<p style="margin: 5pt 0pt;">Absinthe-green <a id="mt8c" title="Auroras" href="http://science.nationalgeographic.com/science/space/universe/auroras-heavenly-lights.html">Auroras</a> course across the Yukon sky in a picture featured March 11 on NASA's <a id="n74z" title="Astronomy Photo of the Day" href="http://antwrp.gsfc.nasa.gov/apod/ap100311.html">Astronomy Photo of the Day</a> site. Captured around dawn on March 11 near Dawson City, Canada, the image is a digital combination of several exposures, which allowed both the northern lights and the paths of stars—which appear to be moving due to Earth's rotation—to shine.</p><p style="margin: 5pt 0pt;">With the vernal equinox, or spring equinox, arriving on Saturday, northern lights should be in abundance this week. For reasons that remain a mystery, the sky shows tend to proliferate around the first day of spring, <a id="oe3y" title="according to NASA" href="http://science.nasa.gov/headlines/y2008/20mar_spring.htm">according to NASA</a>.</p><p style="margin: 5pt 0pt;">Auroras occur as particles from the sun speed toward Earth and become energized as they encounter with the planet's magnetic field lines. As the powered-up particles smash into oxygen and nitrogen in our atmosphere, the particles release their energy as red, green, and blue light. (See <a href="http://photography.nationalgeographic.com/photography/photos/patterns-nature-northern-lights.html">aurora pictures</a>.)</p><p style="margin: 5pt 0pt;">(Related: <a id="wn1b" title="&quot;Giant &amp;squot;Space Tornadoes&amp;squot; Spark Auroras on Earth.&quot;" href="http://news.nationalgeographic.com/news/2009/04/090424-space-tornadoes-auroras.html">"Giant 'Space Tornadoes' Spark Auroras on Earth."</a>)</p>