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What Is Juno? (Grades 5-8)

This article is for students grades 5-8.

Artist's animation of Juno spacecraft
Juno will study the bright auroras at Jupiter’s poles.
Credits: NASA

Juno is a NASA spacecraft that is orbiting Jupiter, the largest planet in the solar system. Juno launched in 2011 and arrived at Jupiter in 2016.

The spacecraft’s name comes from Roman mythology. According to the myth, the god Jupiter would hide behind clouds. But his wife, the goddess Juno, could see through them. As in the story, the planet Jupiter is covered with clouds. And the spacecraft Juno is looking behind the clouds to help NASA learn what the giant planet is like.

How Will Juno Study Jupiter?

The Juno spacecraft launched aboard an Atlas V (Roman numeral for “5”) rocket Aug. 5, 2011. Juno arrived at Jupiter July 4, 2016. Juno did not land on the planet.

Juno is an orbiter. Orbiters fly around, or orbit, other bodies in space to study them. Orbiters circle above the atmosphere of planets. Juno will be in polar orbit for about 20 months. Juno’s first orbit lasts 53.5 days. This long orbit allows the spacecraft to slow down and be captured in the planet’s gravity. Then Juno begins its 14-day science orbits. During the science orbits, all of the spacecraft’s science instruments are on, and Juno is capturing data. Juno will orbit Jupiter 37 times, coming within 4,200 kilometers (2,600 miles) of the tops of the planet’s clouds. At the end of its 37th revolution around the planet, the orbiter will deorbit. The spacecraft will dive into Jupiter’s atmosphere and burn up.

A picture of Jupiter with two areas enlarged to show more detail

Science instruments on board Juno study Jupiter’s atmosphere, magnetic field and gravitational field. The magnetic field is the area of magnetic force around a planet. The gravitational field is the force field of gravity around a planet. Juno is taking the first pictures of Jupiter’s polar regions and studying the huge auroras that light up Jupiter’s north and south poles.

Juno is measuring the amount of water and ammonia in Jupiter’s atmosphere to help scientists learn how giant planets formed. Juno is studying Jupiter’s atmosphere under the clouds to find what Jupiter is made of. By mapping Jupiter’s gravitational and magnetic fields, Juno can determine the mass of Jupiter’s core. And Juno will sample the electrons and ions in Jupiter’s magnetosphere to understand why the planet has the brightest auroras in the solar system.

Juno has three very large solar panels that collect energy from the sun to power the spacecraft. The solar panels extend outward from Juno’s six-sided body. The solar arrays measure approximately 2.65 meters wide by 8.9 meters long (about 9 feet wide by 29 feet long). The spacecraft and solar wings together span more than 20 meters (66 feet). In orbit, the three arrays generate about 450 watts of electricity, which is about the same amount of electricity it takes to operate a computer.

Three LEGO figurines representing the Roman god Jupiter, his wife Juno and Galileo Galilei

Why Is NASA Studying Jupiter?

The goal of the Juno mission is to help scientists better understand how Jupiter and other planets began and have changed over time. NASA is always trying to understand the world around us — Earth, the solar system and the universe beyond.

Jupiter is a type of planet called a “gas giant.” Like the sun, Jupiter does not have a solid surface and is mostly hydrogen and helium. Because Jupiter is made of these gases, NASA knows that Jupiter must be formed from the sun’s leftovers. Because Jupiter is so massive, it still has its original composition and has not changed as much over time as the smaller planets.

By studying Jupiter’s composition, NASA can better understand the history and composition of the solar system. With its 53 named moons plus 14 moons that don’t have official names, Jupiter is like a star in a mini solar system. Besides learning more about our solar system, NASA may also learn more about the planetary systems around distant stars. Hidden beneath Jupiter’s dense clouds are the mysteries that NASA and Juno hope to uncover.

Words to Know

atmosphere: the layer of gases around a planet

polar orbit: the path a satellite takes around a planet in a north-south direction from, or nearly from, pole to pole – so, as a planet spins underneath it, a satellite can scan the entire globe strip by strip

aurora: a natural display of light in the sky 

mass: the amount of matter in an object

ion: an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons 

magnetosphere: the region surrounding a planet where the magnetic field is located

More About Juno and Jupiter:

Infographic: How Fast Can Juno Go?
Mission to Jupiter: Juno Story, Coloring Page and Video
What’s It Like Inside Jupiter?
Why With Nye YouTube Playlist 
Conquering the Gas Giant Movie Trailer
Juno Mission
What Is Jupiter?

Read What Is Juno? (Grades K-4)