The U.S. Justice Department filed a brief in federal appeals court Tuesday to overturn a federal judge's decision that declared the government mask mandate on planes, trains and buses unlawful. Here, a sign stating that masks are required at San Francisco International Airport stands in a terminal after the federal mask mandate was overturned. Justin Sullivan/Getty Images hide caption
The green boxes show portions of the audio spectrogram that artificial intelligence has identified as marine mammal calls. Ocean Science Analytics hide caption
In this 30 second exposure, a meteor streaks across the sky during the annual Perseid meteor shower on Aug. 11, 2021 in Spruce Knob, W.Va. Bill Ingalls/NASA via AP hide caption
A bounty of black holes surround the Sagittarius A supermassive black hole which lies at the center of our Milky Way Galaxy. NASA/CXC/Columbia Univ./C. Hailey et al. hide caption
Scientists have discovered that a drug used to treat HIV helps restore a particular kind of memory loss in mice. The results hold promise for humans, too. ROBERT F. BUKATY/AP hide caption
Black or brown hydrogen is extracted from coal. Gray hydrogen is made by heating natural gas. Both create carbon dioxide. Blue hydrogen captures about 90% of that carbon dioxide and stores it, usually underground. Green hydrogen uses renewable energy to split hydrogen out of water using electricity. Pink hydrogen does the same but relies on nuclear power. Meredith Miotke for NPR hide caption
Kenyan mountaineer James Kagambi (C), 62, is welcomed upon his arrival as the first Kenyan who reached the summit of Mount Everest, the world's highest peak of 8,849 meters, at Jomo Kenyatta International Airport in Nairobi, Kenya, on May 23, 2022. Yasuyoshi Chiba/AFP via Getty Images hide caption
Demonstrators attend a candlelight vigil Wednesday in Fairfax, Va., for the victims of the Uvalde and Buffalo mass shootings. Allison Bailey/Reuters Connect hide caption
Green the Chow Chow sits in the grooming area at the 142nd Westminster Kennel Club Dog Show at The Piers on February 12, 2018 in New York City. The show is scheduled to see 2,882 dogs from all 50 states take part in this year's competition. Drew Angerer/Getty Images hide caption
ATLANTA, GA - MAY 21: People hold signs during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, Georgia. The Georgia "heartbeat" bill would ban abortion when a fetal heartbeat is detected. (Photo by Elijah Nouvelage/Getty Images) Elijah Nouvelage/Getty Images hide caption
Spallanzani infectious disease hospital Director Francesco Vaia talks to reporters at the end of a news conference Friday in Rome. Andrew Medichini/AP hide caption
The shapes in this salt crystal are consistent with what would be expected for microorganisms. Kathy Benison hide caption