The phrase "orbital radius" refers to the distance between an object in space, like a planet or a satellite, and the center of the celestial body it is orbiting around. It helps us understand how far away something is in space. Full definition
«This is the widest range of orbital radii of any planetary system known,» Marois told New Scientist. (newscientist.com)
For an object so big, these flashes are extremely short, implying a radiating surface about the same as a sphere with orbital radius of Jupiter. (seti.org)
They eliminated those with orbital radii less than one tenth that of Earth's, because at that distance moon systems might not remain in stable orbits around their planets on billion - year timescales. (scientificamerican.com)