Question: What color is the most common of all auroras?
About the article "Aurora", section "Auroral mechanism".

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Auroras are associated with the solar wind, a flow of ions continuously flowing outward from the Sun.
The Earth's magnetic field traps these particles, many of which travel toward the poles where they are accelerated toward Earth.
Collisions between these ions and atmospheric atoms and molecules cause energy releases in the form of auroras appearing in large circles around the poles.
Auroras are more frequent and brighter during the intense phase of the solar cycle when coronal mass ejections increase the intensity of the solar wind.
Auroras result from emissions of photons in the Earth's upper atmosphere, above , from ionized nitrogen molecules regaining an electron, and oxygen atoms and nitrogen molecules returning from an excited state to ground state.
They are ionized or excited by the collision of solar wind and magnetospheric particles being funneled down and accelerated along the Earth's magnetic field lines; excitation energy is lost by the emission of a photon, or by collision with another atom or molecule:
oxygen emissions: green or brownish-red, depending on the amount of energy absorbed.
nitrogen emissions: blue or red; blue if the atom regains an electron after it has been ionized, red if returning to ground state from an excited state.
Oxygen is unusual in terms of its return to ground state: it can take three quarters of a second to emit green light and up to two minutes to emit red.
Collisions with other atoms or molecules absorb the excitation energy and prevent emission.
Because the very top of the atmosphere has a higher percentage of oxygen and is sparsely distributed such collisions are rare enough to allow time for oxygen to emit red.
Collisions become more frequent progressing down into the atmosphere, so that red emissions do not have time to happen, and eventually even green light emissions are prevented.
This is why there is a color differential with altitude; at high altitude oxygen red dominates, then oxygen green and nitrogen blue/red, then finally nitrogen blue/red when collisions prevent oxygen from emitting anything.
Green is the most common of all auroras.
Behind it is pink, a mixture of light green and red, followed by pure red, yellow (a mixture of red and green), and finally, pure blue.
An aurora (plural: auroras or aurorae; from the Latin word "aurora", "sunrise" or the Roman goddess of dawn) is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere).
The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth's magnetic field into the atmosphere.
Most auroras occur in a band known as the "auroral zone", which is typically 3° to 6° wide in latitude and observed at 10° to 20° from the geomagnetic poles at all local times (or longitudes).
During a geomagnetic storm, the auroral zone expands to lower latitudes. 
Oldsmobile's original intention for the second generation was to move the Aurora further upmarket, retaining its V8-only drivetrain and sharing a platform with the new Buick Riviera, as the original Aurora had done.
This would have created more room within the Oldsmobile lineup for a four-door Eighty-Eight successor known as the Antares.
However, Buick dropped its Riviera development plans and fiscal trouble found Oldsmobile, so Oldsmobile was forced to re-engineer the Antares into an acceptable Aurora in short time.
Still using the G-body design, the re-engineered Aurora was the result, but retaining its 4.0 V8 Northstar still mounted to a 4T80-E. Oldsmobile also offered a V6 engine in the Aurora for the first time.
The V6 in question was the LX5, a cut-down relation of the DOHC Aurora V8, dubbed the "Shortstar."
The V6-powered Aurora was produced for the 2001 and 2002 model years only, with production ceasing in mid-2002.
This Aurora, though still a competitive luxury sedan, did not attract the attention, nor sales that the original did.
This can be blamed on several reasons.
Most of all was that the new Aurora, as well as the new 2002 Bravada, was overshadowed by GM's announcement in December 2000 that the Oldsmobile marque was to be phased out over the next several years.
Though still retaining its unique styling, it now shared design cues from other Oldsmobiles, as well many parts in common with other GM vehicles.
This took away the "separateness" from other Oldsmobiles that the original had.
It should also be noted, that the 2nd generation Aurora was over six inches shorter than was the 1st generation.
Automobile magazine wrote that "The Aurora's new look is not quite as sensuous or elegant as that of the outgoing model," but the Auto Channel review said, "it was better in every respect.
"The second generation Aurora went into production on November 1, 1999, and went on sale in February 2000 as a 2001 model.
The last V6-powered Auroras rolled off the assembly line on June 21, 2002.
The Final 500 Auroras ended production on March 28, 2003.
These were all a special burgundy color (called "Dark Cherry Metallic"), had special chrome wheels, and Final 500 badging.
The Orion, Michigan plant built a total of 71,722 second-generation Auroras (53,640 in 2001, 10,865 in 2002, 7,217 in 2003). 
Ryan Mania is a Scottish National Hunt jockey from Galashiels, most famous for winning the 2013 Grand National on the Sue Smith-trained Auroras Encore, at starting odds of 66/1.  
The color lapis lazuli is displayed at left.
"Lapis Lazuli" is a color that is a representation of the most common color of lapis lazuli.