This article was automatically translated from the original Turkish version.
Jupiter is the fifth planet in the Sun System and is located at an average distance of 778 million km from the Sun. Acting as a transitional body between the inner and outer planets, Jupiter is also the largest planet, with a mass greater than that of all other planets combined.
Jupiter is easily visible to the naked eye and has been known since ancient times, earning it a place among the place. Therefore, it has no specific “discovery date”; it was observed by Babylonian, Chinese, and Greek astronomers. However, in 1609–1610, Galileo Galilei discovered its four largest moons—Io, Europa, Ganymede, and Callisto—during his telescopic observations and provided one of the most important supporting the idea that planets orbit the Sun.
Jupiter, the largest planet in the Solar System, has an equatorial diameter of approximately 142,984 kilometers, making it about 11 times the size of Earth. With a mass of 1.898 × 10²⁷ kilograms, this dev planet is more massive than the combined mass of all other planets and plays a decisive role in the mass balance of the Solar System. Its average density is only 1.33 g/cm³, indicating that it is composed largely of gases.
Jupiter’s atmosphere consists primarily of hydrogen (90%) and helium (10%). In addition to these gases, it contains ammonia (NH₃), methane (CH₄), water vapor (H₂O), and other work gases. Distinct zonal bands are visible in the atmosphere; these appear as alternating dark dark and light colorful stripes, each driven by winds blowing in different directions. Winds at Jupiter’s poles reach speeds of up to 600 km/h, accompanied by complex cyclonic structures. The most striking atmospheric feature is the Great Red Spot, a massive storm system observed since the 17th century. This anticyclonic building is larger than Earth and has persisted for centuries.
Jupiter has no solid surface; the surface is defined as a virtual reference point where atmospheric pressure reaches 1 bar. Beneath the atmosphere, hydrogen first becomes liquid, and at greater depths, under extreme pressure, it transforms into a metallic hydrogen phase. This phase behaves as a liquid metal capable of conducting free electrons and exhibiting electrical conductivity. This like is critical to the formation of Jupiter’s powerful magnetic field. According to scientific models, beneath these layers lies a core roughly the size of Earth, composed of rocky material and likely molten metals. While the existence of this core is not certain, gravity data from the Juno mission supports its presence.
Jupiter possesses the strongest planetary magnetic field in the Solar System, approximately 10–20 times stronger than Earth’s, generating a vast magnetosphere. This magnetosphere interacts with the solar wind to produce an intense radiation belt around Jupiter. Jupiter also has a thin and transparent ring system; these rings were first discovered in 1979 by the Voyager 1 spacecraft.
Jupiter, the fastest rotating planet in the Solar System, completes one rotation in just approximately 9 hours and 56 minutes, causing it to adopt an oblate shape—flattened at the poles and bulging at the equator. It takes 11.86 Earth years to complete one orbit around the Sun.
Jupiter’s magnetic field is the strongest and largest planetary magnetic field generated by any planet in the Solar System. This magnetic field is approximately 10 to 20 times stronger than Earth’s and can reach up to 14 Gauss at the poles. The magnetic field creates a colossal magnetosphere around Jupiter, which acts like a giant protective shield by deflecting charged particles from the Sun (solar wind). Jupiter’s magnetosphere can extend millions of kilometers downstream when interacting with the Sun’s magnetic influence, making its magnetic environment larger in some respects than the Sun itself.
The source of this powerful magnetic field is the metallic hydrogen layer within Jupiter’s interior. Under immense pressure, hydrogen in Jupiter’s interior transforms into a metallic phase in which electrons move freely and conduct electricity. Rapid rotations and convection currents within this liquid metallic hydrogen layer generate a dynamo effect, producing Jupiter’s immense magnetic field. While Earth’s similar dynamo is driven by flows of liquid iron in its outer core, Jupiter’s is sustained by metallic hydrogen.
Jupiter’s magnetic field not only provides protection against solar wind but also generates powerful radiation belts. These belts trap charged particles—particularly electrons and ions—creating regions of extremely high energy. This situation poses a major challenge for Jupiter’s moons and spacecraft operating in this region. Special shielding systems were developed for NASA’s Galileo and Juno missions to withstand this intense radiation environment.
The magnetic field is also responsible for the spectacular auroral phenomena observed at Jupiter’s poles. These auroras form similarly to Earth’s northern lights but are far larger and more energetic. Data collected by the Juno spacecraft since 2016 indicate that these auroras are not solely driven by the solar wind but also by interactions between Jupiter’s magnetic field and its moons. In particular, ions ejected by the volcanic activity of the moon Io significantly intensify these auroral events.
Jupiter is one of the five planets visible to the naked eye in the Solar System and has been observed by humanity since ancient times. Babylonian, Chinese, and Maya astronomers regularly tracked Jupiter in the sky and recorded its movements in their calendars. The Greeks identified it as Zeus, while the Romans named it Jupiter. However, a pivotal moment in scientific observation occurred in 1609–1610 when Galileo Galilei used a telescope to observe its four large moons—Io, Europa, Ganymede, and Callisto—laying the foundation for telescopic astronomy and providing strong support for the heliocentric universe model.
Until the 20th century, knowledge about Jupiter was limited to telescopic observations. However, beginning in the 1970s, space missions provided far more detailed data. The first spacecraft to reach Jupiter was Pioneer 10. In 1973, this vehicle flew by the planet and made the first direct measurements of Jupiter’s magnetic field and radiation environment. The subsequent Pioneer 11, in 1974, provided additional data on the atmosphere and rings.
Following these initial missions, Voyager 1 and Voyager 2 arrived at the Jupiter system in 1979. These missions returned the most striking images and data on Jupiter’s moons to date. Discoveries such as Io’s volcanic activity and Europa’s icy surface had profound revolution implications for astrobiology. The Voyagers also discovered Jupiter’s faint and tenuous rings.
The Galileo mission, launched in 1995, was the first spacecraft to enter orbit around Jupiter and collect long-term data. Galileo deployed a probe into Jupiter’s atmosphere, directly measuring temperature, pressure, and composition. It also provided key insights into the detailed structure of the magnetic field and surface features of the moons. The mission ended in 2003 when the spacecraft was deliberately directed into Jupiter’s atmosphere.
The most important current mission to study Jupiter is NASA’s Juno spacecraft, which arrived at the planet in 2016. Juno was specifically designed to investigate Jupiter’s polar regions, gravitational field, magnetic structure, and deep atmospheric circulations. Data from Juno have led to more accurate models of the planet’s interior and the metallic hydrogen region. Juno has also pioneered studies of auroras and ionospheric analysis.
The JUICE (JUpiter ICy moons Explorer) mission, developed by the European Space Agency (ESA) and launched in 2023, will reach the Jupiter system in 2031 to conduct detailed studies of icy moons such as Europa, Ganymede, and Callisto. This mission has generated significant anticipation because it is expected to provide crucial data on the subsurface possible oceans of Europa and their potential for habitability.
Jupiter, as the largest planet in the Solar System, is also one of the planets with the most moons. As of 2024, the number of confirmed moons exceeds 95, and this number continues to grow with new observations. However, within this extensive moon system, the four large moons known as the Galilean moons—Io, Europa, Ganymede, and Callisto—are the most scientifically significant. Discovered in 1610 by Galileo Galilei, these moons are considered one of the foundational pillars of modern astronomy. These large moons attract great interest not only due to their size but also because of their unique geological and physical properties.
In addition to these, Jupiter has dozens of smaller, irregularly shaped moons. These small moons mostly have irregular orbits and are likely captured asteroids from the outer Solar System. Clusters such as the Himalia group and the Ananke group are classified among these small moons. Although these moons are not as scientifically compelling as Europa, they provide important clues about Jupiter’s formation and how its gravity influenced the accumulation of surrounding material.
Although Jupiter is striking due to its size and dramatic atmospheric structure, its potential to directly support life is extremely low. The main reasons are its lack of a solid surface, its atmosphere’s extreme pressure and temperature, and its surrounding intense radiation belts. While some layers in Jupiter’s upper atmosphere—at around 50 kilometers altitude—have temperature and pressure conditions somewhat similar to those on Earth, the stability and persistence of these conditions are very low. Moreover, the high wind velocities and chemical composition (such as ammonia, methane, and hydrogen sulfide) in these regions are inhospitable to life.
However, some scientists have proposed that microbial life might exist in transient, short-lived forms within Jupiter’s thick atmospheric layers. This idea is based on the “atmospheric plankton” hypothesis proposed by scientists such as Carl Sagan and Edwin Salpeter in the 1970s. According to this model, free-floating microscopic organisms could persist in certain atmospheric layers with sufficient energy and chemical diversity. However, this remains purely theoretical; yet no observational or experimental finding has confirmed this hypothesis.
Nevertheless, some of Jupiter’s moons—particularly Europa, Ganymede, and Callisto—are considered far more promising targets for life due to the presence of subsurface liquid water oceans. The existence of water, potential energy sources, and tidal heating in these moons suggests the possibility of environments analogous to Earth’s hydrothermal vents.
Thus, scientific focus has shifted from the planet itself to its moons.
Jupiter, one of the brightest objects in the night sky since ancient times, has held an important place in the mythology of many civilizations. The ancient Romans named this giant planet after their king of the gods, Jupiter (Iuppiter), who is equivalent to Zeus in Greek mythology. Jupiter was regarded as the god of the sky and thunder and became a symbol of both divine authority and political power. Roman emperors frequently identified themselves with Jupiter to legitimize their divine authority. Temples, victory ceremonies, and inscriptions became integral parts of this imperial ideology.
In ancient Babylon, the planet Jupiter was associated with the god Marduk, who was revered as the god of creation and cosmic order. Jupiter’s grand and powerful motion across the sky made it a representative of this cosmic order. In China, Jupiter was known as the “Year Star” and formed the basis of the 12-year zodiac system. Each year was named according to Jupiter’s position in the sky, playing a major role in astrological time calculations.
In modern astrology, Jupiter is associated with luck, abundance, expansion, and wisdom. In birth charts, Jupiter’s position is believed to reflect a person’s belief systems, learning patterns, and potential for growth in life. It is described as the “great benefic”; in contrast to Saturn’s restrictive nature, Jupiter is always seen as a opportunity that brings growth and expansion.
This multilayered symbolic past demonstrates that Jupiter has left a deep mark on human history not only through its physical size but also through its cultural and intellectual influence. Its brightness and regular motion in the sky have made it an object interpreted both scientifically and spiritually as a sky entity.
Physical and Structural Properties
Magnetic Field
Observation and Space Missions
Moons
Could There Be Life on Jupiter?
Cultural and Mythological Significance