One of the best books I read during 2014 was Lee Billings’ Five Billion Years of Solitude, a volume both extremely heady and deeply moving. It tells the story of the quest for exoplanets which resemble Earth, places which could possibly provide refuge for us when our mother planet finally dies. Even if we never manage to leave our solar system, just the intellectual odyssey itself is fascinating. From “Searching for Pale Blue Dots,” an Economist article about other-Earth discussions at this week’s American Astronomical Society meeting:

“IN 1990 Voyager took a photograph of Earth that was striking precisely because it showed so little. The spacecraft was six billion kilometres away at the time and the image it sent back was memorably described by Carl Sagan as a ‘pale blue dot,’ Imagine, then, how pale such a dot would be if the planet in the picture were 113,000 billion kilometres away. Yet this is the distance to the nearest confirmed exoplanet—a planet orbiting a star other than the sun. That gives some idea of the task faced by those who study these bodies. Only in the most special of circumstances can they actually see their quarry. Mostly, they have to work with indirect measurements, like watching for slight dips in the intensity of a star’s light when a planet passes in front of it, a phenomenon known as a transit.

But if indirect observation is all that is on offer, then astronomers must make the best of it. And, as numerous presentations to a meeting of the American Astronomical Society held in Seattle this week show, they have both done so, and have plans to do better in future.

The most successful planet-hunting mission so far has been Kepler, a satellite launched in 2009 by NASA, America’s space agency, which collected data using the transit method until 2013, when a mechanical failure disabled it. It has since been revived, but has only recently begun transmitting data. However, combing of the data it collected in its first incarnation continues, and Douglas Caldwell of the SETI Institute, in Mountain View, California, who is one of the mission’s chief scientists, announced to the meeting the discovery of eight new planets. Three of these lie in their solar systems’ habitable zones (that is, they are at a distance from their parent stars which makes them warm enough for water on their surfaces to be liquid, but cool enough for it not to be steam). One of these three, known as Kepler 438b, is thought particularly Earthlike. It is a bit bigger and a bit warmer than Earth, but is probably rocky. It is therefore likely to be the subject of intense future scrutiny.”