On March 17, 1958, a tiny satellite called Vanguard 1 was launched into space. It was only about six inches across, roughly the size of a grapefruit. Soviet leader Nikita Khrushchev mocked it, calling it "the grapefruit satellite." But Vanguard 1 had something the much larger Soviet satellites did not: solar power. While other early satellites ran on batteries that died within weeks, Vanguard 1 used small solar cells to generate electricity from sunlight. It became the first satellite to use solar power, a technology that every modern spacecraft now depends on. The satellite's scientific contribution was also remarkable. By tracking tiny changes in Vanguard 1's orbit, scientists discovered that Earth is not a perfect sphere. It is slightly pear-shaped, bulging a little more in the southern hemisphere. This finding changed how scientists calculated gravity and mapped Earth. Vanguard 1 stopped transmitting signals in 1964, but it is still up there. It has completed over 250,000 orbits and is expected to remain in space for at least another 200 years. That makes it the oldest human-made object still in orbit around Earth. The grapefruit that a world leader laughed at outlasted him and his entire country.