Cairo vs Aurora

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Cairo ( KY-roh; Arabic: القاهرة‎, romanized: al-Qāhirah, pronounced [ælˈqɑːhɪɾɑ] (listen), Coptic: ⲕⲁϩⲓⲣⲏ) is the capital of Egypt and the largest city in the Arab world. Its metropolitan area, with a population of over 20 million, is the largest in Africa, the Arab world, and the Middle East, and the 6th-largest in the world. Cairo is associated with ancient Egypt, as the famous Giza pyramid complex and the ancient city of Memphis are located in its geographical area. Located near the Nile Delta, Cairo was founded in 969 AD by the Fatimid dynasty, but the land composing the present-day city was the site of ancient national capitals whose remnants remain visible in parts of Old Cairo. Cairo has long been a centre of the region's political and cultural life, and is titled "the city of a thousand minarets" for its preponderance of Islamic architecture. Cairo is considered a World City with a "Beta +" classification according to GaWC.

Cairo has the oldest and largest film and music industries in the Arab world, as well as the world's second-oldest institution of higher learning, Al-Azhar University. Many international media, businesses, and organizations have regional headquarters in the city; the Arab League has had its headquarters in Cairo for most of its existence. With a population of over 9 million spread over 3,085 square kilometers (1,191 sq mi), Cairo is by far the largest city in Egypt. An additional 9.5 million inhabitants live in close proximity to the city. Cairo, like many other megacities, suffers from high levels of pollution and traffic. The Cairo Metro is one of the only two metro systems in Africa (the other being in Algiers, Algeria), and ranks amongst the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, and 43rd globally on Foreign Policy's 2010 Global Cities Index.

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