A radar for detecting and mapping terrestrial-type planets around distant suns is described. Using technology not greatly beyond that presently available, this radar will detect and image terrestrial planets up to a few tens of light years away with a mapping resolution of a few tens of kilometers. The radar is bistatic with the transmit antenna ensemble in solar orbit inside Mercury's orbit and the receive antenna ensemble in an orbit beyond Jupiter. The net motion of the phase center of the two ensembles of antennas generates a circular synthetic array with a diameter of about 109km. Such an array will have a synthetic-array angular resolution of 2.5 × 10-13rad at a carrier frequency of 600 MHz, corresponding to a resolution of 2.5 km per light year of range.