A concept in Chinese philosophy describing dualistic opposite forces that are complementary....
Soviet cosmonaut who became the first human to journey into outer space in 1961....
The sex-determining chromosome in males of most mammals....
The world's largest video-sharing platform, launched in 2005 and acquired by Google....
A national park in California celebrated for its waterfalls, giant sequoias, and granite cliffs....
A viral hemorrhagic disease spread by infected mosquitoes, common in Africa and South America....
A mechanical property measuring the stiffness of a solid material....
A country in western Asia at the southern tip of the Arabian Peninsula....
The first national park in the United States, known for geysers and diverse wildlife....
A physical, mental, and spiritual practice originating in ancient India....