The astronomical unit is a unit of length defined to be exactly equal to 149,597,870,700 m. Historically, the astronomical unit was conceived as the average Earth-Sun distance, before its modern redefinition in 2012.
Glasses, also known as eyeglasses and spectacles, are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms, known as temples or temple pieces, that rest over the ears.
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, modern astrophotography has the ability to image objects outside of the visible spectrum of the human eye such as dim stars, nebulae, and galaxies. This is accomplished through long time exposure as both film and digital cameras can accumulate and sum photons over long periods of time or using specialized optical filters which limit the photons to a certain wavelength.
Sunglasses or sun glasses are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes. They can sometimes also function as a visual aid, as variously termed spectacles or glasses exist, featuring lenses that are colored, polarized or darkened. In the early 20th century, they were also known as sun cheaters.
Ray-Ban is a brand of luxury sunglasses and eyeglasses created in 1936 by Bausch & Lomb. The brand is best known for its Wayfarer and Aviator lines of sunglasses. In 1999, Bausch & Lomb sold the brand to Italian eyewear conglomerate Luxottica Group for a reported $640 million.
The Baily's beads, diamond ring or more rarely double diamond ring effects, are features of total and annular solar eclipses. Although caused by the same phenomenon, they are distinct events during these types of solar eclipses. As the Moon covers the Sun during a solar eclipse, the rugged topography of the lunar limb allows beads of sunlight to shine through in some places while not in others. They are named for Francis Baily, who explained the effects in 1836. The diamond ring effects are seen when only one or two beads are left, appearing as shining "diamonds" set in a bright ring around the lunar silhouette.
A 3D display is a display device capable of conveying depth to the viewer. Many 3D displays are stereoscopic displays, which produce a basic 3D effect by means of stereopsis, but can cause eye strain and visual fatigue. Newer 3D displays such as holographic and light field displays produce a more realistic 3D effect by combining stereopsis and accurate focal length for the displayed content. Newer 3D displays in this manner cause less visual fatigue than classical stereoscopic displays.
Laser radiation safety is the safe design, use and implementation of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to government regulations.
Eye protection is protective gear for the eyes, and sometimes face, designed to reduce the risk of injury. Examples of risks requiring eye protection can include: impact from particles or debris, light or radiation, wind blast, heat, sea spray or impact from some type of ball or puck used in sports.
A total solar eclipse occurred at the Moon’s ascending node of orbit on Wednesday, August 11, 1999, with a magnitude of 1.0286. A solar eclipse occurs when the moon passes between earth and the sun, thereby totally or partly obscuring the image of the sun for a viewer on earth. A total solar eclipse occurs when the moon's apparent diameter is larger than the sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring about 3.5 days after perigee, the Moon's apparent diameter was larger.
EN 207 is a European norm for laser safety eyewear. Any laser eye protection sold within the European Community must be certified and labeled with the CE mark. According to this standard, laser safety glasses should not only absorb laser light of a given wavelength, but they should also be able to withstand a direct hit from the laser without breaking or melting, both the filter and the frame. In this respect, the European norm is more strict than the American norm that only regulates the required optical density. More precisely, the safety glasses should be able to withstand a continuous wave laser for 5 seconds, or 50 pulses for a pulsed laser.
The solar eclipse of August 21, 2017, dubbed the "Great American Eclipse" by some media, was a total solar eclipse visible within a band that spanned the contiguous United States from the Pacific to the Atlantic coasts. It was also visible as a partial solar eclipse from as far north as Nunavut in northern Canada to as far south as northern South America. In northwestern Europe and Africa, it was partially visible in the late evening. In northeastern Asia, it was partially visible at sunrise.
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season in its new moon phase, when the Moon's orbital plane is closest to the plane of Earth's orbit. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured. Unlike a lunar eclipse, which may be viewed from anywhere on the night side of Earth, a solar eclipse can only be viewed from a relatively small area of the world. As such, although total solar eclipses occur somewhere on Earth every 18 months on average, they recur at any given place only once every 360 to 410 years.
A total solar eclipse occurred at the Moon's ascending node of orbit on Tuesday, July 2, 2019, with a magnitude of 1.0459. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's and the apparent path of the Sun and Moon intersect, blocking all direct sunlight and turning daylight into darkness; the Sun appears to be black with a halo around it. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring about 2.4 days before perigee, the Moon's apparent diameter was larger.
An annular solar eclipse occurred at the Moon’s descending node of orbit on Thursday, December 26, 2019, with a magnitude of 0.9701. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. The Moon's apparent diameter was near the average diameter because it occurred 7.3 days after perigee and 6.2 days before apogee.
Eclipse chasing is the pursuit of observing solar eclipses when they occur around the Earth. Solar eclipses must occur at least twice and as often as five times a year across the Earth. Total eclipses may occur multiple times every few years.
An astronomical filter is a telescope accessory consisting of an optical filter used by amateur astronomers to simply improve the details and contrast of celestial objects, either for viewing or for photography. Research astronomers, on the other hand, use various band-pass filters for photometry on telescopes, in order to obtain measurements which reveal objects' astrophysical properties, such as stellar classification and placement of a celestial body on its Wien curve.
Eclipses of the Sun and of the Moon have been described by nearly every culture. In cultures without an astronomical explanation, eclipses were often attributed to supernatural causes or regarded as bad omens.
Eclipse photography involves the photographic capturing of solar eclipses and lunar eclipses. This niche field combines elements of astronomy, astrophotography, and sometimes travel photography, as photographers often venture to specific locations to capture these celestial events. Because of the intensity of the sun and the quickly changing conditions, eclipse photography necessitates the use of extremely strong solar filters, usually adhering to the ISO 12312-2 standard.
