Meteorite masquerade Part II – Stardust on a shingle?

Micrometeorites collected from a South Pole water well in Antarctica photographed at high magnification in a scanning electron microscope. Credit: Taylor, Herzog and Delaney

Two weeks ago Brandon Dunovant, who lives in a Chicago suburb, got the idea to collect the grit that had accumulated on his roof in hopes of finding micrometeorites. Maybe you’ve heard of this experiment or even tried it yourself.

As you might guess, micrometeorites are tiny extraterrestrial particles, most under than 2 millimeters in size. They derive from comets, asteroids and even the moon and Mars, entering the atmosphere gently enough to avoid vaporization.

A selection of various spheres and other melted materials discovered by Dunovant on his roof. A tiny percentage may be extraterrestrial. Credit: Brandon Dunovant

Some remain unmelted, others partially melt. Micrometeorites deliver an astonishing 20,000 to 30,000 tons of extraterrestrial material to Earth every year. Enough to inspire some to search their rooftops for asteroid dust. Dunovant got out the hose, sprayed down his shingles several times over and collected the washed-off debris by tying a fine-mesh on the ends of his downspouts. Since many meteorites are attracted to a magnet, he swept through his gritty pile with a powerful rare-earth magnet to separate potential meteorites from twigs and other detritus.

After an entire day tweezing apart the more interesting specimens from shingle grit, what was left made Brandon’s jaw drop.

“What I was looking at were aerodynamically-shaped black metallic pieces, some perfectly round, some pancake shaped, some bars, a couple buttons” and more. Dunovant wondered if they might be melted bits of the Orionid meteor shower which had peaked that weekend.

Closeup view of Dunovant’s collection of melted or cooked debris he collected from his roof. Credit: Brandon Dunovant

Despite their wonderful shapes and magnetic attraction, Brandon’s debris – like the materials found by many others who’ve tried the same experiment – contain few if any meteoric particles. According to Dr. Michael Zolensky, who curates cosmic dust for NASA, a typical Orionid meteor particle strikes the atmosphere at around 50 miles per second “pretty much guaranteeing that all the comet dust gets oxidized, melted, and
vaporized.” Like a leaf taking forever to fall, even a surviving Orionid needs a few days to make the journey from 60 miles up to the ground. That makes it even less likely that Brandon captured one.

Then there’s the size issue. Most micrometeorites are between 1 and 10 microns (a mircon’s a millionth of a meter or 1/1000 of a millimeter) across with bigger ones up to 1/10 to 3/4 millimeter in size. The largest piece, an elongated bar, pictured in Brandon’s gem jar photos above is 3 mm across; most of the others are 1.5mm or smaller.

Typical micrometeorite. It’s 1/5 of a millimeter across. Credit: Taylor et. all

Zolensky and others who researched micrometeorites especially in populated areas have discovered that much of what’s collected by amateurs is a combination of particles released from power plants, smokestacks, commercial boilers as well as tiny balls of clay from distant dust storms. The power plant emissions contain magnetite which responds well to a magnet.

Collection experiments in much cleaner places relatively free of industrial pollution like the ices of the South Pole and Greenland have yielded fine samples of extraterrestrial dust in some though not in all cases. When chemically analyzed, scientists find the same minerals as our found in larger meteorites though weighted toward the carbon-richer carbonaceous types.

Dr. Zolensky

Zolensky looked for micrometeorites at the South Pole years back and essentially found none. More recently, he and a team collected possible cosmic dust on a remote Pacific atoll and expect to have to wade through millions of terrestrial grains to find even a few tantalizing spheres from the asteroid belt.

So Brandon and others who’ve dragged a fine-toothed comb through their roof debris may possibly have something in their cache of curious particles, but the odds of real micrometeorites are slim indeed. Questions still remain. What causes the apparent aerodynamic shapes? I’ve searched fly ash photos online and can’t find any that quite match those in Brandon’s images. If you’d like to try the experiment on your own to see what’s drifting down on your house, click HERE for detailed instructions.

Both today’s blog and yesterday’s Part I are tinged with irony because Dr. Peter Jenniskens realized he was too hasty in evaluating the “rock” found outside Lisa Webber’s house after the recent California meteorite fall. On closer inspection, he determined it was indeed a meteorite. Read more about his change of mind HERE.

Meteorite masquerade – Part I

The rock at left, found by Lisa Webber of Novato, Cal. is not a meteorite despite its convincing appearance. At right is the first real meteorite from the fall found by Brien Cook from the fall. Credits: Peter Jenniskens (left), Brien Cook

Disappointing news. The rock that Lisa Webber picked up after it bounced off her roof in the wake of the October 17 California fireball wasn’t a meteorite after all. NASA’s Peter Jenniskens, who helped in the identification writes this:

“We examined the rock with a petrographic microscope yesterday and quickly concluded it was not a meteorite. I sincerely thought it was, based on what appeared to me was remnant fusion crust. On closer inspection, that crust was a product of weathering of a natural rock, not from the heat of entry.”

A slice of Brien Cook’s meteorite displays metal and darker, shocked areas – classic meteorite characteristics. Credit: Brien Cook

Another specimen weighing 66 grams was found in the fall zone (Mill Valley area) by meteorite hunter Brien Cook on Monday, October 22.

Cook cut three slices from the rock earlier today, and there’s no doubt it’s the real item. The flecks of metal, the dark, shocked areas – if that’s not a meteorite I’ll eat a rock. To my eye it resembles the Park Forest (IL.)  fall of March 26, 2003 which was classified as an L5 chondrite, a fairly common type of stony meteorite.

Meteorites are tricky. Like a Halloween costume, external appearances can mask a rock’s true identity. The Webber stone appears partially covered in a black fusion crust of melted rock typical of freshly-fallen meteorites. It even stuck to a magnet. Jenniskens peered under its disguise to reveal its real origin – Earth.

While the news is a bit of a let down, it does teach us how science works. Much as we’d like to believe our hunches about this or that aspect of nature, careful analysis may prove otherwise. Scientists and meteorite hunters alike know this is simply part of the process and move on. One question remains. What made the ding in Lisa Webber’s rooftop?

Speaking of roofs and shingles, ever heard of looking for tiny meteorites by sweeping a magnet through the grit that falls on your roof? Tomorrow we’ll explore the possibilities in Part II.

** UPDATE Oct. 25: In light of Brien’s find, Dr. Jenniskens has taken a second look at Lisa’s rock and is now convinced it’s the real thing after all. “An apology may have been too hasty,” said Jenniskens. “Lisa’s find is a genuine meteorite.” Ah, the tortuous path one must walk to find the truth!

Sunspot group 1598 unleashes powerful flare

Big sunspot group 1598 in white light (left) this morning Oct. 23 and in ultraviolet light last night during the big X-class flare. Photos taken by the orbiting Solar Dynamics Observatory. Credit: NASA

Sunspot group 1598 is hiding behind its innocent name. Late yesterday evening (CDT), it cut loose a powerful X1-class flare, the fourth large flare since rotating around the eastern limb of the sun a few days ago. While not directed toward the Earth, should the spot group continue its cannonade of subatomic spew, we’ll soon be in the line of fire. That could mean high speed streams of solar protons and electrons messing with the magnetosphere and kindling auroral displays. I’ll update in the coming days.

Saturn, the sun and the Virgo’s brightest star Spica photographed earlier today by SOHO. Credit: NASA/ESA

Have you noticed that the planet Saturn’s missing from the night sky? That’s because it’s nearly lined up with the sun and lost from view in the solar glare. That’s not a problem for the orbiting Solar and Heliospheric Observatory (SOHO) which can see nearly to the sun’s edge with a special instrument called a coronagraph.

Saturn casts a wide shadow across its rings in this Cassini view which looks toward the darkened southern hemisphere of the night side of the planet. The Cassini probe recently celebrated its 15th anniversary in space. It was launched on Oct. 15, 1997. Click pic to read more. Credit: NASA

The device uses a metal disk to block the sun’s glare. SOHO observes from outer space with no atmosphere to reflect and scatter light, so it snap photographs of bright objects very near the sun. Saturn will be in conjunction or closest to the sun Thursday morning Oct.25, when it officially transitions from the evening to the morning sky. We’ll catch our first look at its sumptuous rings again at dawn next month. Of course you don’t have to wait for that either, thanks to the Cassini orbiter, now in its 8th year of loop de loops around the planet. Click HERE to see fresh Saturn photos anytime.

The moon Ganymede, which shines off to the right or east of Jupiter as seen in a typical telescope, casts a shadow on the planet’s cloud tops tonight Oct. 23. Created with Claude Duplessis’ Meridian

If you have a small telescope and want to watch Ganymede’s shadow stride across the planet, tonight’s the night.

Ganymede is the largest moon in the solar system at 3,272 miles in diameter. That’s half again as big as our own moon. Like any object that reflects sunlight, Ganymede casts a shadow, and tonight, beginning at 9:40 p.m. (CDT) you’ll see that shadow take a bite out of Jupiter’s south polar region. Over the next two hours the remarkably black, perfectly circular dot makes its way from one end of the planet to the other until departing the western limb at 11:41 p.m. (CDT). Astronomers call the event a shadow transit.

Ganymede casts the largest shadow of all of Jupiter’s moons, making it easy to see in almost all telescopes. If you could somehow fly a plane or arrange a balloon ride into the shadow and looked up, you’d see the sun eclipsed by the moon. Lucky Jupiterians!

California fireball fragment hits pastor’s home in Novato

Lisa Webber, meteorite finder.

Call it a message from heaven, but the first meteorite reported from the Oct. 17 fireball that lit up the sky over the San Francisco Bay area struck the roof of the Rev. Kent and Lisa Webber’s home in Novato’s Pleasant Valley neighborhood. Kent is pastor of Novato’s Presbyterian Church. Lisa works as the head nurse at the Department of Dermatology of the University of California, San Francisco Medical Center.

While relaxing at home last Wednesday night watching TV, she heard a boom and then something rattling around on the roof. She walked outside for a look, but didn’t find anything amiss … at first.

The dark-crusted rock found by Lisa Webber in Novato, Calif. weighs 63 grams or 2.2 ounces. The meteorite “appears to be a breccia with light and dark parts” according to Dr. Jenniskens. Credit: Peter Jenniskens

Later last week, Lisa’s curiosity was piqued by Dave Perlman’s article in the San Francisco Chronicle on Saturday, describing the NASA/CAMS meteor trajectory predicted impact area centered on Novato. Lisa decided to make a more thorough search and turned up an unusual rock near her side gate. A neighbor’s son suggested she test it with a magnet. She did and it stuck! Not a guarantee of a meteorite but a very good sign all the same.

Preliminary trajectory calculated by Peter Jenniskens from Sunnyvale and San Mateo College Observatory CAMS video data. The possible fall zone is shown in white and contained in the circle. Credit: Peter Jenniskens

Webber contacted Dr. Peter Jenniskens, who runs NASA’s Cameras for AllSky Meteor Surveillance or CAMS, an automated video surveillance program of the night sky in search of meteors.

Two CAMS cameras in different locations in the Bay area triangulated the fireball’s path. Based on the picture data, Jenniskens predicted a potential landing zone in funnel-shaped zone east of San Rafael, over Novato and toward Sonoma.

He and the Webbers’ neighbor Luis Rivera inspected the roof and found an impact pit or divot in a shingle that matched up nicely with the meteorite’s size. Usually the smallest meteorites drop first with the larger ones moving farther ahead before they fall too. Because the fireball traveled from SW to NE, Jenniskens thinks it likely larger fragments dropped nearer Sonoma northeast of Novato.

Luis Rivera points to the impact dent on the Webbers’ roof. Credit: Peter Jenniskens

“The significance of this find”, says Jenniskens, “is that we can now hope to use our fireball trajectory to trace this type of meteorite back to its origins in the asteroid belt,” said Jenniskens. The find also helps start the process of defining the orientation and location of the meteorite drop-zone or strewnfield.

Rain’s expected in the area today – something meteorites don’t like. Rain makes for rust and breakdown by erosion. Jenniskens hopes more of the space bounty comes to light before a soaking. If you’re in the area and think you’ve found a fragment of cosmic rock, contact him at this e-mail: Petrus.M.Jenniskens@nasa.gov

By the way, you’ll still see stories claiming this meteorite came from the weekend Orionid meteor shower. It didn’t. The fireball blew in from a completely different direction opposite Orion.

I want to thank Dr. Jenniskens for pictures and information from the CAMS site used for this article.

** UPDATE Oct. 23, 2012 — The rock is not a meteorite after all! As per Peter Jenniskens:

“We examined the rock with a petrographic microscope yesterday, says Jenniskens, and quickly concluded it was not a meteorite. I sincerely thought it was, based on what appeared to me was remnant fusion crust. On closer inspection, that crust was a product of weathering of a natural rock, not from the heat of entry.” He searched the ground again with Lisa Webber but failed to a meteorite. So how did that hole get in that roof shingle?

Orionid update; R Sculptoris sculpts a spacey spiral

Orionid meteor from near Tucson, Arizona this morning Oct. 21, 2012. Credit: Bill Vaughn

How was your Orionid experience? I hope the loss of sleep was rewarded by at least a few shooting stars. According to the International Meteor Organization’s quicklook data, the shower peaked overnight into this morning with a maximum of 29 meteors per hour. That preliminary number may change as more observers contribute reports. I wasn’t in a position to watch the shower outdoors, but did spend a half-hour peering at the sky from under a window shade from 4-4:30 a.m. before fog slowly blotted out the stars. My tally: one Orionid and one sporadic.

The Atacama Large Millimeter/submillimeter Array radio telescopes have revealed an unexpected spiral structure in the material around the old star R Sculptoris probably caused by a hidden companion star orbiting the star. A bright shell surrounds the spiral. Credit: ALMA (ESO/NAOJ/NRAO)

The European Southern Observatory (ESO) shared news and a photo earlier this week of an extraordinary celestial spiral unwinding around the red giant star R Sculptoris in the southern constellation of Sculptor. The photo was made using data gathered by the ALMA radio telescope array that studies light emitted by stars in the short wavelength (millimeter-long) radio wave spectrum just beyond infrared.

R Sculptoris may once have resembled the sun in size and brightness, but as it aged, the star used up the hydrogen fuel in its core. The fusion of hydrogen atoms under the ferocious heat and pressure in a star’s core converts it into helium, the same gas that pumped into balloons that float away when you let them go. A tiny amount of matter in the reaction – just 0.7% -  is transformed into pure energy a la Einstein’s famous E=mc² equation, and this is what makes stars shine.

Artist’s impression of the structure of a sun-like star and a red giant. The two images are not to scale – the scale is in the lower right corner. Helium burning in the shell around the red giant’s core produces the flashes that create the star’s dust shell. Credit: ESO

The core next contracts and compacts, heating the helium to the burning point. Helium provides the energy that powers the star while transforming itself via nuclear alchemy into carbon and oxygen  “ash”. These collect in the core, which is now surrounded by a thin shell of helium. Once again, pressure and heat inside the star are extreme enough to ignite the shell in a sudden “shell helium flash”. Old-age stars in the sun-size range experience these internal flashes, also called thermal pulses, every 10,000 to 50,000 years. Each flare-up lasts only 200-300 years.

The Hubble Space Telescope captured this picture of another red giant surrounded by multiple dust shells created by a companion star that orbits the giant every 800 years. Each shell formed 800 years after the other in sync with the companion’s period. Credit: ESA/NASA & R. Sahai

The blast from the pulse made  R Sculptoris expel a circumstellar shell of gas and dust into space. Astronomers estimate the most recent pulse happened about 1,800 years ago and lasted for about 200 years. Meanwhile, a companion star, not visible in the photo, shaped the outgoing  wind into a spiral structure through a combination of its gravity and orbital motion around the red giant.

A few billion years from now the sun will become a red giant star like R, shedding its outer atmosphere as a gigantic shell while pulses of helium ignition rock its interior. Since the sun’s a third or fourth generation star, having formed from the matter shed in part by previous red giants, it’s satisfying to know it will give back a little of what it borrowed in its youth to seed the next generation of stars.

Orionid meteor shower, Iridium flares and chance for auroras tonight

Map from Heavens Above showing the path of Iridium 96. The satellite will likely be invisible along much of the path but will flare at 5:36 a.m. Credit: Chris Peat / Heavens Above

Don’t forget to watch for flying Orionid meteors tomorrow morning before dawn. This annual shower peaks Sunday Oct. 21 when up to 25 meteors per hour originating from the constellation Orion might be visible from a dark sky site. No moon will mar the view. Head out around 4 a.m. and face south. I encourage you to share your observations in the comment section below.

While you’re out meteor watching, check to see if any of the Iridium satellites are visible from your location. The Iridiums, a group of some 66 satellites orbiting the Earth in a global ‘constellation’ 485 miles high, are used for relaying voice and data communications.

Normally Iridiums are too faint to see except in binoculars, but they have silver-coated Teflon antenna arrays that reflect sunlight like a mirror. When the angle between satellite and observer is right, a brilliant reflection of the sun from the antennas causes an Iridium to suddenly and spectacularly brighten for 5 to 20 seconds. For Duluth, Minn., the city dear to my heart, a -2 magnitude flare (bright as Jupiter) occurs at 5:36 a.m. tomorrow morning just below Orion’s Belt.

Iridium flares start out faint, rapidly brighten to peak light and then quickly fade away. This photo captured Iridium 96 a few years back. Photo: Bob King

Flares range in brightness from equal to the brightest stars all the way up to -8 or about 20 times brighter than Venus. They’re very exciting to see. The new maps at Heavens Above make finding where and when to look a snap. Log in, select your city and then click the Iridium Flares link. You’ll be shown a table of times and brightness. Just click the time to see the map.

The moon will be a thick crescent in the southwestern sky in Sagittarius the Archer tonight. The lunar terminator defines the crescent’s left side. Photo: Bob King

There’s also a chance for a small display of aurora borealis for the northern U.S. tonight through Monday as a high speed stream of solar wind particles buffets Earth’s magnetic field. If auroras show, they’re usually brightest around midnight – 1a.m. Keep an eye out while you’re meteor watching.

And don’t forget the moon, especially if you’re out early this evening.

Binoculars are excellent for bringing out the bigger craters and dark impact basins (lunar seas). Look along the lunar terminator, the arc-shaped border between day and night where shadows are longest and details most clearly defined, for best viewing.

NASA video of California fireball helps narrow fall zone

San Mateo College student Paola-Castilla photographed the fireball on a cell phone while stuck in traffic. Credit: Paola-Castillo

Either meteorites haven’t been found yet or nobody’s talkin’. But videos and eyewitness reports have allowed Peter Jenniskens, principal investigator at SETI Institute, to paint a more detailed picture of the fireball that blazed over the San Francisco Bay area Wednesday evening.

Jenniskens examined the images recorded by two CAMS (Cameras for AllSky Meteor Surveillance) cameras, one near Sunnyvale and another at San Mateo College. Data from two widely-spaced places gives researchers the ability to triangulate distances and altitudes of a meteor’s flight.


The fireball was so bright in NASA’s sensitive camera, it blew out the image, creating some trippy effects.

The cameras tracked the car-sized space boulder from when it started to glow at 53 miles overhead down to 24 miles, when it exploded to pieces. Top speed was 31,300 mph. Jenniskens believes there’s a “good chance a relatively large fraction of this rock survived.”

Peter Jenniskens

Before meeting its earthly fate, the meteoroid circled the sun with a perihelion (closest point to the sun) of 91.8 million miles in nearly the same plane as Earth’s orbit. Practically a next door neighbor. Jenniskens began his search the hills north of the Bay area Friday for meteorite fragments. Let’s hope he finds a few!

If you were (are) in the area and wish to share videos and photographs and report possible meteorite finds, please email: Petrus.M.Jenniskens@nasa.gov

Wassup with comets Hergenrother, L4 PanSTARRS and S1 ISON

168P/Hergenrother with its short but sweet tail pointing southeast continues to head north into Andromeda in the coming nights. This photo was taken on October 16, 2012 from Austria. Credit: Michael Jaeger

With Comet 168P/ Hergenrother still bright and perfectly placed high in the southeast at nightfall, I wanted to share an updated map for amateur astronomers with 6-inch and larger telescopes who’d like to track the comet. At around magnitude 9.5, it’s still the brightest fuzzball in the fall sky. For the next couple weeks, 168P will track from northern Pegasus into Andromeda as it slowly fades. Put it on your list of autumn night sky targets and you won’t be disappointed.

Comet Hergenrother’s position in Pegasus and Andromeda at 10 p.m. (CDT) nightly beginning Oct. 18. Stars are shown to magnitude 9.5 with the brighter ones labeled. Right click the image and save, then print a copy you can use at the telescope. North is up. Created with Chris Marriott’s SkyMap software

If you don’t see the comet this time around, you’ll have to wait 7 years for its return. Hergenrother is a short period  or periodic comet – one that orbits the sun in fewer than 200 years. That’s what the “P”  stands for in its name. Since its discovery in 1998 by American astronomer Carl Hergenrother, this feathery visitor is making its third observed trip. About 265 numbered periodic comets have been discovered to date. Unnumbered periodic comets number nearly 250.

Next in our comet lineup is comet C/2011 L4 PANSTARRS.  The “C” indicates a long-period comet or one that orbits the sun in more than 200 years. Two hundred? That’s nothing. L4 Pan-STARRS’s period is estimated at 110,000 years. Seeing it’s a once-in-a-lifetime experience for sure.

Comet C/2011 L4 Pan-STARRS sprouts a short tail in this photo taken on Sept. 9, 2012. Credit: Michael Mattiazzo

Right now, the comet looks like a small, dense cotton wad of light in southern Libra visible only from the southern hemisphere low in the west during early evening hours.

Pan-STARRS has plateaued at a dim 11.5 magnitude for the past few weeks, but is expected to slowly brighten through fall and winter. Northern hemisphere observers will have to be patient. We won’t spy it till next March because the comet will either be too near the sun or too low in the sky.

On March 9, 2013 , L4 PANSTARRS passes just 28 million miles from the sun. In the days before and after, solar heating will furiously vaporize ice and dust from its outer crust causing the comet to quickly brighten and develop a substantial tail. A few days later it pops into the evening sky and could shine as bright as -1 magnitude or nearly the equal of Sirius, the brightest star. That’s what the predictions say anyway. More information and a sky chart HERE.

Artyom Novichonok and Vitali Nevski at their observatory. The two discovered the comet in photos taken a half hour before dawn on Sept. 21, 2012.  Copyright: Vitali Nevski and Artyom Novichonok

At least we can see L4 Pan-STARRS with an 8-inch or larger telescope. Comet C/2012 S1 ISON at 17th magnitude dips way below the limit, though amateur astronomers using larger instruments and digital cameras have taken pictures of it. ISON was scooped up by Russian amateur astronomers Vitaly Nevski and Artyom Novichonok in the course of the work for the International Scientific Optical Network (ISON) Survey from near Kislovodsk, Russia on Sept. 21. I hope the two are eventually recognized for their discovery by having their names penned to the comet instead of a survey acronym. Other comets discovered during surveys have received the discoverer’s name. Why not this one?

S1 ISON creeps very slowly across the constellation Cancer in the morning sky this month and next and won’t become visible in typical telescopes until next September. On November 28, 2013, the comet passes just 800,000 miles from the sun. If it survives the encounter, it could become brighter than Venus and be visible in broad daylight. A few days after its near-death experience, ISON swiftly moves northward, becoming visible in both evening and morning skies.

Look closely and you’ll see a small, fuzzy coma around Comet C/2012 S1 ISON’s star-like nucleus in this photo taken Oct. 17, 2012. Credit: Rolando Ligustri

Ernesto Guido and the team of amateur astronomers at the Remanzacco Observatory in Italy have observed a large amount of activity in the comet’s nucleus this fall despite it being 558 million miles from the sun or farther than Jupiter. Mike Mattei, another amateur astronomer, reports that Earth will pass under the incoming leg of ISON’s orbit. If the comet is large and active, he predicts we could see an increase in meteor activity around January 14-15, 2014 spawned by dust cooked off the comet nucleus. Isonids anyone?

Though I’ve heard it’s possible ISON could rival the full moon’s brightness and become one of history’s “Great Comets” when it appears in both morning and evening skies in early December, I’m going to play the conservative card. I’ve been burned by a few comets that haven’t lived up to expectations, and besides, these creatures are unpredictable anyway. That’s their charm. It could easily be fainter or brighter, though the latter is preferable by far. More on the S1 ISON including sky charts HERE.

Oct. 17 California fireball may have dropped meteorites

Last night’s fireball over Belmont, California. The meteor first appears in the constellation Sagittarius and flamed across Ophiuchus and Hercules. The Summer Triangle of Vega, Deneb and Altair is at center and tipped sideways with north to the right. Credit: Wes Jones

Although the Orionid meteor shower’s up at bat this weekend, meteors fall anytime. Those that drop from a random spot in the sky and aren’t connected to a specific comet, as the Orionids are with Halley’s Comet, are called sporadic meteors. On any given night you might see 5-10 sporadic meteors per hour.

Yesterday evening October 17 at 7:42 p.m. local time, a brilliant sporadic meteor created a sensation over the San Francisco Bay-San Jose region where it briefly lit up the night sky like a thousand sparklers. The fireball broke into pieces as it fell, rumbled like thunder and left a glowing train (luminous trail) in its wake. To hear some of the comments posted on the American Meteor Society’s Fireball Report website makes you wish you were there:

“Awesome wild glowing train that turned to smoke.” – Karen

“It must have been really big and/or really bright because it created shadows on the street and the delay between the first shadows appearing and the delayed boom was maybe more than a minute. It was so bright it created shadows on the road from the overhead powerlines.” – Alicia

“The sound was stretched out and there were several pulses, like distant thunder, but louder. After it passed overhead it broke into a number of pieces which continued in the same direction at first and then some diverged near end.” – Frank

“The fireball was clearly breaking up as it flew across the sky. it made the tail appear like a firework sparkler with blue and red and yellow sparks flying off.” – Amanda Titterington


Security cameras at California’s Lick Observatory recorded the fireball. The round, silhouetted structure at left is the telescope dome and the lights in the background are from San Jose.

While some news articles are connecting the fireball to the Orionid meteor shower, it’s completely unrelated. How do we know? The photo above clearly shows it originating in the Sagittarius area located in the opposite part of the sky from Orion. Orionids fly out of Orion which at the time had yet to rise. Because of the meteor’s slow speed, its breakup into fragments and reports of thundery booms that shook residents’ homes after it disappeared from view, there’s a fair chance it may have dropped meteorites. Meteors rumble, thunder and boom when they enter the lower atmosphere traveling faster than the speed of sound.

Meteorite hunters will be checking Doppler weather radar recordings made in the fall zone to see if they can pinpoint a possible search location. Jonathan Braidman of Oakland’s Chabot Space and Science Center, believes that fireball fragments may have fallen in hilly terrain north of Martinez, Cal. For the latest news and reports, please click over to Dirk Ross’s excellent Latest Worldwide Meteorite / Meteorite News site.

See Jupiter, channel Galileo

The eastern sky around 7 p.m. on January 7, 1610, the night Galileo first pointed his telescope at Jupiter and discovered three of its brightest moons – Io, Europa and Callisto. The planet was in Taurus the Bull. Maps created with Stellarium

Every wonder what the sky looked like hundreds of years ago? Where the planets were? We know that the constellations change so slowly that even if you time-traveled King Tut out of ancient Egypt into the present, the star outlines he’d see would hardly differ from those in their own skies.

Unlike the stars, the naked eye planets are constantly on the move as they cycle through the zodiac constellations. Mars completes a loop of the sky in a couple years, Jupiter in 12 and Saturn in 29.5. Because the planets always take the same path through the heavens, they cycle through the same constellations century after century, millennia after millennia. Our pharoah would have no trouble picking out Saturn, Venus and the rest.

Jupiter’s is nearly in the same place in Taurus as when Galileo saw it almost 403 years ago. This map shows the sky facing east around 9:30 p.m. in late October.

While looking up information recently on Jupiter and Galileo I stumbled upon a fun coincidence. Jupiter resides in the constellation Taurus the Bull this season and rises high enough for easy viewing in the northeastern sky around 9:30 p.m. local time. As it happens, the planet shines in nearly the identical spot Galileo first observed it with his homemade telescope on Thursday evening January 7, 1610.

Portrait of Galileo. He was 45 years old when he turned his telescope toward Jupiter.

On the “first hour of the night” he pointed the 20x instrument at Jupiter in Taurus and was surprised to see the planet accompanied by three “stars”, two on one side and one on the other. Oddly, the stars lined up with the planet’s equator and the ecliptic, the path followed by the sun, moon and planets as they circle the sky. The next night Galileo saw something very unexpected. Here’s the passage from his journal:

“When on January 8th, led by some fatality, I turned again to look at the same part of the heavens, I found a very different state of things, for there were three little stars all west of Jupiter, and nearer together than on the previous night.”

A page from Galileo’s journal with drawings of Jupiter and its moons on those pivotal nights in early January 1610.

Since he knew Jupiter was moving from east to west at the time, the three bright objects should have been east of the planet or “left behind” if they were true stars. Over the next few nights he observed that Jupiter not only carried the stars along but that they changed position with respect to each other. On the 13th he spotted Jupiter’s fourth bright moon, Ganymede and by the following Friday, the 15th, came to the realization that he was seeing moons, like Earth’s moon, revolve around another planet. Right before his eyes sparkled a solar system in miniature.

According to the prevailing philosophy at the time, all heavenly bodies, including the sun and stars, revolved around the Earth. Galileo’s discovery of Jupiter and its four bright moons disproved that notion and lent weight to the newly emerging theory, championed by Copernicus, that the sun lies at the center of the solar system orbited by a family of planets.

What better way to celebrate a discovery that swept away the old, Earth-centered cosmos for something far grander than to stand outside tonight and contemplate Jupiter as Galileo did on that cold January evening 402 years ago.

The moon, Mars and Antares, the brightest star in Scorpius, about 20 minutes after sunset in the southwest.

A final note. Tonight and tomorrow night the waxing crescent moon will shine near the planet Mars and star Antares low in the southwestern sky at dusk. The planet’s about 4 degrees from the star and will be closest (3.6 degrees) this Saturday evening. Since they’re low and the sky still light, bring binoculars to help.