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Discovery Adds Mystery to Earth’s Genesis

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Artist's conception of a dusty planet-forming disk orbiting a stellar object known as IRS 46.

Earth and the other rocky planets aren’t made out of the solar system’s original starting material, two new studies reveal.

Scientists examined solar particles snagged in space by NASA’s Genesis probe, whose return capsule crash-landed on Earth in 2004. These salvaged samples show that the sun’s basic building blocks differ significantly from those of Earth, the moon and other denizens of the inner solar system, researchers said.

Nearly 4.6 billion years ago, the results suggest, some process altered many of the tiny pieces that eventually coalesced into the rocky planets, after the sun had already formed.

“From any kind of consensus view, or longer historical view, this is a surprising result,” said Kevin McKeegan of UCLA, lead author of one of the studies. “And it’s just one more example of how the Earth is not the center of everything.”

Salvaging the samples

The Genesis spacecraft launched in 2001 and set up shop about 900,000 miles (1.5 million kilometers) from Earth. It spent more than two years grabbing bits of the solar wind, the million-mph stream of charged particles blowing from the sun.

The idea was to give scientists an in-depth look at the sun’s composition, which in turn could help them better understand the formation and evolution of the solar system.

To that end, Genesis sent its sample-loaded return capsule back to Earth in September 2004. But things didn’t go well; the capsule’s parachute failed to deploy, and it smashed into the Utah dirt at 190 mph (306 kph).

While some of Genesis’ samples were destroyed in the crash, others were salvageable, as the two new studies show. Two different research teams looked at the solar wind particles’ oxygen and nitrogen — the most abundant elements found in Earth’s crust and atmosphere, respectively.

And they did so with a great deal of care, knowing that the crash had limited their supplies of pristine solar material.

“The stakes were raised on the samples that did survive well,” McKeegan told SPACE.com. “There wasn’t as much to go around.”

The Genesis return capsule slammed into the Utah dirt at nearly 200 mph on Sept. 8, 2004 when its parachute failed to deploy.

The Genesis return capsule slammed into the Utah dirt at nearly 200 mph on Sept. 8, 2004 when its parachute failed to deploy.
CREDIT: NASA/JPL

Analzying oxygen

McKeegan and his team measured the abundance of solar wind oxygen isotopes. Isotopes are versions of an element that have different numbers of neutrons in their atomic nuclei. Oxygen has three stable isotopes: oxygen-16 (eight neutrons), oxygen-17 (nine neutrons) and oxygen-18 (ten neutrons).

The researchers found that the sun has significantly more oxygen-16, relative to the other two isotopes, than Earth. Some process enriched the stuff that formed our planet — and the other rocky bodies in the inner solar system — with oxygen-17 and oxygen-18 by about 7 percent.

While scientists don’t yet know for sure how this happened, they have some ideas. The leading contender, McKeegan said, may be a process called “isotopic self-shielding.”

About 4.6 billion years ago, the planets had not yet coalesced out of the solar nebula, a thick cloud of dust and gas. Much of the oxygen in this cloud was probably bound up in gaseous carbon monoxide (CO) molecules.

But the oxygen didn’t stay bound up forever. High-energy ultraviolet light from the newly formed sun (or nearby stars) blasted into the cloud, breaking apart the CO. The liberated oxygen quickly glommed onto other atoms, forming molecues that eventually became the rocky building blocks of planets.

Photons of slightly different energy were required to chop up the CO molecules, depending on which oxygen isotope they contained. Oxygen-16 is far more common than either of the other two, so there would have been much more of this substance throughout the solar nebula, researchers said.

The result, the self-shielding theory goes, is that many of the photons needed to break up the oxygen-16 CO were “used up,” or absorbed, on the edges of the solar nebula, leaving much of the stuff in the cloud’s interior intact.

By contrast, relatively more of the photons that could strip out oxygen-17 and oxygen-18 got through to the inner parts of the cloud, freeing these isotopes, which were eventually incorporated into the rocky planets. And that, according to the theory, is why the sun and Earth’s oxygen isotope abundances are so different.

“The result that we’re publishing this week gives support to the self-shielding idea,” McKeegan said. “But we don’t know the answer yet.”

Nitrogen, too

In a separate study, another research team led by Bernard Marty of Nancy University in France analyzed the nitrogen isotopes in Genesis’ samples. (Nitrogen has two stable isotopes: nitrogen-14, which has seven neutrons, and nitrogen-15, which has eight.)

Marty and his colleagues found an even more dramatic difference than McKeegan’s group did: The solar wind has about 40 percent less nitrogen-15 (compared to nitrogen-14) than do samples taken from Earth’s atmosphere.

Previous studies had hinted that the sun’s nitrogen might be very different from that of Earth, Mars and other rocky bodies in the inner solar system, Marty said. But the new study establishes this firmly.

“Before Genesis and the present measurement of the N isotopic composition of the solar wind and by extension of the sun, it was not possible to understand the logic of such variations,” Marty told SPACE.com in an email interview. “Now we understand that the starting composition, the solar nebula, was poor in 15N, so that variations among solar system objects are the result of mixing with a 15N-rich end-member.”

As to how this enrichment of nitrogen-15 could have happened, Marty as well suggests some type of self-shielding as a possible mechanism. But it’s not a certainty.

“This is a scenario that is consistent with present-day observations,” he said. “We cannot eliminate yet the possibility that these 15N-rich compounds were imported from outer space as dust in the solar system.”

The new results also suggest that most nanodiamonds — tiny carbon specks that are a major component of stardust — likely formed in our own solar system, because they share similar nitrogen isotope ratios with the sun. Some scientists have regarded nanodiamonds as being primarily presolar, thinking they were ejected from other stellar systems by supernova explosions.

Both studies appear in the June 23 issue of the journal Science.

Genesis’ legacy

The two new studies should help scientists get a better understanding of the solar system’s early days, researchers said.

And the results should help rehabilitate the reputation of the $264 million Genesis mission, showing that the capsule crash didn’t render it a failure, McKeegan said.

“We managed to accomplish all the science that we set out to do, all the important stuff,” he said. “The enduring image in everybody’s mind — the picture of the crashed spacecraft in the desert — will be more of a footnote instead of the primary thing that people remember. That’s my hope, anyway.”

 

Via Space

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Comet could be a stunner (or not)

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A newly discovered comet from the farthest reaches of the solar system could become a sky spectacle in 2013, astronomers say. No guarantees, though.

Comet C/2011 L4 (PANSTARRS) was detected on the night of June 5-6 using thePan-STARRS 1 telescope in Hawaii. The next night, astronomers checked it out using the Canada-France-Hawaii Telescope and confirmed that it was indeed a comet.

Calculations suggest that the comet will come within about 30 million miles (50 million kilometers) of the sun in early 2013. That’s roughly equivalent to the distance between the sun and Mercury, the University of Hawaii’s Institute for Astronomy said today in a news release.

“The comet has an orbit that is close to parabolic, meaning that this may be the first time it will ever come close to the sun, and that it may never return,” said University of Hawaii astronomer Richard Wainscoat.

Pan-STARRs’ primary job is to detect potentially hazardous asteroids that might hit Earth someday, but the orbital calculations for C/2011 L4’s path have ruled out any chance that this comet will hit us. The iceball is nevertheless interesting for two big reasons.

First, the comet is coming in fresh from an unspoiled cosmic frontier, trillions of miles away — and is thus likely to be composed of the fluffy stuff from which the solar system was made. That’s a golden opportunity for astronomers who are trying to piece together the grand saga of planetary formation.

Second, it could be a heck of a show.

Right now the comet is 700 million miles (1.2 billion kilometers) from the sun, well beyond the orbit of Jupiter. Its brightness is magnitude 19, which means it can be spotted only with telescopes equipped with sensitive electronic detectors. But observers expect that the comet will be visible to the naked eye when it comes closest to the sun, around March 2013. C/2011 L4 could put on a nightly show in western skies just after sun set. Some even say it has the potential to become “the brightest comet of the decade.”

But most astronomers are reluctant to make predictions about brightness, particularly so soon after the discovery. A comet’s brightness depends not only on how close it comes to the sun and how big it is, but also on how much ice it contains. The transformation of a comet’s ice to gas is a major contributor to its brightness. “More accurate brightness predictions will not be possible until the comet becomes more active as it approaches the sun and astronomers get a better idea of how icy it is,” the Institute for Astronomy said.

C/2011 L4 is inherently unpredictable because this will be its first and perhaps its last journey through the inner solar system. Some comets, such as Comet Halley and Tempel-Tuttle, follow orbits that take them around the sun on a regular, relatively short timetable (every 76 years for Halley, every 33 years for Tempel-Tuttle). But the comets from the Oort Cloud, also known as long-period comets, are infrequent visitors. Examples include Comet Hale-Bopp (which became famous in 1997) and Kohoutek (which fell short of expectations in 1973).

Long-period comets spend most of their time amid the huge reservoir of icy objects that extends a quarter of the way to the next star over. They’re thought to come into the inner solar system only when they’re diverted by gravitational interaction with the other objects out there.

It’s worth noting that some astronomers suspect that a large celestial object — perhaps a brown dwarf or a so-called “Planet X” — may lie in the Oort Cloud and be responsible for variations in the flux of long-period comets. You can read all about the search for such objects, including a little bit about Pan-STARRS, in “The Case for Pluto,” my book about Pluto and other weird worlds.

You’ll probably be hearing more doomsday talk about Planet X, Nibiru, Nemesis and other supposed denizens of the Oort Cloud due to the hype over 2012. Who knows? Maybe Comet C/2011 L4 will provide some with an excuse to whip up the doomsday talk again. But don’t be misled — and whatever you do, DON’T PANIC.

 

– Alan Boyle

Eclipse views turn moon into a star

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If you’re in North America, you may have had no idea that an exceptional lunar eclipse took place this afternoon. But most of the rest of the world got in on the spectacle, and you can, too, after the fact.

This eclipse was notable for several reasons: The moon went right through the center of Earth’s shadow, which means the total phase went on for 100 minutes — the longest duration since the year 2000. Also, last week’s volcanic eruption in Chile was thought to have put enough sulfur in the air to lend a dusky, coppery color to the moon during totality. The reddish shade certainly didn’t disappoint, as you can see in these pictures.

Every total lunar eclipse bring the question, “Why does the moon turn red?” And we have the answer: It’s because the reddish wavelengths of the sun’s blocked light are actually bent around Earth’s disk, lending a sunset glow to the eclipsed moon.

Phases of the eclipse were visible from wide swaths of Africa, Europe, Asia, Australia as well as the Indian Ocean and South America. Pretty much every major land mass in the world, in fact, except for North America and Greenland. If you’re hankering to see a total lunar eclipse with your own eyes, the next opportunity comes on Dec. 10, when the show will be visible from the U.S. West Coast as well as Australia, the Pacific and most of Asia.

Jack Guez / AFP – Getty Images

The moon rises over the Israeli coastal city of Tel Aviv before a total lunar eclipse.

Marko Drobnjakovic / AP

A partially eclipsed moon rises into the skies over Belgrade, Serbia, on Wednesday.

Darrin Zammit Lupi / Reuters

A partial lunar eclipse is seen over the village of Zejtun, lit up for its parish church feast of Saint Catherine, in the south of Malta on Wednesday.

Jack Guez / AFP – Getty Images

This sequence of images shows the progress of the lunar eclipse as seen from Tel Aviv.

Geert Vanden Wijngaert / AP

A lunar eclipse is seen through the Atomium monument in Brussels, which was built for a world’s fair in 1958.

Bullit Marquez / AP

Earth casts its shadow over the moon during a total lunar eclipse as seen from Manila in the Philippines before dawn Thursday.

Ciro Fusco / EPA

The lunar eclipse looms over the Castel dell Ovo (Egg Castle) in Naples, Italy.

Ahmad Yusni / EPA

Malaysian government officials peer at the eclipsed moon through telescopes in Putrajaya early Thursday,

Tim Winborne / Reuters

A lunar eclipse is visible early Thursday amid cables on the Anzac Bridge in Sydney, Australia.

Via MSNBC

Solar forecast hints at a big chill

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The latest long-range space forecast predicts a prolonged drop in solar activity after the next peak — and scientists say that might cool down temperatures here on Earth, or at least slow down the warming trend a bit.

Scientists have studied sunspots and the sun’s 11-year activity cycle for 400 years, and they’re getting increasingly savvy about spotting the harbingers of “space weather” years in advance, just as meteorologists can figure out what’s coming after the next storm.

Storms from the sun are expected to build to a peak in 2013 or so, but after that, the long-range indicators are pointing to an extended period of low activity — or even hibernation.

“This is important because the solar cycle causes space weather … and may contribute to climate change,” Frank Hill, associate director of the National Solar Observatory’s Solar Synoptic Network, told journalists today.

In the past, such periods have coincided with lower-than-expected temperatures on Earth. The most famous example is the Maunder Minimum, a 70-year period with virtually no sunspots from 1645 to 1715. Average temperatures in Europe sank so low during that period that it came to be known as “the Little Ice Age.”

The linkage between solar activity and climate change is still a matter of scientific debate. And even if there is a link, it’s not clear how solar-caused global cooling might interact with industrial global warming due to greenhouse-gas emissions. Climate scientists say the swings in solar activity that they’ve studied so far have had little or no impact on temperatures or other climate indicators — and they don’t expect to see a big impact even if the sun goes quiet for a decade or longer.

But if today’s forecast is correct, solar physicists and climatologists will have a golden opportunity to find out for sure.

Hill said scientists had “no way of predicting” how long the hibernation period might last. “It may very well last as long as the Maunder Minimum … if it occurs,” he said.

Hill and other experts on solar activity announced the long-range forecast today at the annual meeting of the American Astronomical Society’s Solar Physics Division, being conducted this week at New Mexico State University in Las Cruces, N.M.

How do they know?
The forecast is based on three indicators thought to be tied to long-range solar activity, the comparative rise and fall of sunspots over the activity cycle, as well as the brightness of those sunspots; patterns in the sun’s internal “jet stream” of superheated plasma; and the pace of migration in the sun’s magnetic field toward the poles, as seen in the sun’s corona.

An unusually low number of sunspots have been observed during the current cycle, and the spots are fainter than average. Scientists say they have seen no sign of a characteristic east-west flow of internal plasma, which usually sets the stage for future increases in activity. And the magnetic “rush to the poles” appears to be slowing down.

All these signs suggest that the current solar cycle, Cycle 24, “may be the last one for quite some time,” Hill said. The next upswing in solar storms, Cycle 25, may be “very much delayed … very weak, or may not happen at all.”

Beyond the climate effect, solar activity is known to have a significant potential impact on satellite operations, electric power grids and even exposure to radiation at high-altitudes. Solar storms can disrupt satellite signals or air-traffic navigation systems. In 1989, a solar outburst caused a widespread power outage in Quebec. And particularly strong solar flares have forced astronauts to take shelter in shielded areas of the space shuttle or the International Space Station.

Some observers have worried about the possibility of a massive geomagnetic super-storm like the one that swept over Earth in 1859, known as the “Carrington event.” For those folks, the news that the sun appears to be settling down, coupled with indications that the 2013 solar maximum is not expected to be unusually strong, should be reassuring.

About that ice age …
Hill and two other solar physicists involved in formulating the forecast, NSO researcher Matt Penn and Richard Altrock of the U.S. Air Force’s coronal research program, said there was not yet enough data to firm up a climate connection to solar activity. But they and other scientists have noted that historic lulls in sunspots, such as the Maunder Minimum and another solar minimum between 1790 and 1830, coincided with cooler temperatures.

Gavin Schmidt, a climatologist at NASA’s Goddard Institute for Space Studies and one of the founders of the RealClimate blog, said the effects of solar activity on climate over the past 30 years have been “at the margin of what we can detect.”

“They are detectable in the high atmosphere, but when you get down to the surface, there is so much other stuff going on that it’s been really hard to get a clean signal,” he told me.

One of the reasons why so little is known about solar effects on climate is that the sun’s highs and lows have been within such a narrow range in recent history.

“If we were to see a return to what’s called Maunder Minimum conditions in the next 50 years or so, that would be interesting,” Schmidt said. “I think we’d learn a lot about solar physics and solar variability. … It’s going to be scientifically very exciting if all this pans out.”

Even then, however, he estimated that the effect of greenhouse-gas emissions would be on the order of 10 times as great. “What you might see over a 20- to 30-year period is a slight slowdown in the pace of warming,” Schmidt said. “In terms of how we should think about climate change prediction in the future, reducing emissions and so on, it really wouldn’t make much of a difference.”

But what about the Little Ice Age in the 1600s, when Swiss Alpine villages were reported destroyed by encroaching glaciers? Schmidt said that period also coincided with an upswing in volcanic emissions, which are known more definitely to contribute to global cooling.

“Parsing out how much of that was solar, how much of that was volcanic and how much of that was just noise … that’s tricky,” Schmidt said.

Will this latest forecast be used to argue that we don’t need to worry about global warming? Or will the effect of solar hibernation (if it even occurs) turn out to be a blip at best? Feel free to weigh in with your comments below.

 

Via MSNBC

Epic Solar Flare Pops Sun’s Magnetic Cork

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In the early hours of Tuesday morning, our nearest star put on a show that won’t be forgotten for a long, long time. Under the ever-watchful eyes of an armada of solar observatories, the sun unleashed an M2-class solar flare.

Keep in mind that an M2 flare, although powerful, is still only classed as a “medium” explosion. But there was nothing medium about this event.

Erupting from an active region of sunspots (sunspot complex 1226-1227) — where highly stressed and concentrated magnetic fields are forced through the solar surface (the “photosphere”), pushing the hot plasma aside, exposing the cooler plasma below the surface — the flare ejected a huge coronal mass ejection (CME).

A surprisingly large quantity of plasma didn’t escape the gravitational pull of the sun, however, and was dragged back down as a vast cloud of cooler plasma, resembling the foaming, bubbly mess after popping a champagne cork.

The veil of darker plasma (it appears darker as it’s cooler — at a temperature of around 80,000 K, compared with the surrounding million degree coronal plasma) expanded and appeared to cover half the sun’s disk before being funneled along the powerful magnetic field lines, raining back into the photosphere. There even appeared to be sparks of sudden plasma heating as the huge blobs of gas impacted the dense plasma at the surface.

557158main_M2_CME-orig_full

“I’ve never seen material released like this before,” C. Alex Young, solar physicist of NASA’s Goddard Space Flight Center, exclaims in the video depicting the event.

“It looks like somebody just kicked a giant clod of dirt up into the air.”

The plasma that did escape the sun’s gravity in the form of a CME is now racing through space at a breakneck speed of 1,100 kilometers per second (that’s 2,448,000 miles per hour!). A rough calculation reveals the CME will reach the orbital distance of Earth in a little under 40 hours after the event and Spaceweather.com confirms that we may receive a “glancing blow,” potentially causing geomagnetic storms (resulting in aurorae) at high latitudes later on Wednesday.

There’s little cause for concern however. As dramatic at the explosion looks, it’s only predicted to cause some minor interference to communications, satellites and potentially power grids if we do get hit. NASA states that the CME’s impact is expected to be “fairly small.”

Via Discovery

The Milky Way from South Dakota

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Star gazing on the plains of central South Dakota is a treat, if this timelapse video from Randy Halvorson — who braved chilly temps and howling winds this May to capture the Milky Way drifting across the night sky — is any guide.

“There were very few nights, when I could shoot, that were perfectly clear, and often the wind was blowing 25mph+,” he writes on his website. “That made it hard to get the shots I wanted.”

He kept most of the shots low to the ground to prevent the wind from shaking or blowing over his camera. Each ten seconds of video is about 2 hours and 2 minutes worth of time.

Be sure to check out Halvorson’s Dakotalapse website for examples of his work.

Via MSNBC

Written by Nokgiir

June 8, 2011 at 4:25 pm

The incredible time-lapse video which shows the rotation of our planet

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It is a breathtaking look at the South American night sky – with a difference.

As nightfall descends on Chile’s Atacama Desert, the wonders of the universe are clearly on display.

Laser guide stars, zodiacal light, the Large and Small Magellanic Clouds and earth-orbiting satellites are all visible.

But in a subtle twist, the video also dramatically shows the actual rotation of Earth, called diurnal motion, in a clear and moving way.

Sometimes it feels as if the camera is floating free in space.

This is because creators Stephane Guisard and Jose Francisco Salgado digitally rotated the frames, in doing so keeping the stars steady.

Instead, it is Earth that moves beneath them.

The technique contrasts normal time-lapse videos where the stars and sky are seen to move above a steady Earth.

Starry night: Stephane Guisard and Jose Francisco's video shows the Earth rotating instead of the stars

Starry night: Stephane Guisard and Jose Francisco’s video shows the Earth rotating instead of the stars.

Experience: The video dramatically shows the actual rotation of the Earth, called diurnal motion

Experience: The video dramatically shows the actual rotation of the Earth, called diurnal motion.

Optical: The video was shot at the European Southern Observatory's Very Large Telescope in the Atacama Desert, Chile

Optical: The video was shot at the European Southern Observatory’s Very Large Telescope in the Atacama Desert, Chile.

Via DailyMail