We all live in a yellow scrap machine: Saturday Science Roundup #3

We’re up to three weeks already? The weeks fly past so rapidly.

Could there be 100 billion potentially-habitable planets in the Galaxy? The simple answer is “yes”. There are hundreds of billions of stars in the galaxy, and most of them probably have planets. We’ve only known about these planets for 20 years, and we’re biased towards only finding the really weird ones – because if you’re bigger than jupiter and orbit your star every few days, it turns out you’re pretty easy to find. To see Jupiter at Jupiter’s current distance from the sun, it would take >12 years, and you would need a pretty fine telescope to see the effect it has on the sun (the planet itself would be too hard to see). And small rocky planets like the earth are nearly impossible to find, but we’re getting better at looking for them. The article goes into the details of how we estimate how many planets there are, and what makes a planet suitable for life (and then stops because defining what life is and figuring out how we could detect it is a whole other mess.)
Mystery SETI Signal Set Rules of Engagement: Fortunately, we have SETI to step into the breach and come up with guidelines for chatting to aliens and looking for signals from them. In 1967 astronomers discovered the first pulsar, a super dense ex-star that beams out radio signals like a lighthouse, spinning so that every few seconds you see the flash of the lighthouse. They are incredibly regular, and in some cases are better timekeepers than atomic clocks. The only problem is that back in 1967, no one knew what they were looking at, so they dubbed the signal “LGM?” for “little green men?” After several months of careful analysis they calculated that the signal was not coming from a planet, but rather a neutron star, and the panic in that crowd was over, but I imagine it must have been somewhat scary for a little while there. (Prompted by this paper by Alan Penny, which was a nice read, tells several sides of the story, but tends towards paranoia at the end.)
How Beer Gave Us Civilisation: New science is pointing to the idea that human ancestors grew grains for beer before they figured out proper staples such as bread and the like. All the evidence so far is circumstantial, but that’s okay. We had to start somewhere.
Gravity Satellite Felt Japan Quake from Space: When an earthquake takes place, the ground shakes and we can hear the rumbling as sound waves are generated from the movement. But it turns out, the slower movements also cause slower-moving compressions in the atmosphere, infrasound waves, which can travel great distances through the air. And some of these “sounds” will head straight up, to low orbits where they can be detected in the movement of satellites such as the Gravity Ocean Circulation Explorer. I’m not sure precisely what else this satellite is used for, but it’s pretty cool that they were able to “feel” such an earthquake from almost-space.
A Billboard that’s also a moisture farm: This is brilliant and ought to earn its engineers big bucks and all the prizes. They’ve built a billboard that captures and purifies water from the humid air in Lima (Peru) to provide drinking water for the community below. Given that Australia is both full of billboards and frequently in drought, maybe we can employ some of these for our farmers, once the developing world has enough. (Maybe advertisers could sponsor them in a buy-one-get-one-free-in-Peru deal?)
The Other Russian Meteor: Tunguska, the science, and the conspiracy theories! I think my favourite is that it was all Nikola Tesla’s fault, because he was testing one of his death rays up there. We’re not actually sure whether it was a comet or a meteor, or which type of meteor it was (there’s evidence for all of the above), so there’s at least one research group still looking into it. We are certain that it came from space and wasn’t an alien spacecraft.
Elephant Feet, Arizona: Ooh, Geology! There’s not enough of that in my casual reading. These pillars look like a pair of elephant feet, which makes me wonder, what happened to the other two?