Jupiter, the fifth planet from our Sun, holds the title of being the largest planet in the solar system by a significant margin—weighing more than twice the combined mass of all the other planets. As night falls, it gleams brightly, rivaled only by the Moon, Venus, and sometimes Mars.
Long ago, ancient astronomers named this planet “Jupiter,” after the powerful Roman ruler of the gods and heavens, also known as Jove. Little did they know of its true dimensions.
Hubble’s New Portrait of Jupiter, June 27, 2019. © NASA, ESA, A. Simon, and M.H. Wong
Jupiter formed about 4.5 billion years ago, alongside the rest of our solar system, as swirling gas and dust came together under gravity’s pull, forming this gas giant. Interestingly, Jupiter shares the same basic elements as the Sun but didn’t accumulate enough mass to ignite and shine like a star.
In 1610, Jupiter played a pivotal role in changing how we perceived the universe and our place in it. Galileo’s discovery of Jupiter and its four large moons—Io, Europa, Ganymede, and Callisto—was revolutionary. It marked the first time celestial bodies were observed circling an object other than Earth, supporting the Copernican view that Earth was not the center of the universe.
The Galilean moons Io, Europa, Ganymede, and Callisto (in order of increasing distance from Jupiter)
Jupiter boasts a faint system of dusty rings and an impressive number of moons—at least 80. Some of these moons are exceptionally large, with one even surpassing the planet Mercury and three larger than our Moon. Among Jupiter’s moons, Europa stands out with particular interest. Scientists speculate that beneath its icy crust, Europa might harbor an ocean of warm water, possibly supporting some form of life. Meanwhile, the rings around Jupiter could be a result of dust kicked up when interplanetary meteoroids collide with the planet’s small innermost moons.
Jupiter has a radius of 43,440 miles (69,911 km), making it 11 times wider than Earth. To put it in perspective, if Earth were the size of a nickel, Jupiter would be as massive as a basketball.
Size comparison of Jupiter and Earth
This gas giant lies quite distant from the Sun, about 484 million miles (778 million km) away on average, making it 5.2 times farther away than Earth. Surprisingly, Jupiter has the shortest day in the entire solar system, lasting only about 10 Earth hours. When it comes to its journey around the Sun, Jupiter takes its time, completing one orbit in approximately 12 Earth years.
The orbit of Jupiter and other outer Solar System planets
Jupiter is an immense ball of gas with cold and windy clouds of ammonia and water. Within its hydrogen and helium atmosphere, it showcases distinct stripes and swirls, creating a captivating sight for all who gaze upon it. Even with a small telescope, we can admire these features from Earth. While the unique chemistries of the clouds likely contribute to Jupiter’s vibrant colors, the exact reasons behind its beautifully painted appearance remain a mystery.
Jupiter’s iconic Great Red Spot, a gigantic hurricane-like storm larger than Earth, has been raging for centuries. In the late 19th century, it spanned about 30,000 miles (48,000 km) at its maximum size. However, it has been gradually shrinking since then. Currently, it measures around 10,159 miles (16,350 km) wide, still large enough to easily encompass the entire Earth.
Close-up of the Great Red Spot photographed by the Juno spacecraft, April 2018
Jupiter’s unique features continue deep within its atmosphere, where pressure and temperature intensify, converting hydrogen gas into a liquid form. This phenomenon creates the largest ocean in the solar system—made of hydrogen instead of water.
As we delve even deeper into Jupiter, its inner composition remains an enigma. It is uncertain whether a solid core lies at its center or if it resembles a thick, extremely hot, and dense mixture. The temperature there could reach as high as 90,032°F (50,000°C), with the core primarily consisting of iron and silicate minerals, similar to quartz.
Ever since Galileo first observed Jupiter through a telescope, scientists have been enthralled by this mysterious world, studying it both from the ground and from space. In 1979, NASA’s Voyager 1 and 2 spacecraft flew by the gas giant, capturing thousands of images.
Timelapse of Jupiter’s cloud system moving over the course of one month (photographed during Voyager 1 flyby in 1979)
Now, NASA’s Juno stands as the only operational mission at Jupiter, launched in 2011 and successfully entering orbit around the planet in 2016. More missions are on the horizon, with ESA’s Jupiter Icy Moons Explorer (Juice) set to arrive at Jupiter in 2031, right after NASA’s Europa Clipper in 2030, focusing on studying Jupiter’s moon, Europa. The quest to unravel Jupiter’s mysteries continues, promising intriguing discoveries yet to come.
Words of wisdom
“Dwell on the beauty of life. Watch the stars, and see yourself running with them.” ―Marcus Aurelius
“Moonlight drowns out all but the brightest stars.” ―J.R.R. Tolkien
“Time you enjoy wasting is not wasted time.” ―Marthe Troly-Curtin
“The universe is a pretty big place. If it's just us, seems like an awful waste of space.” ―Carl Sagan