Pluto
noun
The underworld king star is the dwarf planet Pluto. Since Pluto was the ruler of the underworld in classical mythology, this makes a lot of sense!
めいおうせい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
冥王星の軌道は不規則で、太陽を一周する期間は約２５０年です。
Pluto's orbit is irregular, and it takes about 250 years to go around the sun once.
冥王星は天文学者クライド・トンボーによって、1930年２月18日に発見された。
Pluto was discovered on February 18 1930 by astronomer Clyde Tombaugh.
冥王星が惑星から準惑星に降格された理由を説明できますか？
Can you explain why Pluto was demoted from planet to dwarf planet?