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Ask Dr. Universe: What are shooting stars made of?

If you are anything like me, you probably like watching for shooting stars in the night sky. A shooting star, or a meteor, is usually a small rock that falls into Earth’s atmosphere.

Michael Allen.
Allen

When I went to visit my friend Michael Allen, a senior instructor of astronomy and physics at Washington State University, he told me a lot of shooting stars are no bigger than a pencil eraser.

“The earth is going to pass a random pebble once in a while and that will make a streak in the sky,” he said.

When a small rock is falling into Earth’s atmosphere, it falls super-fast. Depending on the meteor, it can travel anywhere from 36,000 feet to 236,220 feet in a single second. As it falls, there is a lot of friction between the air and the rock. With all that friction, the rock starts to get really hot.

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WSU Insider

Ask Dr. Universe: How do parachutes work?

Nicholas Cerruti.
Cerruti

Parachutes work a lot like dandelion seeds—using the same invisible forces all around us. Nicholas Cerruti, a physics professor at Washington State University, helped me learn how.

The air around you is packed with tiny things called molecules. You can’t see them, but you’re constantly bumping into them. This is true for you, and for every object in motion on Earth.

“As an object moves through air, it needs to move the air around it,” Cerruti explained.

Parachutes work by creating lots of drag. The same idea appears in nature: in dandelion seeds, bird wings, and more. “Flying squirrels have a skin between their legs that develops like a parachute,” Cerutti said. “Instead of the squirrel dropping out of a tree, they can glide.”

Every year, Cerruti and the Physics and Astronomy Club test these ideas by dropping pumpkins from the top of a tall building.

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Ask Dr. Universe

Ask Dr. Universe: Where does the universe end?

When you look up at the night sky, it can feel like the universe is a big blanket of stars above you. But unlike a blanket, the universe doesn’t have corners and edges. Far beyond what humans can see, the universe keeps going. As far as humans know, it never stops.

Michael Allen.
Allen

When I saw your question, I went straight to my friend Michael Allen, senior instructor of physics and astronomy at Washington State University.

The universe is bigger than the biggest thing you’ve ever seen. It’s bigger than the biggest thing this cat can imagine. It’s so big that even your question has more than one very big answer.

Allen explained that you can think of the universe kind of like a rubber band. If you look at a rubber band’s flat surface, you can see it has no beginning and no end. It keeps going around and around in a loop.

Imagine you drew dots on that rubber band. If you pull on the rubber band, what happens? The rubber band stretches, and the dots move further apart. The universe is like that. The distance between all its galaxies, planets, and stars is stretching all the time, like dots on a rubber band. It never ends, but it’s also constantly expanding.

Scientists don’t think there is a true edge of the universe. But there’s an end to what humans can see of the universe. This is called the edge of the observable universe. It’s the farthest we can see, based on how we get information from light.

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Dr. Universe

WSU experts explain the origins of the Leap Year

While regarded as one of the world’s most powerful and influential historical figures, Julius Caesar wasn’t an expert on math or the stars above.

With 2020 being a Leap Year—a once-every-four-years manifestation created to deal with our imprecise notion of a year being 365 days—WSU experts looked back on the development of the modern calendar to demonstrate just how far humanity has come in its quest.

Michael Allen.
Allen

Ancient civilizations depended on the cosmos above to guide their decisions, said Michael Allen, a senior instructor in physics and astronomy at WSU.

The need to be prepared for changing seasons and related weather events led to the development of the first calendars, which typically were either solar or lunar-based. Ancient Greeks made a tremendous breakthrough some 2,500 years ago when they calculated the length of a year at 365.25 days.

Nikolaus Overtoom.
Overtoom

Meanwhile, during the Roman Republic, the development of the calendar was a process fraught with upheaval, said Nikolaus Overtoom, a clinical assistant professor in Ancient History at WSU.

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Terrified about global warming? Finally, here’s some good news

Advances in science are making green energy cheaper, which could make it more efficient and mainstream.

Here’s some moderately good news in the era of climate change. Wind, solar and other “clean” energy sources are now as cheap or cheaper than dirty fossil fuels at the industrial level, even without taxpayer assistance. And the gap is getting wider.

Costs of cadmium telluride, a key component in solar paneling, could plunge, thanks to a new breakthrough just unveiled at Washington State University’s Center for Materials Research.

“We can have a 45% cost reduction in producing the raw material,” says Santosh Swain, a researcher at the center who co-authored the study in Journal of Crystal Growth with Kelvin Lynn, late professor of physics, and others.

That could get solar power costs below the U.S. Department of Energy’s 2030 cost targets for renewable energy way ahead of schedule, Swain says.

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