Saturday, February 20, 2010

The Sun and Auroras

Thanks to Dr. Eades and Twitter, I found out about a really neat iPhone app this morning. It's called 3D Sun and was written by an astrophysicist in collaboration with NASA scientists. It brings realtime satellite videos of the sun to your iPhone. Your phone will even notify you when a significant event is happening. If you don't have an iPhone, you can still see the same images on the web at the STEREO (Solar-Terrestrial Relations Observatory) website. (The sun looks green because the satellites are taking images in the extreme ultraviolet range.)

Watching the sun and perhaps catching a solar flare while it is happening would be exciting enough, but the app also offers links to other great stuff including images of the auroras as well as movies of previous flares. One fascinating movie shows a comet getting eaten up by the sun.

Apparently we are having some pretty spectacular auroras right now. The sun's activity, manifested in many ways including sunspots, is picking up again after being at its cyclical minimum. Auroras are caused by the geomagnetic storms that this solar activity originates in the atmosphere of our own Earth due to the solar wind. (You can see a movie of a comet's tail waving in the solar wind here.)

The northern (or southern) lights, as auroras are sometimes called, are caused by the excitation of electrons in the upper atmosphere. The colors come from the kind of atom or molecule that gets an electron or has an electron drop to a lower energy state. Oxygen atoms emit a green or brownish-red photon depending on the amount of energy absorbed. Nitrogen atoms emit a blue photon if they gain an electron and red if they are returning to the ground state after being in an excited state. The auroras form shapes because the electrons move along the magnetic field lines. (This is an extreme over-simplification.) When the disturbances are great, the lights can be seen as far south as the southern US and more temperate parts of Europe. For more information on auroras and how they are formed click here. For more on shapes, click here.

I have never seen the aurora. Someday I hope to. I think it would be well worth braving the freezing temps to view something as spectacular as this photo taken by Marketa Stanczykova in Iceland just a few days ago on February 16.


  1. Thanks for the tip on a cool app! I found an ap called Whats Invasive! (free) the other day.

    Perhaps you'd like to collaborate on setting up a list of invasive plants for the PV penninsula?

    I've also enjoyed Moon Globe (free) and Sky Gazer ($$)

  2. Hi Brent,

    I have downloaded Whats-invasive and will try to figure out how to make it work for me. I do not have GPS or phone service with my iPhone. It's a hand-me-down from my son that only works with wi-fi. I already have photos of many invasive plants at Lunada Canyon and other PV places and can continue to collect more. Usually I am more interested in documenting the natives.

    Sky Gazer I have, and will look into Moon Globe. Thanks. Do you have Plants of the Santa Monica Mountains ($$)?

  3. What's Invasive is ready to accept geo-tagged photos of invasives in PV as of about noon today. I have a blog update on it both in comments at my original post and as a new post. I'm kind of excited about trying to do some mapping.

    I don't have Plants of the Santa Monica Mountains. I may have considered it, but I ended up with California Wildflowers (same $9.99 purchase price). I notice there is a SGMPlants app also.

    I also have iBird Explorer 15 (the free version) but you might enjoy the full version since you know so much more about birds. As a know nothing when it comes to birds, I'm easily satisfied.

    DaylightCal is useful and free.

    I wonder if your GPS functionality is disabled in the settings or if you can use cell towers for mapping purposes instead.