With adaptive optics it's possible to achieve resolutions down to ~30 milliarcseconds. At 1400 ly that would subtend a distance of 13 AU, so you wouldn't be ab

With adaptive optics it's possible to achieve resolutions down to ~30 milliarcseconds. At 1400 ly that would subtend a distance of 13 AU, so you wouldn't be able to find Earth-like planets. But even if it's theoretically possible to resolve 13 AU separations at 1400 ly, in practice the light from the star is so much brighter than the planet that it bleeds all over the image and completely washes out the reflected light of the star. To do direct imaging you really need to look at systems near the Earth, maybe a few tens of ly away. Then you can separate the planet from the star by enough that you can hope to mask the light from the star and still be able to detect the planet. To get some idea of the techniques required to do this, take a look here: http://astrobites.org/2013/06/09/lowest-mass-exoplanet-discovered-via-direct-imaging/ http://astrobites.org/2013/06/09/lowest-mass-exoplanet-disco...