Vaccines are being tested against new variants of the coronavirus. Here’s what the latest data are telling us. Plus, ancient cities like Cahokia and Angkor give a new perspective on the rise and fall of urban centers.

President Biden’s COVID-19 relief effort aims to administer 100 million vaccinations in 100 days. Plus, researchers are using bone records to piece together new insights into medieval life. And the placenta is the only organ that can be grown temporarily and then discarded—but it’s hard to study while it’s doing its job.

Harvard astrophysicist Avi Loeb wants you to believe evidence of aliens has been closer than we think. Plus, a farming technique could make soils, and their microbes, better at capturing carbon.

In the absence of federal requirements, the U.S. has developed 50 different vaccination plans. Plus, the science behind the COVID-19 vaccine. And scientist and author Michael Mann explains why corporate change is needed to prevent a climate crisis.

What the latest coronavirus variants might mean to efforts to control the pandemic. Plus, researchers are exploring whether reversing changes to gene expression in aging cells can reprogram them to a younger state.

The annual Christmas Bird Count is still on this year: plus, how the hundred-year-old community science project is guiding scientists. And a trip into the Science Friday archives for a visit from the band They Might Be Giants.

We review the year in science with “Science Vs” host Wendy Zukerman. Plus, Traditional knowledge can help connect young people to both science and Indigenous North American culture. And the Charismatic Creature Corner dives into the weird, beautiful, and amazing world of marine polychaetes.

Atmospheric carbon dioxide is currently as high as it was in the Pliocene Period. Here’s why looking back millions of years can help us understand the next few hundred. Plus, astronomer Janna Levin takes readers on a journey into black holes and their physics.

Gather round for some of the best science books you might have missed this year. Plus, state and local health departments prepare to receive the vaccine. And one year in, how has Europe’s Green New Deal fared?

David Attenborough joins Ira Flatow to call attention to wonder—and peril—in the natural world. Plus, SciFri used to have a community in Second Life. What happened after we abandoned them? And, the long-term health effects of wildfires.