Astronauts had this view of the aurora on September 26, 2011. Credit: NASA
We’ve had some great views of the aurora submitted by readers this week, but this one taken from the International Space Station especially highlights the red color seen by many Earth-bound skywatchers, too. Karen Fox from the Goddard Space Flight Center says the colors of the aurora depend on which atoms are being excited by the solar storm. In most cases, the light comes when a charged particle sweeps in from the solar wind and collides with an oxygen atom in Earth’s atmosphere. This produces a green photon, so most aurora appear green. However, lower-energy oxygen collisions as well as collisions with nitrogen atoms can produce red photons — so sometimes aurora also show a red band as seen here.
A tiny asteroid loitering in a near-Earth orbit for a few months last year may…
A fuzzy form of dark matter may clump up to become the cores of galaxies,…
After the Big Bang came the Dark Ages, a period lasting hundreds of millions of…
When a new space telescope is launched, it's designed to address specific issues in astronomy…
I’ve lost count of the number of times I have seen the Ring Nebula. It’s…
Climate scientists must fear sounding like a broken record when discussing new record temperatures yearly.…