Monthly Archives: May 2012

Don’t miss next week’s rare and wonderful transit of Venus

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The moon will be in conjunction with the Saturn and Spica duo tonight. The view shows the sky at nightfall facing south. Created with Stellarium

Splashdown! The SpaceX Dragon cargo ship landed at departed the space station earlier this morning and landed safely in the Pacific Ocean off Baja California some 560 miles south of Los Angeles 10:42 a.m. CDT.  Once recovered by ships at sea, the capsule will be retrieved and the scientific equipment packed away by the astronauts removed. Nice to see the mission end as successfully as it began.

Tonight be sure to watch a very cool conjunction of the gibbous moon, Spica and Saturn. The three gather routinely once a month in different configurations as the moon rolls by, but this time they’ll be in a straight line one under the other around 10 p.m. CDT.

Venus in transit near the edge of the sun's disk during the June 8, 2004 transit. Photo: Bob King

An even more remarkable alignment occurs next Tuesday June 5 from mid-afternoon through sunset across the Americas when Venus crosses directly in front of the sun. This very rare event, called a transit, happens at intervals of more than 100 years.

What’s nice is that when it does, we get a pair of transits separated by a just a few years. The last one happened on June 8, 2004.

My younger daughter Maria and I at the 2004 Venus transit in Tower, Minn. Not shown are the many mosquitos that enjoyed our visit. Photo: Bob King

That June morning, it was storming like crazy in and around Duluth, Minn. My younger daughter Maria wanted to come along, so I woke her up around 3 a.m. and explained we’d have to drive north as quickly as we could to find clear skies. She got dressed without hesitation, and we were soon on our way. 80 miles later, not far from Tower, Minn., we pulled off a road just as the rising sun cleared the trees at 6. For 20 minutes we watched the little black dot of Venus, plainly visible with naked eye through a safe solar filter, creep to the sun’s edge and then disappear, not to return for another 8 years.

World map showing where and what time of day the transit is visible. For a much larger version, please click on map. Credit: Michael Zeiler, eclipse-maps.com

Here we are 8 years later and it’s transit time again. This go-around, Venus crosses the sun during afternoon hours on June 5 for the Americas. European sky watchers will see it for a short period of time after sunrise June 6 Central European Time, while the entire event will be visible across the Pacific Ocean, eastern Australia, much of China and all of Japan.

If you're able to put your binoculars on a steady mount, the projection method is a good one for viewing the transit. Photo: Bob King

Unlike a solar lunar eclipse, when the moon passes in front of the sun, the transit lasts some 6 1/2 hours because Venus is much further from Earth than the moon and appears to move much more slowly across the sky. It also has a smaller profile – only 1/30 as big as the moon.

This will be a leisurely event that can be enjoyed any which way provided you have a safe solar filter like a pair of eclipse glasses or a #14 welder’s glass.

The black drop effect is caused by a slight smearing of Venus by turbulence in the Earth's atmosphere combined with imperfect telescope optics.

At 1 arc minute in diameter, Venus will be visible as a tiny but distinct black dot against the bright sun. Binoculars, either wrapped with filters or used to project the sun’s image on a piece of white cardboard, will provide a more satisfying view. Telescope owners can thrill to watching the planet slowly enter the sun’s face. Just before Venus “separates” from the inner edge of the sun and again on its departure, watch for the black drop effect, when a black ligament appears to connect the planet to the inner limb of the sun. If the atmospheric seeing is good, observers may even see the slightly hazy appearance of Venus’ own thick atmosphere.

Venus travels from east to west across the sun next Tuesday. Times shown are Central Daylight for Duluth, Minn. and mark the planet's entry and exit points from the sun. Add an hour for Eastern, subtract one hour for Mountain and two hours for Pacific times. Illustration: Bob King

I can’t wait for Tuesday and hope you’re excited about it too. The event starts a few minutes after 6 p.m. Eastern time, 5 p.m. Central, 4 p.m. Mountain and 3 p.m. Pacific. Maximum transit, when Venus is as deep into the sun as it gets, happens around 8:25 p.m. CDT or about half an hour before sunset here in Duluth, Minn. Like the partial solar eclipse of two weeks ago, photo opportunities around sunset should be excellent.

Click HERE for a table listing the transit start, maximum and end times for a list of U.S. cities, HERE for Canadian cities and HERE for the rest of the world. Times vary by only a few minutes across the U.S. and Canada. Be aware that the times for Memphis and Minneapolis are incorrectly shown as Eastern. Subtract an hour for the correct one. Here’s another interactive time link.

I’ll have another installment on the transit in the coming days, so please stop back.

Enjoy a berry nice lunar eclipse on Monday morning

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Mmmm ... tasty. A chocolate-covered strawberry hints at Monday morning's lunar eclipse. Credit: Duluth News Tribune

I like my strawberries dipped in chocolate, but a Strawberry Moon dipped in Earth’s shadow sounds almost as tasty.

On Monday morning before sunrise, much of the U.S., Canada, Central and South America will see a partial eclipse as the moon glides silently into Earth’s shadow just two weeks after the recent solar eclipse.

As eclipses go, this one is very modest. Only 37% of the moon will be covered at maximum. How big of a nibble you see depends on where you live. The northeastern U.S. will have no eclipse at all, since the moon sets and sun rises before the event even begins.

Lunar eclipses only happen at full moon, when the moon is opposite the sun and passes into Earth's shadow. The outer shadow or penumbra is lighter because a portion of the sun still shines there. The sun is completely blocked by Earth from within the dark umbra a bit of light bent around Earth's rim.

Across much of the Midwest and South, the moon will set around sunrise while still in partial eclipse. Westerners will see the maximum of 37% covered and the start of the moon’s exit from Earth’s shadow.

Sky watchers in Anchorage, Hawaii, the Pacific and eastern Australia can watch the event from beginning to end.

Earlier this month, the new moon passed between the Earth and sun giving us a partial solar eclipse.

The path of the moon through Earth's shadow Monday morning before sunrise. Penumbral shading along the moon's lower left edge should be visible around 4:30 a.m. Credit: Tom Ruen with my own additions

Monday morning, the full moon will glide behind the Earth and into the planet’s shadow. The shadow has two parts – a milk chocolate outer layer called the penumbra and the dark chocolate central core or umbra.

Sunlight still filters into penumbra, so it’s not as dark as the umbra, but midway through it, the moon’s lower left edge – the side closest to the umbra – will appear lightly shadowed in gray, giving it a blunted appearance.

The first taste of real chocolate begins at 5 a.m. Central time. For where I live in Duluth, Minn. careful planning will be required. The partial eclipse begins only 24 minutes before moonset in bright twilight with the moon just 2.5 degrees high in the southwestern sky. You’ll need a wide open view and good weather to see it.

The eclipse from Duluth, Minn. and Kansas City shown shortly before sunrise for both cities. Kansas City's location further south and west will allow sky watchers there to see near the maximum covered before moonset. Duluthians will see a smaller percentage. Created with Stellarium.

While the moon’s low altitude can be a drawback, the bright side is you’ll have a great opportunity to photograph it lined up with a favorite landmark. That’s not only true in Duluth but in many areas of the country. Pick a spot in advance, grab tripod and camera and arrive early.

A similar partial lunar eclipse was visible from Duluth, Minn. on July 29, 1999. Photo: Bob King

In addition to the pleasing sight of Earth’s shadow taking a bite out of the moon, observers can watch the shadowed portion change color. Sunlight from countless sunrises and sunrises along the rim of Earth is bent by the atmosphere, spilling into the otherwise inky black umbra and tinting the moon smoky shades of orange, yellow and red.

Since the moon is near the horizon for many of us, it will also appear unusually large thanks to the “moon illusion”, a curious trick our brain and eyes play on us when observing celestial objects very low in the sky.

Coverage map for Monday's partial lunar eclipse. Credit: NASA

Our next lunar eclipse, a minor one with the moon passes only through the outer penumbra, occurs on the morning of November 28. That’s it for the Americas until 2014 when we’re blessed with total lunar eclipses on April 15 and October 8. For more details on Monday’s eclipse click HERE; for upcoming eclipses click HERE.

25 minutes with asteroid 2012 KT42

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Two photos taken at different times this morning show how 2012 KT42 picked up speed as it approached Earth. In the left image, a picture was taken every 30 seconds starting at 11:48 p.m. CDT. Pictures for the right image were taken every 10 seconds starting at 1:06 a.m. Thanks and credit to: Rolando Ligustri

I set a snare and captured my asteroid this morning. 2012 KT42, a space rock estimated at 10-30 feet across, blew by Earth earlier today at a distance of only 8,700 miles, well below the altitude of geosynchronous satellites we rely on for communications around the globe.

Although it sounds Hollywood-movie-scary, the chance of a random asteroid hitting a satellite is extremely remote. If one were to be hit, the smack-down would far more likely come from one of the thousands of much smaller and more common meteoroids that occasionally arrive on Earth as meteorites.

I’ve seen near-Earth asteroids before but nothing like 2012 KT42. Sure they all look like moving stars, but this one took my breath away. In 40 years of sky watching, I’ve never witnessed anything beyond Earth move faster. My snare consisted of two parts: a chart with two possible paths and passage times and a telescope. After pointing the scope at where 2012 KT42 was predicted to arrive at 1:29 a.m. I sat and waited.

The glowing numbers on my watch dial indicated 1:23 a.m., then 1:26 and 1:28 a.m. No asteroid yet. But seconds later, there it was – a “star” moving like a flung rock entered the field of view stage right (east) and never slowed down. Interestingly, the asteroid showed up a minute early, possible due to a change in its orbit by Earth’s gravity.

I timed the asteroid’s passage. At 1:30 it moved the span of two full moons (one degree) in one minute. By 1:53 a.m., its speed had doubled to one degree every 30 seconds. At 64x in the scope, 2012 KT42 moved about as fast as the space station does when viewed with the naked eye.

My particular telescope and eyepiece combination gave me a field of view of one degree, so you can imagine how often I had to push the scope to keep track of the asteroid. If I’d taken my eye away from the eyepiece for a minute, I would have lost it for good.

Pictures of the asteroid 2012 KT42 taken at discovery. Credit: Catalina Sky Survey/Mt. Lemmon Observatory

While tracking the speedy missile, I happened to look up toward my garage, and it occurred to me that if it were possible to lasso 2012 KT42 and bring it down to Earth, I could park it there with room to spare.

With that image in mind, I returned to the eyepiece and tried to comprehend seeing something that small move so quickly across the sky. A few miles closer and it would be a shower of meteorites.

One other interesting aspect of watching the flyby was the change in the asteroid’s brightness. It was never constant for long. At 1:30 a.m. it varied between 12th and 13th magnitude in an irregular way; by 1:50 a.m. it was varied from about 11 to 12th. I assume this was because it had an irregular shape and was rotating. For the sake of explanation, let’s assume 2012 KT42 were shaped like a cigar.When brightest, we’d be seeing the cigar broadside with a maximum amount of surface exposed to sunlight; when faintest we’d see only the butt of the cigar. The brightness variations may also have been due to the changing angle of sunlight on 2012 KT42 as it zoomed across the sky.

Nothing escapes the clouds. Not even asteroids. By 1:53 a.m. the morning’s clear sky quickly turned overcast and I finally lost the asteroid as it flitted between ribbons of white mist. It was a wonderful ride, those 25 minutes.

Asteroid 2012 KT42 zips only 8,700 miles from Earth tonight

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2012 KT42 was nabbed as it move across the sky earlier today. Credit and a big thanks to: Ernesto Guido, Nick Howes and Giovanni Sostero

2012 KT42 was discovered earlier today May 28 by the Mt. Lemmon Survey’s 1.5-meter (59-inch) reflecting telescope north of Tucson, Arizona. The tiny asteroid was only 18th magnitude and estimated at between 10-30 feet wide. While posing no threat, it’s moving rapidly towards closest approach to Earth around 2:10 a.m. CDT tomorrow morning May 29, when it will fly by at the slim distance of 8,700 miles. That would make 2012 KT42 the 6th closest asteroid approach to date. Click HERE to see a list of Top 20 closest approaches.

Earth gets a visit from asteroid 2012 KT42 overnight. The diagram shows the time of closest approach. Credit: JPL/NASA

Savvy amateurs with 6-inch telescopes and larger should be able to see it shining between 12th and 13th  magnitude late tonight through tomorrow morning. Watch out though – the asteroid will move very rapidly across the sky. You’ll need to download its orbital elements at this site and put them into a sky-charting program, so you can make a detailed map to find and follow the zippy rock. Or … you can go to the same site, click the Ephemeris heading, select the date and time interval and then click the Generate Ephemeris button to create a list of positions you can hand plot on a sky chart.

The asteroid will transit across the face of the sun tomorrow for parts of Asia and Africa. It will only be about 6 seconds wide - very tiny. Click map for larger version. Thanks and credit to: Aldo Vitagliano

Once you do find it, don’t let go. You’ll be on a fast train. When closest, 2012 KT42 will be traveling at over 2 arc minutes per second. Two arc minutes is more than twice as big as Jupiter appears through a telescope. That’s plenty fast enough to see move in real time.

Between 1 and 3 a.m. CDT, 2012 KT42 will travel from the constellation Libra in the southern sky all the way to Auriga in the far north!

Viewers along a path that cuts across central Asia and Africa will see the asteroid transit the sun at around 5:10 CDT May 29. It’ll be interesting to see if anyone can spot it through a telescope given its minute size.

PANSTARRS – the next bright comet?

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Comet C/2011 L4 PANSTARRS photographed on May 18. Credit: Ernesto Guido, Giovanni Sostero and Nick Howes

Last June astronomers at the University of Hawaii announced they’d discovered a comet with the 1.8 meter (70.7 inch) telescope atop Mount Haleakala as part of the Panoramic Survey Telescope & Rapid Response System or Pan-STARRS. The survey’s goal is to photograph the entire sky several times a month in search of Earth-approaching comets and asteroids that could pose a danger to our planet.

At the time, Comet C/2011 L4 PANSTARRS (or PANSTARRS for short) was extremely faint and nearly as far away as the planet Saturn.

After more observations pinned down the comet’s orbit, predictions showed it would pass perihelion – its closest point to the sun – at a distance of 28 million miles on the evening of March 9, 2013. That’s close enough to vaporize a lot of cometary ice, releasing the dust needed to form a bright coma and tail.

Just how bright, no one can be certain. We all know how unpredictable comets can be; the break up and fading of Comet Elenin is just one recent example. But estimates based on the PANSTARR’s distance from the sun and Earth at the time of perihelion put it at magnitude 0 or as brilliant as Vega or Arcturus.

Comet C/2011 L4 PANSTARRS will appear in the evening sky just days after perihelion. The date shown here is March 12, 2013 about 40 minutes after sunset. The ultra-thin crescent moon will lie just five degrees to the north of the comet. Maps created with Chris Marriott's SkyMap software

Circumstances for viewing a bright comet couldn’t be better. PANSTARRS pops into the evening sky only a few days after closest approach to the sun. Moving rapidly northward, it soon becomes visible all night long from mid-northern latitudes in April.

PANSTARR's orbit is steeply inclined (84 degrees). Right now it's below the plane of the solar system (dark blue) but after perihelion next March its orbit takes it quickly above the plane (light blue). Credit: JPL/NASA

You might be wondering why I’d bother writing a blog about something happening 10 months down the road. Let’s just say I want as many amateur astronomers as possible to have the opportunity to see the comet early.

Die-hard comet observers have been photographing and observing the comet since late this winter, more than a year before perihelion. I’ll take that as a good sign that PANSTARRS is on schedule.

I sought the comet a week ago using a 15-inch reflecting telescope and was surprised at how easy it was to see. Located near the bright star Antares in Scorpius the Scorpion, I estimated the comet’s brightness at magnitude 12.5 (at discovery it was 19 — faint!). PANSTARRS was a very small but dense knot of light about 20 arc seconds in diameter with a faint star-like center. Its compact appearance is a good indicator of lots of dust activity in the comet’s nucleus – another positive sign for the coming apparition. A second look this past Saturday morning showed it smidge brighter yet.

Use this map to help you find the comet in your telescope. Antares is at left and the head of Scorpius is outlined. The comet is low in the southern sky from mid-northern latitudes. Stars shown to about 10.5 magnitude. PANSTARRS look like a very small "cottonball" with a brighter center at medium and high powers.

If you start observing now, you’ll have the pleasure of watching Comet PANSTARRS brighten and develop on its journey to perihelion and beyond. Following a comet night by night can be very rewarding, comparable to studying a species of bird to better understand and appreciate its behavior. For the moment, you’ll need a 10-inch or larger scope and dark skies but as the weeks and months advance,  it will gradually brighten.

Skywatchers in mid-northern latitudes will be able to follow PANSTARRS through early August before it’s too low to view and lost in the glow of evening twilight. Our next opportunity won’t be until next March post-perihelion. Southern hemisphere observers will fare much better with the comet high in the sky and well-placed for viewing for months to come.

To assist you in your quest, either download comet orbital elements for your favorite star charting program at the IAU Minor Planet Center site  or use the map above which shows the comet’s position around 11:30 p.m. CDT every five nights. PANSTARRS is still 325 million miles from Earth or more than halfway to Jupiter.

Comet Hartley 2 photographed by NASA's EPOXI mission. The bowling pin shaped nucleus is about 1.2 miles long. Jets of material, from ice vaporized by the sun's heat, are being ejected from the nucleus. Credit: NASA/JPL-CalTech/UMD

Returning to the question of the comet’s brightness, that may depend on whether it’s making its first or hundredth trip around the sun. On a first swingby,  exotic ices of nitrogen and carbon dioxide, long preserved in the deep freeze of the outer solar system, vaporize at great distances from the sun, making the comet appear unusually bright. If we’re not careful, we might extrapolate that behavior to the time of closest approach and predict a very bright passage. Unfortunately, once those ices are gone, the comet may have only a modest amount of water ice remaining for the sun to vaporize and not brighten as expected when closer to the sun.

Three types of orbits are possible for bodies in the solar system. Most orbit in ellipses around the sun. Credit: Oracle ThinkQuest Education Foundation

Comets that return time and again all have elliptical orbits around the sun like the planets but more stretched out or elongated. Comet PANSTARRS’ orbit appears for the moment to be nearly parabolic. A parabola is a sort of open-ended ellipse with one end near the sun and the other a return trip to infinity. Most comets on parabolic orbits come from the far edge of the solar system and have their orbits reworked by giant planets Jupiter and Saturn into very long but closed ellipses with orbital periods of hundreds of thousands to millions of years. PANSTARRS might be one of those “fresh” comets and putting on a good show now despite its distance. We’ll have to just wait and see.

Moon flies by Mars, space station flies at dawn, Venus flies away

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The first quarter moon along with Regulus and Mars light up the southwestern sky tonight. First quarter phase is one of the best times to see lunar craters in binoculars. Maps created with Stellarium

It feels like it’s been raining forever.  I have no hope of seeing the first quarter moon alongside Regulus and Mars tonight. That’s why I’m counting on you, fortunate sky watcher with clear skies, to be out there. Face southwest during late twilight and you’ll see the trio high up in the constellation Leo.

Remember how close Mars and Regulus were a month ago? They’ve since separated as the planet hurries eastward in its orbit.

Mars has faded, too. Look far to the left and high above the planet to see the similar-hued Arcturus.

Back in March, Mars outshone Arcturus. With its ever-increasing distance from Earth, the Red Planet has since shed more than a magnitude and now stands humbly in the great star’s shadow.

Mars on May 12. Credit: Damian Peach

Mars is very tiny even in a telescope with a disk only 8 arc seconds across (full moon is 3600 arc seconds). Determined amateurs may still be able to spot the shrinking north polar cap and larger dark markings like Syrtis Major. As the planet continues moving east, it will join Saturn and Spica in mid-August for a fine pair of conjunctions.

Summer’s been underway for the past two months in Mars’ northern hemisphere. Frozen carbon dioxide or dry ice vaporizes from the cap, causing it to shrink and develop dark rifts. As CO2 returns to the atmosphere, the world-wide pressure rises by 25% before the gas refreezes onto the south polar cap in southern winter.  On Earth, you could experience this spectacular rise in pressure by traveling from sea level to the top of a 9000 ft. mountain! Air pressure on our planet varies only a few percent as highs and lows come and go.

From the cupola on the space station, an astronaut photographed this Lyrid meteor burning up south of the Gulf Coast on April 22. Florida's at top and Cuba to the right. Credit: NASA

Now that the SpaceX Dragon cargo ship is docked to the International Space Station (ISS), we’ll have to wait until May 31, when the ship departs, for the next opportunity to spot the two together in the sky. Meanwhile you can still go out any morning in the coming week to see the ISS pass over your rooftop. Times below are for the Duluth, Minn. region. Click on Spaceweather’s satellite flyby site and enter your zip code or check out Heavens Above to find times for your location.  The station travels from west to east across the sky.

* Monday May 28 starting at 3:36 a.m. A high, brilliant pass in the northern sky.
* Tuesday May 29 at 2:44 a.m. Makes its first appearance high in the south. Very bright! Second pass at 4:17 a.m. in the northern sky.
* Wednesday May 30 at 3:24 a.m. in the north
* Thursday May 31 at 2:31 a.m. high in the north. Second pass at 4:06 a.m. in the north
* Friday June 1 at 3:12 a.m.  in the north
* Saturday June 2 at 2:19 a.m. and again at 3:54 a.m. in the north

Venus is low in the northwestern sky shortly after sunset this evening.

Seen Venus lately? It used to be so easy but now requires good planning. The bright planet is only about 5 degrees high in the western sky a half hour after sunset. You might even need to use binoculars to help you find it. Look to the northwest over the sunset point. Its crescent shape should be obvious using 7x magnification or higher. On June 5 it will pass directly in front of the sun in a rare event called a transit. I’ll provide a guide on how best to see it later this week.

New supernova in Virgo bright enough for modest telescopes

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Dragon berthed to the Harmony node of the International Space Station. Credit: NASA TV

The hatch between the newly-arrived SpaceX Dragon capsule and the space station was opened early this morning as the crew began today to unload food, clothes and batteries.

Astronaut Don Pettit commented on the “new car smell” and well-designed layout of the ship. They’ll reload the capsule with science equipment and send it back on its way to Earth soon. The commercial craft was designed to be re-useable;  routine flights to the space station are scheduled to begin in August.

Supernova 2012 cg is in the "V" of Virgo west of Epsilon Virginis and not far from Rho and 20 Virginis. Created with Stellarium

On May 17 the automated Lick Supernova Supernova Search (LOSS)  discovered a new supernova in the galaxy NGC 4424 in the constellation Virgo not far from the planet Saturn. Only 18th magnitude at the time of discovery and impossibly faint to see, the star has since skyrocketed to around 12.7, making it a worthy target for amateur telescopes 6 inches and larger.

Last night it outshone the galaxy’s own nucleus, which is comprised of at least several billion stars. That gives you an idea of how brilliant this exploding star truly is. The supernova is embedded within the galaxy’s hazy disk some 17 arc seconds east of center.

Supernova 2012 cg is 17" east and 1.5" north of NGC 4424's nucleus. The picture was taken by amateur astronomer William Wiethoff of Port Wing, Wis. on May 21. The numbers next to the stars below the galaxy are magnitudes. The higher the number, the fainter star. View is shown through a typical telescope with south up and east to the right.

Using a spectrograph, a device that breaks up a star’s light into a rainbow fingerprint of colors, astronomers have determined that 2012 cg is a Type Ia supernova. Before the explosion, the star was a white dwarf, a superdense, planet-sized object with the mass of the sun. Tiny but mighty, the white dwarf’s powerful gravity pulled material from a nearby companion star down to its surface.

In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to collapse and then explosion.

When a dwarf puts on enough pounds to exceed 1.4 times the sun’s mass, it can longer support itself and collapses and self-detonates in an explosion that blasts it to bits. Lucky earthlings can witness the incredible event from the comfort of their patios.

NGC 4424 is one of many galaxies in Virgo, so take your time using the map to arrive at the right one.

Star-hop from Epsilon to Rho to 20 and over to a trio of galaxies including NGC 4424. It shines 11th magnitude, and looks like a fuzzy patch. The supernova is the little star blazing inside it. Stars shown to mag. 9.5. Created with Chris Marriott's SkyMap software

Since 2012 cg was discovered early in the explosive phase, it brightened quickly and is still climbing. You can watch it change in the coming days and weeks by using the star magnitudes – direct from the American Association of Variable Star Observers (AAVSO) - shown in the photo above. That’s how I estimated the supernova’s magnitude at 12.7 last night May 25. For more information and photos, please stop by David Bishop’s Latest Supernovae site, the one-stop shop place for what’s shakin’ in the world of exploding stars.

Dragon hooks up with space station; Carbon’s journey from stars to Mars

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Dragon cargo ship approaches the space station earlier today. Click photo to watch a live feed of the docking. Credit: NASA

Drum roll and applause please! At 8:56 a.m. CDT this morning space station astronauts Don Pettit and André Kuipers successfully captured the SpaceX Dragon capsule with the robotic arm while flying 251 miles over northwestern Australia. Once berthed, the astronauts will unload about 1,200 lbs. of food and supplies and re-load Dragon with equipment. The cargo ship is designed to safely return to Earth. The mission is the first private, non-governmental venture to the space station.

Methane is one of the simplest organic molecules

Yesterday we met a star that puffs out clouds of carbon soot like a chain-smoker.  All carbon ultimately originates from the interiors of stars, where it’s created through the fusion of simpler elements. Released into space, carbon combines with other elements like hydrogen and oxygen to form organic compounds.

One of the simplest organic compounds is methane, composed of one carbon atoms linked to four hydrogens. While cows are prolific methane producers, the gas can form without any assistance from life. All you have to do is wander over to Uranus and Neptune to get a whiff. Both planets owe their blue color to the presence of methane in their atmospheres. So far as we can tell, no cows were involved.

Organic compounds are found in some meteorites, especially in the carbonaceous chondrite group that includes the Sutter’s Mill meteorite fall in California. More than 14,000 different organics including 70 amino acids and sugar have been discovered in the Murchison meteorite that fell in Australia in 1969.

Artist's view of the early solar system with the newly-formed sun at center. Planets coalesced from the remaining dust and gases in the surrounding disk. Credit: NASA

While life depends upon organic compounds for its existence, the carbon-based molecules form naturally in the raw vacuum in space when carbon (in the form of graphite), water ice and other materials stick together to form tiny interstellar dust particles. Gathered in large clouds and acted upon by their own self-gravity, these clouds collapse to form protoplanetary disks.

At their centers, where the density of material is highest, a star forms, while gas and dust in the outer part of the disk grow into individual planets. After a hundred million years of churning, bashing and kneading, a solar system is born.

During the process, ultraviolet sunlight, heat from radioactive element decay and liquid water provided the energy and materials to convert simple molecules into more complicated ones. 4.6 billion years later, occasional hunks of this original material land on Earth as carbonaceous meteorites containing a storehouse of organic compounds.

Meteorites and comets must have rained down constantly in the early days of our planet. The organic compounds they contained, not to mention what remained in the rocks of the early Earth, provided the vital materials needed for matter to make the leap from non-life to life. Exactly how that happened has yet to be answered.

This 4.5 billion-year-old meteorite ALH84001, is one of 10 rocks from Mars in which researchers have found organic carbon compounds that originated on Mars without involvement of life. It's 3.5 inches across. Credit: NASA/JSC/Stanford University

All this serves as an introduction to a recent examination of 11 Martian meteorites by a NASA-funded study. The meteorites span 4.2 billion years of Martian history, and all but one were found to contain large, complex carbon compounds indigenous to Mars. The molecules were enclosed in crystalline grains that formed in cooling magma, indicating they were created by volcanic activity over the planet’s long history.

One might be tempted to feel disappointment at the news. Far more exciting would be organic compounds left behind by Martian life forms. Some day that may come, but in the meantime we can relish the fact that Mars, like the Earth, started with a storehouse of simpler carbon-containing compounds inherited from the knock-around days of the early solar system and hammered out more complex versions once incorporated into the planet. Versions potential life could use as building blocks.

The Mars Curiosity Rover will study the floor and mountain peak of Gale crater after landing on Mars in August. Credit: NASA

With the Curiosity Rover set to land on Mars this August, the study will help scientists distinguish between carbon molecules formed by non-biological processes from those built by biology.

Matter can’t seem to help itself. Where energy is in abundance, as it is inside stars, collapsing dust clouds and geothermal sources like volcanoes to name a few, simple stuff invariably becomes more complex.

We’ve witnessed this by tracking carbon across the light years. Created within stars by the fusion of helium and released into space by stellar winds, it combines readily with oxygen and nitrogen to form the simplest organic compounds. Further processing during solar system building creates more complex forms which rain down on planets as meteorites and comets.  Over the course of geologic time, these link up with other elements into ever more diverse and complex forms, setting the stage for the formation of life. A messy and wonderful business if there ever was.

The mysterious disappearing act of R Coronae Borealis

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R Coronae Borealis is tucked inside the crown not far from the bright star Gemma (JEH-mah). Maps created with Stellarium

Stars are big and live long lives. You need patience to see for yourself what makes them tick. Since 1982 I’ve kept my eye on an obscure star barely visible to the naked eye in the constellation Corona Borealis. The star goes by the deceptively simple name of “R” for R Coronae Borealis.

R CrB burns with a steady light for years at a time as it did from 2003 to 2007. At 6th magnitude, I could see it from the countryside on any old night without optical aid. Then without warning on July 6, 2007 it began to fade from sight, tumbling headlong into darkness with each passing week. Six months later I needed a 10-inch telescope to see it.

Finding Corona Borealis is a snap. Face south around 10 p.m.-10:30 p.m. and draw an arc from Saturn and Spica up through Arcturus and eastward to Corona's semi-circle of stars.

English amateur Edward Pigott, who scanned the skies in the late 1700s, was the first to notice R CrB’s peculiar habit of fading away. Today we know that R is the prototype of a class of stars called R Coronae Borealis variables that fade away at random intervals only to return to full light weeks, months or even years later.

In 2007 I got a thrill watching it fade by a magnitude a week. How often do you get the chance to see a star change so rapidly? Most of them are the epitome of stability.

Once R CrB bottomed out at 15th magnitude (very faint!) in early 2009 it went into hiding for almost two years. Would the star ever recover, I wondered? Starting in late 2010 through early 2011  R ticked upward a full magnitude, and I looked forward to seeing it shoot to the top. It wasn’t to be. It promptly faded again, putting off a second recovery until the fall of 2011.

A light curve for R CrB based on observations by amateur astronomers shows its dramatic disappearing act and slow recovery. Credit and copyright: Gary Poyner

Some stars fade and re-brighten because they’re partially eclipsed by a companion star. Others are unstable, brightening and fading as they expand and contract in predictable cycles of days to months.

R CrB stars are yellow supergiants 10,000 times as bright as the sun that have lost their outer envelope of hydrogen gas. Their atmospheres are rich in helium and carbon instead.

Stars are element-makers. Inside their searing interiors, hydrogen atoms fuse to make helium. When the hydrogen’s used up, helium fuses to make carbon. Every second, our own sun fuses 700 million tons of hydrogen into 695 million tons of helium and 5 million tons of pure energy. The energy, in the form of gamma rays, takes a million years to reach the surface as the light and heat we cherish.

R Coronae Borealis stars loft carbon dust into space in big puffs. When a puff is aimed in our direction, we see the star eclipsed or blocked by the dust for a time. Credit: ESO

The much hotter and more massive R CrB expels a powerful wind of helium and carbon atoms into space at 100,000 times the rate of the sun’s solar wind. A small percentage of that carbon condenses into discrete “puffs” of soot. If one of these carbon dust clouds happens to be in our line of sight, it blocks the light of R, causing it to dim. Think of the soot that forms on the inner glass of an old-fashioned oil lamp and you get the picture. Only when the cloud has expanded and thinned – or is blown away by continued winds –  does the star return to its normal brightness.

R CrB at its faintest. Like to follow the star's ups and downs in your own telescope? Click on the photo to link to a finder chart with stars labeled with magnitudes (decimals omitted). Credit: Joe Brimacombe

Nobody knows exactly what triggers R CrB’s sooty outbursts, but every few years it belches out another cloud and goes into hiding again. This latest dimming saw the star reach a historical low in brightness; it’s also been the longest fade on record.

Since the fall of 2011, R has been ever-so-slowly climbing in brightness to its current level of 12.5 magnitude. A 6-inch telescope will show it easily enough.

Will it follow through and return to full brightness in the coming weeks or months? Nobody knows. In 30 years, R has shared a half dozen of its ups and downs, trying to tell us on a human time scale what it’s like to be a star. Like listening to a great teacher, I spend a few minutes by its side taking in the lesson every clear night.

Meteorite-dropping fireball named after Sutter’s Mill

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Great view of the interior of a 17.7 gram piece of Sutter's Mill meteorite. Credit: Larry Atkins

It’s official. The meteorites that peeled off the California fireball last month peppering the towns of Coloma and Lotus are named Sutter’s Mill after the famous locale where the California Gold Rush began. As of May 22, 49 fragments had been recovered with a total weight of 437 grams or 17 grams shy of one full pound.

Here are a few details from the Meteoritical Database:

Pinpoint and pinhead-sized bits of olivine and other materials inside my tiny specimen of Sutter's Mill. Magnified about 20x. Photo: Bob King

“A bright daytime east-to-west moving fireball was seen on April 22, 2012, from locations over California and Nevada between 7:51:10 and 7:51:30 am local daylight time (UT-7).

The meteoroid fragmented towards the end of its trajectory. A loud sonic boom was heard in a wide region around Lake Tahoe. Wind gusts were felt and houses shook. At least a kiloton of kinetic energy was released, based on the infrasound signal detected at two stations.”

Eye witnesses in the townships of Coloma and Lotus, El Dorado County, reported hearing whistling sounds and some smelled a “welding” odor. U.S. National Climatic Data Center’s “NEXRAD” Doppler weather radar sweeps detected the falling meteorites.”

“In data analyzed by Marc Fries of the Planetary Science Institute and Robert Matson of S.A.I.C., the radar-defined strewn field is centered on the Sutter’s Mill historic site. On April 24, Robert Ward searched under the radar footprint and collected the first 5.5 g meteorite in Henningsen-Lotus Park.” More details HERE.

Closeup of bubbly crust on a 3 mm-wide fragment of Sutter's Mill meteorite. 30x magnification. Photo: Bob King

Word soon circulated among the meteorite community that Sutter’s Mill was an unusual type of carbonaceous chondrite (car-bon-AY-shuss KON-drite).  These meteorites get their name from the carbon, water and sometimes organic compounds like amino acids they contain. Many of us were on tiptoes waiting for the final classification. Looks like we’re going to have a wait a bit longer.

Scientists were only willing to give it a preliminary “C” (for carbonaceous chondrite) until detailed studies at half a dozen labs are completed.

A week ago a very tiny bit of the meteorite made a second earthly journey straight into my mailbox. Under the microscope at 30x the interior is black as coal with only a few white crystalline flecks. What caught my eye was the crust. Finely stippled to the eye, the scope transforms the little bumps into a landscape of black bubbles that looks like a burnt marshmallow. You can even see where escaping gases punched tiny holes in the bubble tops. This “fusion crust” forms when the outer millimeter or two of the meteorite melts on entering the atmosphere at tens of thousands of miles per hour.

If you stay up past midnight you may find it hard to tear yourself away from the sight of the Milky Way spanning the eastern sky. This picture was taken Monday morning when I should have been sleeping. Details: 15mm lens at f/2.8, ISO 1600, 30-second exposure. Photo: Bob King