Aurora

The sky can glow with beautiful colors.

This happens high up in the air. Small bits from the sun hit the air. This causes the air to glow.

The lights can look like curtains or rays. They can be green, red, or purple. In the north, we call them northern lights. In the south, they are southern lights.

These lights are a wonderful sight to see.

Have you ever seen colorful lights dancing in the night sky? These are called auroras.

They happen high up in Earth's atmosphere. The sun sends out tiny particles called electrons and protons. These particles travel through space on the solar wind. When they hit Earth, they interact with our magnetosphere. The magnetosphere is a shield around our planet.

The particles follow this shield into the upper air. There, they crash into atoms of oxygen and nitrogen. These crashes make the atoms excited. When they calm down, they give off light.

Oxygen makes the sky glow red or green. Nitrogen can make blue or purple colors.

The lights can look like curtains, rays, or spirals. In the north, we call them the aurora borealis. People often call them the northern lights. In the south, they are the aurora australis. These are the southern lights.

Other planets like Jupiter also have auroras!

Have you ever looked up at a night sky filled with dancing colors? These beautiful light displays are called auroras.

They are natural lights that happen in Earth's upper atmosphere. When people see them in high-latitude regions, they are called polar lights. In the Arctic, we call them the northern lights, or aurora borealis. In the Antarctic, they are called the southern lights, or aurora australis.

These lights can look like many different things. They might appear as glowing curtains, bright rays, or even spirals. Sometimes they look like flickering patches that cover the whole sky.

So, how does this amazing thing actually work? It all starts with the Sun. The Sun sends out solar wind, which is a stream of charged particles. These particles include things called electrons and protons.

When these particles reach Earth, they cause disturbances in our magnetosphere. This is a magnetic shield around our planet. The particles follow paths into the upper atmosphere, called the thermosphere or exosphere. There, they crash into atoms of oxygen and nitrogen. This collision makes the atoms "excited," which means they give off light as they settle down.

People have been studying these lights for a very long time. The name "aurora" comes from the Roman goddess of the dawn. She was said to travel from east to west to announce the Sun. The term aurora borealis was used by Pierre Gassendi in 1649. He was describing lights seen all over France in 1621. Before that, the famous scientist Galileo Galilei wrote about them in 1619. Galileo actually thought the lights were just sunlight reflecting off very high, thin clouds.

There are many specific facts about where and how auroras appear. Most auroras happen in a special band called the auroral zone. This zone is about 660 kilometers wide and sits around 67 degrees north and south. The specific area showing lights right now is called the auroral oval.

Colors change depending on which atoms are hit. Oxygen can make the sky look red or green. Nitrogen can create blue or purple colors.

During a huge magnetic storm, like the Carrington Event, auroras can even be seen in the tropics!

It is helpful to remember that Earth is not the only place with these lights. Other planets in our solar system have them too. For example, Jupiter and Saturn both host their own auroras.

You can even see auroras on comets and some moons. Just like the lights in our sky, these planetary lights are shaped by magnetic fields. Whether they are green, red, or blue, they show us how much energy is moving through space. It is a wonderful way to see the invisible forces of our universe in action.

An aurora is a natural light display occurring in Earth's upper atmosphere. These displays are caused by charged particles from the Sun colliding with atoms in our atmosphere. When these collisions happen, they excite oxygen and nitrogen atoms. These atoms then emit light of various colors, such as green, red, and purple.

When observed in high-latitude regions, they are known as polar lights or aurora polaris. In the Arctic, they are called the northern lights, or aurora borealis. In the Antarctic, they are called the southern lights, or aurora australis.

The mechanism behind an aurora begins with disturbances in Earth's magnetosphere. This magnetic shield is affected by enhanced solar wind speeds from coronal holes and coronal mass ejections. These disturbances change the trajectories of charged particles within the magnetospheric plasma. The particles involved are mainly electrons and protons. These particles precipitate into the upper atmosphere, specifically the thermosphere and exosphere.

As they enter, they cause ionization and excitation of atmospheric constituents. This process results in the emission of light with varying colors and complexity. The specific form of the aurora depends on the amount of acceleration given to these precipitating particles.

Auroras appear in distinct forms depending on the viewer's position and the atmosphere's shape. According to Clark (2007), there are five main forms visible from the ground. They range from a mild glow near the horizon to more complex shapes. Patches or surfaces can look like clouds, while arcs curve across the sky. Rays appear as light and dark stripes reaching upwards from these arcs.

Coronas cover large parts of the sky and diverge from a single point. Some auroras are described as curtains due to the way folds appear within the arcs. Discrete auroras can be bright enough to read a newspaper by at night. These shapes are consistent with the way Earth's magnetic field organizes the lights.

Colors in an aurora are determined by the specific gases being hit and the altitude of the collision. At the highest altitudes, excited atomic oxygen emits light at 630 nm, which appears red. Because there are fewer oxygen atoms there, this color is often faint and requires intense solar activity to see. At lower altitudes, collisions with oxygen atoms favor a 557.7 nm emission, which produces the common green color.

Molecular nitrogen also plays a role, helping to transfer energy that results in green light. At even lower altitudes, molecular nitrogen and ionized nitrogen produce blue and purple emissions. These blue and purple colors typically appear at the lower edges of the auroral curtains. Some displays even show white or mauve colors, which come from a wide spectrum of many colors mixed together.

History shows how our understanding of these lights has changed over time. The term aurora borealis was used by Pierre Gassendi in 1649 to describe a display seen in France in 1621. Before this, Galileo Galilei wrote about auroras in 1619. Galileo believed the lights were caused by sunlight reflecting off thin, high clouds.

The word aurora itself comes from the Roman goddess of the dawn. She was said to travel from east to west to announce the coming of the Sun. The terms borealis and australis come from the Greco-Roman gods of the north and south winds. Scientists often use the Latin plural "aurorae," while "auroras" is common in the United States.

Most auroras are found in the "auroral zone," a band about 660 km wide centered at 67 degrees north and south. The specific area currently displaying light is called the auroral oval. This oval can move due to the solar wind, shifting about 15 degrees away from the geomagnetic pole in the noon direction.

During a geomagnetic storm, the auroral ovals expand toward lower latitudes. On rare occasions, the aurora borealis can be seen as far south as the Mediterranean or the southern United States. During the Carrington Event, the greatest geomagnetic storm ever recorded, auroras were even visible in the tropics. Large storms are most common during the peak of the 11-year sunspot cycle.

Auroras are not unique to Earth; they are a widespread phenomenon in the solar system. Other planets, brown dwarfs, comets, and some natural satellites also host auroras. For example, Jupiter and Saturn both exhibit these light displays.

These celestial lights are all connected to the presence of magnetic fields and charged particles. Studying them helps scientists understand the complex relationship between stars and the planets that orbit them.