Galileo’s illusion solved by New York vision researchers

Portrait of Galileo Galilei, 1605-1607, by Domenico Tintoretto. Image courtesy of Wikimedia Foundation.

Portrait of Galileo Galilei, 1605-1607, by Domenico Tintoretto. Image courtesy of Wikimedia Foundation.

It was 1632, and the father of modern astronomy was perplexed as to why Venus, when observed by “naked” eye, would appear substantially larger than Jupiter, which was actually four times larger than Venus. He knew that Venus’ exaggerated size must have something to do with it’s halo, or “radiant crown” as he described it, and that this halo must have something to do with his eyes, and not the celestial objects themselves. Observations via telescope presented a more accurate visual representation of the mathematically-verifiable proportions of the planets.

Almost 400 years later, Neuroscientists Susana Martinez-Conde and Stephen L. Macknik, eloquently explain the January 2014 published findings of the State University of New York’s vision researchers Jens Kremkow, Jose Manuel Alonso and Qasim Zaidi:

By examining the responses of neurons in the visual system of the brain—to both light stimuli and dark stimuli—the neuroscientists discovered that, whereas dark stimuli result in a faithful neural response that accurately represents their size, light stimuli on the contrary result in non-linear and exaggerated responses that make the stimulus look larger. So white spots on a black background look bigger than same-sized black spots on white background, and Galileo’s glowing moons are not really as big as they might appear to the unaided eye.

These now-isolated differences in how our photoreceptors operate also explain why it is easier to read black text on a white page, than to read white text on a black page, a topic of interest to our typographer and font designer friends.

Do you love Galileo as much as we do? Check out the GLIMPSE Cosmos issue, available in our archives.


GLIMPSE journal is an interdisciplinary supercollider of works that examine the functions, processes, and effects of vision and its implications for being, knowing, and constructing our world(s). Each theme-focused issue features articles, visual essays, interviews, and reviews spanning the physical sciences, social sciences, arts and humanities. GLIMPSE contributors are leading and emerging scholars, researchers, scientists and artists from around the world. Some of our contributors are independent thinkers and doers with no formal institutional affiliations, and others are affiliated with the most respected research institutions in the world. Read all about them.

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Suomi Perspective-Check: Hi-Def View of Our Little Earth

Hi-Definition Composite Satellite Photograph of Earth, January 2012

Hi-Definition Composite Satellite Photograph of Earth, January 2012. Image Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

(via NASA.gov, 1/25/2012)  “A ‘Blue Marble’ image of the Earth taken from the VIIRS instrument aboard NASA’s most recently launched Earth-observing satellite – Suomi NPP. This composite image uses a number of swaths of the Earth’s surface taken on January 4, 2012. The NPP satellite was renamed ‘Suomi NPP’ on January 24, 2012 to honor the late Verner E. Suomi of the University of Wisconsin.

Suomi NPP is NASA’s next Earth-observing research satellite. It is the first of a new generation of satellites that will observe many facets of our changing Earth. Suomi NPP is carrying five instruments on board. The biggest and most important instrument is The Visible/Infrared Imager Radiometer Suite or VIIRS.”

The Ever More Accessible Space Oddity

Image courtesy of flickr.com member Tim Fields

While the never-ending slew of new technology that bombards us everyday can sometimes feel overwhelming, complicated, and unnecessary, every so often a product comes along that we at GLIMPSE simply love. Take for example, the SkyProdigy, a point-and-shoot telescope.

SkyProdigy is for people who would love to gaze at the stars but are hesitant to even touch a telescope for fear of breaking something very expensive. You just have to point it towards the sky, push a button, and voila! An incredible view of the moon or the North Star is at your fingertips.

While SkyProdigy doesn’t come out until July, it’s great that astronomy is being made more accessible. Citizen astronomers will love that they can now capture the stunning views their telescopes provide on their iPhones thanks to the ingenuity of the Magnilux Adapter. It seems it’s never been easier to add ‘amateur astronomer’ to your title.