An artist’s conception of Epsilon Aurigae and its dusty companion. Credit: NASA/JPL Caltech

Epsilon Aurigae is one of the few stars that you can see with your own eyes, even in the washed out, big-city sky. It’s big and very bright — except when it isn’t. Sometimes, it’s just not there.

Epsilon Aurigae is what’s known as an eclipsing star. Every 27 years or so, it dims dramatically. In fact, you would have a hard time finding Epsilon Aurigae right now, because the star began dimming last August — and it won’t be fully visible again for more than a year. That’s one of the longest eclipses known to man.

Astronomers have been puzzling over these drawn-out eclipses ever since they were first recorded early in the 19th century. Now, using data from NASA’s Spitzer Space Telescope, they’ve come up with a model that sheds new light on this 200-year-old mystery.

Don Hoard led the researchers at the California Institute of Technology, who looked at all the new data. He tells NPR’s Guy Raz that Epsilon Aurigae is actually two stars spinning around each other.

“About two eclipses ago — so in the mid-1950s, early 1960s — astronomers started to develop a picture that there must be something in this system other than just two stars orbiting each other and eclipsing each other,” Hoard says.

“The idea was formed that there’s probably a disc formed of gas and dust that surrounds one of the stars, and the reason the eclipse lasts so long is because this disc is passing in front of the other star — the brighter star in the system — and it just takes a long time to go past.”

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The planet, tagged CoRoT-7b, first hit the headlines last September when a team of astronomers confirmed the orb as the smallest exoplanet yet found. Its diameter is roughly 1.7 times that of Earth. Based on its size and mass, its density is similar to Earth’s, indicating that it is a rocky Earth-like orb.

But it wasn’t always this small. Scientists estimate that CoRoT-7b initially tipped the cosmic scales at 100 times more mass than Earth and orbited the star at a distance of about 2.3 million miles.

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A Jupiter-like gas giant planet orbits a young star in an artist’s conception. Credit: T. Pyle (SSC), NASA/JPL-Caltech

Of the billions of stars in our Milky Way galaxy, 15 percent may host “twins” of our solar system, a new study says.

While that might not sound like much, the find suggests that several hundred million star systems look a lot like the one we call home, the study authors say.

The research is based on surveys of stars with gas giant planets—similar to Jupiter and Saturn—that orbit far from their stars.

As in our solar system, vast distances stretch between these stars and their gas giants. This creates ample room for rocky planets to thrive in the stars’ habitable zones, the regions where liquid water can exist.

And that boosts the likelihood that other Earths, and maybe even other forms of life, abound in the Milky Way.

“For the first ten years of planet hunting, we were feeling a bit worried—other systems looked so different from our own solar system,” noted Debra Fischer, an astronomer at San Francisco State University who was not involved in the research.

“[These] results are reassuring us that there are solar systems akin to our own. This is real data that strengthens the hypothesis that there are many habitable worlds like our Earth.”

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How similar is exoplanet CoRoT-7b to Earth? The newly discovered extra-solar planet (depicted in the above artist’s illustration) is the closest physical match yet, with a mass about five Earths and a radius of about 1.7 Earths. Also, the home star to CoRoT-7b, although 500 light years distant, is very similar to our Sun. Unfortunately, the similarities likely end there, as CoRoT-7b orbits its home star well inside the orbit of Mercury, making its year last only 20 hours, and making its peak temperature much hotter than humans might find comfortable. Credit: ESO/L. Calcada

Rocky planets — Earth, Mercury, Venus and Mars — make up half the planets in our solar system. Rocky planets are considered better environments to support life than planets that are mainly gaseous, like the other half of the planets in our system: Jupiter, Saturn, Uranus and Neptune.

The rocky planet CoRoT-7 b was discovered circling a star some 480 light years from Earth. It is, however, a forbidding place and unlikely to harbor life. That’s because it is so close to its star that temperatures might be above 4,000 degrees F (2,200 C) on the surface lit by its star and as low as minus 350 F (minus 210 C) on its dark side.

Now scientists led by a University of Washington astronomer say that if CoRoT-7 b’s orbit is not almost perfectly circular, then the planet might also be undergoing fierce volcanic eruptions. It could be even more volcanically active than Jupiter’s moon Io, which has more than 400 volcanoes and is the most geologically active object in our solar system.

“If conditions are what we speculate, then CoRoT-7 b could have multiple volcanoes going off continuously and magma flowing all over the surface,” says Rory Barnes, a UW postdoctoral researcher of astronomy and astrobiology. Any planet where the surface is being remade at such a rate is a place nearly impossible for life to get a foothold, he says.

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In all, the first half of 2009 proved an extremely challenging and rewarding time for NASA. Form January to June, NASA completed a complicated analysis of the Space Shuttle fleets Flow Control Valves, launched the Kepler Space Telescope to search for extra-solar Earth-like planets, conducted the STS-119 Shuttle mission, performed a dual-pad flow for STS-125 and STS-400 and the subsequent and highly successful STS-125 mission to upgrade the Hubble Space Telescope, and launched LRO/LCROSS.

In a recent interview with NASASpaceFlight.com, Space Shuttle Program Launch Integration Manager Mike Moses talked extensively about the incredible year the Shuttle processing teams had and their ability to accomplish everything they did in 2009.

“It was all about the teams and their ability to create triple and quadruple redundancies in schedules,” Moses said.

“On the surface, it didn’t appear that we had all that challenging of a year. But if you take it month by month you can really see the issues the teams worked through and the amazing jobs those teams did to get us into a launch posture six times this year.”

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Or was it?

Maybe the top story was the reassessment of NASA’s plans for human spaceflight. After all, tens of billions of dollars could be at stake. Or maybe it was the series of victories in NASA-backed competitions that had gone unwon for years.

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Taken by astronaut William Anders from the Apollo 8 spacecraft, this December 1968 photo of Earth rising over the lunar surface would become one of the most famous images of the 20th century. Credit: NASA

NASA heads into 2010 with the bittersweet assignment of retiring the space shuttle after nearly three decades. But that’s not all the agency has planned: There are also launches of three new satellites aimed at better understanding the Earth’s climate and oceans, and the sun.

Two of the probes will examine Earth — specifically the concentration of salt in the world’s oceans and the presence of aerosol particles, such as soot, in the atmosphere. A third mission will study the sun and its effect on space weather including solar flares that can disrupt communication on Earth.

All three come at a critical time for NASA. Data from the two Earth probes will likely influence global-warming research, and the trio of launches could serve as bright spots in a year otherwise dominated by debate over the future of the agency’s manned space program.

“They are extraordinary timely,” said Michael Freilich, head of NASA’s Earth-science division, of the two Earth probes. “It is a quest for understanding of the Earth system and [to improve] our ability to predict how our wonderful environment and our planet is going to change in the future.”

Combined, the three missions will cost more than $1.5 billion.

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Geminid meteor pierces the night sky over California’s Mojave Desert Credit: Wally Pacholka, TWAN

Like a silver spear cast from the heavens, the bright streak of a Geminid meteor pierces the night sky over California’s Mojave Desert during the annual meteor shower’s 2009 peak.

Geminids are slower than other shooting stars and are known to make beautiful long arcs across the sky. This could be because they’re born of debris from a dormant comet and so are made mostly of hard, sun-baked rock that takes longer to burn up in Earth’s atmosphere, experts suggest.

Geminid Meteor Shower: Rising Star

The Geminids have been historically overlooked, simply because of their timing so close to the busy holiday season and during frigid winter nights, astronomers say.

But that’s beginning to change, thanks to the Geminids’ rising intensity over the past few decades.

In fact, for many astronomers, the December meteors have now dethroned the more popular August Perseid meteor shower as the shooting star event of the year.

“It may come as a surprise to many, but the Geminids are currently richer and are brighter on average,” said Anthony Cook, astronomy observer at Griffith Observatory in Los Angeles, California.

Why the sudden illumination?

Earth is plowing deeper every year into an ancient stream of rocky debris left behind by a mysterious 3.1-mile-wide (5-kilometer-wide) object that orbits the inner solar system, he said.

When Earth’s atmosphere crosses paths with that debris cloud, the rocks are superheated and burn out—and new Geminids are born.

Geminids’ Mystery Parent

The Geminid meteors all appear to be chips off a mysterious rocky object called 3200 Phaethon.

Other meteor showers come from material shed by melting comets—which are massive chunks of dirty ice and rock—as they pass close to the sun. (See asteroid and comet pictures.)

But no one knows for sure whether the Geminids’ parent object, first identified in 1983, is an asteroid or the core of an ancient comet that simply sputtered out.

Recent observations of Phaethon, though, suggest it’s a nearly dormant comet, and the Geminids’ parent is now officially classified as such by NASA.

The research revealed that Phaethon is the rocky skeleton of a comet that lost its ice after too many close encounters with the sun, according to NASA.

The shooting stars’ rocky, hard exterior—as well as the fact that they, unprotected by ice, get baked by the sun—may help explain why Geminids are slower and last longer in the sky than other shooting stars, said Peter Brown, a meteor expert at the University of Western Ontario in Canada.

“They have the ability to penetrate deeper into Earth’s atmosphere,” Brown said, “and burn up at much lower altitudes than meteors associated with the Perseids and Leonids.”

Blue lines show Earth’s northern magnetic field and the magnetic north pole in an artist’s rendering. Credit: Stefan Maus, NOAA NGDC

Earth’s north magnetic pole is racing toward Russia at almost 40 miles (64 kilometers) a year due to magnetic changes in the planet’s core, new research says.

The core is too deep for scientists to directly detect its magnetic field. But researchers can infer the field’s movements by tracking how Earth’s magnetic field has been changing at the surface and in space.

Now, newly analyzed data suggest that there’s a region of rapidly changing magnetism on the core’s surface, possibly being created by a mysterious “plume” of magnetism arising from deeper in the core.

And it’s this region that could be pulling the magnetic pole away from its long-time location in northern Canada, said Arnaud Chulliat, a geophysicist at the Institut de Physique du Globe de Paris in France.

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It’s natural gas, the same fossil fuel that was in such short supply a decade ago that it was deemed unreliable. It’s now being uncovered at such a rapid pace that its price is near a seven-year low. Long used to heat half the nation’s homes, it’s becoming the fuel of choice when building new power plants. Someday, it may win wider acceptance as a replacement for gasoline in our cars and trucks.

Natural gas’ abundance and low price come as governments around the world debate how to curtail carbon dioxide and other pollution that contribute to global warming. The likely outcome is a tax on companies that spew excessive greenhouse gases. Utilities and other companies see natural gas as a way to lower emissions — and their costs. Yet politicians aren’t stumping for it.

In June, President Barack Obama lumped natural gas with oil and coal as energy sources the nation must move away from. He touts alternative sources — solar, wind and biofuels derived from corn and other plants. In Congress, the energy debate has focused on finding cleaner coal and saving thousands of mining jobs from West Virginia to Wyoming.

Utilities in the U.S. aren’t waiting for Washington to jump on the gas bandwagon. Looming climate legislation has altered the calculus that they use to determine the cheapest way to deliver power. Coal may still be cheaper, but natural gas emits half as much carbon when burned to generate the same amount electricity.

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