Prospects for detection of extra-solar giant planets by next-generation telescopes

THE construction of several large ground-based telescopes^1,2 and the anticipated launches of new space-based ones^3-5, have prompted renewed interest in the means by which extra-solar planets might be discovered^1,6,7-11. The direct detection of light from such a planet would be the most compelling means of discovery, and it may soon be technically feasible^1,6. Jupiter has traditionally been used as a benchmark for observability, but extra-solar giant planets could have a wide range of masses and ages¹², and could be significantly brighter than Jupiter. Here we present calculations estimating the optical and infrared fluxes of extra-solar giant planets with a range of ages, and demonstrate the conditions under which they will be observable with several new telescopes. Giant planets with masses greater than that of Jupiter, and younger than about 1 billion years, are the best targets, and they should be visible using the generation of telescopes now under construction.