Venus, often called Earth’s sister planet due to its similar size and mass, is the second planet from the Sun. It is shrouded in a thick, toxic atmosphere that obscures its surface from direct view. Despite the planet’s substantial gravitational influence, which is nearly equal to Earth’s, Venus currently has no moons in orbit.
The Definitive Answer: Zero Satellites
Venus is one of only two planets in the Solar System, along with Mercury, that does not possess a single natural satellite. Every other major planet, including Mars, hosts at least two moons. Scientific missions, such as the Magellan probe and the Akatsuki orbiter, have conducted extensive mapping and observation of Venus. These missions confirm the absence of any large, permanent orbiting bodies. The scientific consensus is that no natural satellite larger than approximately 0.3 kilometers in radius currently orbits Venus.
Historical Moon Hunting and False Sightings
For over a century, astronomers believed they had found a moon orbiting Venus, eventually naming the hypothetical satellite “Neith” after an Egyptian goddess. The first recorded sighting was by Giovanni Cassini in 1672, who observed the object again in 1686. Several other prominent astronomers supported these early observations throughout the 18th century, reporting a faint object near Venus. These inconsistent sightings occurred sporadically until the late 19th century.
Modern analysis determined that these reports were likely the result of various observational errors. The high brightness of Venus could create optical illusions or secondary reflections within the primitive telescopes of the era. Furthermore, many sightings were attributed to background stars, such as Chi Orionis or Nu Geminorum, positioned near Venus at the time of observation.
Explaining the Absence of Moons
The primary reason Venus lacks moons involves its close proximity to the Sun and the resulting gravitational dynamics. Any object attempting a stable orbit must contend with the Sun’s powerful tidal forces. These forces greatly reduce the size of Venus’s Hill Sphere, the region where the planet’s gravity dominates over the Sun’s.
Venus’s Hill Sphere extends to about one million kilometers, significantly smaller than Earth’s 1.5 million-kilometer zone of gravitational control. This smaller sphere makes capturing a large moon or maintaining a stable, distant orbit far more difficult. The Sun’s constant gravitational tug would destabilize the orbit of any captured object, potentially causing it to spiral away or crash.
Venus’s extremely slow, retrograde rotation is also a factor. This unique spin may have caused any moon formed from an early, massive impact to decay and eventually crash back into the planet’s surface due to reverse tidal forces.
Quasi-Satellites and Temporary Companions
Although Venus lacks a true moon, it interacts with small, temporary objects known as co-orbitals or quasi-satellites. These objects do not orbit Venus itself but share the same orbital period around the Sun, maintaining a complex gravitational dance in a 1:1 mean motion resonance.
The asteroid 2002 VE68 is a well-known example that remains close to Venus by following a looping, quasi-satellite path. These companions are not permanent features, as their orbits are unstable and short-lived, typically lasting for only a few thousand years before moving on. The distinction is that these objects are fundamentally orbiting the Sun, with their paths merely influenced by Venus’s gravity, rather than being gravitationally bound to the planet itself.