I was flicking through a book called “Does anything eat wasps?”, not expecting to find information about the Moon, but surprisingly I did! It is a book of questions and answers from the ‘Last Word’ column of New Scientist, where readers can write in to ask scientific questions. The Moon related question I found was “What would be the effect on Earth if an alien spaceship came along and dragged the moon away?”. What an interesting question! How does the moon directly affect the Earth? What would happen if it disappeared?
This column allows readers to write in with questions, but also allows them to answer their fellow readers’ questions. According to one reader, an alien spaceship stealing the moon would cause catastrophes and ultimate doom! It would mean the end of life on Earth! The reasons behind these seemingly alarmist statements are linked to the fact that the moon acts as a rotational stabilizer. It is a bit like a balance wheel that prevents wild variations in the Earth’s tilted rotational axis, so if it was to disappear there would be wild swings from a position almost perpendicular to the ecliptic plane, all the way to being practically parallel to it. These swings would cause drastic changes in climate, as the author points out ‘when the axis points straight up, each point on the globe would receive a constant amount of heat throughout the year, but when the axis lies parallel to the ecliptic, Earthlings would spend six months of the year sweltering under the unending blaze of the sun, only to spin round and shiver for the next six months, hidden on the frigid surface of the Earth’s dark side’!
Another reader noted that the Moon and the Earth both have a gravitational effect on each other, such that they orbit around a point in between them, and as a pair they rotate around the Sun. If the Moon disappeared, the Earth’s orbit around the Sun would go completely wacko too! This would also result in climate changes that could potentially make our planet uninhabitable!
I suppose a seemingly less drastic change would be that our ocean tides would be affected. As mentioned in an earlier post, both the Sun and the Moon influence the tides on Earth, but the Moon is the dominant force. If the Moon was to disappear, the daily rush of the tides would recede to a gentle ripple, which would certainly upset surfers, but also many tidal marine organisms.
One marine organism called the ‘Nautilus’ would be especially effected by being forever trapped inside its own chamber! It is a Mollusc that lives inside a spiral shell with special compartments. The Nautilus only lives inside the outermost compartment, and each day adds a new layer to its shell. Scientists have shown that the number of layers making up a chamber are directly linked to the number of days it takes the Moon to circle the Earth, so at the end of each month the Nautilus abandons its current compartment, closes it up and moves into a new one. If there were no more Moon, the poor old Nautilus would be forever locked inside the same chamber, waiting to move into its new home!
Finally, most of us do not appreciate the substantial amount of light that the Moon reflects down to us each night. If it were to disappear, our major source of night time light would vanish, affecting the behavior of many nocturnal creatures, not to mention any creature that relies upon the phases of the Moon for its survival.
After considering these points, I value our Moon a whole lot more. It may be a dead rock in the sky, but it certainly has a major influence upon our planet; more than most people care to realize.
Reference:
O’Hare, M. (2005) Does anything eat wasps? And 101 other questions. Profile Books Ltd. Pages 132-134.
