Two spheres, one silver, the other emerald. Great speed, seen from 1/4 mile away.I don't recall what day, or exactly what year, however it occurred in January. Whatever the year was, it was the year of comet Hyukutaki, and the date of the occurance was the night that the comet was to be most visible, for our area and weather.I was driving home from work that evening, and in casual observance I was looking to see if I could spot the comet; not realizing that the comet was to be seen in the eastern night sky, and I was travelling west on hwy. 60. As I rounded the corner by Crysteel Manufacturing, I saw a luminescent sphere the color of silver, appear from the northern horizon proceeding to the southern horizon and disappering in the distance. At first sight I thought it was the comet, yet in a split second I realized that it was something else. As I wathced; this object flew "nap of the earth", as it crossed over the expressway it appeared to be 100' above the ground, and was about the size of a quarter in perspective from my distance to it.(1/4 mile). As it continued its flight south, it crossed over a grove of cottonwood, just grazing the tops and silohueting the branches as it passed each succesive grove of trees. The length of time that I observed this was about 6 maybe 7 seconds, and the distance that it travelled from one horizon to the other is about 6+ miles.Naturally I was in disbeleif of what I saw, even though I knew I saw "something", when about 3 seconds later the second object dropped out of the sky in a very steep angle, as if it had been waiting for the other, and proceeded in the same direction, but with greater speed; the bottom of the second object was at the same tree top height above the ground. This second object was a sphere as well, only of greater magnitude, about football field in diameter. The color of the second sphere was this amazingly emerald green.To this day, I am still amused by the fact that I saw these two objects that were purposefully flying towards some objective, and that they definetly were not some natural phenomenom that were just ambling throught the air! I also cannot get over how pristine and intense the colors of these objects were; that the colors were not necesarily a surface coloration, but rather a luminuous glow emminating from a reflective metalic surface, like the color you get from anodized metal.((NUFORC Note: We believe the comet was visible in the spring of 1997. We have amended the date above. PD))