Moon Wobble – UPSC Prelims

It is a regular oscillation that humans have known about for centuries.

It is one of many factors that can either exacerbate rising sea levels or counteract them, alongside other variables like weather and geography.

The moon revolves around the Earth about once a month, and that orbit is a little tilted. To be more precise, the moon’s orbital plane around the Earth is at an approximate 5-degree incline to the Earth’s orbital plane around the sun.

Because of that, the path of the moon’s orbit seems to fluctuate over time, completing a full cycle, sometimes referred to as a nodal cycle, every 18.6 years.

High tides on this planet are caused mostly by the pull of the moon’s gravity on a spinning Earth. On most beaches, you would see two high tides every 24 hours.

At certain points along the cycle, the moon’s gravitational pull comes from such an angle that one of the day’s two high tides is a little higher, at the expense of the other.

During its most rapid upward phase, it acts to enhance the effective sea level, and during its most rapid downward phase, like we’re in now, it acts to suppress the effective sea level.

As per the study, the wobble could cause high tide levels at a beach to oscillate by 1 or 2 inches over the course of its long cycle, thereby raising the baseline.

The more your baseline is raised, the smaller the weather event you need to cause a flooding event.