By Jove, they’ve done it: Nasa’s Juno spacecraft successfully enters orbit around Jupiter

Braving intense radiation, Nasa’s Juno spacecraft has successfully entered orbit around Jupiter after a five-year voyage to begin exploring the king of the planets.

Ground controllers at the Nasa Jet Propulsion Laboratory erupted in applause on Monday when the solar-powered Juno beamed home news that it was circling Jupiter’s poles.

The arrival at Jupiter was dramatic. As Juno approached its target, it fired its rocket engine to slow itself down and gently slipped into orbit. Because of the communication time lag between Jupiter and Earth, Juno was on autopilot when it executed the daring, one-time-only move.

The spacecraft’s camera and other instruments were switched off for arrival, so there won’t be any pictures at the moment it reaches its destination. Hours before the encounter, Nasa released a series of images taken late last week during the final approach, showing Jupiter glowing yellow in the distance, circled by its four inner moons.

Scientists have promised close-up views of the planet when Juno skims the cloud tops during the 20-month, US$1.1 billion mission.

The fifth rock from the sun and the heftiest planet in the solar system, Jupiter is what’s known as a gas giant — a ball of hydrogen and helium — unlike rocky Earth and Mars.

With its billowy clouds and colourful stripes, Jupiter is an extreme world that likely formed first, shortly after the sun. Unlocking its history may hold clues to understanding how Earth and the rest of the solar system developed.