Most stars that we see are hundreds and thousands of times bigger than... say, a planet like this one. They're so massive, they pull in smaller objects. Most of the time, planets that get pulled in start to orbit - [He shrugs his Incineroar off enough to make a motion with his hands. One circling the other.] - and gives us years.

As... far as why they stay burning... [How the heck do you explain solar nuclear fusion.] ... they're made of elements that - essentially cause a cycle of burning and refueling. They do eventually burn out, but it can take millions of years.

[Nailed it??]

Suns rise and set because of planets rotating. [More hand motions.] Everything in space is spinning, to an extent. Things like planets are too large for us to really notice the rotation. You'd feel it on a smaller asteroid, or ship, but not a planet. So when they turn, we see the sun moving across the sky.

A lot of people live out there. One of my best friends does, actually. She's here if you ever want to meet her.

[Oh he is living, bless you Byleth.]

The moon glows with reflected sunlight. It doesn't have any air, like our planets do, so there's nothing to dim or block the light when it hits. We're seeing it reflect like a big rocky mirror.