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Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

Video produced in partnership with The Great Courses. All Great Courses video content is available only to subscribers with the password sent via email.

The work of decoding the cosmic traveler has surprising relevance right now

Last week’s pinpoint touchdown of NASA’s Mars Perseverance rover in Jezero Crater was historic for many reasons, chief among them the epochal nature of the mission’s task of seeking signs of ancient life—and caching relevant samples for eventual return to Earth. But even if the rover finds no evidence of Martian microbes during its operations, it will have still produced another spectacular “first” for the textbooks, which NASA officials unveiled today: An unprecedented look at the “seven minutes of terror” between Perseverance’s fiery plunge through the planet’s skies and its coming to rest on solid ground far below. This is the first ever high-definition video of atmospheric entry, descent and landing on another world.

Perseverance’s predecessor Curiosity recorded snippets of the final stages of its Mars landing in 2012 that resulted in a short stop-motion video, and in 2005 the Cassini mission’s Huygens lander beamed back images and telemetry data from its chilly descent to Saturn’s moon Titan that were later used to construct remarkable visualizations. And there is, of course, no shortage of lunar landing footage from the Apollo missions of yore. But never before has a spacecraft captured the entire sequence of an otherworldly landing in such lush detail. More than mere eye candy, this data could prove crucial for the design of future, more ambitious voyages to the Red Planet’s surface, which is considered to be one of the solar system’s most technically challenging landing destinations.

Here is NASA's livestream on the footage.

Video credit: NASA/JPL-Caltech

The SARS-CoV-2 coronavirus seems to be suddenly acquiring mutations at a rapid rate. The most worrying variants, first discovered in South Africa and Brazil, increase the virus’s contagiousness and may even help it evade the human immune system. These characteristics are helping the new variants outcompete the original virus, allowing them to spread quickly around the world.

Viruses, including SARS-CoV-2, are constantly evolving and acquiring mutations that don’t affect the virus much. The reason public health experts are concerned is that the new mutations improve the virus’s spike protein, which helps the pathogen enter cells and is the target of most vaccines. If the spike protein evolves sufficiently, the virus may eventually be able to reinfect individuals who have already had COVID-19 or been vaccinated against it.

But scientists say it will likely be years before the vaccine stops working entirely—if it ever does. In the meantime, social distancing remains the best way to fight the new mutants. After all, the more viruses that exist in the world, the greater the chance that one will evolve a dangerous mutation.

In this video, we explain what the new variants actually are, how they arise and spread, and what they could mean for the future of our ability to vaccinate ourselves against the virus.

The 2020 wildfire season was the worst in California’s recorded history, with more than four million acres burned and almost 10,500 structures destroyed across the state. The fires were heavily covered by the news media, and some reportssuggested California had suffered apocalyptic devastation and permanent loss. But the more complicated reality of fire’s long-term impact on forests is often poorly reported and misunderstood.

In this video, we talk to experts who say many accounts of California’s blazes sensationalize the extent of forest devastation while paying less attention to fire’s crucial role in nature.

Chad Hanson is a fire ecologist and director of the John Muir Project, an environmental group that advocates for drastic changes in state and national fire policy. He says fire is a natural and unstoppable reality in California. Hanson believes that in some cases, the state’s forests would be healthier and more resilient if certain fires were allowed to burn. 

Another expert also notes that to understand 2020 in context, we need to take a very long view of fires in the forest: Valerie Trouet, a researcher who studies tree rings at the University of Arizona, has observed evidence of wildfires in giant sequoias in California dating back almost 3,000 years. She says that although today’s fires sometimes burn more intensely, they used to burn longer and over much larger areas.