When is exoplanet news “juicy”? Yesterday at a Kepler press conference held at NASA Ames, Roger Hunter, Kepler project manager, introduced the proceedings as juicy. And as three scientists presented the findings, it turned out to be a good adjective. The researchers believe they have discovered the first water worlds (besides Earth) in our galaxy.

Two systems are providing new evidence of rocky Earth-like planets in the habitable zone—the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water. Kepler 62 has five planets total, but two of those, 62e and 62f, orbit inside the habitable zone. Kepler 69 has two planets but only one in the habitable zone, 69c.

For exoplanets and their stars, size matters when it comes to habitability. At 1,200 light years away, the star Kepler 62 is two-thirds the size of our Sun. That brings the habitable zone in a bit closer to the star. The two planets of interest, 62e and 62f, are 1.6 and 1.4 times the diameter of Earth, respectively. This also puts them in the “just-right” size for habitability.

At the press conference, William Borucki, Kepler science principal investigator at NASA Ames, said that 62e and 62f “are the best candidates to be habitable, not just within the habitable zone.”

Computer models suggest that the largest rocky planets will have a diameter no greater than 1.5 times that of Earth’s, explained Lisa Kaltenegger of the Max Planck Institute for Astronomy and Harvard-Smithsonian Center for Astrophysics. And a planet’s mass, between 1.2-2.5 times Earth’s mass, can be an indicator for liquid water. While Kepler 62e and 62f are too small to measure their mass, Kaltenegger and her team’s modeling makes these planets very wet, indeed.

Kepler 69c, on the other hand, is 2,700 light years away and 1.5 times Earth’s diameter. It orbits near the inner, hotter edge of its star’s habitable zone. Thomas Barclay, Kepler scientist from the Bay Area Environmental Research Institute, likens it to a super Venus, rather than a super Earth. “We don’t have anything like it in our solar system,” he said.

“The Kepler spacecraft has certainly turned out to be a rock star of science,” said John Grunsfeld, at NASA Headquarters in Washington. “The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity.”

The findings are published this week in Science (Kepler 62) and the Astrophysical Journal (Kepler 69).

For an interactive on Kepler’s planetary discoveries and their orbits, click here.

Image: NASA Ames/JPL-Caltech

Dark matter provided a lively topic of discussion at the recent AAAS Meeting in Boston. Michael Turner, of the University of Chicago’s Kavli Institute for Cosmological Physics, explained it this way at a press conference: “It’s something new. No particle in the standard model can account for it.” And he believes the discovery of the culprit particle is right around the corner; hence the decade of the WIMPs.

As Ryan Wyatt mentioned in his post last month from the AAS Meeting (such similar names, I know), both the Large Hadron Collider (LHC) and the Large Underground Xenon Experiment (LUX) are looking for these particles. In addition, a detector onboard the International Space Station, called the Alpha Magnetic Spectrometer (AMS), has joined the hunt. (Okay, I promise no more acronyms.)

The Alpha Magnetic Spectrometer is the brainchild of Nobel laureate Samuel Ting, who also presented at the press conference. It took Ting 16 years to get AMS into space; it’s now been collecting data for 18 months. And it sounds like they may already have results. Ting was vague, no matter how hard reporters tried to press him, but it sounds like his team plans to publish something in the next few weeks. With the length of time it took to make AMS a reality, Ting says, the results will certainly be worthwhile.

Here’s what he did clarify. AMS has seen 25 billion events—not many for a particle detector like the LHC, but quite a few for a space detector. Almost 8 billion of those are electrons and positrons, and scientists are working around the clock to understand how these interact with one another. Does the ratio between the two change over time? Turner explained that if scientists see a rise followed by dramatic fall, that will indicate a unique source—perhaps dark matter.

So now we must wait for the publication.  And remember, according to Turner’s timeline, we have a whole decade to make discoveries. Ting’s paper could take just a small step toward the description of dark matter. Lisa Randall, a theoretical physicist at Harvard, reminded us that a lot of stuff can mimic dark matter. So it could be a step in the wrong direction. But for her, how models of dark matter fit into these experiments of dark matter is all part of the process. “We’re learning more along the way.”

AMS particle detector: NASA

Yesterday, James Hansen of NASA’s Goddard Institute and Thomas Karl of NOAA’s National Climatic Data Center held a joint press conference, describing very similar findings for last year’s warmer than average temperatures around the world. A pdf with their organizations’ side-by-side comparisons is available here.

The average temperature globally in 2012 was about 58.3 degrees Fahrenheit, which is 1.0 F (0.6 C) warmer than the mid-20th century baseline. The average global temperature has increased about 1.4 degrees F (0.8 C) since 1880, according to the new analysis.

The scientists emphasized that weather patterns always will cause fluctuations in average temperature from year to year, but the continued increase in greenhouse gas levels in Earth’s atmosphere assures a long-term rise in global temperatures. Each successive year will not necessarily be warmer than the year before, but on the current course of greenhouse gas increases, scientists expect each successive decade to be warmer than the previous decade.

“The U.S. temperatures in the summer of 2012 are an example of a new trend of outlying seasonal extremes that are warmer than the hottest seasonal temperatures of the mid-20th century,” Hansen said. “The climate dice are now loaded. Some seasons still will be cooler than the long-term average, but the perceptive person should notice that the frequency of unusually warm extremes is increasing. It is the extremes that have the most impact on people and other life on the planet.”

In fact, according to Reuters, Americans are feeling the impact of climate change already—consequences that affect “health, infrastructure, water supply, agriculture and especially more frequent severe weather.”

But studies show we can do something about it. Nature Climate Change has an article this week describing how cutting emissions can reduce impacts from climate change. (Read more at Scientific American.) And New Scientist reports that while global talks breakdown over the subject, individual nations are doing something about it. Let’s hope the trend continues.

Want to engage more in the changing climate? Tomorrow Science will host a live chat, “Can We Conquer Climate Change?” Sign in here.

Image: NASA Goddard’s Scientific Visualization Studio

Launched in 1977, Voyager 1 is the most distant human-made object in our galaxy, and is close to passing beyond the limits of our solar system.  This week, the team announced that Voyager 1 has entered the “magnetic highway,” a region between the heliosphere and interstellar space. Scientists coined the new term “magnetic highway” to describe the place where the Sun’s magnetic field lines connect with interstellar magnetic field lines. As Stone said at yesterday’s meeting, “The new region isn’t what we expected, but we’ve come to expect the unexpected from Voyager.”

Voyager has three instruments on board to measure changes in the magnetic environment—one that detects the low-energy particles that come from the solar wind within the heliosphere; one that detects the high-energy particles from interstellar space (remnants from supernovae explosions millions of years ago); and a magnetometer, which measures the strength and direction of magnetic fields.

How do the scientists know the magnetic highway isn’t just interstellar space? First, both low- and high-energy particles are detected.  Also, the magnetic field from the Sun runs east to west, and that should change dramatically once the spacecraft enters interstellar space.

Voyager 1 first merged onto this highway in late July, but then quickly exited. The same thing happened in early August, and finally Voyager entered for good in late August. Stone predicts that interstellar space can’t be too far for Voyager 1. “We believe this is the last leg of our journey to interstellar space,” Stone said. “Our best guess is it’s likely just a few months to a couple years away.” (Hopefully well before the spacecraft’s power is due to shut off in 2025.)

Because Voyager 1 is now located about 11 billion miles away from the Sun, the signal from the spacecraft takes approximately 17 hours to travel to Earth. Voyager 2, the longest continuously operated spacecraft, is about 9 billion miles away from our sun, headed in a completely different direction. While Voyager 2 has seen changes similar to those seen by Voyager 1, the changes are much more gradual. Scientists do not think Voyager 2 has yet reached the magnetic highway.

Another climate and water story

Last week, we featured a series of stories on climate change and water issues and this one slipped by. A study in Nature last week reported how trees physically respond to drought. And the news is not good. Plants undergoing drought stress experience reduced pressure in the xylem (the vessel that transports water from the soil to the leaves).

Head over to NPR to read (or listen to) their piece on the study.

Melting ice sheets and sea level rise

A NASA/ESA study, published in Science this week provides the most thorough representation of the rate of melting ice sheets and corresponding sea level rise to date. Using extensive satellite data, scientists report that the ice sheets covering Greenland and Antarctica are losing more than three times as much ice each year as they were in the 1990s. About two-thirds of the loss occurs from Greenland, with the rest from Antarctica.

Combined, melting of these ice sheets contributed 0.44 inches to global sea levels since 1992. This accounts for one-fifth of all sea level rise over the 20-year survey period. The remainder is caused by the thermal expansion of the warming ocean, melting of mountain glaciers and small Arctic ice caps, and groundwater mining.

“Both ice sheets appear to be losing more ice now than 20 years ago, but the pace of ice loss from Greenland is extraordinary, with nearly a five-fold increase since the mid-1990s,” NASA’s Erik Ivins says.

Ocean acidification and fighting back

Ocean acidification is already having an effect on marine life, according to a study published this week in Nature Geoscience. Shells of live mollusks from the Southern Ocean are showing signs of “severe dissolution.” New Scientist has more information.

Washington State is taking action to curb ocean acidification and protect the state’s large shellfish industry. A report, released this week, outlines plans to target pollution that causes acidification (including carbon emissions and agriculture run-off) and has a $3.3 million backing. More information is available here.

Maybe more coastal states (and nations) will follow Washington’s lead, says the Ocean Conservancy.

A Sad Factoid

A final thought from the editors at grist.org, who note that “if you’re 27 or younger, you’ve never experienced a colder-than-average month.” A truly sobering fact gleaned from the NOAA “State of the Climate” report for October 2012.

Image: Ian Joughin

Two researchers hypothesize that an asteroid belt, just the right size and distance from its star, might be necessary for a star system to support a life-bearing planet.

This might sound surprising, since asteroids can occasionally impact Earth and trigger mass extinctions. Ouch! But an emerging view proposes that asteroid collisions with planets may provide a boost to the birth and evolution of complex life.

For one thing, asteroids delivered water and organic compounds to the early Earth. Consistent with the theory of punctuated equilibrium, occasional asteroid impacts might also accelerate the rate of biological evolution by disrupting a planet’s environment to the point that species must evolve new adaptation strategies.

Rebecca Martin, of the University of Colorado, and Mario Livio, of the Space Telescope Science Institute, looked at our solar system and used theoretical models and actual observations of other star systems and exoplanets to study the theory that life needs an asteroid belt.

They suggest that the location of an asteroid belt relative to a Jupiter-like planet is particularly favorable to life. The asteroid belt in our solar system, located between Mars and Jupiter, is a region of millions of space rocks sitting near the “snow line,” beyond which volatile materials such as water ice are far enough from the Sun’s heat to remain intact.

Our solar system’s formation was just right for life, Livio says. “To have such ideal conditions you need a giant planet like Jupiter that is just outside the asteroid belt [and] that migrated a little bit, but not through the belt,” he explains. “If a large planet like Jupiter migrates through the belt, it would scatter the material. If, on the other hand, a large planet did not migrate at all, that, too, is not good because the asteroid belt would be too massive. There would be so much bombardment from asteroids that life may never evolve.”

Using our solar system as a model, Martin and Livio proposed that asteroid belts in other solar systems would always be located approximately at the snow line. They created models of protoplanetary disks, the dense gas and dust around a newly formed star; then they looked at observations from NASA’s Spitzer Space Telescope of 90 such regions that have warm dust, which could indicate the presence of an asteroid belt-like structure. The warm dust fell right near the snow line.

But for life to exist, the system also needs a large gas giant, like Jupiter, to “manage” the size of the asteroid belt. So Martin and Livio looked at data for 520 giant planets found outside our solar system. Only 19 of them reside outside the snow line, suggesting that most of the giant planets that formed outside the snow line have migrated too far inward to preserve the right-sized asteroid belt needed to foster life on an Earth-like planet near the belt. The team calculated that less than four percent of the observed systems may actually harbor such a compact asteroid belt.

“Our study shows that only a tiny fraction of planetary systems observed to date seem to have giant planets in the right location to produce an asteroid belt of the appropriate size, offering the potential for life on a nearby rocky planet,” says Martin. “Our study suggests that our solar system may be rather special.”

Their findings are published in the Monthly Notices of the Royal Astronomical Society: Letters.

Image: NASA, ESA, and A. Feild (STScI)