horizon view to the west, you should be able to find Venus too, beaming low through the haze.

Looking east at dawn around 5 a.m. Friday morning August 29. Orion and his three Belt stars just clear the treetops to the right. Pollux and Castor in Gemini the Twins are the two bright stars atop on another in the left half of the frame. The constellations of winter are returning for both insomniacs and early risers. Photo: Bob King / News Tribune 

We’re so used to the sun’s constancy. It’s doesn’t suddenly brighten and then fade. It’s the same size day to day, even millenium to millenium. The sun is reliable, which is probably why life has had the opportunity to flourish in so much variety on our planet. Stars like the sun remain well-behaved over much of their lives because they’ve struck a delicate balance between the powerful force of gravity, which wants to crush them into tiny balls, and their tremendous energy output, which would otherwise blow them to bits.

To find the variable star Eta in Aquila the Eagle, first locate the Summer Triangle above bright Jupiter. The star to look for is Altair, the bottom apex of the triangle. Use the map below to zero in on Eta. — created with Stellarium

There are other stars however whose light is not constant. Stars that puff themselves up, flare and otherwise can’t seem to settle down. These are the variable stars and there are lots of them. Most of 9000 or so stars visible across the sky with the naked eye are steady or nearly so, but a few undergo obvious changes in brightness. One of them, which goes by the Greek alphabet letter of Eta (AY-tuh) in Aquila the Eagle, shines over us every clear night of the summer and fall.

Eta is located about one outstretched fist below Altair, on the lower side of the Eagle’s left wing. Eta, and its neighbors Delta and Iota, are dimmer but not faint, and easily visible in suburban and rural skies. — created with Stellarium

Eta is a Cepheid (SEF-ee-id) variable. Cepheids are giant and supergiant stars much larger and brighter than the sun. Changes deep within their nuclear-burning cores cause them to lose their balance, so to speak. Instead of holding steady like the sun, they pulsate or puff in and out with periods of one to 70 days. As they do, their size and surface temperature changes.  Eta, located over 1100 light years away and some 60 times the size of our sun, is one of the few Cepheids whose brightness changes are easy to follow. The time it takes to go from bright to dim and bright again — its period – is just a bit more than seven days. 

Eta is brightest tonight (August 29-30), shining nearly as bright as its neighbor Delta. By next Wednesday the 3rd, it will have shrunk and faded to near minimum brightness, and more closely resemble the fainter Iota. Check for yourself. It’s easy to compare. Once you see the changes, you’ll wonder what else’s been going on up there all these clear August nights.

The animation (at right), created by Professor Robert Buchler at University of Florida, beautifully illustrates the pulsations of stars like Eta. Notice that the star is brightest when it’s expanding most rapidly, and faintest when it’s fading fastest.  After slowly fading in the coming days, Eta will quickly brighten to maximum again on the nights of September 5 and 6. (If you can’t see this animation, please click here for a direct link.)

Cepheids, whose namesake is Delta Cephei in Cepheus the King, may sound like an obscure subject but they allow us the privilege of seeing ongoing physical changes in evolving stars right from our own backyards.

There are many types of variables but stars like Eta might be the most fascinating of all. Back in the early 20th century, scientists learned to use them to probe the vast distances between galaxies. Cepheids were responsible for awakening Earthlings to the fact that we live in a universe much larger than we ever supposed. Later this weekend, we’ll look at these curious stars in more depth when we revisit Edwin Hubble’s discovery of the first Cepheid beyond the Milky Way.

A striking display of crepuscular rays around the sun this morning, August 28. Although the rays appears to focus on the sun, they’re actually parallel to one another. The "railroad track" effect makes them look like they’re converging toward the sun. Photo: Bob King / News Tribune

I walked out of Marshall school this morning, where I’d been photographing a story, and into the glaring eye of the sun. And I mean eye. Surrounded by a ominous, grey cloak of crepuscular rays, it looked like the fabled Eye of Sauron from J.R.R. Tolkien’s Lord of the Rings trilogy. One ring to bind them all! I dared to photograph the scene then hurried back to the office to keep the orcs off my trail.

We talked about crepuscular rays earlier this summer. These shafts of sunlight poke through holes in the cloud deck, illuminating dust and water vapor in the atmosphere. They can show up any time of day but are most striking near sunset when the rays shoot up from the horizon in great columns like the opening to judgement day. It’s especially interesting when the clouds that cause the rays are beyond the local horizon and invisible. They announce their presence all the same by casting beams of dark and light in a clear, blue sky. Amazing.

Anti-crepuscular rays crown the eastern sky just after a sunset this past July. They blend into the Earth’s shadow, which is the dark band just above the horizon. Photo: Bob King / News Tribune

If you see those pearly shafts of light and shadow at early dusk, turn around and look in the opposite direction (east). As the sky darkens, you might just get to see the anti-crepuscular rays. These are the extensions of the crepuscular rays clear across the sky, where they appear to converge in the east just above the dark wedge of the Earth’s shadow. The convergence is an optical illusion, the same as our view of the crepuscular rays. In reality, they’re all parallel just like railroad tracks. Click on this link for a full-sky, fisheye view that shows the entire scene.

The anti-crepusculars are considerably fainter than the rays in the sunset direction. Watch for dark wedges to form in the pink band above the Earth’s shadow — a sure sign a display is underway.

Let’s hope for some tonight. If it’s clear, you can also watch for a bright flare from the Iridium 75 satellite. Look four outstretched fists high in the east-northeast at 10:07 p.m. in the Duluth-Superior area. A new "star" will suddenly materialize, become almost as bright as Jupiter, and then disappear.

Look due east three fists below Cygnus (the Northern Cross) around 9:30 p.m. to find Pegasus the Winged Horse and its easily-recognized Great Square. The Square is large, measuring some two "fists" across. You can also use the "W" of Cassiopeia to guide you there. — created with Stellarium

With September knocking on the door, what’s to do but introduce you to the Great Square of Pegasus (PEG-uh-sis). This is the quintessential celestial asterism of early fall. The square, which looks more like a baseball diamond, ascends the eastern sky around 9:30 p.m., three outstretched fists below Deneb in the Northern Cross. Recall that Deneb is the easternmost (left) apex of the Summer Triangle. Click here to see a diagram of the Summer Triangle.

The winged horse shares the eastern sky with Cassiopeia the Queen, Pisces the Fish and Andromeda the Chained Maiden. — created with Stellarium

Pegasus is the fabled flying horse of Greek mythology. He was caught by Bellerophon and ridden by him to slay the Chimaera, a monster who had a lion’s head, a goat’s body and a dragon’s tail. Pegasus also hauled around thunderbolts for Zeus himself for a time. These days, the winged steed carries the news that autumn is coming. The sight of the big "baseball diamond" rising in the east, its center devoid of any bright stars, strikes terror into the hearts of those who would not let go of summer.

Bellerophon rides Pegasus to his task of slaying the Chimaera. Credit: Mary Hamilton Frye from "Myths Every Child Should Know".

The stars of the Square are about as bright as those of the Big Dipper or a little less. Pegasus’ neck and head extend to the right and above the Square, ending with Enif, an Arabic name meaning "the nose". I’ve never been able to discover why the horse is depicted as flying upside down. Perhaps the star pattern just makes more sense that way.

As the winds begin to pick up and the leaves fall to the ground, you may want to hop on Pegasus for a ride through the late summer sky. He’ll be our guide to many of the fall constellations. 

Jupiter has been very assertive these nights. Even in early twilight, the planet stands out bold as a brass button in the southeastern sky. I saw it at 8:15 yesterday evening. By nightfall, it’s so bright, it steals the attention of anyone looking south. To find it, look about three outstretched fists high in that direction around 8:30-9 p.m.

Yes, you must give in to Jupiter’s fatal attraction. After all, it’s the largest planet in the solar system. It’s gravity is so strong, that a 100-lb. human would tip the scales at 236 lbs. there. Man, I don’t want to be dragging that around. Give me the moon, where the same person would weigh only 16 lbs. To see how much you’d weigh on Jupiter or any other planet in the solar system, check out this website.  

Jupiter as seen in a 7-10x pair of binoculars tonight (August 26) between 9 and 11 p.m. The moon Callisto will look like a small star immediately to the right of the planet. You might also see a tiny "star" or two between Jupiter and Callisto; these are more of Jupiter’s moons (see below for a detailed look). All the other points of light in the circle are stars of varying brightness in the field of view. — created with Stellarium

  Tonight we have a fine opportunity to see at least one of Jupiter’s four brightest moons. Callisto will lie about as far from Jupiter as its orbit will allow, and should be easily visible in 7x to 10x binoculars. At 2,996 miles in diameter, Callisto is Jupiter’s second largest satellite and the most heavily cratered moon in the solar system. Its battered icy crust features the spectacular Valhalla impact structure, an enormous multi-ringed crater. Valhalla’s center is 180 miles across and the whole feature stretches 900 miles in diameter.

Icy Callisto’s surface still records the scars of asteroids and meteorites that bombarded all the solar system’s planets and moons about four billion years ago during their formation. The large bullseye is the Valhalla impact structure. Photo credit: NASA

Just like a planet orbiting the sun, Callisto orbits Jupiter. Telescopic observers can watch it wend back and forth from one side of Jupiter to the other over a period of about 16 days. Galileo’s observations of orbiting Jupiter’s moons gave him the proof that Copernicus was correct in asserting that the Earth orbits the larger sun instead of the other way around.

Jupiter and his family of moons through the telescope tonight around 9 p.m. — created with Stellarium

If you have a small telescope, you can easily find three more of Jupiter’s moons tonight — Ganymede, Europa and Io. They’re arranged in a compact triangle just to the west or right of the planet.

Noctilucent clouds taken by the crew of the ISS. These very unusual clouds are some 70-80 miles high, far above the more familiar clouds, which form in our lower atmosphere. Noctilucents are may form from water vapor condensing on meteor dust. Read more here. Photo: ISS/NASA

One last photo I wanted to share has been making the rounds on the Internet the past week. We’ve talked about noctilucent clouds here on several occasions, and looked at pictures of them taken by several different photographers. This photo, by the crew of the International Space Station while orbiting Earth, is one of the most beautiful I’ve seen of these peculiar clouds. What a unique vantage point!

The last rays of sunlight paint the clouds Saturday evening, August 23 as seen from Duluth. Bob King / News Tribune

 Raspberries to the rescue! It was a warm walk in the woods yesterday despite cooler temperatures. I was happy that raspberry bushes appeared just often enough to satisfy my desire for something sweet. The dog gobbled the little handfuls I offered her with equal enthusiasm. Late summer was everywhere a part of the landscape. The creeks had run dry, spider webs glinted between thistle stems, and the wind lazily swept the topmost leaves of the birches. Summer seemed as settled in as my dad in his recliner. 

The waning crescent moon and constellation of Orion the Hunter greet early-risers tomorrow morning (August 26). Look to the east around 5-5:45 a.m. to see the return of the winter sky. Orion’s Belt is located about three outstretched fists to the right and below the moon. — created with Stellarium

That all changed this morning. Frost touched northern Minnesota, and the air had that sharp edge that winter will hone into a knife. My thoughts turned to winter stars like Orion and the most common question I’m asked by beginning sky observers: "Where’s Orion’s Belt?"

Most of us are familiar with that famous triplet of bright stars, and I’m happy to announce that Orion has returned to duty in the morning sky. The Hunter disappeared in evening twilight last April, spent time in the daytime sky near the sun and has emerged again in morning twilight. This cycle is a reflection of Earth’s motion around the sun during the course of a year. You can read more about it here. The Belt is flanked by the  bright stars Betelgeuse and Rigel. Both are supergiant stars with distinctly different colors. Betelgeuse looks tomatoey while Rigel is pure white. 

You might be able to see the International Space Station (ISS) tomorrow moring as it starts up another round of dawn passes over our region. Look low in the south-southeastern sky between 6:04 and 6:08 Central time. The ISS will only rise about two fists above the horizon at best, and the sky will be light. As the week goes on, the passes will get better.

Oh, one last bit of advice. Don’t forget to wear a coat tomorrow. Not only will it be chilly out, but looking at Orion just wouldn’t be the same without one.

Last night I spent a couple hours with a nice family in Duluth’s Lakeside neighborhood studying the sky through their small telescope. We looked at star clusters, Jupiter, double stars and spotted a slew of satellites. I was surprised how easy it was to see the Cygnus Star Cloud (see yesterday’s blog). It helps that it’s so high up in the sky where thick air and city lights can’t touch it.

View looking south around 9:30-10 p.m. You can use Jupiter and Altair, the bottom star of the Summer Triangle, to guide you to the Alpha and Beta stars of Capricornus the Sea-Goat. They’re about three outstretched fists to the left of Jupiter. The Alpha star, known as Algedi, is really two stars very close together.– created with Stellarium

We also split double stars with our bare eyes. The pair of Mizar and Alcor in the bend of the Big Dipper’s Handle was easy for everyone. How about something a little more difficult? Algedi (all-JED-ee) in Capricornus came to mind. This tight little pair was just coming into good viewing position in the southeastern sky. Young and old alike split this one too, and it was all the more thrilling because the stars were so close together.

A closeup of Algedi (Alpha 1,2) in Capricornus. The left star, Alpha 2, is the brighter. To split the pair with your eyes alone, stare directly at it rather than off to the side. It might seem hard at first but I think you’ll be pleasantly surprised. — created with Stellarium

Algedi is really two separate and unrelated stars, Alpha-1 and Alpha-2 Capricorni. The pair is one of the better chance alignments in the sky, since their separation of only 1/6 the apparent diameter of the full moon mimics the appearance of a real, physically-connected double star.

Alpha-2, the brighter one to the left or east, is a giant yellow star 43 times more luminous than the sun and 109 light years away. Its "companion", Alpha-1, is 690 light years away and only appears fainter because of its great distance. In reality, Alpha-1 is a supergiant star some 20 times larger than the sun and over 900 times brighter!

Capricornus depicts a goat with tail of a fish. The constellation was handed down to us from the Babylonians and Sumerians. The ancient Greeks saw the god of the countryside, Pan, in it stars.

Alpha and Beta Capricorni form the western end of the peculiar constellation of the Sea-Goat (or Water-Goat). The goat’s association with fish probably had to do with the sun being in this region of the sky during the spring rainy season. Other nearby constellation like Aquarius (Water-Bearer), Pisces (Fish) and Cetus (the Sea Monster) are often referred to as the watery constellations for the same reason.

Capricornus has no bright stars but an interesting shape. I’ve always seen a cat’s face in its bent, triangular outline. Besides Algedi, the Sea-Goat is home to a number of telescopic galaxies and a globular star cluster we’ll drop in on in a future blog. If it’s clear by you tonight, stare down the two alphas, and if you split ‘em, let us know.

The Milky Way cuts right through the Summer Triangle as seen from a dark sky. Look high in the southeast around 9:30-10 p.m. to spot the Triangle’s three brightest stars — Vega, Deneb and Altair. Just below Vega and Deneb, you’ll see the sausage-shaped Cygnus Star Cloud. Photo: Bob King / News Tribune

With a clear sky in view for tonight, it’s time to return once more to the Milky Way. There are just so many things there to see. Tonight we’ll look at the stretch framed by the Summer Triangle and focus on one of the brightest sections, the Cygnus Star Cloud.

The Cloud is located in Cygnus the Swan (Northern Cross) and measures one outstretched fist across. It’s fabulously rich in stars. I’ll bet this was one of the first places Galileo pointed his telescope back in 1610 when he revealed the true nature of the Milky Way: "For the galaxy is nothing else than a congeries of innumerable stars distributed in clusters. To whatever region of it you direct your spyglass, an immense numbers of stars immediately offer themselves to view, of which many appear rather large and very conspicuous but the magnitude of the small ones is truly unfathomable." So wrote Galileo in his book The Starry Messenger.

I looked at the Cloud in binoculars last night and stars jumped out all over the place. It’s a wonderful place to get that tingly Galilean feeling of discovery. Just below and to the right of the center of the cross figure is a curvy little chain of stars I like to call the Caterpillar. Can you see it? The Cygnus Star Cloud consists of many, many stars stacked up behind one another into the deep distance as we look down one of our galaxy’s spiral arms.

An enormous dark rift defines the cloud’s eastern border. The top part of the rift just below Deneb is often referred to as the Northern Coalsack after its better known counterpart,the Coalsack, near the Southern Cross. The Rift splits the Milky Way down the middle and runs all the way from Cygnus through Sagittarius and down to the southern constellation Carina. It consists of enormous clouds of interstellar dust and gas in the plane of the galaxy that blot out the more distant stars. If you could suck it all up with a monster vacuum cleaner and expose the billions of stars otherwise hidden, the Milky Way would be bright enough to cast shadows.

Start with the Northern Coalsack and follow the Rift across the sky down toward the southern horizon. As you do, your gaze literally reaches across the galaxy, moving from the local spiral arm into a more distant one. The Rift broadens as you go because it approaches our solar system more closely en route from Cygnus to Sagittarius.

The spiral galaxy NGC 891 in the constellation Andromeda is 30 million light years away and home to billions of stars. The dust lane in this galaxy would cut a dark path along the NGC 891 "Milky Way" for an inhabitant living there just as the Great Rift does in our own galaxy. Photo: Jim Misti

Many spiral galaxies like the Milky Way have dark clouds along their equators. Dust left over from the evolution of stars into white dwarfs and supernovas settles there and is used again to create new generations of stars.

When I look up at the Milky Way on a dark August night far from town, I’ll recall the picture of another galaxy, NGC 891. Photos and looking at galaxies through the telescope help me to see and appreciate the full breadth and grandeur of our own galaxy. Those nights leave my neck stiff but with a head full of happiness. Are you ready for some of the same? Grab your binoculars and go out tonight.

Clouds, clouds, clouds. They’re a welcome relief. No need to wear sunglasses to keep from squinting. As an amateur astronomer, I enjoy the occasional respite clouds provide, not only from sunlight but they keep my eyes earthbound at night, allowing me to focus on things other than celestial.

Wispy clouds captured above a vast plain of sand by the Opportunity rover near Victoria Crater on Mars on October 2006. Red dust in Mars’ atmosphere colors the sky a pale orange. Credit: Mars Exploration Rover Mission, Cornell, JPL, NASA

Earth is one of seven planets in the solar system that has clouds. Only Mercury – and if you still count Pluto – are without, since the atmosphere of each is nearly a vacuum. We don’t often think about Mars clouds but the rovers still active on its surface have been photographing high, cirrus-like clouds for the past several years. Mars’ atmosphere is mostly carbon dioxide with very little water vapor but enough for occasional clouds and mists to form. Temperatures are low enough for dry ice (carbon dioxide) clouds as well.

The Russian Venera 13 ship (foreground), which landed on Venus on March 1, 1982, survived for two hours and seven minutes before succumbing to the planet’s hellish heat and pressure. This photo, recently reprocessed by Don P. Mitchell, shows the rocky surface and overcast sky.

There are no clear nights on Venus – ever. The planet is completely swathed in a thick layer of toxic sulfuric acid clouds that circulate through its dense carbon dioxide atmosphere. Even for cloud lovers, there are no pleasant days on Venus. The landscape is primarily volcanic, the atmosphere is 90 times the pressure of Earth’s (equal to what you’d feed a 1/2 mile under the ocean), the air temperature hovers around 800 degrees Fahrenheit and it drizzles a powerful acid rain. Such are the woes of a planet where the greenhouse effect has been out of control for a very long time. Let’s hope our planet never takes that route whether brought on by us or something beyond our control.

The cloud belts of Jupiter and its Great Red Spot. A couple Earth’s would comfortably fit inside the Spot. Credit: NASA/JPL

Jupiter’s clouds, made of ammonia ice crystals, are the most colorful of any planet. The belts you see in the photo are associated with alternating east and west winds in hurricane-force jet streams. These are not winds of nitrogen and oxygen as on Earth, but of hydrogen and helium. When the Galileo probe descended into the planet’s atmosphere in 1995, it measured winds of 192 mph at the cloud tops to 391 mph at 28 miles down. Before measurements ceased at about 80 miles, winds were still shrieking between 380 and 390 mph. The Great Red Spot has been visible in telescopes since the 1600s and is a colder, higher-elevation region of high pressure in Jupiter’s atmosphere.

This NASA animation, compiled with spacecraft images, shows the circulation of Jupiter’s clouds over 10 Earth days. The spherical planet has been "flattened" into a long strip so we can see all the way around. Notice that some bands are blowing one way, others are blowing the opposite. The Great Red Spot is also rotating just the way high and low pressure areas on Earth do.

Storm clouds break up over Duluth’s Hillside after a storm last month. Clouds form from water vapor that condenses in the colder air high above Earth’s surface. Photo: Bob King / News Tribune

We wrap up with the clouds of Earth. Their various and changing forms always keep the sky interesting. By tomorrow night, they’ll be gone from our region, leaving a clear night sky. That’ll be ideal for exploring the Cygnus Starcloud, tomorrow’s blog topic.