date_of_birth wolf bickel
The Rhine (, , ) is a European river that begins in the Swiss canton of Graubünden in the southeastern Swiss Alps , forms part of the Swiss - Austrian , Swiss - Liechtenstein , Swiss - German and then the Franco - German border , then flows through the Rhineland and eventually empties into the North Sea in the Netherlands . The largest city on the river Rhine is Cologne , Germany , with a population of more than ___MASK18___ , 050 , 000 people . It is the second - longest river in Central and Western Europe ( after the Danube ), at about , with an average discharge of about . North Rhine - Westphalia (, commonly shortened to NRW ) is the most populous state of Germany , with a population of approximately ___MASK68___ million , and the fourth largest by area . Its capital is Düsseldorf ; the most populous city is Cologne . Four of Germany ' s ten largest cities  Cologne , Düsseldorf , Dortmund , and Essen  are located within the state , as well as the largest metropolitan area on the European continent , Rhine - Ruhr . The Bergisch Gladbach Observatory is an astronomical observatory located in Bergisch Gladbach , Germany , at . Its observatory code is ___MASK53___ . Astronomer Wolf Bickel . Wolf Bickel ( born ___MASK82___ July ___MASK78___ , Bensberg ) is a German amateur astronomer and a prolific discoverer of asteroids , observing at his private Bergisch Gladbach Observatory , Germany . As of 2016 , he is credited with the discovery of 647 numbered minor planets during 1995  2010 . In terms of total discoveries , this makes him the most successful German discoverer of asteroids , ahead of ( professional ) astronomer Freimut Börngen and the first amateur astronomer to claim this honor in more than 150 years . Bergisch Gladbach , is a city in the Cologne / Bonn Region of North Rhine - Westphalia , Germany , and capital of the Rheinisch - Bergischer Kreis ( district ). Wolf Bickel is a German astronomer . He is a prolific discoverer of asteroids , working at the Bergisch Gladbach Observatory . He is credited with 638 discoveries during ___MASK54___ - 2010 . A comet is an icy small Solar System body that , when passing close to the Sun , warms and begins to evolve gasses , a process called outgassing . This produces a visible atmosphere or coma , and sometimes also a tail . These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet . Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice , dust , and small rocky particles . The coma may be up to ___MASK11___ times the Earth ' s diameter , while the tail may stretch one astronomical unit . If sufficiently bright , a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30 ° ( 60 Moons ) across the sky . Comets have been observed and recorded since ancient times by many cultures . An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside of the scope of Earth . They look at stars , planets , moons , comets and galaxies , as well as many other celestial objects  either in observational astronomy , in analyzing the data or in theoretical astronomy . Examples of topics or fields astronomers work on include : planetary science , solar astronomy , the origin or evolution of stars , or the formation of galaxies . There are also related but distinct subjects like physical cosmology which studies the Universe as a whole . Physical cosmology is the study of the largest - scale structures and dynamics of the Universe and is concerned with fundamental questions about its origin , structure , evolution , and ultimate fate . Cosmology as a science originated with the Copernican principle , which implies that celestial bodies obey identical physical laws to those on Earth , and Newtonian mechanics , which first allowed us to understand those physical laws . Physical cosmology , as it is now understood , began with the development in ___MASK27___ of Albert Einstein ' s general theory of relativity , followed by major observational discoveries in the 1920s : first , Edwin Hubble discovered that the universe contains a huge number of external galaxies beyond our own Milky Way ; then , work by Vesto Slipher and others showed that the universe is expanding . These advances made it possible to speculate about the origin of the universe , and allowed the establishment of the Big Bang Theory , by Georges Lemaitre , as the leading cosmological model . A few researchers still advocate a handful of alternative cosmologies ; however , most cosmologists agree that the Big Bang theory explains the observations better . A planet is an astronomical body orbiting a star or stellar remnant that The term " planet " is ancient , with ties to history , astrology , science , mythology , and religion . Several planets in the Solar System can be seen with the naked eye . These were regarded by many early cultures as divine , or as emissaries of deities . As scientific knowledge advanced , human perception of the planets changed , incorporating a number of disparate objects . In ___MASK33___ , the International Astronomical Union ( IAU ) officially adopted a resolution defining planets within the Solar System . This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit . Although eight of the planetary bodies discovered before ___MASK60___ remain " planets " under the modern definition , some celestial bodies , such as Ceres , Pallas , Juno and Vesta ( each an object in the solar asteroid belt ), and Pluto ( the first trans - Neptunian object discovered ), that were once considered planets by the scientific community , are no longer viewed as such .