Astro Blog

Source:   Compiled by Web Designer Depot, USGS National Center for the EROS and NASA Landsat Project Science Office www.webdesignerdepot.com/2009/08/60-stunning-satellite-photos-of-earth/

Source:   Ker Than, National Geographic News Excerpt: The gases that make up Earth's atmosphere came from a swarm of comets, not from bubbling volcanoes as long thought, a new study says. The new theory came about after scientists discovered that pristine samples of the elements krypton and xenon, recently collected from deep within the Earth, have the same chemical makeup as ancient meteorites. …It's still true that volcanoes spewed out some gases, "but [that] contribution was insignificant" for the creation of Earth's atmosphere," Ballentine said. …Based on their research, Ballentine and colleagues claim that our atmosphere likely formed when gas and water-rich comets bombarded Earth, shortly after its formation 4.54 billion years ago. …Scientists have already discovered that the comet barrage likely formed Earth's oceans…. news.nationalgeographic.com/news/2009/12/091210-comets-swarm-earth-atmosphere.html