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α Cephei
Alpha Cephei (α Cephei, abbreviated Alpha Cep, α Cep), officially named Alderamin , is a second magnitude star in the constellation of Cepheus near the northern pole. The star is relatively close to Earth at 49 light years (''ly''). Nomenclature ''α Cephei'' ( Latinised to ''Alpha Cephei'') is the star's Bayer designation. It has a Flamsteed designation of 5 Cephei. It bore the traditional name ''Alderamin'', a contraction of the Arabic phrase ''الذراع اليمين'' ''al-dhirā‘ al-yamīn'', meaning "the right arm". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included ''Alderamin'' for this star. Visibility With a declination in excess of 62 degrees north, Alpha Cephei never rises south of −27° latitude, which means for much of South Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldebaran
Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent visual magnitude 0.75 down to 0.95, making it (typically) the fourteenth-brightest star in the night sky. It is located at a distance of approximately 65 light-years from the Sun. The star lies along the line of sight to the nearby Hyades cluster. Aldebaran is a giant star that is cooler than the Sun with a surface temperature of , but its radius is about 44 times the Sun's, so it is over 400 times as luminous. It spins slowly and takes 520 days to complete a rotation. Aldebaran is believed to host a planet several times the mass of Jupiter, named . The planetary exploration probe Pioneer 10 is heading in the general direction of the star and should make its closest approach in about two million ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Diego
San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eighth most populous city in the United States and the county seat, seat of San Diego County, the List of the most populous counties in the United States, fifth most populous county in the United States, with 3,338,330 estimated residents as of 2019. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches and parks, long association with the United States Navy, and recent emergence as a healthcare and biotechnology development center. San Diego is the List of municipalities in California, second largest city in the U.S. state, state of California, after Los Angeles. Historically home to the Kumeyaay people, San Diego is frequently referred to as the "Birthplace of California", as it was the first site vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or dwarf stars. These are the most numerous true stars in the universe and include the Sun. After condensation and ignition of a star, it generates thermal energy in its dense core region through nuclear fusion of hydrogen into helium. During this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass but also based on its chemical composition and age. The cores of main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iota Cephei
Iota Cephei (ι Cephei, ι Cep) is a star in the northern constellation Cepheus (constellation), Cepheus. Based upon an annual parallax shift of as seen from the Earth, it is located about from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 3.5. It is a K-type star, K-type giant star with a stellar classification of K0 III. It is currently at an stellar evolution, evolutionary stage known as the red clump, indicating that it is generating energy through the fusion of helium at its core. It has 11 times the Sun's radius and about 2.15 times the mass of the Sun. Its luminosity is 57 times that of the Sun, and its surface has an effective temperature of 4,768 K. Pole star Iota Cephei is located within 5° of the Precession, precessional path traced across the celestial sphere by the Earth's North Pole, North pole. In about 3,000 years, it will be one of the closest visible stars to the celestial north pole, along with Alfirk whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pole Star
A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body. Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its northern axis that serves as a pre-eminent star in celestial navigation, and a much dimmer magnitude-5.5 star on its southern axis, Polaris Australis (Sigma Octantis). From around 1700 BC until just after 300 AD, Kochab (Beta Ursae Minoris) and Pherkad (Gamma Ursae Minoris) were twin northern pole stars, though neither was as close to the pole as Polaris is now. History In classical antiquity, Beta Ursae Minoris (Kochab) was closer to the celestial north pole than Alpha Ursae Minoris. While there was no naked-eye star close to the pole, the midpoint between Alpha and Beta Ursae Minoris was reasonably close to the pole, and it appears that the entire constellation of Ursa Minor, in antiquity known as '':wikt:Cynosura, Cynosura'' (Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deneb
Deneb () is a first-magnitude star in the constellation of Cygnus, the swan. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. It is the brightest star in Cygnus and the 19th brightest star in the night sky, with an average apparent magnitude of +1.25. A blue-white supergiant, Deneb rivals Rigel as the most luminous first-magnitude star. However, its distance, and hence luminosity, is poorly known; its luminosity is somewhere between 55,000 and 196,000 times that of the Sun. Its Bayer designation is α Cygni, which is Latinised to Alpha Cygni, abbreviated to Alpha Cyg or α Cyg. Nomenclature ''α Cygni'' (Latinised to ''Alpha Cygni'') is the star's designation given by Johann Bayer in 1603. The traditional name ''Deneb'' is derived from the Arabic word for "tail", from the phrase ذنب الدجاجة ''Dhanab al-Dajājah'', or "tail of the hen". The IAU Working Group on Star Names has recognised t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terrestrial planet with a thin atmosphere (less than 1% that of Earth's), and has a crust primarily composed of elements similar to Earth's crust, as well as a core made of iron and nickel. Mars has surface features such as impact craters, valleys, dunes and polar ice caps. It has two small and irregularly shaped moons, Phobos (moon), Phobos and Deimos (moon), Deimos. Some of the most notable surface features on Mars include Olympus Mons, the largest volcano and List of tallest mountains in the Solar System, highest known mountain in the Solar System and Valles Marineris, one of the largest canyons in the Solar System. The North Polar Basin (Mars), Borealis basin in the Northern Hemisphere covers approximately 40% of the planet and may be a la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polaris
Polaris is a star in the northern circumpolar constellation of Ursa Minor. It is designated α Ursae Minoris ( Latinized to ''Alpha Ursae Minoris'') and is commonly called the North Star or Pole Star. With an apparent magnitude that fluctuates around 1.98, it is the brightest star in the constellation and is readily visible to the naked eye at night. The position of the star lies less than 1° away from the north celestial pole, making it the current northern pole star. The stable position of the star in the Northern Sky makes it useful for navigation. As the closest Cepheid variable its distance is used as part of the cosmic distance ladder. The revised ''Hipparcos'' stellar parallax gives a distance to Polaris of about , while the successor mission ''Gaia'' gives a distance of about . Calculations by other methods vary widely. Although appearing to the naked eye as a single point of light, Polaris is a triple star system, composed of the primary, a yellow super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pole Star
A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body. Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its northern axis that serves as a pre-eminent star in celestial navigation, and a much dimmer magnitude-5.5 star on its southern axis, Polaris Australis (Sigma Octantis). From around 1700 BC until just after 300 AD, Kochab (Beta Ursae Minoris) and Pherkad (Gamma Ursae Minoris) were twin northern pole stars, though neither was as close to the pole as Polaris is now. History In classical antiquity, Beta Ursae Minoris (Kochab) was closer to the celestial north pole than Alpha Ursae Minoris. While there was no naked-eye star close to the pole, the midpoint between Alpha and Beta Ursae Minoris was reasonably close to the pole, and it appears that the entire constellation of Ursa Minor, in antiquity known as '':wikt:Cynosura, Cynosura'' (Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Magnetic North Pole. The North Pole is by definition the northernmost point on the Earth, lying antipodally to the South Pole. It defines geodetic latitude 90° North, as well as the direction of true north. At the North Pole all directions point south; all lines of longitude converge there, so its longitude can be defined as any degree value. No time zone has been assigned to the North Pole, so any time can be used as the local time. Along tight latitude circles, counterclockwise is east and clockwise is west. The North Pole is at the center of the Northern Hemisphere. The nearest land is usually said to be Kaffeklubben Island, off the northern coast of Greenland about away, though some perhaps semi-permanent gravel banks lie slightly clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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