Today, nearly 1,500 satellites are orbiting the Earth, helping to make scientific discoveries and assist military communication. Here's a brief history of them: http://nbcnews.to/2zWRvzK | NBC News Science

NASA Earth satellite views and data visualizations help us understand the Earth and how it’s changing. This #EarthDay, we invite you to share how you #PictureEarth too. Share photos of some of your favorite natural features with the location and hashtag #PictureEarth: https://go.nasa.gov/2UMkEJf | NASA - National Aeronautics and Space Administration