By Rachna Arora
Oh! look at the moon, | She is shining up there. | Oh! Mother, she looks | Like a lamp in the air.
This classic poem by Eliza Lee Cabot Follen stirs vivid memories of childhood and fascination for our closest neighbour in the solar family. Who has not looked up at the moon with awe and wonder? Remarkably familiar but alien, so close yet so far.
Moon is just not a beacon of light in the night sky, it is an imperative piece for the existence of life, probably having contributed to its creation 3.5 billion years ago.
Simulation-based studies lend due credence to the prevailing theory of the moon tearing apart from earth during the nascent stages of formation of the solar system. With the moon spinning away, earth’s rotation slowed from a five-hour day to the present 24-hour day. Imagine a five-hour day scenario on earth had this phenomenon not have happened.
Our moon is still on the move, receding roughly 1.5 inches from the earth, to brighter horizons. This is confirmed by measurements made using the mirrors placed on the moon since maiden lunar mission in 1969, which reflect the lasers beamed from the earth thereby establishing the distance between earth and the moon. The very tides that are produced by the moon are pushing the moon away and in the process, decelerating the earth and increasing the duration of the day by 2 milliseconds every 100 years.
Many of us wonder, whether the moon will simply vanish someday only to be a point object in the night sky? If this were to happen, every night would be a new moon night, a dream come true for star-gazers and astronomers giving them an unhindered view of the dark space sprinkled with stars.
However, the tides would shrink by about 75 per cent, jeopardising the life of the inhabitants in the tidal zones. The disruption of the food chain including posing serious threat to the entire coastal ecosystems and spawning cycle of many organisms are the adverse fallouts. This could be a potential trigger of mass population decline on sea and land within decades to follow.
The tides enable the cold polar waters to mix with the warm waters in the tropics thereby balancing the temperature and stabilising the climate worldwide. Without the moon, weather forecasts would be very difficult if not impossible with the difference in the temperature on the earth going to life threatening extremes.
However, the most dramatic and devastating effect would be instability in the earth’s axis. It is primarily the gravitational pull of the moon which keeps the earth’s axis at 23.5 degrees. In its absence it will make the earth wobble (just like a slow, spinning top) anywhere between 10 to 45 degrees pushing it out of control. This will not augur well for the planet Earth and its seasons and the climate. In the past, an extra tilt of just 1- 2 degrees has caused ice age. And, we take the moon for granted!
Thankfully, the scientists believe that the moon is never going to leave us, although it is constantly moving away. For sure, it will cause the dramatic changes manifesting slowly and steadily over billions of years.
In about 50 billion years from now, will come the tipping point when the moon will reach an orbit farthest from us. At this point, the moon and the earth will be on a synchronous rotation, with earth tidally locked with the moon having a rotation period of 45 days as against 24 hours presently. Since the moon is already tidally locked with earth, we cannot see the far side of the moon. Given this scenario, the moon will never set or rise and only one side of the earth will see the moon.
Gazing 50 billion years into the future throws up more questions than answers. The future is as dynamic, as unpredictable as can be. The sun is slated to be a red giant by this timeline and would have devoured the earth and the moon. Maybe man would have already colonised the neighbouring planets and ventured deep into space in search of a better life and in pursuit of science.
But before we go across the sea of space, we cannot stop aiming for the moon, understanding its significance, and unravelling its mysteries.
(The writer is PGT- Physics at Shiv Nadar School, Noida.)