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The northern lights, auroras, have been a hot topic over the past few years and all over social media. They have also been a point of fascination for centuries!

We saw them a few times recently, if you were lucky, right here in Pennsylvania. So what are they? Why have we been able to see them more often? Let’s find out!

What causes the northern lights?

To understand the northern lights, first let’s understand Earth’s atmosphere. Our molten outer core on Earth helps create Earth’s magnetic field, which forms a protective bubble around our planet called the magnetosphere.

This magnetosphere helps protect us when the Sun sends out flares of gases and particles that try to enter our atmosphere. These charged particles travel along Earth’s magnetic field lines toward the poles and collide with gases in the upper atmosphere. The atoms in these gases then get excited and release energy as light. This leads to the colorful northern lights in the sky!

Sometimes the Sun sends out what are called Coronal Mass Ejections, or CMEs. During these solar storms, is when the northern lights can be visible further south, like Pennsylvania. During times of CMEs, there can be impacts to satellites and electricity. It can also affect internet and GPS systems.

Why have they been more visible lately?

Why have we been seeing the northern lights more compared to in the past? There are a few factors for this.

First, the Sun has a solar cycle. It hits a maximum about every 11 years. In fall of 2024, we entered a solar maximum year. That means there has been more activity on the Sun that sends these particles our way. This then creates more auroras. However, we will likely be exiting this part of the cycle soon.

Second, 11 years ago not everyone had a camera readily available on their phone to capture the northern lights. Now that everyone has camera phones, we can take long exposure photos capturing the beauty. This means we get to see the lights more often even when they are not that bright thanks to technology!

Lastly, NASA and NOAA are now tracking space weather. Forecasting space weather is tough, but they are getting better at it. These forecasts give us a heads up of when these solar flares are likely and may allow us to see the lights dance!

What creates the different colors in the sky?

Depending on the gases, and where in the atmosphere they get excited, will change the color of the aurora. The most common color is green. The green is created from excited oxygen about 60–120 miles above Earth’s surface.

Above that, oxygen can produce red auroras. Nitrogen can look purple above 60 miles into atmosphere. While lower altitude interactions with nitrogen can produce blue colors. Blue, red, and purple typically occur when there is a lot of solar activity. The colors can look like they mix together leading to a white hue or different colors. That is rare too.

When should I go outside to look for them?

How can you know when the next aurora will take place in your area? Forecasts are still primitive, but getting better. You can head to NOAA’s Space Weather Prediction Center page to see the current activity and forecast of the Sun. The Kp Index is used to measure the intensity of geomagnetic storms.

If you are in the mid-latitudes, like Pennsylvania, you will usually need a Kp forecast to be around a 7 or higher. A higher forecast gives you a better chance to see the northern lights.

Tips for viewing the Aurora Borealis

The best place to look is in an area with not much light pollution. Use a tripod with your phone and point it north at a longer exposure, or in “night mode.” It is easier to see the northern lights with a camera compared to just your eyes. With our eyes, they will look less vibrant compared to your camera or phone picture. To view the auroras with just your eyes, you need to be closer to the poles, or it needs to be a really intense storm.

Typically we notice auroras more from September to March when there is more darkness in the northern hemisphere. They can be visible from sunset to sunrise. They also move and change through the night!

Auroras can have different shapes

Auroras can also be classified as different shapes that you can see in the sky.

A common type of aurora is a curtain.

A rare type of aurora, if it is happening overhead, is called a corona. It looks like rays are coming down above the person viewing it!

Rays look like they are going upwards.

We continue to learn more and more about auroras, but yet there is still so much learning to do! If you happen to see an aurora, make sure you report it at aurorasaurus.org.

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Have you gotten to see the northern lights before? I’d love to hear all about it in the comments! I keep missing them in Pennsylvania, but was lucky enough to see them Iceland! We were lucky enough to be there during a big solar storm in October 2024! All the photos in this article are from that trip! We viewed them three nights in a row!