Pedro zigzagged around Great-Aunt Luisa's dark front yard, holding his phone up.
He was trying to get a stronger signal.
Great-Aunt Luisa lived in the countryside, where there wasn't much to do.
Pedro was staying with her for a whole month.
"Are you taking pictures of the moon?" a voice called.
Pedro spotted a girl in a neighbor's yard.
"No. I was just trying to get a signal."
He glanced upward.
The nearly full moon looked much brighter than it looked at home in the city.
The girl smiled. "I'm Luna. Want to take a look through my telescope?"
"Sure." Pedro walked over to where Luna had set up her telescope.
"I've never seen the moon through a telescope before."
"One day I'd like to see it up close." Luna's eyes shone.
"My dream is to become an astronaut and explore the moon."
"You sure like the moon a lot.
Is it because your name means 'moon' in Spanish?" Pedro asked teasingly.
Luna grinned. "It could be.
Hey! There's a full moon tomorrow.
Want to watch it with me?"
Pedro smiled. "Definitely!"
The next night Pedro met Luna in her yard.
"The moon is a different shape tonight," he said.
Luna giggled. "The moon doesn't really change shape, you know.
The sun lights up the moon's surface.
As the moon orbits around Earth, the amount of the sunlit surface we can see changes.
These changes are the phases of the moon."
"Aha," Pedro said.
"How long does it take for the moon to orbit Earth?"
"About four weeks—one lunar month," Luna said.
"Oh. Is tonight the start of a lunar month?"
"Nope! The full moon is halfway through a lunar month," Luna explained.
"The new moon is the start of a lunar month.
But it's a confusing name."
"Why?" Pedro asked.
"Because that's when the unlit surface of the moon is facing Earth.
We can't see the moon then."
"That should be called a 'no moon' then!" Pedro grinned.
Luna laughed. "After a new moon, the moon waxes—or looks like it gets bigger.
A few days later, it's a waxing crescent.
One week after the new moon is the first-quarter moon.
That's when half of the moon's surface is visible from Earth."
"Why is it a quarter moon if half of it is visible?"
"Because it's one quarter of the way through the lunar month," Luna said.
"Finally after another week, we have a full moon, like this one.
Are you enjoying it?"
Pedro put his eye to the telescope again.
"It's awesome!"
For the next few nights, Pedro and Luna watched the moon slowly seem to disappear.
"It's waning. This is a waning gibbous," Luna explained, pointing to the football-shaped moon.
"In a few days, we'll see the third-quarter moon."
Over a week later it was a new moon, and the sky was moonless.
Soon the moon reappeared, and the waxing moon slowly grew again.
One night, under a full moon, Pedro's mom arrived to pick him up.
"Hey, Pedro!" Luna called as Pedro put his stuff into Mom's car.
Luna was holding a big, long box.
"I thought you might like this."
"Whoa! I can't take that," Pedro said.
It was her telescope!
Luna grinned.
"I'm getting a new one soon.
So please take this one."
"Thanks!" Pedro said.
"That's really generous, Luna.
I'm sorry that I don't have anything for you though."
"That's okay." Luna smiled.
"Just promise me we can moon-gaze together when I visit the city."
Pedro smiled back. "Deal!"