On Earth Day: At least 171 nations to sign hard-won climate pact

At least 171 world leaders gathered today at the United Nations to sign a sweeping climate agreement negotiated last year and aimed at slowing global warming. While the ceremony is something of a culmination, it’s only the second of three steps to make the comprehensive climate deal a reality.

In honor of Earth Day: National Geographic photos sharing on Instagram

After 46 years, people around the world are still honoring Earth Day with a different theme every year. This year’s theme is Trees for the Earth. Earth Day Network is calling people to action by encouraging them to plant trees through organized events around the world. Celebrate Earth Day with National Geographic by sharing your best pictures that illustrate the mysteries and magic of our planet.

Astronaut Photography from Space Helped ‘Discover the Earth’

In December 1968, the crew of Apollo 8 became the first humans to leave Earth orbit and head for the moon. They also became the first to look back at their home planet and see the entire world in one glimpse. The view they shared had an everlasting impact. “When you see the beauty of our planet, it is striking, it’s sobering…”