Brazil environment minister Marina Silva stands near a sign for the United Nations' COP29 climate conference in Baku, Azerbaijan, which came to a close Saturday. Sergei Grits/AP hide caption

A helicopter contracted by the province drops water on a hot spot in Yankeetown, Nova Scotia. Communications Nova Scotia/The Canadian Press via AP hide caption

Smoking has been used around the world as a method to preserve food for thousands of years. This episode, we explore why it's also the key to tender, juicy meat. MIGUEL MENDEZ/AFP via Getty Images hide caption

This artist's concept shows stars, black holes, and nebula laid over a grid representing the fabric of space-time. Ripples in this fabric are called gravitational waves. Astronomers have found evidence of gravitational waves created by black holes billions of times the mass of the Sun. NANOGrav collaboration; Aurore Simonet hide caption

This kelp forest in the Galapagos is made up of an unknown kelp species and grows at a depth of 50 to 60 meters. Salomé Buglass hide caption

Researchers are expanding the catalog of animals used in research beyond mice and rats. Clockwise from top left: Zebra finch (Getty); Ptychodera flava, a worm (ASA); a planarian, Schmidtea mediterranea (JOH); African turquoise killifish (ASA); Pomacea canaliculata, a snail (ASA) AlexandraPhotos/Getty Images//Alejandro Sánchez Alvarado//Julianna O. Haug hide caption