Monday, August 1, 2016

Astronomy, astrology and astrophysics

Astronomy: definition
1. The scientific study of matter in outer space, especially the positions, dimensions, distribution, motion, composition, energy, and evolution of celestial bodies and phenomena. 2. A system of knowledge or beliefs about celestial phenomena: the various astronomies of ancient civilizations. 
The American Heritage® Dictionary of the English Language, Fourth Edition. © 2000. https://web.archive.org/web/20040811115723/http://www.bartleby.com/61/79/A0487900.html 

Astrology: definition 
1. The study of the positions and aspects of celestial bodies in the belief that they have an influence on the course of natural earthly occurrences and human affairs. 2. Obsolete 
Astronomy. The American Heritage® Dictionary of the English Language, Fourth Edition. © 2000. https://web.archive.org/web/20050125022403/http://www.bartleby.com/61/68/A0486800.html 

So what is the difference? 

  • Astrology is the ancient practice of using the locations of the planets to look into a person’s personality or predict the future. This is a totally non-scientific field that does not involve and use science. By contrast, astronomy is the scientific study of the universe. Astronomers observe the night sky to determine their origins and learn more about the origin and structure of the universe. 
  • Ancient astronomers practiced astrology.
Astrophysics: definition 
Application of the theories and methods of physics to the study of stellar structure, stellar evolution, the origin of the solar system, and related problems of cosmology. The distinction between astrophysics and modern astronomy is disappearing in scientific usage.
The Columbia Encyclopedia, Sixth Edition. © 2002 Columbia University Press https://web.archive.org/web/20050312114141/http://www.bartleby.com/65/as/astrophy.html 

What is astrophysics?

  • The same as astronomy but refers to the addition of the laws of physics by Isaac Newton 
  • Astrophysics assume that the terrestrial laws of physics hold throughout the universe
  • Astrophysics, therefore, is the application of the fundamental laws of nature to gain an understanding of the stars, galaxies, and the origin and fate of the cosmos
  • Astronomy is synonymous with astrophysics, they both refer to the same discipline 

Astronomy 

  • Astronomy is the science in which the entire universe is studied. It requires knowledge of several sciences, including physics, chemistry, geology, mathematics, engineering, computer science 
  • Professional astronomers today are more properly called astrophysicists, because they apply the laws of physics to celestial phenomenon in order to better understand them
  • Most professional astronomers work at colleges or universities, at government sponsored research centres or observatories or in private industry related to aerospace 
  • Much of the research work of modern astronomers done on computers
  • Professional astronomers encouraged to collaborate so can share observing time and resulting data
  • Astronomy an international science, often many nationalities on same team
  • With more complex instrumentation need to include technologists on teams 
  • Often regarded as the oldest science o Humans were making astronomical observations and keeping records as far back as recorded history
  • Provided basis for the calendar o Months and year determined by astronomical observations
  • Served in navigation, surveying and timekeeping 
Origins of astronomy – Time
  • The Sun, Moon and stars served humanity for thousands of years as a clock and a calendar. Their motions were predictable. 
  • Today we have other means of measuring time but long ago an accurate understanding of the skies could mean life or death 
  • Studying the skies told people when to plant and harvest, when to go out to sea, when to expect good or bad weather, etc.
Ancient astronomical site

  • Stonehenge, built in England c. 2100 BC
  • Alignment of some of the stones with the midsummer sunrise and midwinter sunset suggest Stonehenge used for seasonal astrological festivals 
Astronomy: a unique science

  • Cannot experiment directly
  • Must observe passively 
  • Must combine known facts with imagined possibilities
  • Astronomy is unique among the sciences in that we cannot walk to a nearby star and inspect it close up, take a sample of it, or probe its interior 
  • All astronomical observations are necessarily remote – far removed from the object of study
  • The only thing that astronomers can study is the light emitted by the object
  • Astrophysics, therefore, is really about the subject of radiation and how radiation interacts with matter
  • With the exception of experiments carried out in space by spacecraft, our knowledge of the universe comes from light reaching us from outer space
  • Because of the speed of light, we observe objects not the way they are, but the way they were when the light left them

Problems in identifying of celestial objects

  • Relative positions of objects in the universe are not fixed 
  • Sky looks different if observed in different wavelength ranges
    • Infrared
    • Visible
    • Radio 
  • What you “see” depends on the type and sensitivity of tool used
    • The more sensitive the tool, the more crowded the sky 

Astronomy 

  • Draws on sciences such as 
    • Mathematics 
    • Physics 
    • Chemistry
    • Geology
    • Atmospheric sciences 
    • Biology
  • Draws on technical disciplines such as 
    • Optics 
    • Mechanics 
    • Electronics 
    • Remote sensing 
    • Data analysis
  • Astronomy is a visual science 
  • Hubble Space Telescope Public Pictures http://opposite.stsci.edu/gallery/
  • The Gateway to Astronaut Photography of the Earth http://eol.jsc.nasa.gov/SearchPhotos/ 
  • Able to attract the interest of a wide spectrum of people, especially the young 
  • Popular literature readily available 
  • Planetaria offer shows for public 
Many aspects
  • Ability to see into the future sets astronomy apart 
    • Eclipses
    • Meteor showers 
    • Comets 
  • Religious aspects
  • Pseudoscience aspects
  • Space related science fiction
    • Print and AV (movies, cartoons, tv series) 
Public interest 

  • Public interest in astronomy high 
    • Hobbyists 
    • “Hollywood”
    • Popular press
      • Hubble telescope
      • Comets
      • Meteors
      • Planets
      • Space travel
      • UFOs 
  • Compulsory in some provincial school curricula 
  • Level of scientific literacy low 
Amateur astronomers 
  • Armchair amateur 
    • Generally a passive interest, e.g. reading magazines, attending lectures, viewing programmes, etc. 
  • Active amateur 
    • Observe, often with own instruments (can contribute to professional astronomy) 
  • Worldwide, amateur astronomers greatly outnumber professionals 
Astronomy in schools 
  • Compulsory units in many science curricula
  • Manitoba Grade 6: The Solar System 
    • Students develop an understanding of the Earth in space, the solar system, and the role of space research programs in increasing scientific knowledge
  • Manitoba Senior 1: Exploration of the Universe 
    • Leads students through an exploration of the universe starting with some basic hands-on astronomy and ending with a critical look at issues surrounding space science and technology. Students observe and locate visible celestial objects. 
Popular topics 
Public/media interest themes 
  • Extrasolar planets
    • Are we alone in the universe? 
  • Near-Earth objects? 
    • Could Earth be annihilated? 
  • Spectacular visible events 
    • Solar eclipses; bright comets 
Societies 
  • Royal Astronomical Society of Canada (1903) http://www.rasc.ca/ 
    • Amateurs and professionals 
      • >4,500 members 
  • Canadian Astronomical Society (1970) http://www.casca.ca/ 
    • Professional astronomers 
    • 452 members in August 2004 
Heck, A. “Information Handling in Astronomy.” High Energy Physics Libraries Webzine. Issue 3. March 2001. https://web.archive.org/web/20070806091657im_/http://library.cern.ch/HEPLW/3/papers/2/flow.gif

Literature of astronomy 
  • Astronomy literature in forefront of using computer-based tools and systems
  • Conferences especially important in some fields
  • High reliance on star catalogues
  • Research published in refereed journals makes up almost 80% of cited material
  • Nearly 56% of all references to materials published in last seven years (1998-2005)

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