Charged oxygen in ionosphere may offer biomarker for exoplanets
(PHYSorg.com Space & Earth)

On January 9, 1992, astronomers announced a momentous discovery: two planets orbiting a pulsar 2,300 light years from our sun. The two planets, later named Poltergeist and Draugr, were the first confirmed `exoplanets`-worlds outside our solar system, circling a distant star. Scientists now know of 3,728 (confirmed) exoplanets in 2,794 systems, each one begging the question: `Is anyone else out there?`