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No surface to stand on
Jupiter is composed primarily of hydrogen and helium. Descending from the cloud tops, the pressure increases until the hydrogen transitions into a liquid metallic state—conducting electricity and generating the strongest magnetic field among the planets, approximately 20,000 times that of Earth.
There is no clear boundary between the "atmosphere" and a "surface." The Galileo probe, deployed in 1995, ceased operations after 58 minutes at a depth of only about 150 km.
Great Red Spot
An anticyclonic storm wider than Earth, which has been continuously observed since approximately 1831. Cassini once described a "Permanent Spot" at the same latitude between 1665–1713, but that structure dissipated and there is no observational chain linking it to the current spot—astronomers consider these to be two different vortices. Winds at the periphery reach about 430 km/h. Notably, it is shrinking: from about 40,000 km in width in the late 19th century to about 14,000 km today.
A satellite system like a miniature planetary system
The four Galilean moons were discovered by Galileo Galilei in 1610—an observation that directly refuted the geocentric model:
- Io — the most volcanically active body in the Solar System
- Europa — an ice shell covering a saltwater ocean, one of the most promising places to search for life
- Ganymede — the largest satellite in the system, larger than Mercury, and the only moon with its own magnetic field
- Callisto — an ancient surface, densely cratered
Role in the system
Jupiter's gravity shapes the asteroid belt and influences the orbits of comets. Its role as "Earth's protective shield" is often mentioned, though recent simulations suggest a more complex picture: it simultaneously deflects some objects while nudging others toward the inner Solar System.
Further reading
References
- [1]The Origin of Jupiter's Great Red Spot — Geophysical Research Letters (2024)
- [2]Planetary Fact Sheet — NASA NSSDC (2024)
Image: NASA, ESA, and A. Simon (Goddard Space Flight Center) — Wikimedia Commons, Public domain.
