LOS ANGELES — A NASA spacecraft bound for Jupiter will swing by Earth today to get the boost it needs to arrive at the giant gas planet in 2016.

Using Earth as a gravitational slingshot is a common trick since there isn’t a rocket that’s powerful enough to catapult a spacecraft directly to the outer solar system.

Launched in 2011, the Juno spacecraft zipped past the orbit of Mars and fired its engines to put it on course for a momentum-gathering flyby of Earth. During the maneuver, Juno will briefly pass into Earth’s shadow and emerge over India’s east coast. At closest approach, Juno will fly within 350 miles of the Earth’s surface, passing over the ocean off the coast of South Africa shortly before 12:30 p.m.

The rendezvous was designed to bump Juno’s speed from 78,000 mph relative to the sun to 87,000 mph — enough power to cruise beyond the asteroid belt toward its destination.

During the gravity assist, the spacecraft’s JunoCam, a wide-angle color camera, will snap pictures of the Earth and moon. Weather permitting, skywatchers in India and South Africa with binoculars or a small telescope might see Juno streak across the sky. Ham radio operators around the globe were encouraged to say “hi” in Morse code — a message that may be detected by one of the spacecraft’s instruments.

Despite a government shutdown that has prevented NASA from updating its website or tweeting, the space agency’s missions continue to operate. Earlier this week, NASA’s newest spacecraft, LADEE, slipped into orbit around the moon.