Jupiter, the largest planet in our solar system, is an immense gas giant with a volume large enough to hold more than 1,300 Earths. Unlike the rocky planets of the inner solar system, Jupiter lacks a solid surface, meaning temperature measurements must be taken from its visible atmosphere. Scientists define the planet’s temperature by measuring the cloud tops, which represent a layer of immense atmospheric pressure far above any hypothetical solid ground.
The Cold Reality of Jupiter’s Atmosphere
The average temperature of Jupiter’s visible cloud layer is approximately \(-234^\circ\text{F}\). This frigid temperature is also equivalent to about \(-145^\circ\text{C}\). This measurement is specifically taken at a level within the atmosphere where the pressure is roughly equal to Earth’s sea-level pressure, known as the 1-bar level.
At this elevation, the atmosphere is composed of swirling clouds of frozen ammonia crystals and other compounds. The cold is consistent across the planet, with minimal temperature variation between day and night or between the equator and the poles. This uniformity is a function of Jupiter’s rapid rotation and the nature of its massive, circulating atmosphere. Temperatures in the upper reaches of the atmosphere can be even colder, dropping to nearly \(-260^\circ\text{F}\).
Why Jupiter is So Cold
Jupiter orbits at an average distance of \(5.2\text{ astronomical units}\) (\(\text{AU}\)), which is more than five times the distance between the Earth and the Sun. This tremendous separation means that the amount of solar energy, or insolation, that reaches Jupiter is severely diminished compared to what warms the inner planets.
Jupiter’s massive, deep atmosphere also plays a role in its surface-level coldness by efficiently radiating away the minimal solar heat it does absorb. The planet’s gaseous composition, consisting mostly of hydrogen and helium, does not retain heat from the distant Sun effectively in the upper layers. The lack of a solid, heat-retaining surface prevents solar energy from being trapped, contributing to the persistent atmospheric chill.
Temperature Gradients From Cloud Tops to Core
While the visible cloud tops are extremely cold, the temperature within Jupiter is not uniform and changes dramatically with depth. As atmospheric pressure increases with descent, the temperature begins to rise significantly, a phenomenon known as the adiabatic lapse rate. This gradient means that only a few hundred miles below the \(-234^\circ\text{F}\) cloud tops, the temperature would be much warmer, though the pressure would be crushing.
The heat source for this internal warming is not the Sun, but the planet itself. Jupiter generates a vast amount of internal energy, radiating more heat into space than it receives from the Sun. This heat is leftover from the planet’s formation billions of years ago and is continuously produced by the slow, ongoing gravitational compression of its immense mass.
Descending further, the temperature continues to climb as the hydrogen gas becomes a super-dense, liquid metallic state under extreme pressure. At the planet’s center, the temperature is estimated to be high, reaching up to \(43,000^\circ\text{F}\). This core temperature is hotter than the surface of the Sun, illustrating the remarkable temperature extremes that exist across the gas giant’s structure. Conversely, the very highest layers of Jupiter’s atmosphere, the thermosphere, can also be surprisingly hot, reaching approximately \(1,340^\circ\text{F}\) due to interactions with the planet’s magnetic field and solar wind.
Contextualizing the Extreme Chill
The coldest air temperature ever recorded on Earth was \(-128.6^\circ\text{F}\) (\(-89.2^\circ\text{C}\)) at the Vostok Station in Antarctica. Jupiter’s average cloud-top temperature of \(-234^\circ\text{F}\) is nearly twice as cold as this terrestrial record. Even the coldest satellite-measured surface temperatures on the East Antarctic Plateau, which reached about \(-144^\circ\text{F}\), are still significantly warmer than the Jovian cloud layer.
Jupiter’s atmosphere is also colder than the freezing point of many common gases on Earth. For instance, methane freezes at \(-296^\circ\text{F}\), while nitrogen, the main component of Earth’s air, freezes at \(-346^\circ\text{F}\). Jupiter’s cloud-top temperature is cold enough to freeze ammonia into the ice crystals that form its prominent cloud bands.