The Sputnik 1 rocket body was the second stage, or "core booster", that carried the Sputnik satellite into orbit. The rocket body itself also reached orbit and was visible from the ground as a magnitude 1 object. In fact, this was actually the "Sputnik" people saw from the ground over the next few months, the small but highly polished sphere of the Sputnik 1 satellite was barely visible at sixth magnitude.
Sputnik was launched from Baikonur Cosmodrome at Tyuratam (370 km southwest of the small town of Baikonur) in Kazakhstan, Soviet Union, at 19:28:34 UT (near midnight local time) on 4 October 1957. The launch vehicle was a Semyorka R-7 ICBM. The tank emptying system failed 16 seconds after launch, which resulted in the kerosene running out and the engine shutting down one second earlier than planned, putting the rocket in an orbit with an apogee about 80 to 90 km lower than expected. After reaching orbit, it released the Sputnik 1 satellite. The orbit of the rocket body decayed on 1 December 1957, estimated at 08:46 UT, re-entering the atmosphere at about 45 N, 106 E over Outer Mongolia.