Everyone knows about the Aurora Borealis, a.k.a. the Northern Lights. This atmospheric light show is caused by the collision between charged solar particles and the atoms in our own atmosphere, resulting in a swirling spectacle of colors for lucky viewers up north. However, the Northern Lights has its own opposite number down under, appropriately called Aurora Australis, or the Southern Lights.
On March 23, the first-ever round-trip charter flight to the Aurora Australis took off, producing remarkable photos and videos of the oft-forgotten spectacle's ethereal beauty. In case this is the first you’ve ever heard of the Southern Lights, here are five facts you need to know.
For the Aurora Australis, you’re obviously going to have to head to the Southern Hemisphere for your best chance to get a glimpse.
Places like the Falkland Islands; South Georgia Island; Tasmania; and Stewart Island, New Zealand are about as close as you're going to get to the lights, unless you're willing to park yourself at the South Pole.
Generally, the best months to spot the Northern Lights are from December through April, with the middle of northern winter being the ideal time (if you can deal with the cold). For the Southern Lights, you’d want to head down anywhere from March through September. This is the general wintertime for the Southern Hemisphere, when the polar region is locked in virtual darkness, creating optimal visibility. The lights exist all year round, but unless there are favorable viewing conditions (read: darkness), they won't be easy to spot.
One of the reasons why the Southern Lights aren’t as popular as their partner up north is because there's not a lot of land down south from which to view them. Even if you’re at the southern tip of Chile or Argentina, or you’re hanging out on the Falkland Islands, you’re still not that close to the South Pole, which is where the lights will be brightest. An aurora is most visible during a geomagnetic storm in the South Pole, but if that storm isn’t strong enough to reach New Zealand or any other region to the north, chances are the light show won’t reach many, if any, human eyes. It also doesn’t help that a forecast of one of these storms isn’t really accurate until a few hours before it hits.
Though auroras are most commonly associated with the cascades of green we've come to recognize, there are also times when the lights can appear red, orange, yellow, violet, and blue. Since the lights are caused by charged solar particles colliding with our own atmospheric atoms, the type of atoms and the altitude involved will produce different colors.
Oxygen atoms at a lower altitude, for example, will cause that signature green light, but at higher altitudes, they’ll yield a red one. Conversely, nitrogen atoms will give off a range from violet to a pinkish-red, depending on altitude. Bluish or purple aurora lights might appear invisible to the naked eye, so certain specialized equipment or cameras may be needed to pick up on them.
For years it was assumed by scientists that the Northern and Southern Lights were symmetrical, but that might not be the case. The charged particles that cause the aurorae follow Earth’s magnetic lines, and scientists believed that they were distributed evenly to the poles where the lights are born. But in a study published in Nature, one team believes that’s not the case.
“Here we report observations that clearly contradict the common assumption about symmetric aurora: intense spots are seen at dawn in the Northern summer Hemisphere, and at dusk in the Southern winter Hemisphere,” study co-authors Nikolai Østgaard and Karl Magnus Laundal wrote. “The asymmetry is interpreted in terms of inter-hemispheric currents related to seasons, which have been predicted but hitherto had not been seen.”
All that science-y talk basically boils down to this: The Northern and Southern Lights are siblings but not twins, as Universe Today explains.