i was driving my semi east on interstate 40 about 50 0r so miles from tucumcari NM. i saw a light moving along the ridge to my left. i watched it for about 15 seconds. then it came towards me and crossed the road in front of me about 50 ft off the ground and out into the desert and dissapeard over the ridge on my right. the disatance it traveled was approx. 20 miles. it crossed that distance in less than a fraction of a second. my rough calculation is about 60,000 miles an hour. as it passed me, my truck and all electronics went dead. a few observations i made are as follows. even though the object was so bright no details were visible. it didnt light up the surrounding desert like it should have. there was no bowshock or wind disturbance of any kind from its passing. the paper and debris on the road was undisturbed.it appeared as a huge dome of light about 300 feet across and maybe 100 ft high.there was also nosound and after it passed my electronics came back on.