Leiden vs Aurora

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Leiden (, Dutch: [ˈlɛi̯də(n)] (listen); in English and archaic Dutch also Leyden) is a city and municipality in the province of South Holland, Netherlands. The municipality of Leiden had a population of 123,856 in August 2017, but the city forms one densely connected agglomeration with its suburbs Oegstgeest, Leiderdorp, Voorschoten and Zoeterwoude with 206,647 inhabitants. The Netherlands Central Bureau of Statistics (CBS) further includes Katwijk in the agglomeration which makes the total population of the Leiden urban agglomeration 270,879, and in the larger Leiden urban area also Teylingen, Noordwijk, and Noordwijkerhout are included with in total 348,868 inhabitants. Leiden is located on the Oude Rijn, at a distance of some 20 kilometres (12 miles) from The Hague to its south and some 40 km (25 mi) from Amsterdam to its north. The recreational area of the Kaag Lakes (Kagerplassen) lies just to the northeast of Leiden. A university city since 1575, Leiden has been one of Europe's most prominent scientific centres for more than four centuries. Leiden is a typical university city, university buildings are scattered throughout the city and the many students from all over the world give the city a bustling, vivid and international atmosphere.

Many important scientific discoveries have been made here, giving rise to Leiden's motto: ‘City of Discoveries’. The city houses Leiden University, the oldest university of the Netherlands, and Leiden University Medical Center. Leiden University is one of Europe's top universities, with thirteen Nobel Prize winners. It is a member of the League of European Research Universities and positioned highly in all international academic rankings. It is twinned with Oxford, the location of the United Kingdom's oldest university. Leiden University and Leiden University of Applied Sciences (Leidse Hogeschool) together have around 35,000 students. Modern scientific medical research and teaching started in the early 18th century in Leiden with Boerhaave. Leiden is a city with a rich cultural heritage, not only in science, but also in the arts. One of the world's most famous painters, Rembrandt, was born and educated in Leiden. Other famous Leiden painters include Lucas van Leyden, Jan van Goyen and Jan Steen.

Source: Wikipedia

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An aurora (plural: auroras or aurorae), sometimes referred to as polar lights (aurora polaris), northern lights (aurora borealis), or southern lights (aurora australis), is a natural light display in the Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras are the result of disturbances in the magnetosphere caused by solar wind. These disturbances are sometimes strong enough to alter the trajectories of charged particles in both solar wind and magnetospheric plasma. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/exosphere).

The resulting ionization and excitation of atmospheric constituents emit light of varying color and complexity. The form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere. Proton auroras are usually observed at lower latitudes.

Source: Wikipedia