What is an Aurora? NASA tells when and how to watch one

Auroras, or the northern or southern lights, are spectacularly glowing displays of colors that appear in the night sky. Auroras are found in the ionosphere, the upper layer of Earth’s atmosphere, and arise with activity on the Sun. 

The coronal mass ejection, associated with solar activity, wherein the Sun releases charged particles that speed across the solar system which collide with Earth's magnetosphere, creating auroras

When too much energy is pent up, the magnetic field lines snap and release energetic particles that follow magnetic field lines to rain down on Earth’s poles. When they strike atoms in the atmosphere, the energetic particles cause the atoms to glow, creating auroras. This happens more often and more strongly when the Sun is at its peak activity level in its 11-year cycle, called solar maximum.

The various colors of auroras are created by different atoms and molecules in the atmosphere. When an energetic particle hits an oxygen atom, it releases red or green light depending on the energy of the oxygen atom.

Auroras happen all the time but are most visible during solar maximum. It’s not until the storm of particles reaches space weather monitoring satellites an hour out from Earth that scientists have a better grasp of the likelihood of auroras. At that point, scientists know the orientation of the Sun’s magnetic field, which is critical for understanding where auroras may be seen.

Strong auroras can be best seen in areas without pollution. It is seen in the northern hemisphere and appears close to the horizon. They last whole night but can be of shorter duration. They may be seen as early as sunset and as late as sunrise, but maximize around midnight.

To capture auroras from a camera, switch it to manual focus and set the focus at or near infinity. NASA suggests setting the aperture as large as possible (such as f/2.8) to capture more light quickly.  Wide angle lenses with large apertures (f/2.8) are the go-to choice for most aurora photographers.

In very bright shots reduce the ISO and in dark increase it.  If the aurora is moving quickly, keep your exposure time down by increasing your ISO. Every aurora is unique, so experiment with your settings until you get the photo you want.

Most newer smartphones have a “night” mode that can be great for photographing auroras. Using a tripod or leaning your phone up against a fixed object can help stabilize your shots.

Credit: NASA