disappearing moon -- 12/21/22
Today's selection -- from Eureka! with an introduction by Jim Al-Khalili. What would happen to Earth if the moon were no longer there?:
"The most immediate difference would be the disappearance of the tides. Both the sun and moon influence the tides on Earth, but the moon is the dominant force. Remove the moon and the daily rush of the tides would recede to a gentle ripple.
"The next omen of doom would be wild swings in the Earth's rotational axis from a position almost perpendicular to the ecliptic plane all the way to being practically parallel to it. These swings would provoke drastic climate changes: 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.
|The near side of the Moon (north at top) as seen from Earth|
"Of all calamities, though, the creature to be pitied first is the marine organism called 'nautilus'. This mollusc lives in an elegant shell shaped like a perfect spiral partitioned off into compartments. The nautilus only lives in the outermost partition, and each day adds a new layer to its shell. At the end of each month, when the moon has completed one revolution around Earth, the nautilus abandons its current compartment, closes it up with a partition, and moves into a new one. Scientists have proved 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. Remove the moon and the nautilus lies stranded, forever locked in the same chamber and wishing ruefully for the days when it could look forward to a new home.
"Thankfully, it seems unlikely that an alien spaceship would come along and steal the Moon, even for civilisations with a sense of humour that is advanced many millions of years beyond our own."