Kepler solar array

But before a spacecraft can fly, there's a lot of work to be done. This view shows the solar array side of the nearly completed Kepler construction.

The business end of Kepler is its photometer, a 0.95-meter telescope with a field of view of 105 square degrees--"comparable," NASA says, "to the area of your hand held at arm's length." Such a relatively large field of view for an astronomical telescope is needed so that Kepler can monitor the brightness of 100,000 stars.