Watch a Whole Planet Vanish in the Daytime Sky Tomorrow!

Professor Pip adjusted his slightly crooked spectacles and patted the bulging pockets of his green lab coat. "Aha! Here we are." He pulled out his small brass telescope, his pocket notebook labeled Notes, and — for some reason — a shiny silver dime.

Mia and Leo had climbed all the way to the top of the grassy hill with him. The afternoon sun was warm on their cheeks. The blue sky was huge.

"Today," Pip announced, his fluffy tail swishing, "we are going to watch a planet disappear."

"A whole planet?!" gasped Mia.

"Where does it GO?" said Leo.

Pip's whiskers twitched with delight. "It doesn't go anywhere. It just gets hidden. And the thing that hides it… is not very big at all." He held up the dime, then pointed at the distant church steeple on the far side of the valley. "Watch this. Leo, hold this dime out at arm's length and close one eye."

Leo did. He squinted hard.

"Now — slowly — line the dime up with the steeple."

"WHOA," said Leo. "The dime hid the whole steeple!"

"But the steeple is HUGE," said Mia. "And that's just a tiny dime!"

"Precisely!" cried Pip, paw-clapping. "The dime is smaller — but it is closer to your eye. When a closer thing lines up exactly with a farther thing, the closer thing can cover it completely. Scientists call that an occultation. Oh-cull-TAY-shun."

Pip raised his little telescope and pointed up. "Tomorrow afternoon, our Moon — which is much smaller than Venus, but much, much closer to us — is going to slide right in front of Venus. Venus will vanish for almost an hour. Then it'll peek out from the other side, like a tiny diamond appearing out of nowhere."

"In the DAY?" said Leo. "I thought you only saw planets at night!"

"Venus is so bright you can spot it during the day — if you know exactly where to look," said Pip. "It's the brightest planet in our sky. And tomorrow, the Moon is its hiding spot."

Mia tilted her head. "Oh! Like when you walk in front of me and block the whole TV!"

"Exactly right!" Pip beamed and scribbled in his notebook. "You are smaller than the TV, but much closer to your eye. Same trick as the Moon and Venus." He looked up at the blue sky and smiled. "An ordinary afternoon — and a whole planet about to play hide-and-seek."

He tucked his telescope away and turned to the kids. "Tomorrow afternoon, stand in the shadow of your house — that's important, never look near the bright sun! — and find the slim crescent Moon high in the sky. Watch for the tiny bright dot beside it. That is Venus. Then watch it slip away."