In a recent article about Mars at opposition, I mentioned Jupiter in passing without proper introduction. To remedy this, let’s take a closer look at the largest planet in our solar system. Over the next few weeks, I’ll also be spotlighting other planets visible in the night sky, providing a comprehensive tour of our celestial neighborhood. If you missed my Mars article, you can read it here.

Jupiter: The Solar System’s Behemoth

Jupiter is the colossus of our solar system, boasting a diameter 11.6 times larger than Earth’s—spanning 86,881 miles. Its sheer volume could house over 1,300 Earths, and its immense gravitational pull makes it a solar system within a solar system, with 95 known moons as of this writing. Some of these moons, such as Io, Europa, Ganymede, and Callisto, are among the most fascinating objects in our solar system.

The Galilean Moons: A Mini Solar System

Discovered by Galileo Galilei in 1610, the four largest moons of Jupiter offer diverse landscapes and intriguing mysteries:

• Io: The most volcanic body in the solar system, its surface constantly renews due to intense tidal forces from Jupiter.
• Europa: Beneath its icy crust lies a global ocean, making it one of the prime candidates for extraterrestrial life.
• Ganymede: The largest moon in the solar system, even bigger than Mercury, it has a magnetic field of its own.
• Callisto: A heavily cratered moon, its ancient surface preserves a record of the solar system’s history.

These moons are visible even through a modest pair of binoculars, appearing as small dots lined up near Jupiter.

Jupiter in the Night Sky: What to Look For

Jupiter is a showstopper, with its golden glow and characteristic stripes of red and white. These bands represent different layers of its atmosphere, composed mostly of hydrogen and helium, with trace compounds that give the planet its colorful appearance. Through a telescope, you might spot the Great Red Spot, a centuries-old storm twice the size of Earth.

In 2025, Jupiter will be prominently visible for much of the start and end of the year, though it doesn’t reach opposition again until January 26, 2026. Here are some key celestial events involving Jupiter in 2025:

• January 10: Waxing gibbous Moon near Jupiter in Taurus.
• March 5: First quarter Moon close to Jupiter and Aldebaran.
• May 28: Jupiter paired with the crescent Moon, visible in the west-northwest just after sunset.
• August 6–18: Venus and Jupiter in close proximity during predawn twilight, reaching their closest on August 12.

The Science of Jupiter: Current Missions

Jupiter remains a hub of scientific exploration, with several missions seeking to unlock its secrets.

• NASA’s Europa Clipper: Launched in October 2024, this mission will begin a six-year journey to Jupiter’s moon Europa, arriving in 2030. By performing nearly 50 flybys of Europa, it aims to determine whether the icy moon could harbor life. Learn more about the mission here.
• ESA’s Juice Mission: The European Space Agency’s Jupiter Icy Moons Explorer (Juice) is currently en route to Jupiter, having launched in April 2023. It will make detailed observations of Jupiter and its moons Ganymede, Callisto, and Europa, arriving in July 2031. Juice will study these moons as potential habitats and explore Jupiter’s magnetosphere in unprecedented detail. Read about Juice here.

Jupiter’s Legacy: A Planet of Myths and Science

Named after the king of the Roman gods, Jupiter has fascinated humanity for millennia. Ancient civilizations marveled at its brightness and steady presence in the sky, while modern science reveals its role as a cosmic protector, using its gravity to shield the inner planets from asteroid impacts.

Jupiter’s moons even played a pivotal role in history, serving as one of the first standardized clocks. Observing their movements allowed sailors to calculate longitude and laid the groundwork for time zones based on Greenwich Mean Time.

Why It Matters

Jupiter is not just a gas giant—it’s a gateway to understanding planetary systems, atmospheric dynamics, and the potential for life beyond Earth. Whether you’re peering at its moons through binoculars, marveling at its bands through a telescope, or following groundbreaking missions like Europa Clipper and Juice, Jupiter reminds us of the boundless possibilities that lie beyond our blue sky.

Stay tuned as we continue our planetary journey. Next up: Saturn, the jewel of the solar system. For an up-close view of Jupiter, join one of our astronomy programs here.