Sixty-nine years ago this day, the Soviet Union launched Sputnik 1, the first satellite to orbit Earth, opening the Space Age and setting off a race with the United States.

Ten years later, on October 10, 1967, the Outer Space Treaty came into force.

In 1999, the United Nations started observing World Space Week – from October 4 to 10 – to celebrate the contribution of space technology for the benefit of humanity. Schools, space agencies, museums and astronomy clubs around the world hold stargazing nights, science classes, exhibitions and talks by astronauts and scientists.

Today, more than 80 countries have put satellites into orbit, and people from over 50 of those have travelled to space.

In this visual explainer, Al Jazeera looks at which countries have done so, how many space travellers have been women, and what comes next for human spaceflight.

The first man in space – Yuri Gagarin

On April 12, 1961, Soviet astronaut Yuri Gagarin became the first human in space.

On board the Vostok 1 spacecraft, he completed one orbit of Earth at about 27,400km/h (17,025mph) during a 108-minute flight. He later ejected from the spacecraft and landed by parachute.

The mission demonstrated that humans could survive launch, weightlessness and re-entry, giving the Soviet Union a major early victory in the Cold War Space Race.

Six years later, on October 10, 1967, the Outer Space Treaty entered into force. Signed by the US, the United Kingdom and the Soviet Union, it established that space should be explored and used peacefully and that no country could claim it as territory.

Less than two years later, NASA’s Apollo 11 mission landed the first humans on the moon. On July 20, 1969, Neil Armstrong became the first person to walk on its surface.

Where does space begin?

There is no single agreed boundary for where space begins: most international bodies use the Karman line, 100km (62 miles) above Earth, while the US military, NASA and the Federal Aviation Administration count anyone who flies above 80km (50 miles).

Either way, it is closer than it sounds: if Earth were the size of an apple, space would begin about as far from the surface as the thickness of its skin.

Which countries have sent people to space?

By the Karman line measure, at least 746 people from 52 countries have travelled to space, including professional astronauts and paying tourists.

Some hold dual nationality, and some flew for countries that no longer exist, such as the Soviet Union.

The graphic below breaks down space travellers by country.

Two countries still dominate the list. The US has sent 369 people to space, and the Soviet Union and Russia have sent 138 combined. China, the third country to launch people on its own rockets, has sent 29.

One in seven space travellers is a woman

Space remains a male-dominated frontier. Science fiction may be full of women commanding starships, but of the 746 people who have travelled to space, only 112, or 15 percent, have been women, about one in seven.

Soviet astronaut Valentina Tereshkova became the first woman to travel to space in June 1963. The US did not follow for another 20 years, until Sally Ride flew in June 1983.

The share of women is rising, though, largely because of commercial flights. More than half of the women who have flown since 2020 went up as paying passengers or guests on Blue Origin’s suborbital rocket.

The typical space traveller is 40

Most people who have flown to space were in their 30s or 40s on their first flight, which together account for 85 percent. The median age is 40. Commercial flights have widened that range.

The youngest traveller, Oliver Daemen, was 18 when he flew in 2021. The oldest, Ed Dwight, was 90 years and eight months old when he flew in 2024, about two months older than William Shatner had been on his flight three years earlier.

What comes next for human spaceflight?

In April 2026, the Artemis II crew flew around the moon and reached about 406,771km (252,756 miles) from Earth, breaking the distance record set by Apollo 13 in 1970.

Next is Artemis III in 2027, a rehearsal in Earth orbit to test docking with lunar landers built by SpaceX and Blue Origin. NASA is targeting 2028 for Artemis IV, which aims to land astronauts near the moon’s south pole, the first crewed landing since 1972.

India plans its first crewed Gaganyaan flight in 2027, making it the fourth country to launch people on its own rocket. China aims to land astronauts on the moon around 2030.