Pale Blue Dot

Pale Blue Dot

I am still thinking about the Astronomy lectures I have listened to over the past year.  The above image of the pale blue dot has stayed with me; that faint blue dot in the yellow streak is the Earth.

When people think of the Earth, they likely conjure the image taken from orbit—the beautiful blue marble on a jet black canvas.  That was the image I always had.  While it does show the Earth as a finite object, it is still a magnificent, awe-inspiring image.  At least to me, it does not call forth terms like fragile or insignificant.

In one of his lectures, Richard Pogge talks about the image you see at the top of this post.  The name typically given is the pale blue dot, coined by Carl Sagan.  Before powering down its camera equipment, Voyager 1 took this picture of Earth from 6 billion kilometers away; that is 40 times the distance between the Earth and the Sun.  It was so far away that it took the signal carrying the image 5 hours to reach the earth.  Our everyday experience with light is virtually instantaneous, but imagine someone sitting on Earth pressing a button to tell Voyager to snap a picture.  Five hours later Voyager would receive the request and take the picture.  However, the image it collects would not be of the earth 5 hours from when the request was sent, but from the actual time the request was sent.  The light from the Earth would arrive at the same time as the signal, so Voyager would be viewing the Earth as it was 5 hours in the past.  Another 5 hours later, for a total of 10 hours, the picture would finally appear on Earth.

After traversing these vast distances—while the may be vast to us, they are tiny in the cosmic sense—the image we see shows the earth as nothing but a speck of dust.  The streaks of color are artifacts caused by the glare of the sun.  This world that is so immense to us and encompasses everything we have ever known is just a speck in the infinite blackness of space.  To me, this may be the most amazing image I have ever seen.

A quote from Carl Sagan is commonly associated with this image.  You can view the entire quote on Wikipedia, but one line really resonates with me.

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.

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