The Pale Blue Dot

by Nicholas Mee on March 7, 2018

The Earth appears as a tiny dot in a beam of sunlight reflected from Voyager’s sunshade. Credit: NASA/JPL.

Voyager I was launched by NASA in September 1977, on course for the outer solar system and beyond. Carl Sagan realised the mission was an opportunity to highlight the immensity of the cosmos and acquire a new perspective on our place within it. After some persuasion, NASA agreed and in 1990 Voyager’s cameras were directed homewards for a final glimpse of our blue planet. In the resulting Pale Blue Dot photograph, the entire Earth occupies a mere fraction of a pixel.

Sagan presented the image in a talk at Cornell University:

We succeeded in taking that picture, and, if you look at it, you see a dot. That’s here. That’s home. That’s us. On it, everyone you ever heard of, every human being who ever lived, lived out their lives. The aggregate of all our joys and sufferings, thousands of confident religions, ideologies and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilizations, every king and peasant, every young couple in love, every hopeful child, every mother and father, every 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.

He concluded:

To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we’ve ever known.

Zooming In

Thirty years on and David Nadlinger from the University of Oxford has given us another new perspective on our place in the universe at the opposite end of the distance scale.

Single Atom in an Ion Trap by David Nadlinger.

Nadlinger’s image shows a single atom of strontium suspended between two needle tips that are two millimetres apart. The atom, which has been ionized by the removal of one of its electrons, is held almost motionless by electric fields emanating from the surrounding metal electrodes. The atom is bathed in blue laser light of just the right frequency to excite an electron. The electron absorbs a photon, hops to a higher energy level, then immediately falls back down emitting another blue photon. This absorption and emission of photons occurs incredibly quickly and continues for as long as the laser illuminates the atom. The picture is a long exposure photograph taken with an ordinary camera through a window of the ultra-high vacuum chamber that houses the ion trap.

It is not see easy to identify the atom in the low resolution image above, so the image below shows the crucial part of the photograph between the needle tips.

The strontium atom is much clearer after zooming in.

Nadlinger described how he produced the image:

The idea of being able to see a single atom with the naked eye had struck me as a wonderfully direct and visceral bridge between the minuscule quantum world and our macroscopic reality. A back-of-the-envelope calculation showed the numbers to be on my side, and when I set off to the lab with camera and tripods one quiet Sunday afternoon, I was rewarded with this particular picture of a small, pale blue dot.

Nadlinger’s remarkable photograph has won the overall prize in a science photography competition, organised by the UK’s Engineering and Physical Sciences Research Council (EPSRC).

A video version of this post is now available here: The Pale Blue Dot on The Cosmic Mystery Tour YouTube Channel. Please don’t forget to click the subscribe button.


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