Have you ever seen one of the nature’s magic painted across the night sky with shimmering, colored lights? They are famously called the northern or southern lights. Do you know the secret behind their magic? Watch to find out! #STEMvee
Transcript: Those who live at or visit high latitudes might at times experience colored lights shimmering across the night sky. These are known as ‘Aurora borealis’ in the northern hemisphere and ‘Aurora australis’ in the southern hemisphere. They are also commonly known as the Northern and Southern Lights. What causes these brilliant lights to appear? Well, it all starts with the sun! Great storms on the sun will send gusts of charged solar particles hurtling across space. When the charged particles from the sun strike atoms and molecules in the Earth’s atmosphere, they excite those atoms, causing them to emit light. How does an atom emit light? Atoms consist of a central nucleus and a surrounding cloud of electrons encircling the nucleus. The atom has several energy levels (from low to high) and their electrons are generally in a relaxed, ground state. When charged particles from the sun strike atoms in the Earth’s atmosphere, electrons will move to a higher energy level. However, once the electrons are in the excited, higher energy level, they are in an unstable position. The electrons will quickly fall back down to the lower energy level. And by doing so, they emit photons, or light. Because the energy of a charged particle absorbed must be equal to the energy of a photon emitted, the size of transitions between energy levels rely on the amount of energy absorbed. If the amount of energy absorbed is large, then the size of transition between the energy levels will also be large. If the amount absorbed is small, then the size of transition will be also small. Let’s use the visible light spectrum to explain how different colors are emitted. On the left end of the spectrum where there are reds and oranges, they are low energy colors. On the right end of the spectrum where there are blues and violets, they are high energy colors. If a lowly charged solar particle excites an atom, the transition between two energy levels will be small and the atom will emit reds and oranges. If a highly charged solar particle excites an atom, the transition will be much larger and the atom will emit blues and violets. However, no atom can emit any color on the spectrum. This fact has to do with how each atom/element is structured, which means they can only absorb or emit specific amounts of energy which will correspond to specific colors. So, when you look up and see varying colors dance in the night sky, you might wonder how these colors appear. The appearance of colors depends on the type of atoms, their location in the atmosphere, and the amount of energy from these solar particles. Red appear in the Aurora when solar particles react with Oxygen at higher altitudes, generally above 150 miles. Green appear when the reaction with Oxygen occurs at an altitude of around 60 to 150 miles. Blue and purple appear when the reaction occurs with Nitrogen at an altitude of 60 miles or less. Fascinating, right? Now, book a trip to see the Northern or Southern Lights! When you are staring up at the brilliant colors dancing in the sky, take a moment to appreciate all of the intricate details that had to happen for us to be awed at this display of magic.
