The northern lights appear when charged particles from the Sun hit gases high in Earth’s atmosphere and make them glow. Seeing them takes dark, clear skies, a view towards the poles, and some luck with solar activity.
What are the northern lights?
The northern lights, or aurora borealis, are natural displays of light in the night sky. They are seen most often at high latitudes near the Arctic. They can look like a faint glow on the horizon, or like moving curtains, arcs and rays that ripple and change shape within minutes. The name joins Aurora, the Roman goddess of the dawn, with a Greek-derived word for the north wind. People have described the lights for thousands of years, and many northern cultures have folklore about them. Today they are treated as both a scientific phenomenon and a spectacle. People travel to see them, photograph them and follow them closely online. Google’s US search data, the source for this article, shows that they are currently a trending search topic.
What causes the aurora to happen?
The aurora starts at the Sun. The Sun constantly sends out a stream of charged particles called the solar wind, and sometimes it releases much larger bursts of material. When these particles reach Earth, most of them are deflected by the planet’s magnetic field. Some of their energy gets into the magnetosphere, the region of space controlled by Earth’s magnetism. It is then channelled along magnetic field lines towards the polar regions. There, particles crash into atoms and molecules in the upper atmosphere and give them extra energy. When those atoms and molecules release that energy, they give off light. The result is an aurora. This is why displays usually form in rings around the magnetic poles and not randomly across the sky.
Why do the lights come in different colours?
The colour depends on which gas is struck and how high up the collision happens. Green, the most common colour, comes from oxygen at moderate altitudes. Oxygen higher up can produce red light, which is often seen at the top of tall displays or as a deep glow during strong events. Nitrogen produces blue and purple shades, often along the lower edges of moving curtains. Mixtures of these colours can create pinks and other blends. How bright and how saturated the colours look also depends on how much energy is coming in. Faint auroras can look almost colourless to the naked eye. In such cases, observers may notice only a pale, greyish arc until a camera reveals the colour.
Is there a southern version of the northern lights?
Yes. The same process happens around the southern magnetic pole, where it is called the aurora australis, or southern lights. It forms at the same time as the northern display and for the same reasons. Far fewer people see it, because the area around the southern auroral zone is mostly ocean and Antarctic ice, with few large towns. During strong events it can be seen from parts of the southern hemisphere’s inhabited lands. Scientists sometimes use the general term “polar lights” for both. Auroras also occur on other planets with atmospheres and magnetic fields, and space telescopes have observed them on giant planets in the outer Solar System.
Why are the northern lights trending in the United States?
The source for this article is Google’s US trending searches. It shows that people are searching for the northern lights and the aurora borealis, but it does not explain why. Nothing about a particular display, forecast or event is confirmed here. More generally, interest in the aurora tends to rise when space weather forecasters warn of heightened geomagnetic activity, or when people share photographs of the lights seen further south than usual. In those cases, many people search for whether the lights might be visible where they live. Readers who want to know about current conditions should check official space weather forecasts. Social media posts are not a reliable guide.
Why can the aurora sometimes be seen far from the Arctic?
Normally the aurora stays in a band around the polar regions known as the auroral oval. When the Sun sends a particularly strong burst of particles and magnetic field towards Earth, it can cause a geomagnetic storm. During such storms the auroral oval grows and moves towards the equator. Displays can then reach latitudes where they are rarely seen. Observers in these places usually see the aurora low on the poleward horizon, though in exceptional storms it may appear overhead. Solar activity rises and falls over a recurring cycle that lasts several years. Strong storms tend to be more frequent around the cycle’s most active phase, but they can happen at other times as well.
How are aurora forecasts made?
Aurora forecasts are part of the wider field of space weather forecasting. Agencies watch the Sun with spacecraft and ground-based instruments. They look for eruptions and estimate whether ejected material is heading towards Earth and how long it might take to arrive. Monitors positioned between the Sun and Earth measure the solar wind shortly before it reaches the planet, which allows short-range warnings. Forecasts often use scales such as the Kp index, which summarises how disturbed Earth’s magnetic field is. They may also come with maps showing where the aurora could be visible. Forecasts are much less precise than ordinary weather forecasts. A storm can arrive early, late, more weakly than predicted, or not at all.
What conditions give the best chance of seeing them?
Darkness matters most. The aurora is hard to see in twilight, under bright moonlight or near city lights, so a rural spot away from street lighting helps. Clear skies are essential, because cloud blocks the view entirely, however active the aurora is. Observers at middle latitudes should look towards the poleward horizon, which is north in the northern hemisphere, ideally with an unobstructed view. Activity often peaks in the hours around local midnight, though displays can happen at any time during the night. Patience is important, because auroras can brighten and fade quickly. Letting your eyes adjust to the dark without looking at a bright phone screen makes faint glows much easier to spot.
Why do phone cameras often capture more than the eye?
Human night vision is good at detecting faint light but poor at seeing colour in the dark. Faint auroras can therefore look grey or whitish to an observer. Camera sensors, especially when set to long exposures or a phone’s night mode, collect light over several seconds and record colour much more effectively. So a photograph may show vivid green or pink bands when the person holding the camera saw only a soft glow. This gap explains why social media images sometimes look more dramatic than what people saw in person. It also means a quick test photograph of the northern sky can show that a weak aurora is present before it is obvious to the naked eye.
Can geomagnetic storms affect technology on Earth?
Yes. The same space weather that produces strong auroras can disturb technology. Geomagnetic storms can interfere with high-frequency radio communication and reduce the accuracy of satellite navigation. They can also increase drag on satellites in low orbit by heating and expanding the upper atmosphere. In severe cases they can induce electrical currents in long conductors such as power lines and pipelines. That is one reason grid operators and satellite companies pay attention to space weather warnings. For most people watching the sky, a geomagnetic storm has no noticeable effect apart from the display. Space weather agencies issue alerts so that the organisations most at risk can take precautions.
Sources and further reading
- NOAA Space Weather Prediction Center: US government forecasts, alerts and explanations of geomagnetic activity scales
- NASA: educational material on the Sun, the solar wind and Earth’s magnetosphere
- British Geological Survey: background on geomagnetism and aurora alerts for observers at higher latitudes
- Met Office Space Weather Operations Centre: UK space weather forecasting and public guidance on auroral visibility
Surfaced from the google:US signal “northern lights interest”. AI-assisted draft, editorially reviewed.
