These Volunteer Toad Crossing Guards Help Nature Thrive In Philadelphia

It’s that time of year again, when thousands of toads are migrating across busy roads toward their breeding grounds — and hundreds of human crossing guards are there to make sure they arrive safely without being squashed by cars.

Toad Detour” takes place each spring in and around Philadelphia’s Schuylkill Center for Environmental Education.

The operation is designed to protect the thousands of local American toads that leave the Schuylkill Center’s 340 acres of forest, where they’ve been sleeping through the winter, to head for a nearby reservoir where they’ll make a whole lot of babies.

That’s all good, except for the perilous part of the journey that involves crossing two city streets, points out the Schuylkill Center’s Claire Morgan. She has the world’s best job title, “toad detour coordinator,” and the duty of ensuring that traffic is rerouted on nights when the migration is taking place.

To help these critters make it to where they’ll be able to make it, volunteers block traffic with plastic barriers for a couple of hours every night, with city permission.

They also help corral any toads that hop outside barricaded areas.

Toad detouring started in 2009, when local animal lover Lisa Levinson noticed toads were meeting their maker instead of their mates. She decided to help them out by organizing volunteers and securing permits to close off the roads. The program’s been officially part of the Schuylkill Center since 2011. (You can see some great video from previous years in the documentary at the top of the page.)

Last year, some 300 volunteers including families, scouts —> Read More

Here’s How Long It Would Take To Fall Through The Center Of Earth

Just how long would it take to fall through the center of the Earth, traveling from one side of our planet to the other?

Physicists have long calculated the answer to that question as being 42 minutes, but now, new calculations show that the theoretical trip would actually take around 38 minutes — and we can blame gravity for the discrepancy.

The traditional calculation to measure a fall through Earth assumes that our planet has a constant density throughout its many layers. Since the gravitational attraction between two objects is proportional to their masses (or density) and inversely proportional to the square of the distance between them, if Earth’s density were constant, the only change in gravity we’d experience would be due to how far we were from Earth’s center.

But as Alexander Klotz, a graduate student at McGill University in Canada, came up with the new calculations, he took into consideration how Earth’s density changes layer by layer. And as a result, the gravitational speed at which we would fall through each layer changed too.

Klotz measured the different densities found in Earth’s interior using seismic data. Indeed, our planet has a less dense crust and mantle and a more dense core, Science magazine reported.

A paper describing the new thought experiment results was published in the March 2015 issue of the American Journal of Physics.

“This is the kind of paper we love,” Dr. David Jackson, editor of the journal and a physicist at Dickinson College in Carlisle, Pennsylvania, told Science magazine. “This is a nice addition to the classic problem.”

Want to learn more about our planet’s internal layers? Take a journey to the center of the Earth in the “Talk Nerdy To Me” video —> Read More

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