After over 20 years of searching for a ninth planet, Planet “X”, Pluto was discovered. It was discovered on February18, 1930 by Clyde Tombaugh after looking at photographs taken in January of that year. In August of 2006, the IAU (International Astronomical Union) came together to create a definition of a planet. According to the IAU there are now three criteria's of a planet.
1. It is in orbit around the Sun.
2. It has sufficient mass to assume hydrostatic equilibrium (a nearly round shape).
3. It has “cleared the neighborhood” around its orbit.
|Image Credits: NASA.gov|
Pluto Meets the first two but does not meet the third one. To have a “cleared neighborhood” an object needs to be large enough have no other objects similar in size next to it except for its satellites. Pluto is not large enough to have enough gravity to clear its neighborhood.
What does the future hold for Pluto? The new information gained from New Horizons confirms that Pluto meets the first and second criteria however it still does not meet the third criteria. The IAU will meet in Honolulu this August and at this time there are no requests to put it on the agenda. For now Pluto remains a dwarf planet.
What are your thoughts about Pluto? Do you think it should be reinstated as a planet or keep its dwarf planet status?