Stars fall on Alabama, meteorite hunters find them in a flash

Dr. Moody James shows where Ann Hodges was struck in the hip by an 8.5 lb meteorite that crashed through her roof (right). The photos appeared in the Dec. 13, 1954 issue of Life magazine.

It’s been 58 years since the last witnessed meteorite fell from Alabama skies. That one made a big impression. It was the first confirmed extraterrestrial object to injure a human being. On November 30, 1954 at 2:46 p.m. an 8.5 lb rock crashed through the roof of a home not far from the town of Sylacauga (sil-la-CAW-ga).

The grapefruit-sized Sylacauga meteorite that struck Hodges

It hit a radio console, bounced off the floor and struck the hand and hip of 31-year-old Ann Hodges who was asleep on the couch at the time. She awoke in surprise and pain thinking that a space heater had blown up, but when she noticed the hole in the roof and rock on the floor, Hodges figured the neighborhood kids had been up to no good.

Fortunately her injuries weren’t serious. Ann became a sudden celebrity; her photo even appeared on the cover of Life magazine with a story titled “A Big Bruiser From The Sky”. In 1956 she donated the meteorite to the Alabama Museum of Natural History in Tuscaloosa, where you can still see it to this day. A second meteorite from the fall weighing 3.7 lbs. was picked up the following day by Julius K. McKinney in the middle of a dirt road. McKinney sold his fragment to the Smithsonian and used the money to purchase a small farm and a used car. These days a single gram – if you can find any – costs about ten grand.

Ann and her husband Hewlett Hodges with the roof hole (left). At the time, the Hodges lived across the way from the Comet Drive-In movie theater. Cosmic coincidence.

For more on the fall including how the meteorite turned out to be anything but good luck for  Hodges, click HERE and HERE.

Fast forward to October 30, 2012. That evening at 5:30 p.m. (CDT) a boulder-sized meteor broke into pieces as it came booming over northern Alabama between Birmingham and Huntsville. The sonic boom created by the faster-than-sound meteorite even registered on several area seismographs. Doppler weather radar sweeps picked up a rain of cosmic fragments and meteorite hunters were soon on the ground including a six-member NASA team.

Front and back side of the first meteorite found from the Alabama fall found by the search team of Stephen Beck, Tommy Brown, Jerry Hinkle, and Robert Woolard. It’s provisionally named Addison. The stone is covered in black fusion crust, features a metal vein (upper right) and weighs about 60 grams or 2 ounces. Credit: Tommy Brown

Meanwhile another pair of hunters, Robert Woolard and his pal Jerry Hinkle of Little Rock, Ark., had just subscribed to Galactic Analytics, a service run by Marc Fries that retrieves and examines Doppler radar weather data to create maps of potential meteorite falls. With maps in hand, Hinkle jetted off to Alabama to meet up with Woolard’s other friends, Tommy Brown and Stephen Beck, and by the end of the day Saturday (Nov. 3), they’d found the first meteorite!

Weather radar data (in blue) indicates the trail of the meteorite that fell in northern California near Sutter’s Mill on April 22, 2012. Credit: Google Earth / Marc Fries

This is incredible for at least two reasons. First, it took only 4 days from fall to find, proving yet again that radar is quickly becoming the tool of choice for locating fresh-falling meteorites.

Doppler’s better than eyewitness accounts because meteors stop flaring around 30 miles up yet continue moving along their flight path. Called “dark flight”, this portion of a meteorite’s journey may be invisible to the eye but detectable by reflected radio waves. The closer we’re able to track potential meteorites before they strike the ground, the better our chances of finding them.

Meteorites are named after the closest city or landmark to where they’re found. Provisionally named “Addison”, this is the 11th witnessed meteorite fall of the year,  the most seen in one year since the new century began. So if it seems I’ve been writing a lot about meteorite falls lately, there’s a good reason for it. We’re on a hot streak!

Doris Day sings Stars Fell on Alabama 

Maybe you’re familiar with the 1930s tune Stars Fell on Alabama. It was inspired by yet another meteoric event – the spectacular 1833 Leonid meteor storm, when thousands of meteors an hour rained from the sky. Enjoy.

Be your own spaceship, visit Vesta and Ceres this month

Both the asteroid Vesta (left) and dwarf planet / asteroid Ceres are easily visible in binoculars this month and next as they travel through the early winter constellations Taurus and Gemini. Ceres is 590 miles in diameter; Vesta 326 miles. Credit: NASA, ESA

Would you like to pretend you’re riding piggyback on NASA’s Dawn mission hopping from the asteroid Vesta to its next target Ceres? All you need is a pair of 7×35 binoculars, a reasonably dark sky and a bit of imagination. November may not be the most pleasant month for skywatching in the northern hemisphere, but Ceres and Vesta, two of the brightest, biggest asteroids, are making their closest approach to the Earth in 2012 at nearly the same time. Surely this fortunate coincidence will inspire you to bundle up and brave the chill.

Vesta comes to opposition (closest to Earth) on December 9 when it will shine just below the naked eye limit at magnitude 6.4; Ceres reaches opposition only nine days later at magnitude 6.7. While the two almost-planets will be brightest then, they’re already nearly as bright and an easy catch now that the moon has retired from the evening sky.

Ceres is close to Eta Geminorum the next few nights. Later it passes under the open cluster M35. Positions are shown for 11 p.m. (CST) every five days. Stars are plotted to magnitude 9. North is up and west to the right. Maps created with Chris Marriott’s SkyMap software

Ceres is especially easy to spot over the next few nights since it keeps close company with the naked eye star Eta Geminorum in the toes of Gemini the Twins. Watch for it to buzz just south of M35 – one of the prettiest star clusters in the sky for both telescopes and binoculars – around Thanksgiving time. Consider their juxtaposition another reason to be thankful.

Ceres begins November at magnitude 8.0 but brightens to 7.3 by month’s end. Vesta meanwhile sidles up the south side of Taurus the Bull, home to the V-shaped Hyades star cluster and brilliant Jupiter. At magnitude 7.2 this week, you’ll find it a tad brighter and easier to see than Ceres. On the map, notice that Vesta glides through the northern edge of the bright, loose star cluster Collinder 65. Another bonus.

Vesta spends the next week crossing through the edge of the open cluster Collinder 65 as it works it way in Jupiter’s direction in the constellation Taurus. Stars plotted to magnitude 8. West is up and north to the left.

Both asteroids are presently traveling west – opposite their normal orbital motion – in what astronomers call a retrograde loop. The outer planets perform the same crazy backwards move around the time of their oppositions, too. Ceres and Vesta aren’t defying orbital mechanics. They only appear to move backwards because the faster Earth is passing them by, much like a car in the right lane appears to move backward as you pass it on the left. Soon enough, they’ll resume their routine eastern motion through the constellations as the viewing geometries of Earth and asteroids change.

A wide view of the sky facing east around 11 p.m. (CST) will help you get oriented when you look for the asteroids. The boxes show the general area covered in the more detailed charts above. Created with Stellarium

Dawn spent about a year in orbit around Vesta and finally departed late this summer with its sights set on a February 2015 encounter with Ceres. We learned lots at Vesta including that it differentiated into core and crust much like planets do. Rocks in its crust studied from orbit are a match for a suite of meteorites found on Earth called eucrites, diogenites and Howardites. No need for a sample return mission – pieces of Vesta have been falling from the sky for centuries.

Ceres is the largest asteroid – a dwarf planet actually – and another place altogether. By examining sunlight reflected from its surface, Ceres appears more carbon and water-rich than Vesta and a closer match to carbonaceous chondrite meteorites.

You can share in these discoveries and the road ahead by stepping outside the next clear night with binoculars and chart in hand. There’s nothing like seeing the real thing.

Let me know how you like the maps. I reversed the stars, going with black-on-white for greater clarity. Hopefully, they’re easier to read. To use a map, right-click and save to your desktop and then print out a copy. I’ll update them later this month, so you can continue to “mission along”.

Curiosity finds Mars may have lost much of its (h)air

On Halloween, Curiosity used its hand lens imager to shoot 55 high-resolution pictures that were stitched together for this self-portrait. You can see the four scoops in the sand (left) and the base of Mt. Sharp in the background. Click to explore a large, hi-res image. Credit: NASA/JPL-Caltech/Malin Space Science Systems

Mars’ atmosphere is 100 times thinner than Earth’s and composed mostly of choking carbon dioxide. The second most common gas found is argon which is also present in Earth’s atmosphere. The Mars Curiosity Rover recently took a sniff of Martian air and analyzed the contents. In the current early spring season in Gale Crater, CO2 comprises 95.6% of the air, argon and nitrogen 2% each and oxygen a mere 0.14%.  Curiosity also made a most interesting discovery. It seems that the heavier versions of carbon in the carbon dioxide as well as its argon are more common than their lighter cousins.

Each element in the periodic table from hydrogen to carbon to lead has an certain weight, called its atomic weight, based on the number of protons and neutrons in the atom’s nucleus. Nearly all the oxygen we breathe has 8 protons and 8 neutrons for an atomic weight of 16. Oxygen-16, as it’s known, comprises 99.762% of all the oxygen found in nature.

Table showing the five most abundant gases in Mars’ atmosphere measured by the Sample Analysis at Mars Instrument Suite (SAM) last week. Researchers will use SAM to check on seasonal changes in the atmosphere. Credit: NASA/JPL-Caltech, SAM/GSFC

Variants or isotopes of oxygen exist in nature that have the same number of protons but a different number of neutrons. Oxygen-17 has 9 neutrons and oxygen-18 has 10. Both are stable isotopes with properties that differ slightly from the common form of the element.

Curiosity found a 5% enrichment of heavier isotopes of carbon and 2,000 times as much argon-40 as argon-36 compared to isotope ratios when Mars and the other planets formed 4.5 billion years ago. The results suggest the top of Mars’ atmosphere may have been lost to space as the lighter versions of carbon and argon escaped or were picked off by solar radiation, leaving more of the heavier isotopes behind.

It’s been suspected for some time that Mars was once wetter with a much thicker atmosphere. Otherwise how could water have flowed as a liquid on its surface? The isotope ratios are a clue that Mars lost much of that early atmosphere, evolving from a wet world to a dry, cold planet with the thinnest of air.

The Martian soil examined by the Chemistry and Mineralogy (CheMin) instrument shows the “fingerprint” of the mineral olivine, shown here on Earth as tumbled crystals about 1/4-inch in size. The semi-precious gem peridot is a variety of olivine. Credit: Caltech

Also this week, Curiosity blasted a tiny sample of the Martian soil with X-rays and learned its composition is similar to volcanic soils in Hawaii. The X-ray diffraction technique reads minerals’ internal structure by recording how their crystals distinctively interact with X-rays. Scientists found olivine, feldspar, pyroxene and weathered volcanic glasses. None was unexpected based on previous examinations by other rovers and probes.

Mauna Kea in Hawaii shows an area of volcanic soils that contain minerals similar to those identified in the “Rocknest” region on Mars by NASA’s Curiosity rover. Credit: NASA/JSC

The soil and windblown dust sampled and analyzed represent more recent processing of materials on Mars compared to the outcrop of compacted pebbles that settled into place several billion years ago when water likely flowed across the floor of Gale Crater.

See the feisty fireballs of November’s Taurid meteor shower

At least four fragments are seen in this closeup of Comet Hergenrother’s bright nucleus taken early on Nov. 2, 2012 by the Gemini North telescope in Hawaii. The comet is currently 266 million miles from Earth. Credit: NASA/JPL-Caltech/NOAO/Gemini

November’s brightest comet – 168P/Hergenrother – continues to splinter. On Oct. 25, the Italian amateur astronomer team of Ernesto Guido, Nick Howes and Giovanni.Sostero  were the first to photograph a fragment shed from the comet’s bright head or nucleus using the 79-inch Faulkes Telescope.

Deeper observations with the National Optical Astronomy Observatory’s huge 323-inch Gemini North telescope on Mauna Kea in Hawaii now show at least four chunks broken loose from the nucleus:

“We have resolved that the nucleus of the comet has separated into at least four distinct pieces resulting in a large increase in dust material in its coma,” said Rachel Stevenson, a post-doctoral fellow working at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The more dust, the brighter the comet will appear since there’s more material to reflect sunlight. Hergenrother has faded some recently but still shines at about 10.5 magnitude (my estimate) and makes a fine target for amateur telescopes. Look for it high in the southeastern sky during early evening hours. Click HERE for a finder chart.

The Northern and Southern Taurid meteor showers are active in early November. Taurids are sparse but often bright and appear to radiate from the direction of the Pleiades star cluster in Taurus. Map shows the sky facing east around 11 ‘o clock local time. Created with Stellarium

Meteors come from comets. They’re the dust that gets boiled off the comet’s nucleus and pushed down the tail by sunlight. As a comet travels around the sun, it leaves a trail of gritty crumbs in its wake. Earth crosses some of these trails at particular times of year giving rise to familiar meteor showers like the August Perseids and December Geminids.  Dust slams into our atmosphere at thousands of miles an hour and quickly vaporizes, creating a glowing tube of light or meteor.

The Taurid shower contains larger comet crumbs than other showers. They travel relatively slowly – 65,000 mph – compared to the Leonids or Perseids and show as bright, slow fireballs. Credit: NASA

There’s more going on besides the election next week. Nov. 5-13 marks the peak of the Northern and Southern Taurid meteor showers. Showers usually hit maximum over a one or two day period, but the Taurids have a broad plateau lasting weeks. At peak, you might see around 7 meteors per hour.

You’re welcome to pull up a chair and face east or south for an hour, but you may be disappointed. Given their broad distribution, Taurid meteors are more likely something you’ll see while you’re outside at night doing something else.

While sparse, the dual showers are famed for their slow fireballs. If you see a brilliant, orange-colored meteor slowly arcing across the sky and can trace its path back toward the Pleiades, chances are you’ve caught a Taurid. I’ve seen a few over the years and remember them as not only bright but breaking into pieces as they burned up overhead.

Comet Encke and the trail of dust and debris it leaves behind in its orbit photographed by the Spitzer Space Telescope. Credit: NASA

The Southern Taurids peak on the 5th; the northern version on Nov.12-13th. Both showers are connected to Encke’s Comet or possibly a larger comet that broke into fragments in a manner similar to Comet Hergenrother. One of the fragments became Encke’s Comet while other chunks of debris may have evolved into the dual showers.

Meteor showers normally appear to radiate from one spot in the sky. The double radiant for the Taurids tells us this is an ancient meteor stream that has diverged and spread out over time from the accumulated gravitational tugs of the sun and planets. This year we’re expected to cross a thicker-than-usual stream of comet dust, so expect a slightly better chance of seeing your first Taurid meteor. The best time to watch is later at night after 11 o’clock, when Taurus and the Pleiades are high are in the eastern sky. For more details on the Taurids click HERE.

Whopper of a meteorite dug up in Poland

The moon meets Jupiter last night as seen from my yard in Duluth, Minn. Orion is rising at lower right and Taurus’ brightest star Aldebaran is to the upper right of the moon. Photo: Bob King

I hope you were able to see last night’s Jupiter-moon conjunction. It was one of those sky events that made you stare and wonder even if you didn’t know you were looking at Jupiter. Too bad the aurora didn’t join in the show. Maybe next time.

One of the meteorite craters, now a pond, in the Morasko Meteorite Preserve. Credit: Wikipedia

In 1914 during World War I soldiers digging trenches on what’s now the northern edge of Poznan, Poland uncovered metal fragments that were later found to be meteorites. Further study of the site turned up eight craters and numerous iron meteorites covered in clay and rust.

Magdalena Skirzewska stands in the bottom of the 7-foot-deep hole next to the newly found meteorite. Copyright: Lukasz Smula

The first one dragged out from the trenches weighed 171 lbs. More have been found over the years bringing the total up to around 660 lbs. When cut, polished and etched with an acid solution, Morasko meteorites display an attractive pattern of gleaming iron-nickel crystals. Scientists estimate that a large meteorite broke up after entering Earth’s atmosphere, pelting the Polish landscape with numerous fragments around the year 3000 B.C.

A 69 gram slice of the iron-nickel Morasko meteorite measuring about 2.5 inches across. Metal meteorites like this one are though to originate in the cores of asteroids. Copyright: Lukasz Smula

Today the craters are protected in a 136-acre park known as the Morasko Meteorite Reserve. A bus will drop you off a half mile away. The largest of the eight is 328 feet across and 36 feet deep. Last month, meteorite hunters Lukasz Smula and Magdalena Skirzewska used metal detectors to discover the largest specimen to date buried over 7 feet deep in the dirt. The two search for the Adam Mickiewicz University in Poznan.

What a happy couple! The husband and wife team Lukasz Smula and Magdalena Skirzewska pose with their spectacular new Morasko meteorite find. Click image to see a gallery of pictures of the recovery operation. Copyright: Lukasz Smula

With the help of friends they dug down to the meteorite and built a chain hoist to raise the massive rock from its hole. At 660 lbs. it’s a real whopper and the largest meteorite ever found in Poland. It now resides in a considerably cleaner environment at Adam Mickiewicz University where it’s under study.

11.7 gram slice of the stony Novato, California meteorite. The shattered or brecciated texture tells us that the original meteorite was probably shocked and crushed by an earlier asteroid impact. Piece is about 1-inch across. Credit: Brien Cook

One of the great truths of meteorite hunting is that the best place to look for space rocks is where they’ve already been found. Invariably, more await the thorough hunter. Congratulations to Lukas and friends on their wonderful find!

Closer to home, another couple meteorites from the Oct. 17 San Francisco Bay area fireball has been found, bringing the total to at least four. Searching has been anything but easy, and now that rains have fallen, new finds will be more difficult as the rocks begin to weather. While we still are waiting for an official name, this new arrival from the asteroid belt is now classified as an L6 (low iron) stony meteorite.

Jupiter-moon main dish with a side salad of aurora tonight

Jupiter and the moon tonight

Don’t forget. Tonight Jupiter and moon are in conjunction and only about 2 degrees (four moon diameters) apart. Watch for the pair to rise in the northeastern sky around 8 p.m. local time.

While you’re out, turn your gaze to the northern sky. Recent solar CMEs (coronal mass ejections) have set the Earth’s magnetosphere aquiver, dumping high speed particles into the upper atmosphere to create auroras. The sky lit up over Norway last night from solar storms. Sky watchers in the northern U.S. may have their turn tonight. I’ll update the blog later today if auroras are imminent.

Moonlight reflects off waves on Lake Superior Monday night. Photo: Bob King

On Monday evening I got out in time to watch the full moon rise over Lake Superior. Moonrise occurred just 10 minutes before sunset, giving sky watchers that key 15-minute “photo window” when moonlight is balanced by the fading light of day. How pleasing to the eye to see a pink moon against Earth’s purplish shadow.

The full Hunter’s Moon rises over the lighthouse at the end of the Duluth, Minn. ship canal Monday night. Photo: Bob King

Is Earth under attack by Google Sky glitches?

The “green asteroid” on Google Sky. All atlas photos in this article credit: Google Sky/DSS Consortium

Last June, a Web user happened to notice an artifact in Google Sky, a site that features several different star atlases you can drill down into to see closeups of nebulas, galaxies and stars. It’s a great tool even with its occasional foibles which we’ll explore in just a moment. Anyway, this guy claimed he found a new, green-glowing “asteroid” which no one else had seen before and posted it on Youtube complete with an ominous soundtrack. Claims later appeared that it was moving toward the Earth. As you’re no doubt aware, Youtube is nearly as good at disseminating nonsense as it is useful, funny and educational content.

The object’s appearance in Google Sky at left. Astronomical coordinates at lower left give its position or coordinates in the sky. Panel at right uses an original catalog, the DSS or Digitized Sky Survey. Nothing is visible at the same position. Click to learn more about the DSS.

A quick look at the “asteroid” will tell you right off it couldn’t possibly be a real object. First, asteroids move. During a time exposure, the green blob would have appeared as a line (or a series of repeated images depending on how the picture was taken), not a sharply-defined object. Even if by some exceedingly rare chance it was headed directly toward Earth and not off to one side or another, its edges would appear soft in the many minutes it took to expose the image.

Second, it’s too big to have been missed. Professional automated surveys as well as an army of amateur astronomers equipped to the teeth with big scopes and high-end electronic cameras would have picked up such a large object. You can measure the object’s apparent size by comparing its length to the known distance between stars on the atlas. I measured conservatively and came up with 30 arc seconds or 1/60th the diameter of the full moon.

The largest asteroid / dwarf planet Ceres photographed by the Hubble Space Telescope. It’s the next destination of NASA’s Dawn spacecraft mission in Feb. 2015. Credit:NASA / ESA

The dwarf planet Ceres, located in the asteroid belt, is 590 miles in diameter and measures about one arc second across. The green “asteroid” would be 30 times larger or 17,700 miles. That’s more than twice the size of Earth. Naaah … I don’t think we’d miss that one.

Of course, I’m assuming it’s located in the asteroid belt between Mars and Jupiter. If it’s farther, it’s even bigger. But if it’s much closer, it could look bigger but in reality be much smaller. Ah, but there’s the rub again. If it’s closer, it would appear to move faster and make an even more obvious trail during a time exposure.

Finally, you can go back to check the original source catalog. When you do, you’ll discover there’s nothing at all at the scary green asteroid’s position. As for it moving toward the Earth, even if it was real, you’d need more than one image of it to know in what direction it was moving.

Another malevolent object on Google Sky? No, it’s a scratch on a photographic plate used to compile the interactive atlas.

So what is it? Probably a piece of fuzz or maybe a defect in the photographic plate used to take the picture or some sort of glitch that popped up when Google Sky was stitched together by digitizing and compiling photos from original catalog sources like the Sloan Digital Sky Survey and Digital Sky Survey Consortium.

Just for fun, I poked about Google Sky to see what else I could dig up that looked menacing and was delighted to stumble across a wonderful assortment of oddities, a literal zoo of weird flares, scratches, fuzz, blobs, overexposures and more that at first glance might be used by the overzealous to announce a new planet, UFO or world-ending asteroid. Sharpness was a dead giveaway in most of the artifacts. A real, extraterrestrial object would trail or show multiple images during a time exposure.

And that’s my point. Before jumping to conclusions and tossing out over-the-top “theories” about some oddity in a photo, it’s important to consider logical alternatives, gather background information and if necessary, go back to the original source. Google Sky has known problems with missing chunks of data during the digitizing process, over and underexposed pictures, flares and lots more, but for all its flaws, it’s fun and useful. Now on with the show!

The Attacking Space Spider. This is one of many internal reflections caused by a nearby bright star. It’s a silhouette of the outline of the diagonal mirror and its holder (called a ‘spider’) inside the telescope.

The Blue Amoeboid. Most likely a harmless piece of dust or fabric.

Attack of the Borg. Probably another kind of internal reflection.

Triangle UFOs. More flares caused by overexposure of the bright stars pictured.

Red Rectangle of Death. Not sure what this is but it’s another artifact, one of many in Google Sky.

The Fatally Flamboyant Flower Pot. More internal reflections / overexposure from a bright star.

Wheat Check Cereal Monster. Not sure (probably bad data) but yet another tasty artifact.

Piece of sky the government doesn’t want us to see.  Not really. There are lots of these little squares  of missing data scattered about Google Sky. It’s not a deliberate attempt to hold back information, just data lost in the complicated atlas-stitching process.

Dust is probably the culprit once again for this Figure 8.

I only spent about a half hour looking for artifacts. There are many more. If you do see something in Google Sky that makes you wonder, you can check it out by using the Aladin previewer, which uses maps from the original sources without the errors introduced through stitching. Type in the object’s coordinates – called right ascension (R.A.) and declination (Dec.) – in the target box and press Go. For instance, the coordinates of the featured asteroid glitch are R.A. 5 11 33.7, Dec. -12 50 30. You can also use the Simbad Astronomical Database to search a whole variety of original catalogs and atlases. More information on Google Sky glitches can be found HERE.

Waning moon stalks Jupiter as Halloween approaches

The waning gibbous moon heads toward Jupiter in the next few nights. The two will be closest – only 2 degrees apart – the day after Halloween. The map shows the sky facing east around 9:30 p.m. local time. Created with Stellarium

Jupiter doesn’t know it, but the stealthy moon is on track to make a close approach to the planet this Thursday night. Tonight you’ll find the waning gibbous moon in edging into the constellation Taurus about one outstretched fist to the right of the Seven Sisters or Pleiades. Since it’s only one day past full, you’ll probably need binoculars to see the cluster. On Thursday, Jupiter and the slimming moon combine forces to shine with a mesmerizing radiance in the northeast around 9:30 p.m. and later.

Jupiter’s innermost bright moon Io moves into the planet’s shadow starting at 11:10 p.m. CDT this evening. Even a small telescope will show the eclipse. Create with Meridian software

If you have a telescope, you’ll see Jupiter’s moon Io to disappear as it’s eclipsed by Jove’s giant shadow. Eclipse occurs at 11:10 p.m. (CDT) tonight Oct. 30. Start watching a few minutes before that time. By 11:15 the moon will be gone.

Jupiter Wednesday night Oct. 31 at 9:30 p.m. (CDT) with Io’s shadow transit already in progress. South is up in both Jupiter panels. Created with Meridian software

Halloween night offers up yet another telescopic treat. As soon as Jupiter’s up in the east, you can follow the progress of Io’s inky shadow as it tracks across the clouds of the planet’s southern hemisphere. The event is called a shadow transit.

It begins at 8:18 and wraps up at 10:28 p.m. If you return at around 11:15 p.m. you’re in for another surprise – Io itself will exit the west side of the planet and appear like a bright pearl pinned to Jupiter’s limb.

Jupiter on Oct. 14 with the shadow of Io visible as a dark dot inside the planet’s limb. The two prominent stripes are the north and south equatorial cloud belts. Click image to see the video of Jupiter rotating. Credit: Damian Peach

Amateur astronomer and astrophotographer Damian Peach, who takes some of the finest, most detailed pictures of the planets and moon, recently compiled a sequence of photos of Jupiter made between Oct. 10 and 13 into a very cool animation. Click the link to watch an entire 9.8 hour rotation of the planet condensed into less than a minute. Peach hails from the UK and uses an 11.8 inch (30cm) Meade Schmidt-Cassegrain for his photography.

Hurricane Sandy gets an unwanted boost from today’s full moon

Last night’s nearly full moon finds a break in the clouds as it shines over Lake Superior. The small ring of color centered the moon is called a corona. Photo: Bob King

Yikes! Normally I’d be thrilled to announce that tonight’s the Hunter’s Moon, the full moon named after the hunting season that traditionally begins after the harvest. While the moon will rise around sunset and shine the night long in Aries the Ram, it offers little solace to the people living along the east coast of the U.S. Never mind that the moon will be hidden beneath rolls of clouds spun out by Hurricane Sandy. The real concern is tides. Full and new moon are when tides are highest.

Hurricane Sandy bears down on the U.S. Atlantic coast in this satellite photo taken yesterday. Credit: NOAA/NASA

Tides are a normal occurrence along the Eastern Seaboard but those from the full moon are 20 percent higher than normal tides. That wouldn’t necessarily be a bad thing except for timing. The combined influence of the moon and sun today and tomorrow will magnify the hurricane’s expected storm surge adding insult to injury. Water is expected to rise 4-8 feet along the New Jersey to Connecticut coasts leading to massive flooding and beach erosion.

“A gravitational lag usually causes the highest tides to come a day or two after every full moon,” says Joe Rao, a meteorologist with News 12 TV (Long Island) and astronomy enthusiast. That could mean Tuesday might be the worse day.

The moon’s gravitational pull creates tidal bulges of water on both sides of the Earth. Credit: Mike Guidry, University of Tenn. (csep10.phys.utk.edu/astr161/)

Tides have been a fact of life ever since the moon was fashioned from the debris created when a Mars-sized asteroid sideswiped Earth some 4 billion years ago. The gravitational pull of the moon and sun cause the tides. In spite of its much smaller size, the moon’s the stronger puller because it’s so much closer than the sun.

The moon’s gravity causes the oceans to bulge in its direction. A second bulge is raised on the opposite side of the globe because the moon pulls the Earth toward it and away from the water on the farside. Since the planet is rotating while this is happening, there are two high tides and two low tides a day. While the physics of tides is more complicated than I’ve described that gives us a basic understanding.

The strongest high tides happen at new and full moon when the sun, Earth and moon are all in a line. The weakest tides occur at the quarter moons. Credit: Mike  Guidry, University of Tenn. (csep10.phys.utk.edu/astr161/)

When the moon and sun line up on either or the same side of Earth, their combined gravity  create high or spring tides (‘spring’ here derives from the German verb ‘springen’ - to jump). Either lineup has approximately the same strength.

The lowest high tides, called neap tides, occur during quarter moons when the sun and moon are at right angles to one another. The sun’s gravitational force partially cancels out the moon’s and the difference between high and low tide reaches a minimum.

Hurricane Sandy photographed by moonlight early Sunday morning. Lights from cities near and along the East Coast are visible. Credit: NASA/Suomi NPP

So twice a month – at full and new moon – the sun re-enforces the moon’s pull to create spring tides, and twice a month at the quarters, the sun thwarts the moon’s pull and we get neap tides.

The highest of the high tides – called perigean spring tides – happen when the new or full moon is at perigee or closest to Earth. Its gravitational pull is felt most strongly at those times. We can be grateful that the Hunter’s Moon is only a few days from apogee, its most distant point from Earth, otherwise the news for the East Coast would be even worse. Let’s hope everyone gets through this big storm safely.

Paparazzo Curiosity snaps photos of Martian rock stars

Curiosity took this photo of several rocks with fascinating, wind-sculpted textures at the Rocknest site on Oct. 24, 2012. Click this and the other images for large versions. Credit: NASA/JPL-Caltech

Hungry for fresh photos from Mars, I went digging around the Curiosity mission’s raw image archive this weekend and found some amazing portraits of rocks. The rover remains parked next to a ripple of sand at the “Rocknest” site as it chemically analyzes samples of Martian soil scooped up earlier this week.

Two very pitted, chunky-textured Mars rocks photographed by Curiosity’s mastcam. Credit: NASA/JPL-Caltech

Intense erosion by wind-blown sand is apparent in some of the rocks as fluting, parallel grooves and severe abrasion. We see similar markings on boulders subjected to steady, same-direction winds here on Earth. We’ve all noticed trees that grow bent in one direction from prevailing winds, often from the west. Steady, uni-directional winds leave their mark in many ways.

Closeup of the 2-inch trough left in the sand by Curiosity’s scoop. A Mars sand sample is being analyzed inside the rover this week. Mars’ soil, which is largely composed of eroded volcanic rock, is covered in a powdery layer of reddish oxidized iron dust that formed when the planet was wetter than it is now. Credit: NASA/JPL-Caltech

Scientists hypothesize that Mars was much warmer and wetter several billion years ago. Rivers likely coursed across its surface including the now dry Peace Vallis, an ancient stream that winds down the wall of Gale Crater where Curiosity sits. Over geologic time, flowing river watercourses and lapping waves from lakes or oceans erode rocks into sand and clay. When the rivers went dry, sand would have been picked up by the whistling Martian winds and blown across the landscape, abrading rocks. By studying erosion patterns in the boulders pictured, scientists can learn something about the prevailing winds of the planet’s long-ago climate.

These rocks, photographed on Oct. 19, 2012, show evidence of layering, possibly from ancient lava flows. Credit: NASA/JPL-Caltech

How old are the grooves and pits we’re seeing? Hard to say without further study, but using the meteorology instruments on Curiosity, scientists can compare current wind speeds and wind direction with that inferred from the rocks to see whether they’re related or not.

More fluting on rocks likely carved by windblown sand. Credit: NASA/JPL-Caltech

Even though “they’re only rocks” it’s satisfying to get one’s nose right into the Martian landscape. They photos are high enough quality it’s not hard to imagine being there provided you bundle up. Although it’s still late winter at Gale Crater, air temperatures as measured by Curiosity’s Remote Environment Monitoring Station (REMS) have passed the freezing mark on more than half of the Martian days. The hottest temperature recorded to date is 43 degrees F, four degrees warmer than my thermometer registered at noon today and warmer than expected for Martian late winter. At this rate highs could reach into the 60s or 70s by summer.

A wind-sand chiseled boulder in Death Valley (left) and a similar wind-worked rock on Mars photographed by the Spirit Rover. Rocks sculpted by wind-blown sand or ice are called ventifacts. Credit: Daniel Mayer (left) and NASA

Just make sure you get your rock hunting done in daylight. Temperatures drop rapidly after sundown in the planet’s thin atmosphere, bottoming out around -94 F at dawn at Rocknest. On Tuesday Oct. 30 starting at 1:30 p.m. (CDT) NASA will host a live media teleconference with the latest update from the Curiosity mission. Hopefully mission science staff will have information on the composition of the first soil sample.