14
(about 5 million mi/h), or about 2.22*10^6 m/s, much
slower than light speed c. It takes about 40 hours for the
storm to reach the Earth. When these charged particles
penetrate the Earth’s ionosphere and collide with atoms
in the atmosphere, the atoms become “excited” and reach
higher energy levels. Excited atoms will then “de-excite”
and go down to lower energy levels, during which photons
I have yet to observe aurorae in person, but
this is definitely on my list of things I must
do at least once in my life! The next time you
get to see aurorae, keep in mind that you are
observing a beautiful physics phenomenon
unfolding before your eyes. Now that is what
I call awesome!
are released and produce aurorae in the sky. The Earth’s
magnetic field plays a role in this phenomenon as well—it
is responsible for aurorae being visible only from extreme
northern and southern latitudes. The Earth’s magnetosphere helps shield the Earth from the solar storm, but only
succeeds in shielding mid-latitude to equatorial regions
of the Earth. The flow of charged particles then follows
the magnetic field lines and is directed towards the poles,
where the majority of aurorae are produced. Aurorae do
sometimes reach lower latitudes as well, usually when the
sunspot count is high during solar maximum. The colors
produced depend on the kind of atom the charged particles come in contact with. Striking oxygen atoms produces
green and red aurorae, while colliding with nitrogen atoms
creates blue and purple/violet aurorae. The most common
color formed is green, while the rarest are red and blue.
Aurorae form at altitudes ranging from 80 to 640 kilometers (50 to 400 miles) above the Earth’s surface.
ICY SCIENCE | WINTER 2013- 2014
Top Image: Wikipedia
Further Reading:
http://www.