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Astronomers Detect Four Earth-Sized Planets Orbiting The Nearest Sun-Like Star (ucsc.edu)
Tim Stephens reports via The University of California in Santa Cruz: A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water. The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second. The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets.
Is speed of the wobble what was meant? I thought it must be 30cm/second of rotational arc, which translates to a 200km peak variation as the planet orbits from one side 180 deg around to the other.
>we still don't know the answer to Fermi's paradox.
"Space is big. Really big. You just wonâ(TM)t believe how vastly hugely mindbogglingly big it is. I mean you may think itâ(TM)s a long way down the road to the chemistâ(TM)s, but thatâ(TM)s just peanuts to space." - The Hitchhikerâ(TM)s Guide To The Galaxy
I know some space enthusiasts talk about even a single civilization sending out a Von Neumann probe resulting in the whole galaxy being blanketed in a few hundred million years... but space is big, hostile, slow to traverse, and resources are really tough to get access to.
It's very much possible that there's no single answer to the Fermi Paradox, but it's a little bit of all the factors. The base raw materials for life are likely extremely common (similar clouds of gas collapsing into similar systems), but life may be rare and I would expect complex life building technologically advanced space-faring (or even communicating) civilizations to be a fraction of those.
Combine the likely rarity of intelligent life with the massive distances (involving massive time delays)... and you can get a lot of lonely species all thinking there's nobody else out there simply because they can't communicate with each other in any practical way.