May 27, 2011 | 5
Late Wednesday night I bumped into an old friend on the subway. It was past 11:00, and she, an actress, was returning from a party at the home of her movement teacher at which each attendee was asked to bring a short performance piece as a gift for the host. I, a science writer, was making my way home from the American Astronomical Society (AAS) conference in Boston. We were each, she pointed out, emerging from the depths of our respective esoteric worlds.
She asked me what I had learned at the conference. I found that I had a hard time summing it up into tidy, easily explainable tidbits of news. But I nonetheless felt that I had gained much from attending, and not just in the usual conference ways of putting faces to names and having the chance to engage in casual conversation with people whom I usually encounter in the more formal reporter–source setting.
I had left Boston convinced that, despite the gloomy fiscal outlook that I wrote about earlier this week, astronomers will have plenty of exciting news to tell us in the coming months and years.
The most obvious example comes from Kepler, a NASA spacecraft that is looking for—and finding—planets outside the solar system. Kepler has made splashy announcements at other AAS meetings, but the news from Kepler this time was more incremental, more of a progress report as the mission inches toward its ultimate goal of finding Earth-like planets where life might be able to take hold.
The spacecraft is functioning well and continues to deliver unprecedented amounts of information about the planetary population in our galaxy. Kepler scientists are now busy using telescopes on the ground to try to confirm some of the 1,235 promising objects that have already been publicly announced as possible planets, plus whatever else they may know about but are keeping close to the vest. And the Kepler data have already spurred a bounty of research; a handout at the AAS meeting listing all the Kepler-related presentations covered a full page in small-print type. A Twitter word cloud of AAS-tagged tweets shows that "Kepler" was the buzzword of the meeting. (Full disclosure: I tweeted regularly from AAS and probably used the word "Kepler" often enough to boost the numbers somewhat.)
So how long before Kepler can begin to find potentially habitable, Earth-like planets—or begin to show that our pale blue dot is of an exceedingly rare breed? "I really think that by three years from now, we will have that answer," Kepler principal investigator Bill Borucki of NASA Ames Research Center told me. "The mission is designed to do it in that period of time." In the meantime Kepler ought to discover scores more worlds of almost unimaginable diversity—small ones and large ones; hot ones and cold ones; dense, rocky ones and puffy ones with the density of Styrofoam.
Another intriguing possibility for a near-term discovery involves a hypothetical object much closer to home. That would be Tyche, a body of perhaps a few times Jupiter’s mass that some researchers think could be lurking in the outer solar system’s Oort Cloud, orbiting the sun at tens of thousands of times the Earth–sun distance. A bias in the orientation of comets that come streaking from those outer reaches of the solar system and into Earth’s neighborhood hints that there may be a large celestial object gravitationally perturbing them and nudging them inward.
"We have this anomaly in the distribution of comets where there’s no other simple explanation for it," Jack Lissauer of NASA Ames said in an AAS talk called "A Jovian-Mass Object in the Oort Cloud?" Lissauer cautioned that Tyche’s existence is far from certain, hence the punctuation mark in the title of his talk. "The question mark is appropriate," he said. The Tyche hypothesis and others like it have been around for a while, and not without controversy, but the interesting thing now is that Tyche is plausibly detectable in the all-sky surveys taken by the Wide-Field Infrared Survey Explorer (WISE) spacecraft.
WISE’s survey is complete but researchers are still sifting through the data. The mission’s principal investigator, Ned Wright of the University of California, Los Angeles, said that Tyche would be hard to see if it were at the lower end of its hypothesized mass, about the same mass of Jupiter. But if it had two Jupiter masses or more, Tyche might show up on WISE’s list of possible low-mass brown dwarfs. "If it’s something following this hypothesis that it’s out there and it’s at the two-Jupiter-mass range, then it’s going to be probably found and followed up," Wright said.
Many researchers might hold out more hope for a different kind of survey for unseen objects in the solar system. Matt Holman of the Harvard–Smithsonian for Astrophysics and his colleagues are using the newly completed Pan-STARRS-1 telescope in Hawaii to conduct a census of objects out near the giant planets in our solar system. Pan-STARRS-1 is optimized to quickly scan the sky to pick up moving objects nearby, such as asteroids, or short-lived astrophysical phenomena far away, such as supernovae.
If there are more dwarf planets of the kind that led to Pluto’s demotion lurking in our solar system, there’s a good chance Holman and his collaborators will find them. He said that it was not clear how thoroughly the solar system had been scanned for dwarf planets but that some tallies put the completeness estimate at about 50 percent. Given that three dwarf planets (Makemake, Haumea and Eris) have been discovered in the past decade, joining the long-known Pluto and Ceres, there could well be a few more dwarf planets out there awaiting discovery in the months or years to come.
All that was a bit too much to convey to my actress friend, who soon alighted from the subway. But as I continued alone on my ride home, I couldn’t help but think about all the things we stand to learn about our solar system, our galaxy and our universe—and what news I might have to tell friends after the next AAS meeting.
Photo of Pan-STARRS-1 telescope: Rob Ratkowski