Alexandria vs Vega

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Alexandria ( or ; Arabic: الإسكندرية‎ al-ʾIskandariyya; Egyptian Arabic: اسكندرية‎ Eskendereyya; Coptic: ⲣⲁⲕⲟϯ Rakodī; Greek: Αλεξάνδρεια Alexandria) is the second-largest city in Egypt and a major economic centre. With a population of 5,200,000, Alexandria is the largest city on the Mediterranean - also called the Bride of the Mediterranean by locals - the sixth-largest city in the Arab world and the ninth-largest in Africa. The city extends about 40 km (25 mi) at the northern coast of Egypt along the Mediterranean Sea. Alexandria is a popular tourist destination, and also an important industrial centre because of its natural gas and oil pipelines from Suez. Alexandria was founded in c. 331 BC by Alexander the Great, king of Macedon and leader of the Greek League of Corinth, during his conquest of the Achaemenid Empire. An Egyptian village named Rhacotis existed at the location and grew into the Egyptian quarter of Alexandria. Alexandria grew rapidly to become an important centre of Hellenistic civilization and remained the capital of Ptolemaic Egypt and Roman and Byzantine Egypt for almost 1,000 years, until the Muslim conquest of Egypt in AD 641, when a new capital was founded at Fustat (later absorbed into Cairo).

Hellenistic Alexandria was best known for the Lighthouse of Alexandria (Pharos), one of the Seven Wonders of the Ancient World; its Great Library (the largest in the ancient world); and the Necropolis, one of the Seven Wonders of the Middle Ages. Alexandria was the intellectual and cultural centre of the ancient Mediterranean world for much of the Hellenistic age and late antiquity. It was at one time the largest city in the ancient world before being eventually overtaken by Rome. The city was a major centre of early Christianity and was the centre of the Patriarchate of Alexandria, which was one of the major centres of Christianity in the Eastern Roman Empire. In the modern world, the Coptic Orthodox Church and the Greek Orthodox Church of Alexandria both lay claim to this ancient heritage. Following the Arab conquest of Egypt in AD 641, the city was plundered and lost its significance before re-emerging in the modern era. From the late 18th century, Alexandria became a major centre of the international shipping industry and one of the most important trading centres in the world, both because it profited from the easy overland connection between the Mediterranean Sea and the Red Sea, and the lucrative trade in Egyptian cotton.

Source: Wikipedia

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Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only 25 light-years from the Sun, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood. It is the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun". Vega was the northern pole star around 12,000 BC and will be so again around the year 13,727, when its declination will be +86° 14′. Vega was the first star other than the Sun to be photographed and the first to have its spectrum recorded. It was one of the first stars whose distance was estimated through parallax measurements. Vega has functioned as the baseline for calibrating the photometric brightness scale and was one of the stars used to define the zero point for the UBV photometric system.

Vega is only about a tenth of the age of the Sun, but since it is 2.1 times as massive, its expected lifetime is also one tenth of that of the Sun; both stars are at present approaching the midpoint of their life expectancies. Vega has an unusually low abundance of the elements with a higher atomic number than that of helium. Vega is also a variable star that varies slightly in brightness. It is rotating rapidly with a velocity of 236 km/s at the equator. This causes the equator to bulge outward due to centrifugal effects, and, as a result, there is a variation of temperature across the star's photosphere that reaches a maximum at the poles. From Earth, Vega is observed from the direction of one of these poles.Based on an observed excess emission of infrared radiation, Vega appears to have a circumstellar disk of dust. This dust is likely to be the result of collisions between objects in an orbiting debris disk, which is analogous to the Kuiper belt in the Solar System. Stars that display an infrared excess due to dust emission are termed Vega-like stars.

Source: Wikipedia