EVERYDAY SCIENCE

Detailed explanation-1: -Pluto was discovered in 1930, the first object in the Kuiper belt. It was immediately hailed as the ninth planet, but it was always the odd object out, and its planetary status was questioned when it was found to be much smaller than expected.

Detailed explanation-2: -In a similar way, due to perturbations observed in the orbit of Neptune, in 1930, the planet Pluto was discovered, which, according to the observations made so far, is the last planet in the solar system.

Detailed explanation-3: -Poor Pluto. On August 24, 2006 at the International Astronomy Union (IAU) General Assembly the ninth planet was scrubbed only 76 years after its discovery. Even weirder is that it actually got voted out, and by astronomers, not planetary scientists.

Detailed explanation-4: -The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet. Essentially Pluto meets all the criteria except one-it “has not cleared its neighboring region of other objects.”

Detailed explanation-5: -On February 18, 1930, Tombaugh discovered the tiny, distant planet by use of a new astronomic technique of photographic plates combined with a blink microscope.