The search for habitable planets around other stars has taken a step forward by, ironically, looking at our own planet. To test whether we would be able to detect oceans on exoplanets, researchers used the Deep Impact spacecraft to observe Earth, as if we were aliens looking at Earth with the tools we might have in ten years.
The Deep Impact spacecraft hit the headlines in July 2005 when it fired a copper projectile into the comet 9P/Tempel 1, creating a huge outburst on the comet’s icy surface. Since it still has fuel and power, astronomers have since been employing it in other jobs. For instance, at the beginning of this year it began using its cameras to search several stars for the telltale dips in light that indicate transiting planets.