The northern lights are one of the most spectacular sights on Earth, but astronomers are just as interested in the science behind them.
Now NASA has revealed plans to fly through them with two rockets to study how our planet exchanges energy with the surrounding space.
The aurora borealis, also known as the aurora borealis, occurs at the boundary between the neutral atmosphere that surrounds our planet and the electrically reactive matter known as plasma that makes up the cosmos.
Sometimes, when electrically charged particles from space enter our atmosphere, they collide with neutral particles and ignite them, causing us to see beautiful dancing waves of light in the sky.
However, the aurora also excites the wider boundary layer, and it is the effect on this layer that NASA hopes to study in its upcoming INCAA (Ion Neutral Compound During Aurora Active) mission.
Conceptual animation showing how electrons move along the Earth’s magnetic field lines, collide with particles in the Earth’s atmosphere, causing the aurora.
WHAT IS THE POLAR LIGHTS AND WHAT CAUSES AMAZING NATURAL APPEARANCES?
The Northern and Southern Lights are spectacles of natural light that occur in our atmosphere and are also known as the “aurora borealis”.
There are two types of Aurora – Aurora Borealis, which means “dawn of the north”, and Aurora Australis, “dawn of the south”.
The displays light up when electrically charged solar particles enter the Earth’s atmosphere.
Normally, the particles, sometimes called a solar storm, are deflected by the Earth’s magnetic field.
But during stronger storms, they enter the atmosphere and collide with gas particles, including hydrogen and helium.
These collisions emit light. Auroras come in a variety of colors, although pale green and pink are common.
“As inhabitants of the troposphere, the lowest layer of the Earth’s atmosphere, we are accustomed to air composed of neutral particles. The oxygen and nitrogen we breathe are magnetically balanced atoms and molecules that account for all of their electrons,” explains NASA.
“But hundreds of miles above us, our air begins to fundamentally change its character. Under the influence of unfiltered sunlight, electrons are detached from atoms, which then acquire a positive charge.
“The once neutral gas turns into an electrically reactive state of matter known as plasma.”
There is no hard boundary where neutral gas ends and plasma begins; instead, there is an extended boundary layer in which the two types of particles mix.
Daily winds and magnetic disturbances push particles in different directions, sometimes causing them to collide and release energy.
“Friction is a great analogy,” said Steven Keppler, assistant professor of physics and astronomy at Clemson University in South Carolina and principal investigator for the INCAA mission.
“We all know that if you rub your hands, you will get hot. It’s the same basic idea, except now we’re dealing with gases.”
When aurora is added to the mixture, the amount of friction increases dramatically, according to Kappler.
“It’s like storming the football field after a college game,” he said.
“People at the top of the stadium are running towards the field, and as you get closer to the field, the crowd gets thicker and thicker. This is the case with electrons colliding with the increasing neutral density of the upper atmosphere.”
When electrically charged particles from space enter our atmosphere, they collide with neutral particles and ignite them, causing us to see beautiful dancing waves of light in the sky (file image)
The INCAA mission will include sending two small “sounding rockets” to the edge of space when the northern lights are visible overhead.
Sounding rockets are small launch vehicles designed to lift into space for a few minutes of measurements before returning to Earth, making them ideal for studying short-term, transient phenomena such as auroras.
On the way up, the first rocket will release “steam tracers” – colorful chemicals similar to those used in fireworks – before reaching a maximum altitude of about 186 miles.
Vapor tracers create visible clouds that researchers can see from the ground by tracking winds in a neutral atmosphere, such as dropping food coloring into a sink full of water to see how the water moves.
A second rocket will be launched shortly after, reaching an altitude of about 125 miles, to measure the temperature and density of the plasma in and around the aurora.
Kepler hopes these data will shed light on how the aurora shifts the boundary layer where electrified air meets neutral air—whether pushing it further toward the ground, lifting it higher, or causing it to curl up.
“All these factors make this physical problem interesting to study,” Kappler said.
The launch window for the INCAA mission will open at the Poker Flat research site in Poker Flat, Alaska on March 23rd.
SOLAR STORMS PRESENT A CLEAR HAZARD TO COSMONAUTS AND CAN DAMAGE SATELLITES
Solar storms or solar activity can be divided into four main components that can affect the Earth:
- Solar flares: A large explosion in the Sun’s atmosphere. These flares are made up of photons that are fired directly from the location of the flare. Solar flares only affect the Earth when they occur on the Earth-facing side of the Sun.
- Coronal Mass Ejections (CME’s): Large clouds of plasma and magnetic field that erupt from the Sun. These clouds can break through in any direction and then continue in that direction, breaking through the solar wind. These clouds only affect the Earth when they are directed towards the Earth.
- High-velocity solar wind streams: These come from coronal holes on the Sun that form anywhere on the Sun, and usually only when they are closer to the solar equator do the winds impact the Earth.
- Solar Energetic Particles: High-energy charged particles thought to be ejected primarily by shock waves generated at the front of coronal mass ejections and solar flares. When a CME cloud passes through the solar wind, particles of solar energy can form, and because they are charged, they follow magnetic field lines between the Sun and Earth. Only charged particles that follow the magnetic field lines that cross the Earth are affected.
Although it may seem dangerous, astronauts are not directly at risk from these phenomena due to the relatively low orbit of manned missions.
However, they should be concerned about cumulative exposure during spacewalks.
This photograph shows the coronal holes of the Sun in an X-ray image. The outer solar atmosphere, the corona, is structured by strong magnetic fields which, when closed, can cause sudden and violent release of bubbles or tongues of gas and magnetic fields called coronal mass ejections.
damage from solar storms
Solar flares can damage satellites and have huge financial costs.
Charged particles can also threaten airlines by disrupting the Earth’s magnetic field.
Very large flares can even create currents in electrical networks and disable the power supply.
When coronal mass ejections hit the Earth, they cause geomagnetic storms and enhanced auroras.
They can disrupt radio waves, GPS coordinates, and overload electrical systems.
A large influx of energy can enter high-voltage electrical networks and permanently damage transformers.
This can shut down businesses and homes around the world.
Source: NASA – Solar Storm and Space Weather.