Pale Blue Dot

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For Carl Sagan's book related to this photograph, see Pale Blue Dot (book).
For the ambient album by American musician Benn Jordan, see Pale Blue Dot (album).
Seen from 6 billion kilometres (3.7 billion miles), Earth is a dot obscured in a beam of sunlight. Full image.

The Pale Blue Dot is a photograph of planet Earth taken in 1990 by Voyager 1 from a record distance, showing it against the vastness of space. Both the idea for taking the distant photo and the title came from scientist and astronomer Carl Sagan, who also wrote the 1994 book of the same name.[1] In 2001, it was selected by Space.com as one of the top ten space science photos.[2]

Contents

[edit] The photograph

Voyager 1 was launched on September 5, 1977. Sagan had pushed for Voyager to take a photo of the Earth when its vantage point reached the edge of the solar system.[3][4][5] [6] On February 14, 1990, having completed its primary mission, NASA commanded the spacecraft to turn around to photograph the planets of the Solar System.[7][8][5][6] Between February 14, 1990 and June 6, 1990, one image Voyager returned was of Earth, showing up as a "pale blue dot" in the grainy photo.[3][9] [10]

Approximate location of Voyager 1 while taking the photograph is shown in green

Sagan gives the distance as 3.7 billion miles in his book. According to NASA's Jet Propulsion Laboratory HORIZONS software system,[11] the following table displays the distances calculated from Voyager to the Earth on the dates indicated.

Distance of the Voyager 1 Spacecraft from Earth
Unit of Measurement February 14, 1990 June 9, 1990
Astronomical Units 40.4722269111071 40.6835761263791
Converted to Kilometres 6,054,558,968.024 6,086,176,360.601
Converted to Miles 3,762,136,324.748 3,781,782,502.403

The picture was taken using a narrow-angle camera at 32° above the ecliptic, and created using blue, green, and violet filters.[12] Narrow-angle cameras, as opposed to wide-angle cameras, are equipped to photograph specific details in an area of interest.[13] The light band over Earth is an artifact of sunlight scattering in the camera's optics, resulting from the small angle between Earth and the Sun.[9][6] Earth takes up less than a single pixel — NASA says "only 0.12 pixel in size."[12]

The "family portrait" of the Solar system taken by Voyager 1

Voyager took similar pictures of Venus, Jupiter, Saturn, Uranus and Neptune, creating a portrait of the Solar System.[12] Mercury's proximity to the Sun prevented it from being photographed and Mars was not visible due to the effect of sunlight on the camera's optics.[14] NASA compiled 60 images produced into a mosaic, called the Family Portrait.

[edit] Reflections by Sagan

In his book, Pale Blue Dot, Sagan wrote:[15]

“ "While almost everyone is taught that the Earth is a sphere with all of us somehow glued to it by gravity, the reality of our circumstance did not really begin to sink in until the famous frame-filling Apollo photograph of the whole Earth — the one taken by the Apollo 17 astronauts on the last journey of humans to the Moon." ”

In a commencement address delivered May 11, 1996, Sagan related his thoughts on the deeper meaning of the photograph:[16][5]

“ Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

 ”

[edit] Use in media

Al Gore's 2006 documentary film An Inconvenient Truth featured the "Pale Blue Dot" photo at the end. Gore used it in a slide show to underline his belief that global warming is a serious problem,[17] paraphrasing Carl Sagan with the statement, "That's all we've got".

[edit] See also

[edit] References

  1. ^ Sagan, Carl (1994). Pale Blue Dot: A Vision of the Human Future in Space (1st edition ed.). New York: Random House. ISBN 0-679-43841-6. 
  2. ^ Britt, Robert Roy (25 September 2001). "Experts Pick: Top 10 Space Science Photos". Space.com. http://www.space.com/scienceastronomy/astronomy/top10_images_010925-11.html. 
  3. ^ a b Sagan. "Chapter 1. You Are Here". Pale Blue Dot. http://www.planetary.org/explore/topics/space_missions/voyager/pale_blue_dot.html.  The quote is much copied elsewhere on the web.
  4. ^ Sagan, Carl; Freeman J. Dyson, Jerome Agel (2000). Carl Sagan's Cosmic Connection: An Extraterrestrial Perspective. Cambridge University Press. p. XV. ISBN 0521783038, 9780521783033. 
  5. ^ a b c Bennett, Jeffrey O. (2008). Beyond UFOs: The Search for Extraterrestrial Life and Its Astonishing Implications for Our Future. Princeton University Press. p. 181-183. ISBN 691135495, 9780691135496. 
  6. ^ a b c Von Baeyer, Hans Christian (2000). Taming the Atom: The Emergence of the Visible Microworld. Courier Dover Publications. p. Xxi. ISBN 0486414477, 9780486414478. 
  7. ^ "Pale Blue Dot". The Planetary Society. https://planetary.org/bluedot_poster.html. Retrieved on 2006-07-27. 
  8. ^ Cockell, Charles (2003). Impossible Extinction: Natural Catastrophes and the Supremacy of the Microbial World. Cambridge University Press. p. 24. ISBN 0521817366, 9780521817363. 
  9. ^ a b Gonzalez, Guillermo; Jay Wesley Richards (2004). The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery. Regnery Publishing. p. X,224. ISBN 0895260654, 9780895260659. 
  10. ^ Visible Earth: A catalog of NASA images and animations of our home planet. Retrieved 2009-02-28
  11. ^ NASA's JPL Horizon System for calculating ephemerides for solar system bodies
  12. ^ a b c "Solar System Portrait – Earth as 'Pale Blue Dot'". NASA. http://visibleearth.nasa.gov/view_rec.php?vev1id=1947. 
  13. ^ "SPACECRAFT - Cassini Orbiter Instruments - ISS". NASA. http://saturn.jpl.nasa.gov/spacecraft/instruments-cassini-iss.cfm. 
  14. ^ "Solar System Portrait – Views of 6 Planets". NASA. http://visibleearth.nasa.gov/view_rec.php?id=600. 
  15. ^ The Pale Blue Dot, Chapter 1, end of the fifth paragraph
  16. ^ "Reflections on a Mote of Dust". https://planetary.org/bluedot_poster.html. Retrieved on 2007-04-07. 
  17. ^ Gore, Al (January 15, 2004). "Al Gore Speaks on Global Warming and the Environment". MoveOn.org. http://civic.moveon.org/gore3/speech.html. Retrieved on 2006-12-18. 

[edit] External links

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