Question

question 4 of 5
when was pluto formally downgraded from planet to dwarf planet?

a. after the hayden planetarium’s solar system exhibit opened
b. after a vote by the international astronomical union
c. after the new york times published an article about pluto
d. after dr. tyson received a letter from a concerned child

Explanation:

Pluto was formally reclassified from a planet to a dwarf planet in 2006 after a vote by the International Astronomical Union (IAU) established a new definition for planets. The other options (A, C, D) are related to events or publications that did not lead to the formal reclassification.

Answer:

B. After a vote by the International Astronomical Union