Aurora Borealis . By: Danna & Karin Science 9 Block:C. CONTENTS. What is an Aurora? When do they happen? Where do they happen? Auroras on other planets How do they happen? Colours Colous-2 Colours-3. CONTENTS. 9) Different Names 10) Best places to view auroras
By: Danna & Karin
9) Different Names
10) Best places to view auroras
11) Best places to view auroras-2
12) Legends of the lights
13) How long do they last?
14) Different types of auroras
15) Auroral shapes and motions
16)When can I see an aurora?
An aurora is an effect of collisions between electrically charged particles in Earth’s atmosphere. They can be described as a dance of lights in the night sky. A sight wanted to be seen by many.
Researchers have found that auroras appear in a cycle. About every 11 years and the 3 years after that peak. 2013 was the last peak.
Auroras are visible at the poles of the both the Northern and Southern hemispheres. This place is called the auroral zone. They have also been observed on other planets such as Saturn, Jupiter, Neptune and Uranus.
Saturn and Jupiter have strong magnetic fields and auroras have been observed on both.
How do they happen?
An aurora is a collision between charged gaseous particles and particles from the sun. Free electrons and protons leave the sun’s atmosphere from holes in the magnetic field. Then float to earth on solar winds. Most particles are deflected but there are weaker spots at the poles so some get in and collide with gas particles. These collisions create light which we see as the “dancing” in the sky.
Auroras come in lots of colours. Their colour depends on the type of gas particle the charged particles collide with. For example the most common colour a light yellowish-green is created with oxygen molecules found about 60 miles above earth.
When mixed with high altitude (200ft) oxygen it creates a very rare red aurora
Nitrogen produces a blue or sometimes purplish-red coloured aurora.
All over the world aurora borealis has been given different names throughout history. In the north they are known as ‘Aurora borealis’ or “Northern Lights”. And in the south as ‘Aurora australis’ or “Southern Lights”. The Cree call it “Dance of the Spirits”.
Because of the location of the magnetic poles there is limited places to view this phenomenon. However the best places to watch the lights in Canada are the Yukon, Northwest Territories, Nunavut and Alaska (even though it is technically the U.S.) The displays of colour can also be viewed on the tip of Greenland and Iceland. As well as northern parts of Siberia and Norway. Southern auroras are more rarely seen because they are concentrated right around Antarctica.
Auroras are visible in northern Canada and northern Europe as well as a circle around Antarctica.
In the north the aurora borealis is named after the roman goddess of dawn Aurora, and Boreas the Greek word for north wind. In Medieval Europe auroras were considered to be signs from god, bringing hard times. Many people of northern Europe and North America thought the lights were reflections of fire and torches in the sky. The Inuit of Alaska thought that they were the spirits of the animals they hunted. Other aboriginal people thought they were human spirits.
Auroras can last anywhere from a few minutes to a few days. Very faint ones only last a couple minutes at most. But they usually last 1 to 2 hours. In rare cases there are auroras that last for days fading away and reappearing. They’re called aurora storms.
Auroras are classified into two different types. They are either diffuse or discrete. Diffuse auroras are extremely faint and don’t have colour. They are also not visible to the naked eye. Even on a very dark night. Discrete auroras have very defined features and are brighter than diffuse auroras. But they are usually only visible at night, and because they are closer to earth.
When auroras are viewed from space they are seen as bright ovals over the poles. But from the ground they resemble a shifting curtain in the night sky. Words that are used to describe auroras can be as follows: rays, draperies, arcs, bands, spirals and curls.
You might get a chance to see an aurora in the next year or so, if you’re lucky. If not your prime time would be in the year 2024 which is the next peak in the eleven year cycle. Ten years from now.
On both the 28th of August and the 2nd of September 1859 scientists recorded one of the best geomagnetic storms in history. Auroras appeared all over the United States, Europe, Japan and Australia. Because of the power of the storm, they were extremely widespread and bright.
Info- Encyclopaedia of Earth and Physical Sciences