“When I consider thy heavens, the work of thy fingers, the moon and the stars, which thou hast ordained; what is man, that thou art mindful of him? and the son of man, that thou visitest him?”
Do you feel sorry for Pluto? It isn’t a planet anymore.
Of course, you might want to point out to me that this is old news. Pluto was reclassified in 2006, being downgraded to the new category of dwarf planet. Thus, the Solar System went back to being a collection of eight planets, just as it had been before the discovery of Pluto in 1930.
Many people my age were brought up being taught that there were nine planets. Those of us who enjoyed astronomy as children sometimes feel that the International Astronomical Union (IAU) has taken away a good chunk of our childhood.
Because of the discovery of other large Trans-Neptunian Objects (TNO), the IAU devised a new set of criteria to determine whether or not a body was a planet. Pluto (and, indeed, that other well-known TNO, Eris) fulfill all the criteria for planethood except one. It is this:
It must have cleared the neighborhood around its orbit.
When did Pluto fail, and Neptune succeed, in clearing their orbits of debris? Surely this process has not been observed. If the IAU’s criteria suggested merely that the body’s orbit had to be clear of debris to be described as a planet is one thing. To be able to show that the planet has actually done this is a bigger problem which requires one to know what has actually happened in the past. But no one has seen this process occur. It is a supposition, based on an old-earth framework. To be a planet or a dwarf planet requires knowledge of an evolutionary process that never actually happened.
Along with the hymnwriter, when we consider all the works Your hand has made, Lord God, we declare “How Great Thou Art!” Amen.
Author: Paul F. Taylor
Ref: Encyclopaedia Britannica, , accessed 7/13/2017. Image: New Horizons, NASA, Public Domain.