This image of "Block Island" was taken on July 28, 2009, with the front hazard-identification camera on NASA’s Mars Exploration Rover Opportunity. Scientists will be testing the rock to get composition measurements and to confirm if indeed it is a meteorite. Image Credit: NASA/JPL-Caltech

I’ve spent the past few days in the Boundary Waters wilderness chasing cloud reflections with my canoe paddle. More on that soon. In the meantime, keep your eye on the planet Jupiter because Saturday we’ll look at why it appears to be traveling backward in the sky this month.

A closeup of a possible new meteorite on Mars. Credit: NASA/JPL-Caltech 

In a news item released today by NASA, it appears that the Mars Rover Opportunity may have discovered another meteorite on Mars. These photos were taken Tuesday this week and show a pock-marked rock about two feet across seemingly out of place on Mars’ sandy plains. If it does prove to be a meteorite, the dimpling may have been caused by the heat of atmospheric entry, which melts away softer, less resistant parts of a meteorite to create the tell-tale pattern.

This fanciful drawing depicts the "Space Train" that will leave the Duluth’s Depot Friday night for a trip to the stars. Credit: Eric Norland

The Duluth Art Institute will host a special Space Train ride this Friday July 31st. For a $25 ticket, you can listen to live music from the band Tangier 57 and eat pizza as you travel to the dark skies of Larsmont, just south of Two Harbors. There you’ll disembark and spend a pleasant evening stargazing with members of the Arrowhead Astronomical Society. The train leaves at 9 p.m. and returns home by 1 a.m. If you’d like to come along, contact the Institute at 218-733-7560 or getart@duluthartinstitute.org

The southern Delta Aquarid shower is admittedly one of the weaker ones of the year, especially for northern hemisphere skywatchers, but it does kick out about 30 meteors per hour for southern hemisphere observers. The radiant is in Aquarius just to the left of brilliant Jupiter and above the bright star Fomalhaut (FOE-mal-howt). Illustration created with Stellarium.

As we learned yesterday, meteor activity starts heating up in late July with early Perseids but several other minor showers are active as well. One of the better-known ones originates in the dim constellation of Aquarius the Water Carrier. Since the radiant, or the point in the sky from which the meteors to originate, is rather low in the southern sky, the further south you live, the higher the radiant and the more you’ll see. If you’re reading this in New Zealand, you’ll see up to 30 per hour, but if you’re in Bozeman, that number drops to around 10.

Delta Aquarids are on average rather faint and of medium speed. The best time for viewing the shower will be Thursday morning from 2:30 on. Look toward the south a fist to the left of Jupiter. Most of the meteors will flash into view to the north, east and west of the radiant. While you’re out, expect to see other meteors that you can’t necessarily trace back to Aquarius. Maybe even a Perseid or two. If it’s cloudy Thursday, the shower will be nearly as active Friday through Sunday mornings.

Crumbly bits of rock, ice and dust trail between the fragments of comet Schwassmann-Wachmann 3 in 2006. Some may eventually find its way to Earth and burn up as meteors in our atmosphere. Credit: NASA/JPL-Caltech/W. Reach (SSC/Caltech)  

Most meteor shower meteors originate in comets. As a comet loops through the inner solar system it sheds dusty debris from its head and tail. Earth crosses a particular comet trail yearly and when it does, we plow into the dust at 18 1/2 miles per second. The comet crumbs collide with the upper atmosphere and incinerate in flashes of light. No one knows which comet is responsible for the Delta Aquarids. Perhaps its orbit was changed by one of the giant planets so it now follows a different path. All that’s left are its tiny siblings, which spark sparsely in the south every July. 

My friend Rick is here for a visit and the two of us spent about an hour staring at the northern sky last night hoping to see noctilucent clouds. None appeared but the moon was golden and low and we had time just to talk. A bit of advice for anyone having a conversation while watching the sky. Keep watching the sky. While I turned to Rick to make a point about something or other, a spectacular meteor burst through the Big Dipper. He saw it and raved while I looked too late.

Even in this wide-angle photo, you can see both of the clusters comprising the Double Cluster as two "knots" of starlight. Details: 28mm lens at f/2.8, 45-second time exposure at ISO 3200. Photo: Bob King

We’re finally getting back to the occasional clear night and I see Cassiopeia, the celestial W, is again climbing up in the northeastern sky. It’s a good idea to keep an eye on Queen Cassiopeia because you’re likely to see some early Perseid meteors. While the Perseids peak in activity on August 12, you’ll often see a sprinkling of early arrivals two weeks or more in advance of the horde. Shower members appear to radiate from a spot in the sky just below the W. In fact, I saw one very nice Perseid while shooting the photo (above) last week.

This is how the Double Cluster appears in a small telescope. Notice the scattering of red stars within and around the duo. The clusters’ official names are NGC 884 (left) and NGC 869. Credit: Hunter Wilson

Cassiopeia is about two outstretched fists high in the northeast at nightfall. Once you spot the W, look about three finger-widths below its left side. Skywatchers in the outer suburbs or countryside may be able to discern a small fuzzy patch there with the naked eye. If not, then just point your binoculars at the spot and you’ll alight on the Double Cluster of Perseus, a pair of side-by-side star clusters around 7000 light years from Earth. Through binoculars they look like two dense, starry heaps. Their closeness is no accident; the clusters are only about 100 light years apart. Telescope users will really get a treat since even low power will resolve the Double Cluster into at least a hundred stars. Scattered among the many gems are a few bright ruby red members.

The Double Cluster has been a favorite of mine since I saw it for the first time from the Chicago suburb where I grew up. Happy early Perseid watching!

The Cygnus Bubble appears to float among the stars and gas clouds in the constellation of Cygnus the Swan, also known as the Northern Cross. Astronomers discovered this striking nebula just last year. Credit: T.A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF

I ran across this photo a few days ago and was so taken by it I thought you’d enjoy it too. Called the Cygnus Bubble, it’s one of the most symmetrical planetary nebulae known. Planetary nebulas are so called because they have round shapes that reminded early telescopic observers of planets. Planetaries vary in size but a typical one might be about a light year across or some 500 times the diameter of the solar system.

How do these cosmic jewels form? As modest stars like our sun burn through their fuel supply, they experience a series of pulsations that cast off their outer layers into space. What’s left behind is a tiny, Earth-sized star called a white dwarf (the compressed core of the original star) surrounded by a bubble or bubbles of gas that were once part of the star’s atmosphere. The dwarf is incredibly hot and emits lots of ultraviolet light, causing the shells to glow eerie greens and pinks.

A gallery of planetaries photographed by the Hubble Space Telescope. From left to right: the Butterfly, Cat’s Eye, Ring and Hourglass Nebulas. Our sun will likely evolve into a planetary nebula some five billion years from now. Most of these beautiful shells and envelopes will dissipate into space after a few tens of thousands of years. They are truly works of art. Hi-res version here. Credit: NASA/ESA

Of course if it were that simple, all planetary nebulas might just be nice round balls, but astronomers now believe that their wonderful and complex shapes are caused by interactions between the white dwarf and a closely-orbiting companion star or planets. The gallery is only a small sampling of how diverse these beautiful baubles can be.

Back to the Cygnus Bubble. It’s so faint that it was overlooked by the astronomers who study photographs taken with large telescopes. All except David Jurasevich of Mt. Wilson Observatory in California, who discovered the Bubble in photographs he made of the region last July. Only a few days later amateur astronomers Mel Helm and Keith Quattrocchi independently discovered it, proving once again that dedicated amateurs can make real contributions to science.

To see additional photos of planetaries, check out this complete Hubble gallery. More information about the topic can be found here.

Does the forecast look clear by you tonight (Monday 7/27)? Then face the moon in the southwestern sky a little more than an hour after sunset to see it buddy up with Virgo’s brightest star, Spica. Created with Stellarium.

Night is that little mouse that makes a surprise appearance in your kitchen when the house is quiet. You see something move out of the corner of your eye and suddenly you’re aware of a new creature padding about.

Have you noticed that the sky is getting darker earlier? It kind of crept up on us, slowly at first, but now it’s unmistakeable. In Duluth, we’ve gained a half hour of evening darkness both from earlier sunsets and shorter twilights — 15 minutes apiece for each. The pre-dawn sky has seen a larger share of dark sky with a gain of 42 minutes. That’s almost an hour of nighttime enjoyment since the June solstice.

This map shows the sky around 10:15-30 p.m. as you face south. Scorpius and bright Antares are tipping off to the west while Sagittarius the Archer (a.k.a. Teapot) is gaining prominence. The star in the pot’s handle, Nunki, is ten times larger than the sun and several thousand times hotter. Nunki also forms part of the "Milk Dipper" asterism. Created with Stellarium.

Earlier nights sure help summer skywatchers catch up on their sleep. Instead of waiting until 11 or later for darkness to set in, we can peruse the heavens at 10:15-10:30 while we’re still awake. To celebrate the return of night, let’s feast our eyes on the stars of the southern sky. Scorpius is dominated by the bright orange star Antares (An-TAR-eez), which is two outstretched fists high in the south-southwestern sky. Antares represents the heart of Scorpius the Scorpion. The head of the beast is formed by three stars to the right of Antares. The body of the scorpion trails off toward the southern horizon. To see it, you’ll need a wide open vista to the south.

Two fists east or left of Scorpius is Sagittarius the Archer, better known as the Teapot because of its distinctive shape. The Milky Way runs right through the teapot and if you point your binoculars above the pot’s lid and keep moving upward or north, you’ll run into small, fuzzy nebulas and occasional starry clumps or star clusters. Many nebulas evolve into star clusters as the gas their composed of becomes compacted through gravity and transformed into stars. These windows into stellar evolution lie right before our eyes.

A favorite feature of Sagittarius is a dipper-shaped group of stars headed up by the constellation’s second brightest star, Nunki (NUN-kee). This asterism is sometimes referred to as the "Milk Dipper" because it ladles the milky light of the Milky Way. If you’re someone who likes milk with their tea, you’ll feel right at home in Sagittarius.

Like the scorpion, your best chance to see the Teapot and Milk Dipper is from a location with a clear view to the south.

Jupiter at 1:30 Sunday morning seen through a 10-inch scope at 240x. The impact spot is the grey patch at top. At the same time, the moon Europa hovered over the western limb of the planet. The dark stripes are some of the planet’s cloud belts. South is at top in this sketch. Credit: Bob King

I set a vigil early this morning to get my first look at Jupiter’s dark impact spot. Clouds were a problem until 1:15, when for about 20 minutes the sky finally cleared enough to get a look. It was amazing to see the little grey oval near the far southern end of the planet. Even after a week, Jupiter’s winds still haven’t torn it apart. As always, the amount of turbulence in the air determines how small an instrument will show it. I was using a 10-inch reflecting telescope at 240x and thought it fairly easy to see once the air settled down. When turbulence returned, the spot blended right back into the planet and disappeared from view. On a good night, I think a 6-inch telescope would snag it. Let us know if you find the new spot. To assist your efforts, here are some times when it will be easiest to see:

* Tues. July 28 around 3:30 a.m. Central time
* Tues. July 28 around 11:30-midnight
* Thurs. July 30 around 5 a.m.
* Fri. July around 1 a.m.
* Sun. Aug. 2 around 2:30 a.m.

If you want to stay in touch with what Jupiter observers are seeing and photographing, consider joining the ALPO (American Assn. of Lunar and Planetary Observers) online Jupiter group.

The Hubble Space Telescope took this picture on July 23 of the dark spot. South is down in the photo. The spot started out round but winds in Jupiter’s atmosphere have caused it to spread out. Credit: NASA/ESA/H. Hammel at SSI and the Jupiter Impact Team.

 
 Io’s Tvastar volcano releases a 205-mile-high plume of sulfur and sulfur dioxide gas into space. The photos were taken over an eight-minute span by the New Horizons spacecraft as it flew by Jupiter in March 2007 on its way to Pluto. Jupiter’s moon Io, which is about the size of our moon, is the most volcanically active body in the solar system. Credit: NASA/JHUAPL/SwRI

Amazing animation isn’t it? Sometimes after a day along the creek or river, I like to imagine the sound of water running constantly day and night, whether I’m there or not. It’s a comforting thought, knowing that something that gives me pleasure is always out there churning and bubbling away despite the worries of the moment. With over 400 active volcanoes, Io is continuously active, as much so as my creek. Next time I’m attending a meeting that goes on as long as the Pleistocene I’ll think of Io and all that lava oozing from its searing calderas.

A co-worker alerted me to a funny and thought-provoking illustration of how far television signals have traveled in space since the 1930s, the early days of the technology. TV is transmitted as microwaves, a form of invisible light.  Radio waves, X-rays, microwaves and the light we use to see are all forms of electromagnetic radiation, and they all have one thing in common — they race across space at 186,000 miles per second.  

This illustration, which is much too small here to
fully appreciate, maps the location of some favorite
TV shows and how far from our planet they’ve traveled.
Click here for the large version. (via the Abstruse Goose)

That means that our TV programs have been leaking into outer space at the speed of light since regular transmissions from Europe and the U.S. began about 70 years ago. Where are they now? Like spreading waves around a stone dropped in a pond, the earliest transmissions have reached nearly to Mizar (78 light years away), the star in the bend of the Big Dipper’s handle. In eight years, any Mizarians out there will be able watch and listen to president Franklin Roosevelt at the opening of the New York World’s Fair in April 1939. That’s old news for Aldebaran, located 65 light years away in Taurus the Bull. Scenes from World War II are just now flickering on saucer-shaped alien TV sets there.

Closer to home, the final season of the original Star Trek passed by Arcturus (36 light years away) three years ago while the first Seinfeld episode will finally arrive at Vega in five years. The Sirians of Sirius, the brightest of all stars, have just given up on Earth after watching a full season of Spongebob Squarepants.

It’s fun to think about human culture spreading into space via light waves, and a wonderful way to get a handle on the huge distances between the stars. Unfortunately it’s unlikely that any of these transmissions will make it much beyond the solar system. Light loses intensity with distance. A flashlight is sure bright when someone shines it in your face but fades as they back off. Do you think you could spot the beam a mile away, ten miles away? 

The same thing happens with TV "light" or microwaves. The original transmission is strong and covers a large area but eventually thins out to a faint whisper the further from the source it travels. By the time those TV signals are halfway to the Alpha Centauri system, the nearest star beyond the sun, they’re lost in a noisy background of cosmic microwaves. Can you guess the source of these waves? It’s none other than the Big Bang itself. The white-hot radiation at the universe’s origin has cooled to a tepid few degrees above absolute zero and now soaks all of space in a bath of softly vibrating microwaves. 

Unfortunately Gilligan’s Island doesn’t stand a chance of popping up on the alien TV network. Looks like if they want to find out what’s happening on Earth, they’re just going to have to put down their remotes and shake a leg.

To read more about dwindling interstellar TV options, take a look at this story from NPR.

Evening passes of the International Space Station (ISS) / shuttle combo are winding down this week for our region. There are just three nights left before a several-week-long hiatus followed by a re-appearance in the morning sky. The ISS will first appear in the western sky, cross the southwest and disappear in the south-southeast.

Tonight at 10:20 p.m.
Fri. July 24 at 9:09 p.m. (bright pass!)
Sat. July 25 at 9:34 p.m.

A huge cumulus congestus cloud billows upward on a recent evening here in Duluth. The white portion is lit by the sun while the darker cloud is in shadow and silhouetted against the taller. Credit: Bob King

The clouds have been spectacular here the last couple days. The eye-grabbers are the big cumulus clouds that develop into towering thunderheads with multiple turrets topped by anvils of delicate cirrus. They dump rain in fine purple strands that you see from miles away. In the clouds pictured above, the contrast between the illuminated cloud and the one in shadow is very dramatic. This photo will help us understand why the Milky Way appears to be split in two by what astronomers call the Great Rift. 

The Great Rift, composed of giant clouds of interstellar dust, is the chunky dark lane cutting through the center of the picture. It begins at the top of the Summer Triangle and continues all the way to the southern horizon. The photo is tipped so north is left and south is at right. If you need a map to find the Summer Triangle, click here. Credit: Ingo Berg

Round about late July the Milky Way is high in the east at nightfall. If you live in the suburban fringe or the country, you’ll have no problem seeing the soft band of hazy light that first-time observers often mistake for approaching clouds. Even a casual inspection will show that the band is not evenly-textured. In particular, there’s a large gap or split extending from the Northern Cross all the way down to Sagittarius in the south. That’s the Great Rift.

While it may appear to be starless, the rift is packed with suns, millions of them, but they’re obscured and hidden by enormous clouds of fine dust many light years deep. Tiny dust particles as well as tasty molecules of water, ammonia, salt and others are spewed by older, evolved stars and exploding stars called supernovas. The fine molecular mix settles in the plane of the galaxy where over the eons, it gets re-compressed into new stars. While the dust is really sparse, it adds up over the light years to form a thick, dark band that appears to slice the Milky Way right in half.

Interstellar dust, arranged in huge patches and tentacles called molecular clouds, is silhoutted against the stars in the midplane of the galaxy NGC 891 in Andromeda. Credit: NASA/Hubble Space Telescope

That brings us back to the cumulus cloud photo. We see the dark dust because it’s silhouetted against a rich backdrop of stars just like the unlit cloud is silhouetted against the lit one. If you look around at other galaxies, you see these dark bands too. The inhabitants of planet Gloobo 3 orbiting the center of NGC 891 (above) would have their own version of the Great Rift. Should we meet someday, we’ll have something in common to talk about.

About one outstretched fist to the left of Deneb at the top of the Summer Triangle, you’ll spot a dark slash in the Milky Way sometimes called the Funnel Cloud Nebula. This string of dark, dusty nebulas form a funnel shape that’s easy to see from a dark sky. It’s pretty big — more than a fist from top to bottowm. Details: 20mm lens at f/2.8, 30-second time exposure at ISO 3200. Credit: Bob King

Another name for all these dark dusty patches is dark nebulas. Now that you’ve found your way into the Great Rift, it’s time to visit one of my favorite dark nebulas, sometimes called the Funnel Cloud Nebula. It’s an inky slash perpendicular to the Great Rift and visible just to the left or north of Deneb. The shape is dramatic, starting out wide at top and narrowing to a tip a fist below or east of Deneb. To see it even better, use the astronomer’s technique of averted vision, where you don’t start directly at it but instead sweep your eye around the nebula.

Once upon a time, the materials that eventually formed the sun and solar system were part of a larger dusty nebula. Now all is light and life. As you gaze into the dusty deep, consider its potential.

Here’s a small selection of pictures I thought you might enjoy from Wednesday morning’s total solar eclipse across east Asia.

The diamond ring shines during total solar eclipse observed from a ship sailing near Kita Iwojima, 650 miles south of Tokyo, Japan, at 11:26 a.m. on Wednesday, July 22, 2009. The diamond on the ring is the last bit of sun visible before totality. Credit: AP Photo/Kyodo News, Akiko Matsushita

A partial solar eclipse silhouettes birds surrounding a minaret of the shrine of Sufi Saint Bah-ud-din Zakria in Multan, Pakistan on Wednesday, July 22, 2009. Credit: AP Photo/Khalid Tanveer

Sadhus, or Hindu holy men, watch the solar eclipse through specially-designed viewing glasses in Allahabad, India, Wednesday, July 22, 2009. Credit: AP Photo/Rajesh Kumar Singh

The northern lights dance across the sky over Bemidji, Minn. during the early morning hours Wednesday July 22, 2009. Credit: AP Photo/Eric Stromgren, Bemidji Pioneer

We were cloudy here in Duluth last night but other parts of Minnesota, the Dakotas, Montana and Canada got a surprise show of the aurora borealis.  A high speed stream of particles from the sun called the solar wind tickled the Earth’s magnetic field, igniting the display. While there’s no telling if the lights will return tonight, it might be worth your while to take a look at the northern sky before you go to bed just in case. Let us know if you see them.

Multiple bands of aurora borealis as seen from Ward County, North Dakota Wednesday morning. Credit: Paul L. Meisel

This infrared (heat) image taken with the Keck II telescope in Hawaii shows the new feature observed on Jupiter and its relative size compared to Earth. The spot is bright because it’s warmer than its surroundings. Credit: Paul Kalas (UCB), Michael Fitzgerald (LLNL/UCB), Franck Marchis (SETI Institute/UCB), James
Graham (UCB)

I’m starting to see spots before my eyes. After Monday’s discovery of Jupiter’s black spot, now confirmed as an impact of a comet or asteroid, another amateur astronomer reports a unique bright spot on Venus. Planetary observer and long-time amateur astronomer Frank Melillo of Holtsville, New York, photographed an intense bright spot in the southern hemisphere of Venus on July 19. Melillo used an ultraviolet filter to make his sequence of images. Unfortunately we’re not likely to see the feature with our telescopes. "By eye, the UV light is too faint and only the camera can see it," said Melillo.

A sequence of pictures of Venus taken several minutes apart that show the new white spot. Credit: Frank Melillo

What makes it potentially very interesting is that the spot may be associated with volcanic activity on the planet’s surface. Beneath its perpetual clouds, Venus shows many volcanic landforms including lava swells and volcanoes but no one has ever seen activity directly. Melillo has been in touch with Venus expert Dr. Sanjay Limaye of the University of Wisconsin so in time we’ll have a better idea of just what happened.

Venus proves its ability at geometry by forming a right triangle with Mars and Aldebaran tomorrow morning. This map shows the sky in early morning twilight about an hour and a half before sunrise as you look northeast. Created with Stellarium.

Venus is in the morning sky and looks like a little gibbous moon through a small telescope. Tomorrow it will form a nearly perfect right triangle with Mars and Aldebaran, the brightest star in Taurus the Bull. 

The volcano Maat Mons is shown in this computer generated three-dimensional perspective of the surface of Venus. Radar data gathered by the Magellan spacecraft was used to penetrate the planet’s clouds and create the image. Lava flows extend for hundreds of miles around the base of the volcano. Credit: NASA/JPL