Mars
noun
The fire star is Mars. This should be easy to remember, because Mars is the only planet in our solar system that's the color of fire.
かせい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
今夜は火星と土星が見えるよ！
Mars and Saturn will be visible tonight!
火星には水がありますか？
Is there water on Mars?
オリンポス山は、火星にある火山の名です。
Olympus Mons is the name of a volcano on Mars.