Explorer 1, officially 1958 Alpha 1, was the first artificial satellite placed in Earth orbit by the United States. It was released at 22:48 EST hours on January 31 (03:48 of February 1 in UTC) of 1958 from Launch Complex 26 (LC-26) of the Cape Canaveral Air Force Station aboard the Juno I rocket, as part of the International Geophysical Year and in response to the launching of Sputnik I and Sputnik II by the Soviet Union, thus giving rise to the space race, closely related to the Cold War.
The Vanguard 1 is the fourth satellite placed in orbit in history, the second by the United States, and the oldest satellite that currently remains in orbit as its predecessors (Sputnik 1, Sputnik 2 and Explorer 1) re-entered into atmosphere and were destroyed shortly after its release.
Sputnik 1, launched on October 4, 1957 by the Soviet Union, was the first artificial satellite in history.
"Kepler's Third Law of Planetary Motion" <span>states that the square of the orbital period of a planet is directly proportional to the cube of the semimajor axis of its orbit
