The Moon and the Northern Lights

The Northern Lights are known as one of the most important and beautiful attractions of the Arctic. The brilliant panoply of colors that the Northern Lights are have been a point of fascination for humans for centuries. With the advent of modern technology, people around the world can now partake in auroras easier than ever before by traveling to the North Pole. With that in mind, many are wondering if the moon plays a role in the Northern Lights.

The answer is sort of. While the moon has no direct effect on the Northern Lights, it is possible for a full moon to drown out weaker auroral displays. At the same time, the moon can also make the Northern Lights more spectacular. Read on to learn how the moon can affect the Northern Lights.

The Moon and the Northern Lights

As a hard rule, the Northern Lights can only be viewed at night. This is because the sun’s light is so strong that it prevents auroras from forming during the daytime. Because of this, auroras are best viewed in the northern hemisphere between the months of September and April, because this is the only time that there is sufficient night darkness for them to be seen. The tilt of the Earth’s axis means that the Arctic experiences near-total daylight during the summer and near-total darkness during the winter, preventing auroras from being seen during the former.

While the moon gives off light in the night sky, it does not generate light on its own. What appears as “moonlight” is actually light being reflected from the sun. This is the cause of the moon cycle, a period of roughly one month where the moon goes from being fully visible (a full moon) from the Earth’s surface to invisible (a new moon).

The lunar cycle is a product of the moon’s revolution around Earth. The moon is “tidally locked” to Earth due to its revolution around the Earth being the same as its revolution on its own axis. This means that the same side of the moon is always facing Earth; the “dark side” of the Moon can only be seen by satellites in space. During a full moon, the sun and moon are on opposite sides of Earth, causing the sun’s light to fully illuminate the moon’s surface. Conversely, during a new moon, the sun and moon are on the same side of Earth, causing light to impact the far side of the moon instead. Half-moons, crescent moons, and other moon shapes are the result of sunlight only partially lighting up the visible moon surface.

Auroras are created by solar wind, a scientific term for streams of radioactive particles given off by the sun, and as a result, the moon does not play a direct role in the formation of auroras. Solar wind that impacts Earth’s magnetosphere is neutralized and deflected. Most of the magnetosphere is located in the space surrounding Earth, but portions of it extend into the atmosphere at the North and South Poles due to those locations being the source of the planet’s magnetic field. Interactions between solar wind and atmospheric particles create the phenomenon known as the Northern Lights.

However, the moon can impact the visibility of auroras due to the fact that excess light, particularly from full moons, can drown out weaker, smaller auroras. This is the same effect that light pollution from cities and cars creates, which is why auroras are best viewed in secluded, rural areas. In general, the smaller an aurora, the more likely it will be dissipated by moonlight. Moonlight is also capable of drowning out the visibility of stars and planets from the Earth’s surface.

Strong auroras, however, can withstand the excess light put out by the moon, and a full moon can actually make some displays more striking. Some Arctic photographers prefer to take pictures of auroras during full moons, in part because moonlight causes the sky to turn dark blue, in contrast to the normal black.

The moon’s cycle takes place over the course of a month, and only one full moon occurs per cycle. Because of this, it is unlikely that you will experience a full moon during your aurora trip, since a full moon only lasts for one day. However, if the moon is visible during your aurora vacation, you might be treated to a more memorable experience.

Conclusion

Understand that the moon does not influence the Northern Lights itself; it is purely a product of the sun’s interaction with the Earth. While the moon can have an effect on the visibility of auroras, it does not influence aurora formation itself. Indeed, depending on solar conditions during your trip, a full moon might make your aurora viewing experience even more unique, giving you a vacation that you will remember for a long time.