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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Experience Sunset: James Turrell’s Skyspace at the Ringling Museum of Art

Imagine staring into a deep dark blue pool of calm water and getting lost in its depth.

Now imagine lying on your back on a floor of a museum and the ‘pool’ is the sky seen through a deftly designed 24-foot square ‘hole’ in the ceiling. Enter Skyspace and experience Joseph’s Coat by James Turrell at the Ringling Museum of Art in Sarasota, Florida.

Color photograph

James Turrell. Joseph’s Coat, 2011 © James Turrell, Photo by Giovanni Lunardi.

Turrell’s kinesthetic art is an invitation to experience energy in relation to light, sound, wind, and the canvas of a changing sky by quieting the mind and observing. Opening our senses and our consciousness to the world around and within us, while lying on a bench or the floor to experience the sky, allows and even encourages a transformation of one’s perception.

The brochure given at entry to the sunset experience states; “James Turrell wants you to be aware of your active participation in perception – and see yourself seeing.”

Entering the courtyard of Joseph’s Coat, a gallery lined with long wooden benches felt to me like any other indoor courtyard until I looked up. The ceiling thinned at the opening to the sky. If inverted it could be a sheer dropoff without ledge or dimension. The floor was a slightly inclined square with a perimeter of drains to carry rain away and which double as light tubes for the sunset show.

I placed my mat on the floor between benches and noticed the small-leafed vines that climbed the plaster walls forming elegant green pathways upward. The scent of jasmine vines wrapped around a pillar nearby enlivened the air and brought greenery to the sparse courtyard.

Turrell’s Skyspace draws us in just by looking up, and I found that it offered me a chance to pause, to listen, to feel and yes, to see. The experiential nature of his work including lying on one’s back and watching the sky change, especially brilliant at sunset, is a dance between an artist’s work and the viewer’s evocative experience: the powerful essence of art. There for an hour, relaxing on my mat, hearing my breath, I tried not to fidget. I became mesmerized watching the grey clouds pass over following a strong summer storm. A train whistle in the distance caught my attention, like a Tibetan gong just before meditation.

The post storm breezes moved the clouds quickly and constantly changed the sky as if lifting layer upon layer of veils to reveal finally, a blue sky. A bird, then another, darted through the air on a strong gust followed by a jet’s contrail that curiously, as if on tiptoe, entered the square and moved diagonally from upper right to lower left, thinly sketched as if with a fine-tipped brush, then slowly dissolved by the wind into a series of thick wavy lines. Soon the remaining thick grey clouds thinned to wisps, faded to lighter pink, then to salmon and coral and with the help of the LED lights subtly projected up from the floor and elsewhere I couldn’t discern, the walls changed color too.

Deep ocean – blue sky set in and from the deepest part of the pool, a star, then another glimmered at the edge of the ethereal canvas. Cream to green to red walls and deep dark sky descending. We were entering the night. Or, maybe the night was entering the dozen viewers on the floor and benches of the Skyspace.

“How is it,” I thought to myself, “That this dance is ongoing every millisecond of our lives, at night quietly swirling above us and around us as we work, love, play and sleep? Yet, we are not aware of it.”

The movement and realization of energy, of dynamic molecules, and the give and take of this seemingly innocuous hole to the sky gave me a chance to pause, to listen, to feel and breathe, and yes, to see.

Molecules and light beams, daylight and darkness, starlight and Self and Other. To stare into a pool of space within the dynamic nature of changing light, makes life art and all that is, the world beyond and within us, Art. Clearly, it is a glimpse of the ongoing creative process. I’m a relative newcomer to the art of Mr.Turrell but through my discovery, I am drawn back… or should I say, drawn in again and again.


One can experience Joseph’s Coat Skyspace every day that the Ringling Museum of Art is open and two nights each week for sunset viewing. Yoga mats are encouraged. Check with the museum for specific schedules and details.


By Pamela Erickson, GLIMPSE journal correspondent. Erickson is an author, artist and librarian who lives on the Florida Gulf Coast with her husband and pets. Having taught for over 30 years, she seeks writing as a form of reflection, exploration, conversation and solace. Her novel, Each Other, is available here.

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.”

NASA joins the 21st century by offering mobile apps

NASA's new app for the iPad

NASA's new app for the iPad

Funding in flux? Assert your agency’s  relevance by offering iPhone and iPad apps!

Don’t get us wrong… we love NASA. And we love apps. And the two, really, are a match made in the heavens.

Below are a few of the applications that the United States’ National Aeronautics and Space Administration has made available for free download:

The NASA App HD: From satellite tracking to live NASA TV, the app delivers an extensive selection of dynamically updated mission information, images, videos and Twitter feeds from NASA right on your iPad.

3D Sun for iPhone: A major solar flare erupts on the sun. Before long, your phone chirps in your pocket to let you know! Pulling out your phone, you see a 3D view of the sun — a digital reconstruction of satellite images freshly downloaded from NASA’s “STEREO” satellites.

Lunar Electric Rover Simulator App for iPhone:
You don’t need a driver’s license, but you still need to buckle up as the Simulator gives you a glimpse of what it might be like to support the activities of a functioning Lunar Outpost.

We suspect these tools were quickly ushered through the Apple App Store approval process…Now, to get iPads into the hands of every school-aged child so the wonders of the universe unfold at their touch…

View all of NASA’s iPhone and iPad apps at http://www.nasa.gov/connect/apps.html

Star light, star bright, Jupiter shines extra bright tonight…

The good people of Sky & Telescope report that tonight, Monday, September 20, Jupiter will be its brightest in quite some time. The planet is especially close to earth at a mere 368 million miles away.

…But it remains nearly this close and bright (magnitude -2.9) throughout the second half of September… Also, according to legendary planetary observer Richard Schmude, Jupiter is an additional 4% or so brighter than usual because one of its brown cloud belts has gone missing.

Happy 20th Birthday to the Hubble Space Telescope!

Today, Glimpse celebrates the Hubble Space Telescope’s 20 remarkable years in orbit! Check out our Cosmos issue, where we offer a reflection on the HST’s invaluable contributions to our knowledge of the Universe.

Image of the Omega Nebula captured by the Hubble Space Telescope. Courtesy of S. Beckwith (STScI), Hubble Heritage Team, (STScI/AURA), ESA, NASA.

What is your favorite Hubble image? Share your thoughts in the comments section!

Taking a step back…4 billion miles

We’re channeling Carl Sagan for this week’s “perspective check,” since it never hurts to take a step back once in a while.

Sagan reflects on the view of home from 4 billion miles away. This photo was captured in 1990 by Voyager I. Courtesy of NASA

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.