Building The World’s Largest Animal Crossing Outside of LA There’s a spot on Highway 101 in Agoura Hills, it’s pretty inconspicuous. There’s brown and green rolling hills on either side of the highway. Homes are sprinkled here and there. And then a small metal gate that leads off on a hiking trail. You probably wouldn’t know it, but soon this spot will be the location of the world’s largest animal crossing. This crossing will reconnect habitats that have been cut off from each other for three quarters of a century and it’ll do it over a highway that is constantly buzzing with cars — 300,000 pass by this spot every single day. In this piece we’re going on a geography voyage — from the north side of the highway to the south, and up the hills, above the highway, to get the real view. We’ll start here — there’s a big open space on the northern side of the highway. It’s at the entrance to Liberty Canyon and where I meet Beth Pratt. To continue reading, go to sciencefriday.com. Over 5,000 Exoplanets Have Now Been Discovered In March, the NASA Exoplanet Archive logged the 5,000th confirmed planet outside of our solar system. This marks a huge advance since the first exoplanet discovery in 1992, when astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the pulsar PSR 1257+12. Now, the Archive contains confirmed sightings of planets in a wide range of shapes and sizes—from “hot Jupiters” to “super Earths”—but they still haven’t found any solar systems just like our own. In many cases, all astronomers know about these distant planets is their size and how far away from their stars they orbit. The TESS (Transiting Exoplanet Survey Satellite) mission currently in orbit may eventually add ten thousand more candidates to the lists of possible planets. The Nancy Grace Roman Space telescope and ESA’s ARIEL mission, both planned for launch later this decade, could add thousands more. And the James Webb Space Telescope, currently undergoing commissioning, will attempt to characterize the atmospheres of some of the planets astronomers have already discovered. Astronomer Jessie Christiansen, the NASA Exoplanet Archive Project science lead, joins John Dankosky to talk about what we know about planets around distant suns, and how researchers are working to learn more about these far-off worlds. Scientists Release The First Fully Complete Human Genome Two decades ago, scientists announced they had sequenced the human genome. What you might not know is that there were gaps in that original sequence—about 8% was completely blank. Now, after a years-long global collaboration, scientists have finally released the first fully complete assembly of the human genome. Researchers believe these missing pieces might be the key to understanding how DNA varies between people. Six scientific papers on the topic were published in a special edition of the academic journal Science. Ira talks with Karen Miga and Adam Phillippy, co-founders of the Telomere to Telomere Consortium, an international effort that led to the assembly of this new fully complete human genome. Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

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