Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 May 13
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Planet Aurora
Image Credit: Scott Kelly, Expedition 44, NASA

Explanation: What bizarre alien planet is this? It's planet Earth of course, seen from the International Space Station through the shimmering glow of aurorae. About 400 kilometres (250 miles) above Earth, the orbiting station is itself within the upper realm of the auroral displays. Aurorae have the signature colours of excited molecules and atoms at the low densities found at extreme altitudes. Emission from atomic oxygen dominates this view. The eerie glow is green at lower altitudes, but a rarer reddish band extends above the space station's horizon. Also visible from the planet's surface, this auroral display began during a geomagnetic storm. The storm was triggered after a coronal mass ejection impacted Earth's magnetosphere in June of 2015.


Tomorrow's picture: more water than earth


< | Archive | Submissions | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.