27 relations: Apparent magnitude, Astronomical spectroscopy, Binary star, Contact binary, Durchmusterung, Earth, Eclipse, Gustav Müller, Henry Draper Catalogue, Hipparcos, Light-year, Main sequence, Monthly Notices of the Royal Astronomical Society, Nuclear fusion, Orbital period, Parallax, Parsec, Paul Kempf, Smithsonian Astrophysical Observatory Star Catalog, Solar mass, Solar radius, Stellar classification, Stellar magnetic field, Ursa Major, Variable star, Variable star designation, W Ursae Majoris variable.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light and radio, which radiates from stars and other celestial objects.
A binary star is a star system consisting of two stars orbiting around their common barycenter.
Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.
The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.
Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.
Christmas traditions vary from country to country.
In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes.
In astronomy, Durchmusterung or Bonner Durchmusterung (BD), is the comprehensive astrometric star catalogue of the whole sky, compiled by the Bonn Observatory (Germany) from 1859 to 1903.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.
Karl Hermann Gustav Müller (May 7, 1851–July 7, 1925) was a German astronomer.
The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars.
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
In astronomy, the main sequence is a continuous and distinctive band of stars that appear on plots of stellar color versus brightness.
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.
New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.
In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.
In nuclear physics, nuclear fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons or protons).
The orbital period is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars.
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.
The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System.
Paul Friedrich Ferdinand Kempf (3 June 1856 – 16 February 1920) was a German astronomer.
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue.
The solar mass is a standard unit of mass in astronomy, equal to approximately.
Solar radius is a unit of distance used to express the size of stars in astronomy.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star.
Ursa Major (also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory.
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates.
Variable stars are designated using a variation on the Bayer designation format of an identifying label (as described below) combined with the Latin genitive of the name of the constellation in which the star lies.
A W Ursae Majoris variable, also known as a low mass contact binary, is a type of eclipsing binary variable star.
2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.
2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.