Also (sticking to the space theme here) - SpaceX sends a supercomputer and lots more science experiments to space station.


Sunlight damages the eye in two distinct ways

Exposing your naked eye-ball to sunlight causes solar retinopathy (aka photic retinopathy or solar retinitis), which involves two types of damage to the retina, particularly the fovea: burns and photochemical toxicity.

The former may be the most easily understood. A big chunk of sunlight is near-infrared radiation (700 to 1,500 nanometers), which can cause heat and thus burns, Calkins and Sternberg note. Because our eyes lack pain receptors, we can scorch the fovea without even noticing as we gaze at the Sun.

But, the eye experts write, a "more pressing concern" is photochemical toxicity. The large wallop of visible light from the Sun gets soaked up by photoactive materials in the eye that are just itching to form free radicals and reactive oxygen species. These include heme proteins, melanosomes, lipofuscin, and other chemicals. Once generated, free radicals and reactive oxygen species can attack many types of molecules and break down membranes, leading to tissue damage and cell death. Once retina tissue is destroyed, it cannot regenerate.

The authors say that a study of 45 people who damaged their eyes during a 1999 eclipse in the UK supports the idea that photochemical toxicity is a frequent cause of vision damage in solar retinopathy. In those cases, most of the damage was not permanent. Only four of the 45 reported lingering symptoms—discomfort and vision problems—after seven months.

But, of course, irreversible damage is more likely with longer and larger exposures. A case report published by Ta C. Chang and Kara Cavuoto of the University of Miami’s Bascom Palmer Eye Institute detailed lasting injuries in a 12-year-old girl. She suffered severe vision damage after staring at the full Sun for about one full minute. The eye experts presented images of her damaged retina, one of which was obtained by optical coherence tomography (OCT), which is kind of like an ultrasound for the eye that uses light to create cross-sectional tissue images. The images show bright pitted spots (see white arrows) in her fovea where photoreceptor segments have been wiped out by Sun damage. On follow-up exams, her vision hadn’t gotten better.