Dear Andrea,

You're right. If we took a trip into the mountains, we would find that it felt a lot colder. It all has to do with our atmosphere. We may not always think about it, but we are basically living in a giant ocean of air.

Dear Nisi,

Just like humans, us cats lose hair. Have you ever brushed your hair and found that some ends up on the brush? Sometimes human hair falls out. It is the body’s way of shedding, or getting rid of dead skin and hair.

Dear Coleman,

People have wondered if Mars has life for a long time. About a hundred years ago, an astronomer named Percival Lowell looked through a telescope and thought he saw canals—a possible sign of water and life as we know it—on Mars.

Dear Karri,

Because cats and dogs are different species, they aren’t usually friends in nature. Dogs in the wild see cats as prey, and cats see dogs as a threat.

Dear Brayton,

Snakes slither to move around because they have no legs. They rely on their muscles and scales.

The scales on a snake are made from a material called keratin. That’s the same material that makes up human fingernails. They help the snake move on different surfaces.

Dear Charleigh,

Whenever there’s heavy rains or winds, butterflies seem to disappear. This is because butterflies hide when it rains. That’s what I found out from my friend David G. James who is an associate professor at Washington State University. He studies insects, including butterflies, in the Pacific Northwest.

Dear Brianna,

A parasite is an organism that steals resources from another organism in order to survive. Our planet is home to all kinds of parasites and organisms that host them.

Dear Brody and Friends:

While a stove or oven produces heat, a fridge can’t actually produce something called “cold.” So, how does a refrigerator manage to keep all your food cool?