Med thumb northern lights

The Northern Lights are an ethereal, phantasmagorical display of colored light that streak and dance across the night sky at certain times of year — and in places that are chafe-your-butt-cheeks cold. As one of nature’s most spectacular astronomic phenomenon, they sit high atop many globe-trotters’ bucket lists.

These dramatic light displays take place in both the northern and southern hemispheres near the Earth’s magnetic poles. The Northern Lights were christened “aurora borealis” in 1621 by French scientist Pierre Gassendi, who named them after the Roman goddess of the dawn, Aurora, and the god of the north wind, Boreas. According the Library of Congress website, Galileo, too, is cited as having witnessed the same display, on the same day.

The northerly light show is slightly more accessible for viewing than the southern display, or “aurora australis,” which occurs atop Antarctica and the Southern Indian Ocean—places where only the most grizzled explorers hang out. They’re most frequently visible in a radius that extends over Scandinavia, Greenland, Iceland, Alaska and other states along the U.S.-Canada border, as well as Canada. Occasionally, the light show can be seen in the skies further south.

And while these light shows may appear mystical and enchanting, they are actually rooted in spectacular violence.

How so?

Great explosions of magnetic energy from the sun produce vast amounts of charged particles (electrons), which hurtle through space and eventually reach Earth. The lights “are a form of intense weather, a result of the atmosphere shielding the Earth against the fierce solar particles that would otherwise make our planet uninhabitable,” according to discovery.com.

Then, as the charged particles smash into the upper atmosphere, the energy from the collision is released as photons — particles of glowing light. Aurorae are typically seen at the poles because Earth’s magnetic field “siphons them around the planet. Picture water moving around a rock protruding from a river.”

The gases involved in the collision, and how far up the impact takes place, affect the colors observers see:

  • Green, the most common color shade, is the result of collisions with oxygen molecules 60 to 150 miles above the Earth.
  • Red color occurs when the particles collide with oxygen and nitrogen, at a higher altitude, 150 to 250 miles up.
  • Blues, purples and violet colors are visible when those particles smash into nitrogen, usually less than 60 miles up.

For some context, commercial jets fly about five and a half miles above the surface of the Earth; and the ozone layer sits between 12 and 18 miles up.

When’s the best time to see this spectacular display?

The darker skies and clearer nights of winter months, from early September through March, are the best times, but whether or not you’ll see them is unpredictable. Cloud cover can thwart the best-laid plans. The best time of day (or, rather, night) to watch for auroral fireworks is around midnight local time (adjusting for daylight savings).

While there may be sightings in states such as the Dakotas, Wisconsin and Minnesota, the best places in North America to watch them are Alaska and northwestern parts of Canada — the Yukon, Nunavut and Northwest Territories. Areas that have less light pollution (read: sparsely populated) tend to offer the most spectacular displays.

Light visibility also fluctuate with levels of solar activity, which tend to follow an 11-year cycle. Although the most recent peak year for that activity burst was 2013, according to Travel + Leisure we’re not only “in the midst of a solar maximum (when aurora activity is at a peak), but the United Nations also named 2015 the International Year of Light, making dark sky preservation and global awareness of light pollution priorities.” So if you haven’t finalized travel plans for this year, get cracking.

An interesting note: Most people associate the Northern Lights with wintertime, assuming that’s the only time they’re visible, but in fact they are present year-round. It’s just that we can’t see them if the sky is light.

Yukon’s Northern Lights Tours recommends taking the moon’s cycle into consideration as well. A new moon (the phase when it’s invisible from Earth) means a darker night, the better for seeing the aurora borealis. They also suggest loading up on heavy-duty winter gear since the mid-winter temperatures drop to almost -30 degrees Celsius. That won’t just chafe, it’ll freeze your ass.