Moon Wobble

• Vaid's ICS, Lucknow
• 20, Jul 2021

Why in News?

Recently, a study has published that the Wobble effect of Moon is expected to lead to more flooding here on Earth in the middle of the next decade.

What is Moon Wobble?

• It is a regular oscillationthat 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.
• It was first documentedway back in 1728.
• The wobble takes over an 6-year period to complete, and continues in a cyclic fashion.

Key Highlights:

• The study aimed to untangle all of those variablesin an effort to improve predictions about the future of floods.
• The results underscored a basic fact separate from the movement of the moon that our oceans are rising because of climate change.
• The rising temperatures caused by greenhouse gas emissionsare not the only cause of higher flood risks and the report explored the interplay of many variables that push and pull at ocean levels.
• The study warned that we should expect this wobble to heighten high tides in the middle of the 2030s.

Development of Wobble Effect:

• The high tides on this planet are caused mostly by the pull of the moon’s gravity on a spinning Earthand on most beaches, we would see two high tides every 24 hours.
• The moon also revolves around the Earth about once a month, and that orbit is a little bit tilted.
• The path of the moon’s orbit seems tofluctuate over time and completing a full cycle (referred to as a nodal cycle) every 18.6 years.
• At certain points along the cycle, themoon’s gravitational pull comes from such an angle that it yanks one of the day’s two high tides a little bit higher, at the expense of the other.
  • It does not mean that the moon itself is wobbling, nor that its gravity is necessarily pulling at our oceans any more or less than usual.
• The high-tide flooding related to climate change is expected to break records with increasing frequencyover the next decade.

What is the effect of wobble?

• The effect of the wobble couldcause high tide levels at a beach to oscillate by 1 or 2 inches over the course of its long cycle.
• In half of this lunar cycle, Earth’s regular daily tides are diminished, with high tides lower than usual and low tides higher than usual.
  • In the cycle’s other half, the situation is reversed, with high tides higher and low tides lower.
• The moon wobble impacts the gravitational pull of the moon, and therefore, indirectly influences the ebb and flow of tideshere on the Earth.
• The lunar cycle is expected to shift again by mid-2030, and in the coming phase, thetides will amplify once again.

Link between Moon Wobble and Climate Change:

• The upcoming changes in the lunar cycle will pose a serious threat, as theamplified high tides coupled with the rising sea levels will make the risk of flooding far greater across all coastal regions of the globe.

The study predicts that the high tide-associated floods, also known as nuisance floods or sunny day floods, may occur in clusters that could last for months or even for longer periods.

Facts for Prelims:

Near-Earth Asteroid (NEA) Scout:

• It is a small spacecraft, about the size of a big shoebox.
• Its main mission is to fly by and collect data from a near-Earth asteroid.
• It will also be America’s first interplanetary missionusing a special solar sail propulsion.
• It will usestainless steel alloy booms and deploy an aluminum-coated sail measuring 925 square feet.