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Is Pluto a planet again or not?

Dr. Universe,

Is Pluto a planet again or not? 🙂

-Heidi, Cincinnati, OH

Dear Heidi,

It’s a big week for Pluto as NASA’s New Horizons spacecraft gets a close-up look at the distant, icy world. But first, the answer to your question: Pluto is not a planet. » More …

Q&A: Shark Week

It’s Shark Week, so I made a visit to my friend Jon Mallatt. He’s a Washington State University biologist who has studied the jaws of ancient sharks.

dru-hero-poseDr. Universe: What is something a lot of people might not know about sharks?

Jon Mallatt: Some of them, such as tiger sharks, cat sharks, and even great white sharks, have quite large brains—relative to their body weight— and are intelligent. They are not “primitive” animals. The shark relatives, Manta rays and devil rays, have even larger brains than any shark.

Dr. U: How long have sharks been around, anyways?

JM: At least 420 million years and maybe 460. It is hard to tell for sure because they do not have bone, so their skeletons usually are not preserved as fossils. Hard teeth and scales do fossilize, but may not tell us enough. Their teeth evolved from the tiny scales on their rough skin called denticles. But the first sharks may have had no teeth, or their teeth were the same as these denticles so we would not recognize them.

Older fishes without jaws evolved before sharks did, and the oldest fish of all is 520 million years old. This was not long after the first great evolution of all animals at 540 to 520 million years ago. Thus, sharks are very old, maybe appearing only 100 million years after the first animals.

Dr. U: What are some of the coolest things you’ve learned about sharks in your job as a scientist?

JM: They do not get cancer very often. They build up a lot of urea, or “pee poison” in their blood and it does not hurt them. They can feel fast, sharp pain, but not slow burning pain so they probably do not suffer. They show how successful the vertebrates became as predators after fish first evolved jaws about 460 million years ago.

Dr. U: I heard some sharks lose 1,000 teeth in their lifetime. Why do they lose them?

JM: The reason they lose teeth is that most sharks bite really hard when they chomp on their prey. That means their teeth break, come loose, and are lost, so it is good to have replacement teeth throughout life. Sharks also have lots of rows of new teeth covered by the gum inside the jaw, which are always growing up to replace the exposed teeth when they shed.

Dr. U: Woah! Okay, one last question. I think the cat shark is my favorite. Do you have a favorite kind of shark?

JM: I like the six and seven-gilled sharks, which are related. These include the cowshark, Hexanchus, and the frill-shark, Clamydoselachus. Scope them out online. Especially the frill shark: looks a like a cross between an eel and a dragon. They may represent the oldest line of living sharks and they have some primitive features. They are mysterious too, from the deep ocean.

What materials would you use to make a rocket?

Dr. Universe: What materials would you use to make a rocket?

-Freya, Scotland

Dear Freya,

Whether it’s a model rocket you build in the backyard or one that launches a space shuttle, there are lots of materials you could use. So, when I saw your question I grabbed my lab coat and safety goggles, and zoomed over to my friend Jake Leachman’s lab. He’s a rocket scientist and engineer at Washington State University. » More …

What is wind?

Dr. Universe,

My fourth grade students and I want to know: What is wind?

Thank You!

-Ms. Flores, East Alton, IL

Dear Ms. Flores and 4th graders,

There’s wind in the Alton, Illinois, forecast this week, so it’s prime time for an answer. In fact, it looks like there’s wind all around Earth and even some gusts out on other planets. » More …

Why do we get jealous?

Why do we get jealousy? I can feel it sometimes, too, but I don’t know why.  -Hailey, 10, London, Ontario

Dear Hailey,

Cats love attention, but we don’t get jealous like humans do. It’s one of those emotions that set human beings apart from other creatures in the animal kingdom. But I can’t imagine it’s the most pleasant. The poet William Shakespeare once called jealousy a green-eyed monster. Still, it’s an emotion that can help you navigate the world.   » More …

Can you grow clothing?

Can you grow stuff like thread, cloth, silk, and most importantly, clothing? -Jay, Colorado

Dear Jay,

We can use all kinds of animal, bug, and plant materials to make cloth. Even some of the tiniest living things on the planet can make cloth, too.

I heard about this from my friend Hang Liu, a Washington State University professor who studies the science of materials we use and wear every day.

» More …