“Look again that dot. It’s here. It’s home. It’s us. (…) On it, (…) Every human being who has ever existed has lived his own life”. With these words, the famous astronomer and popularizer Carl Sagan celebrated theiconic photography of the earthknown as Pale Blue Dot (“pale blue dot” in Italian). After 35 years, this image continues to hold the Record of more distant photos ever taken of the planet Earth. The photo was taken in fact the February 14, 1990 from the probe Voyager 1once the NASA Voyager program had finished exploration of the giant planets of the external solar system: Jupiter, Saturn, Uranus and Neptune. In this historical and spectacular image on the ground appears as a small dotdue to the enormous distance of the probe from our planet, approximately 6 billion km beyond the orbit of Neptune, while his blue color reflects the vast ocean expanses that cover a large part of the surface of our planet. A inspirational vision If we think that we are all alone passengers They dart on board a small globe immersed in the immensity of the space, the only place known to us capable of hosting forms of life.
How and when the photo was taken
The Pale Blue Dot He was taken from the probe Voyager 1 The February 14, 1990. The voyager probes were launched in the late 70s with the aim of exploring the planets of the external solar system for the first time in history, namely Jupiter, Saturn, Uranus and Neptune (the last two had never been approached before by one space probe). Voyager 1 reached Jupiter in March 1979 and Saturn in November 1980, while the Voyager 2 probe, in addition to exploring Jupiter and Saturn in 1979 and 1981, succeeded in the objective of extending its exploration mission to Uranus in January 1986 and Neptune in 1989.
The Voyager 1 probe, after the close encounter with Saturn and its moon Titan, entered an orbit that brought it out of the plane of the ecliptic (the plan where the planets of the Solar System orbit) towards the interstellar spacewhich reached in 2012 (It was the first space probe that came out of the Solar System). Voyager 1 is currently theobject built by man furthest from the earth: recently has reached a distance of 25 billion km from our planet, so vast that even light (the fastest physical entity ever) it takes almost one day To cover it.
The idea of taking a photo of the earth from the boundaries of the Solar System came to the astronomer and popularizer Carl Saganwho suggested to NASA to create a sort of “Family portrait” of the planets of the Solar System seen from billions of km away. Between the February 14 and June 6, 1990the NASA probe took a photo (above) of every planet visible at that moment from the position of the probe, namely Venus, Terra, Jupiter, Saturn, Uranus and Neptune (Mercury and Mars were not visible from the position of the probe).
The photo to the earth was taken when the probe was 32 ° on the level of the ecliptic at 6.05 billion km from the earth. There band in which the earth seems immersed in the cover photo is due to Solar rays reflected in the room that made the image. In this photo, the earth appears as a soft blue dot big one 0.12 pixels.
The importance of Pale Blue Dot
The image of the earth taken by Voyager 1 inspired the title of one of Carl Sagan’s most famous books, Pale Blue Dot: A Vision of the Human Future in Space. In the text, the American astronomer reflects deeply on the cultural meaning of that vision. Earth appears as a small and fragile blue dotlonely in the immensity of space, one cosmic house Where every human being who has ever existed has experienced his entire existence. The author invites us to reflect on the fact that that blue dot represents theThe only place known to us in the universe able to support life. It is therefore our duty preserve itso long as There is no planet B Where humanity can take refuge and in all the vastness of the cosmos there is no trace that help can come somewhere else to save ourselves.
But Sagan’s reflections are not limited to environmentalism. In his book we also find a profound Message of peace and universal brotherhood:
Think of the rivers of blood poured by all those generals and emperors so that, in glory and triumph, they could become for a moment of a fraction of a dot. Think of the endless cruelty inflicted by the inhabitants of a corner of this pixel to the poorly distinguishable inhabitants of some other corner, how frequent the misunderstandings, how much the eager to kill each other, as fervent their hatred. Our ostentations, our imaginary self -esteem, the illusion that we have some privileged position in the universe, are questioned from this point of pale light.
