Venus' Moon: NASA Theory on Its Disappearance

Venus, a planet known for its swirling cloud patterns, may have once had a moon, some NASA scientists theorize. No longer simply a subject of speculative space fiction, the idea is being seriously explored, thanks to planetary science.

The Case of Venus's Missing Moon

Venus may have once had a moon, no longer orbiting our nearest celestial neighbor either because of a calamitous collision. But why does this slight planet do so much damage to its neighbors? This relatively low-density planet could have pulled in and trapped the moon in a chaotic gravitational embrace, ultimately dooming it to a collision with the planet. What happens to moons and Venus? A planet's rotation matters for planetary astronomer in determining whether it is stable over time. Some researchers argue that a planet's rotation affects the formation and lifespan of its moons. Venus's moon would have been pulled in by Venus's gravity. The moon’s orbit would have decayed faster, and Venus would have consumed its moon when it had spiraled in too close—a theory supported by the ill-famed planet’s rotation. What makes Venus's moon so interesting? Some theories conclude that the moon may have crashed into the planet's surface. A planet of similar size and mass, such as our own Moon, could have been engulfed by Venus. But our neighboring planet has been on a much slower path. It is believed to have been involved in a close interaction with the moon, which eventually led to the moon being consumed by the planet.

The curious case of planetary rotation

The theory of Venus’s moon fate has greater implications for how we understand planet-moon dynamics. Why does the planet's rotation matter? Venus has an extraordinarily slow rotation, approximately 243 Earth days for a single rotation. This slow rotation could have caused its moon to slip into a "decaying orbit". Experts say lower rotation speed creates a stronger tidal force between the planet and the moon, ultimately dooming the moon to destruction. Venus’s moon didn't disappear because of a lack of interesting celestial phenomena. Instead, this fascinating celestial phenomenon underscores the importance of studying a planet's rotation and its impact on the formation and stability of its satellites.

How lower rotation speeds kill moons

As the moon spirals toward Venus, the gravitation of the planet causes it to decelerate (orbit) due to the energy of the planet's tidal force, until finally, the moon disintegrates and is consumed. Some scientists estimate that the decaying orbit of Venus's moon took millions of years, but Venus ultimately won out. The planet is swirling with activity and has swirling clouds and a thick atmosphere, making it even more deadly.

The cataclysmic consequences

When the moon's orbit spirals in to the point where the moon is close enough to the planet, the tidal forces caused by the gravitational force are so strong they can tear apart the moon. The resulting debris could have impacted the surface of Venus, but it also could have been absorbed by the planet. As the moon gets closer and closer to Venus, the planet's gravity pulls it in, ultimately sucking it in and consuming the moon. The moon would experience tidal heating from Venus's gravitational pull, heating up the moon and causing it to swell and then collapse. The moon could have eventually melted and been vaporized. Even if it had escaped destruction, it would have gotten so close to the planet that the moon's orbit would be heavily disrupted. Its proximity to Venus and the gravitational pull of the giant celestial body will eventually throw the moon off course.

The unpredictable orbital dance

Not all moons would have this fate. Moons that are six times smaller than their host planets typically survive close encounters. But Venus’s moon may have been doomed to a future of collision with the planet due to the planet's ultra-slow rotation. The gravitational pull of Venus could have caused this celestial body to spiral toward the planet and eventually be consumed.

What to spot near Venus

Interested in spotting Venus' ancient celestial events? Start with a telescope. No need for an exotic night at an observatory. A backyard telescope is enough to see spots on the planet in the night. Venus remains, even without its moon, a spectacular sight in the night sky. Spotting Venus in daytime or at night involves little training. The planet can be viewed in the twilight sky, and some Earthlings report having seen its cloud patterns quite clearly even with an unassisted eye. These swirling patterns are vast enough that it is possible to see them without the use of a telescope. Of course, a telescope would be best to achieve greater accuracy. Digital cameras and telescopes may be used to record and track cloud patterns on Venus to identify changes in its cloud patterns. Venus's swirling cloud patterns are one of the reasons the planet is so recognizable. The clouds are composed of sulfuric acid and other chemicals, and they reflect sunlight, making Venus one of the brightest objects in the night sky, only second to our Sun. These clouds are also responsible for Venus's extreme temperature and atmospheric pressure.