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Astronomy
For other uses, see Astronomy (disambiguation).
A giant Hubble mosaic of the Crab Nebula, a supernova remnant
A giant Hubble mosaic of the Crab Nebula, a supernova remnant
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Astronomy is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.

Astronomy is one of the oldest sciences. Astronomers of early civilizations performed methodical observations of the night sky, and astronomical artifacts have been found from much earlier periods. However, the invention of the telescope was required before astronomy was able to develop into a modern science. Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, and even astrology, but professional astronomy is nowadays often considered to be synonymous with astrophysics. Since the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring and analyzing data, mainly using basic principles of physics. Theoretical astronomy is oriented towards the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the observational results, and observations being used to confirm theoretical results.

Amateur astronomers have contributed to many important astronomical discoveries, and astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery and observation of transient phenomena.

Old or even ancient astronomy is not to be confused with astrology, the belief system that claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin and a part of their methods (namely, the use of ephemerides), they are distinct.[1]

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Lexicology

The word astronomy literally means "law of the stars" (or "culture of the stars" depending on the translation) and is derived from the Greek αστρονομία, astronomia, from the words άστρον (astron, "star") and νόμος (nomos, "laws or cultures").

Use of terms "astronomy" and "astrophysics"

Generally, either the term "astronomy" or "astrophysics" may be used to refer to this subject.[2][3][4] Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the earth's atmosphere and of their physical and chemical properties"[5]and "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, and dynamic processes of celestial objects and phenomena".[6] In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject.[7] However, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics.[2] Various departments that research this subject may use "astronomy" and "astrophysics", partly depending on whether the department is historically affiliated with a physics department,[3] and many professional astronomers actually have physics degrees.[4] Even the name of the scientific journal Astronomy & Astrophysics reveals the ambiguity of the use of the term.

History

  • Stellar nucleosynthesis
  • Big Bang nucleosynthesis
  • Supernova nucleosynthesis
  • Cosmic ray spallation
    		•
    Related topics

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    Theoretical astronomers use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[21][22]

    Theorists in astronomy endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.

    Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

    Topics studied by theoretical astronomers include: stellar dynamics and evolution; galaxy formation; large-scale structure of matter in the Universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

    Some widely accepted and studied theories and models in astronomy, now included in the Lambda-CDM model are the Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics.

    A few examples of this process:

    Physical process Experimental tool Theoretical model Explains/predicts
    Gravitation Radio telescopes Self-gravitating system Emergence of a star system
    Nuclear fusion Spectroscopy Stellar evolution How the stars shine and how metals formed
    The Big Bang Hubble Space Telescope, COBE Expanding universe Age of the Universe
    Quantum fluctuations Cosmic inflation Flatness problem
    Gravitational collapse X-ray astronomy General relativity Black holes at the center of Andromeda galaxy
    CNO cycle in stars

    Dark matter and dark energy are the current leading topics in astronomy, as their discovery and controversy originated during the study of the galaxies.

    Subfield of astronomy for specific astronomical objects

    Solar astronomy

  • Astrobiology: the study of the advent and evolution of biological systems in the universe.
  • Archaeoastronomy: the study of ancient or traditional astronomies in their cultural context, utilizing archaeological and anthropological evidence.
  • Astrochemistry: the study of the chemicals found in space, usually in molecular clouds, and their formation, interaction and destruction. It represents an overlap of the disciplines of astronomy and chemistry.
  • Cosmochemistry: the study of the chemicals found within the Solar System, including the origins of the elements and variations in the isotope ratios.

    • Amateur astronomy

  • What is the origin of the stellar mass spectrum? That is, why do astronomers observe the same distribution of stellar masses—the initial mass function—apparently regardless of the initial conditions?[51] A deeper understanding of the formation of stars and planets is needed.
  • Is there other life in the Universe? Especially, is there other intelligent life? If so, what is the explanation for the Fermi paradox? The existence of life elsewhere has important scientific and philosophical implications.[52][53]
  • What is the nature of dark matter and dark energy? These dominate the evolution and fate of the cosmos, yet we are still uncertain about their true natures.[54]
  • Why did the universe come to be? Why, for example, are the physical constants so finely tuned that they permit the existence of life? Could they be the result of cosmological natural selection? What caused the cosmic inflation that produced our homogeneous universe?[55]
  • What will be the ultimate fate of the universe?[56]

    • See also

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    Lists

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    References

    1. ^ Albrecht Unsöld; Bodo Baschek, W.D. Brewer (translator) (2001). The New Cosmos: An Introduction to Astronomy and Astrophysics. Berlin, New York: Springer. . 
    2. ^ a b B. Scharringhausen. [http://curious.astro.cornell.edu/question.php?number=30 Curions About Astronomy: What is the difference between astronomy and astrophysics?]. Retrieved on 2007-06-20.
    3. ^ a b S. Odenwald. Archive of Astronomy Questions and Answers: What is the difference between astronomy and astrophysics?. Retrieved on 2007-06-20.
    4. ^ a b Penn State Erie-School of Science-Astronomy and Astrophysics. Retrieved on 2007-06-20.
    5. ^ Merriam-Webster Online. Results for "astronomy".. Retrieved on 2007-06-20.
    6. ^ Merriam-Webster Online. Results for "astrophysics".. Retrieved on 2007-06-20.
    7. ^ a b c F. H. Shu (1982). The Physical Universe. Mill Valley, California: University Science Books. . 
    8. ^ George Forbes (1909). History of Astronomy (Free e-book from Project Gutenberg), London: Watts & Co.. 
    9. ^ Eclipses and the Saros NASA. Retrieved on 2007-10-28.
    10. ^ Hipparchus of Rhodes School of Mathematics and Statistics, University of St Andrews, Scotland. Retrieved on 2007-10-28.
    11. ^ a b Arthur Berry (1961). A Short History of Astronomy From Earliest Times Through the Nineteenth Century. New York: Dover Publications, Inc.. 
    12. ^ (1999) in Michael Hoskin: The Cambridge Concise History of Astronomy. Cambridge University Press. . 
    13. ^ Electromagnetic Spectrum. NASA. Retrieved on 2006-09-08.
    14. ^ a b c d e f g h i j k l m n A. N. Cox, editor (2000). Allen's Astrophysical Quantities. New York: Springer-Verlag. . 
    15. ^ a b P. Moore (1997). Philip's Atlas of the Universe. Great Britain: George Philis Limited. . 
    16. ^ Penston, Margaret J. (2002-08-14). The electromagnetic spectrum. Particle Physics and Astronomy Research Council. Retrieved on 2006-08-17.
    17. ^ G. A. Tammann, F. K. Thielemann, D. Trautmann (2003). Opening new windows in observing the Universe. Europhysics News. Retrieved on 2006-08-22.
    18. ^ Calvert, James B. (2003-03-28). Celestial Mechanics. University of Denver. Retrieved on 2006-08-21.
    19. ^ Hall of Precision Astrometry. University of Virginia Department of Astronomy. Retrieved on 2006-08-10.
    20. ^ Wolszczan, A.; Frail, D. A. (1992). "A planetary system around the millisecond pulsar PSR1257+12". Nature 355: 145 – 147. 
    21. ^ H. Roth, A Slowly Contracting or Expanding Fluid Sphere and its Stability, Phys. Rev. (39, p;525–529, 1932)
    22. ^ A.S. Eddington, Internal Constitution of the Stars
    23. ^ a b Johansson, Sverker (2003-07-27). The Solar FAQ. Talk.Origins Archive. Retrieved on 2006-08-11.
    24. ^ Lerner & K. Lee Lerner, Brenda Wilmoth (2006). Environmental issues : essential primary sources.". Thomson Gale. Retrieved on 2006-09-11.
    25. ^ Pogge, Richard W. (1997). The Once & Future Sun (lecture notes). New Vistas in Astronomy. Retrieved on 2005-12-07.
    26. ^ D. P. Stern, M. Peredo (2004-09-28). The Exploration of the Earth's Magnetosphere. NASA. Retrieved on 2006-08-22.
    27. ^ J. F. Bell III, B. A. Campbell, M. S. Robinson (2004). Remote Sensing for the Earth Sciences: Manual of Remote Sensing, 3rd, John Wiley & Sons. Retrieved on 2006-08-23. 
    28. ^ E. Grayzeck, D. R. Williams (2006-05-11). Lunar and Planetary Science. NASA. Retrieved on 2006-08-21.
    29. ^ Roberge, Aki (1997-05-05). Planetary Formation and Our Solar System. Carnegie Institute of Washington—Department of Terrestrial Magnetism. Retrieved on 2006-08-11.
    30. ^ Roberge, Aki (1998-04-21). The Planets After Formation. Department of Terrestrial Magnetism. Retrieved on 2006-08-23.
    31. ^ (1999) in J.K. Beatty, C.C. Petersen, A. Chaikin: The New Solar System, 4th, Cambridge press. . 
    32. ^ Stellar Evolution & Death. NASA Observatorium. Retrieved on 2006-06-08.
    33. ^ (1994) in Jean Audouze, Guy Israel: The Cambridge Atlas of Astronomy, 3rd, Cambridge University Press. . 
    34. ^ Ott, Thomas (2006-08-24). The Galactic Centre. Max-Planck-Institut für extraterrestrische Physik. Retrieved on 2006-09-08.
    35. ^ Faulkner, Danny R. (1993). "The Role Of Stellar Population Types In The Discussion Of Stellar Evolution". CRS Quarterly 30 (1): 174-180. Retrieved on 2006-09-08. 
    36. ^ Hanes, Dave (2006-08-24). Star Formation; The Interstellar Medium. Queen's University. Retrieved on 2006-09-08.
    37. ^ Van den Bergh, Sidney (1999). "The Early History of Dark Matter". Publications of the Astronomy Society of the Pacific 111: 657-660. 
    38. ^ Keel, Bill (2006-08-01). Galaxy Classification. University of Alabama. Retrieved on 2006-09-08.
    39. ^ Active Galaxies and Quasars. NASA. Retrieved on 2006-09-08.
    40. ^ Zeilik, Michael (2002). Astronomy: The Evolving Universe, 8th, Wiley. . 
    41. ^ Hinshaw, Gary (2006-07-13). Cosmology 101: The Study of the Universe. NASA WMAP. Retrieved on 2006-08-10.
    42. ^ Galaxy Clusters and Large-Scale Structure. University of Cambridge. Retrieved on 2006-09-08.
    43. ^ Preuss, Paul. Dark Energy Fills the Cosmos. U.S. Department of Energy, Berkeley Lab. Retrieved on 2006-09-08.
    44. ^ The Americal Meteor Society. Retrieved on 2006-08-24.
    45. ^ Lodriguss, Jerry. Catching the Light: Astrophotography. Retrieved on 2006-08-24.
    46. ^ F. Ghigo (2006-02-07). Karl Jansky and the Discovery of Cosmic Radio Waves. National Radio Astronomy Observatory. Retrieved on 2006-08-24.
    47. ^ Cambridge Amateur Radio Astronomers. Retrieved on 2006-08-24.
    48. ^ The International Occultation Timing Association. Retrieved on 2006-08-24.
    49. ^ Edgar Wilson Award. Harvard-Smithsonian Center for Astrophysics. Retrieved on 2006-08-24.
    50. ^ American Association of Variable Star Observers. AAVSO. Retrieved on 2006-08-24.
    51. ^ Kroupa, Pavel (2002). "The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems". Science 295 (5552): 82-91. Retrieved on 2007-05-28. 
    52. ^ Complex Life Elsewhere in the Universe?. Astrobiology Magazine. Retrieved on 2006-08-12.
    53. ^ The Quest for Extraterrestrial Intelligence. Cosmic Search Magazine. Retrieved on 2006-08-12.
    54. ^ 11 Physics Questions for the New Century. Pacific Northwest National Laboratory. Retrieved on 2006-08-12.
    55. ^ Was the Universe Designed?. Counterbalance Meta Library. Retrieved on 2006-08-12.
    56. ^ Hinshaw, Gary (December 15, 2005). What is the Ultimate Fate of the Universe?. NASA WMAP. Retrieved on 2007-05-28.

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