[LINK] Two exoplanet links

[rfmcdonald]

Wired Science has quite good coverage.

Lisa Grossman covers the Kepler mission's discovery of any number of multiple-planet systems. Kepler-11 features prominently, of course.

The five inner planets all orbit the star once every 46 days or less, and the outer planet orbits once every 118 days. If this system were dropped into our solar system, all the planets would be closer to the sun than Venus.

Compared to Earth, the planets are remarkably light for their size. The five inner planets range from 1.97 to 4.52 times Earth’s radius and 2.3 to 13.5 Earth’s mass. The outer planet, whose radius is 3.66 times Earth’s, is too far away for its mass to be completely determined, but astronomers know it is less massive than Jupiter.

These planets are unlike anything in our solar system. From the planets’ masses and radii, astronomers can calculate their density, a clue to composition. Although the planets around Kepler-11 are fairly small, they’re all much less dense than Earth, making them more like mini-Neptunes than super-Earths. The inner two could be mostly water, with a thin atmosphere of hydrogen and helium. The farther-out planets may have much thicker hydrogen and helium atmospheres that comprise up to 20 percent of the planet’s mass.

But there are other spectacular discoveries.

Of the 1,235 new planet candidates, 68 are Earth-sized, 288 are super-Earth sized, 622 are similar to Neptune, and 165 are as big as Jupiter. 54 of the candidates orbit in the habitable zone, the right distance from their stars to sustain liquid water.

One of those candidates is smaller than Earth. Four are super-Earth-sized, and most are Neptunes or Jupiters. But all the moons of those Jupiters would also be in the habitable zone, noted Kepler science principal investigator William Borucki of NASA Ames Research Center in a press conference Feb. 2.

“For your Christmas vacation you could go from one moon to another, and have a vacation on that different moon,” Borucki said. “I’m not saying that happens every day, but it’s possible.”

Grossman also has an interview with astronomer Geoff Marcy, the man who was one of the first to discover planets. His search paid remarkably well. Why did he do it?

You want the real answer? It’s personal. After I got my PhD at Santa Cruz, I was really lucky and I got a post-doctoral fellowship at the Carnegie Institute of Washington, which is in Pasadena.

And in brief, my research wasn’t going very well. A Harvard astronomer criticized my PhD thesis. And I felt pretty bad. Everyone seemed smarter than me. I felt a little bit like an impostor, like they haven’t figured out that I’m not as smart as them, that I’m not really smart enough to be a scientist. I thought okay, well now the jig is up. Maybe my career is over.

But I still have a year and a half on my post-doc! I remember one morning in my apartment in Pasadena, as I took my shower, thinking, I can’t suffer like this anymore. I’ve got to just enjoy myself, do research that really means something to me.

So I thought, what do I care about? I would love to know if there were other planets around other stars.

This was a question that nobody was asking. It was 1983, and nobody was even talking about planets. Even our own solar system was considered boring at the time.
“Of course the real question isn’t whether there are habitable Earthlike planets. It’s how common are they? Are they one in 100, one in 1000, in in a million? How far do we have to travel to find the nearest, lukewarm, rocky planet with an atmosphere?”

So by the time I turned off the shower, I knew how I was going to end my career. I quickly realized that this was kind of a lucky moment. By knowing that I was a failure, I was free. I could just satisfy myself, and hunt for planets — even though it was a ridiculous thing to do. At that time, I hadn’t heard of anybody actively hunting for planets.

Go, read!