Hot, Hot Tidal Heat

Let's face it, the Earth is in a sweet spot. We're not too close to the sun or too far away. While those poor bastards on Mercury and Venus can't go outside without burning their skin off, we can spend our weekends lounging on blankets, perfecting our tans/melanoma. Which is why it was once thought that the habitable zone around a star would be a fairly fixed area. If we were going to find life on other planets, the thinking went, their orbits would have to be similar to ours relative to their stars' heat output. Not so, according to some know-it-all scientists. A planet's Goldilocks zone can be a lot larger thanks to tidal heating. When a planet has an elliptical orbit, tidal forces squish it in the middle when it's closest to a star. The further away it travels, the less squishing it suffers. The more severe the ellipse, the more squishing/unsquishing action you have. Like bending a piece of metal over and over again, this tidal action produces heat. In other words, some planets are able to generate enough heat to sustain liquid water and life because of their orbits. Knowing this, we can broaden our search for life-supporting extrasolar planets that might one day fall to the horrible plunder of the Human Galactic Empire. Here's hoping, at least. More details here.