Sagittarius is ruled by Jupiter, the planet of luck, good fortune, manifestation, and exploration.
Jupiter loves contemplating the big topics—waxing poetically on the origins of the universe and what exists “out there.” This planet is on the hunt for answers, just like the zodiac sign it rules. Sagittarius will eat up books of all varieties in order to gain as much wisdom on the many answerless questions of the universe.
Additionally, this is why Sagittarius enjoys traversing the globe. Jupiter is the consummate explorer but enjoys such just for the fun of it.
Jupiter is also the bringer of luck and good fortune, which fits Sagittarius like a glove. I mean, who else can collect such great friends around them, serendipitous opportunities to travel the world, and get themselves out of a jam, lickity split?(Their luck especially shines when it comes to money.)While Sagittarius generally has a lot to be thankful for, Jupiter should be at the top of that list.