Which of the following events occurred earliest in history?

Which of the following events occurred earliest in history?

• A. Sputnik launch
• B. Explorer 1 launch
• C. Yuri Gagarin spaceflight
• D. Navstar GPS launch

Answer: (A)

Understanding the timeline of spaceflight milestones is key here. Sputnik 1, launched by the Soviet Union on October 4, 1957, was the first artificial satellite to reach orbit, kicking off the space age. Explorer 1, the United States’ first satellite, followed on January 31, 1958, a bit more than a year later. Yuri Gagarin’s historic spaceflight occurred on April 12, 1961, marking the first time a human orbited Earth. Navstar GPS began with a launch in 1978, establishing the modern global navigation system. Since Sputnik 1 predates all of these events by several years, it is the earliest.

Understanding the timeline of spaceflight milestones is key here. Sputnik 1, launched by the Soviet Union on October 4, 1957, was the first artificial satellite to reach orbit, kicking off the space age. Explorer 1, the United States’ first satellite, followed on January 31, 1958, a bit more than a year later. Yuri Gagarin’s historic spaceflight occurred on April 12, 1961, marking the first time a human orbited Earth. Navstar GPS began with a launch in 1978, establishing the modern global navigation system. Since Sputnik 1 predates all of these events by several years, it is the earliest.