It's your day, Planet Earth. We've been celebrating #EarthDay for more than 50 years—and in 2024, we're shining the spotlight on our home world's oceans. The ocean holds about 97% of Earth's water and covers 70% of our planet's surface; it's home to 50%-80% of life on Earth. NASA currently operates 26 missions in orbit that observe Earth's oceans, land, ice, and atmosphere. We're studying how they change over time, working with institutions around the world to protect our planet. This classic "blue marble" photo of the Earth was taken on Dec. 7, 1972, by the crew of Apollo 17: astronauts Eugene A. Cernan, Ronald E. Evans, and Harrison H. Schmitt captured the Earth's Southern Hemisphere on their journey to the Moon. Four days later, Cernan and Schmitt touched down on the Moon, becoming the final Apollo astronauts to walk on the lunar surface. Our #Artemis missions will return to the Moon, establishing a long-term presence to help us prepare for the exploration of Mars—while taking car...