Pluto has a mass that is 1/500 of the Earth and 1/6 of the Moon, even though in 1930 it was thought to be 10 Earth masses. There are many trans-Neptunian objects besides Pluto, and it is not the largest one.
Its orbit is far more eccentric than any planet (occasionally bringing it closer to the Sun than Neptune.) Its orbit is far more inclined to the ecliptic than any planet. Its orbit is not stable enough to allow for the development of a long-term theory of Pluto’s position. It shares all of these orbital anomalies with asteroids and not planets.
All asteroids orbit the Sun and have regular rotation periods. Some asteroids are round, and some have satellites. For nearly 50 years after the first asteroids were discovered they were referred to as planets. Considering their small sizes and similar orbital characteristics, astronomers realized that it would make more sense to create a separate class for them. A rational classification system helps scientists as they seek to determine the origin, characteristics and future of natural objects and systems. Hence, it may make more sense to place all Kuiper Belt Objects, including Pluto, into a separate class from either the major planets or asteroids.
If the high school graduate who was assigned in 1930 the arduous task of comparing sky photographs and his mentors had not been so eager to discover a planet, they may have stopped to realize that they were seeing an example of a new class of objects that demanded further scientific investigation. The Kuiper Belt might then have been called the Tombaugh Belt - a far more impressive scientific accolade then having been the first to see a particular celestial body in a photograph.
Just because our third grade teachers had us learn by rote the multiplication tables and the names of the planets, does not imply that both accomplishments were equally valid. We’ll just have to accept that our teachers and their sources may have occasionally dispensed imperfect information. Acceptance of change and errors is an important aspect of living.
Its orbit is far more eccentric than any planet (occasionally bringing it closer to the Sun than Neptune.) Its orbit is far more inclined to the ecliptic than any planet. Its orbit is not stable enough to allow for the development of a long-term theory of Pluto’s position. It shares all of these orbital anomalies with asteroids and not planets.
All asteroids orbit the Sun and have regular rotation periods. Some asteroids are round, and some have satellites. For nearly 50 years after the first asteroids were discovered they were referred to as planets. Considering their small sizes and similar orbital characteristics, astronomers realized that it would make more sense to create a separate class for them. A rational classification system helps scientists as they seek to determine the origin, characteristics and future of natural objects and systems. Hence, it may make more sense to place all Kuiper Belt Objects, including Pluto, into a separate class from either the major planets or asteroids.
If the high school graduate who was assigned in 1930 the arduous task of comparing sky photographs and his mentors had not been so eager to discover a planet, they may have stopped to realize that they were seeing an example of a new class of objects that demanded further scientific investigation. The Kuiper Belt might then have been called the Tombaugh Belt - a far more impressive scientific accolade then having been the first to see a particular celestial body in a photograph.
Just because our third grade teachers had us learn by rote the multiplication tables and the names of the planets, does not imply that both accomplishments were equally valid. We’ll just have to accept that our teachers and their sources may have occasionally dispensed imperfect information. Acceptance of change and errors is an important aspect of living.
For astronomical graphics, including
monthly wallpaper calendar, visit:
CurtRenz.com/astronomical
Curt Renz
