NASA has also released guidance on how to test your eclipse glasses. The space agency recommends putting on your glasses and finding a bright light. If the light appears extremely dim, or doesn't appear at all, when you look at it through the glasses, they are legitimate. You should only be able to see the filament of the bulb, not its glow.

filter: (n.) Something that allows some materials to pass through but not others, based on their size or some other feature. (v.) The process of screening some things out on the basis of traits such as size, density, electric charge. (in physics) A screen, plate or layer of a substance that absorbs light or other radiation or selectively prevents the transmission of some of its components.

Elliptical polarization

The 2024 total solar eclipse is today — and if you're hoping to get a glimpse of the phenomenon, it's best to make sure that you have real, working eclipse glasses that can protect your eyes.

Without tools like sunglasses, humans typically can’t detect the polarization of light. But other animals can. Examples include mantis shrimp, fiddler craps and some beetles, birds and fish.

Polarization oflight

If you're reusing glasses from a previous solar eclipse, it's important to double-check that they are still in good condition. NASA warns against using glasses that have any marks or scratches on them. This damage can diminish the protection they offer. Glasses that have punctured lenses should also not be used.

That international safety standard, which is set by the International Organization for Standardization, means the glasses reduce visible sunlight to a safe level, and block ultraviolet and infrared radiation, according to the American Astronomical Society website. According to the ISO, the safety standard is reviewed every five years.

The American Astronomical Society advises against ordering from Amazon, Temu or other online marketplaces, and recommends against ordering if prices seem to be too good to be true. The AAS also said it's best to purchase from manufacturers based in the United States. CBS News previously reported that counterfeit glasses have been sold by companies based overseas.

Founded in 2003, Science News Explores is a free, award-winning online publication dedicated to providing age-appropriate science news to learners, parents and educators. The publication, as well as Science News magazine, are published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.

Glasses that are more than three years old should not be used to view the 2024 total solar eclipse, according to the National Eye Institute — so if you saved your glasses from the 2017 eclipse, you may want to think about finding a new pair.

Light can become polarized when it bounces off of a surface. The amount that it is polarized depends on the angle at which the light hits the surface. It also depends on what the surface is made of.

Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

Electric polarization

If you already bought the glasses, check the arm for the the "ISO 12312-2" label. The standard may also be written as "ISO 12312-2:2015," the AAS says on its website. Either designation means that the glasses will block light and radiation.

Political polarization

Light is made up of waves. They wiggle as they zip through space. They can wiggle up and down, left and right, and any angle in between. Light is polarized when its waves all wiggle at the same angle.

Light sources from lamps to stars typically give off light waves that wiggle at a range of different angles. This jumble of waves is known as unpolarized light. Polarized light, on the other hand, is unjumbled: its waves all wiggle the same way, at the same angle. (For help picturing this, check out the artist’s depictions at 1:30 in this PBS video.)

If you're not buying glasses, it is possible to make an indirect viewing method for viewing the eclipse at home. An indirect viewing method means that you don't look directly at the sun so your eyes remain protected even without eyewear.

Blocking that radiation is important. Ultraviolet, or UV, radiation can damage the cells of the eyes, while the infrared, or IR, radiation can generate heat that causes thermal damage, according to the National Eye Institute.

mantis shrimp: A marine animal related to crabs and lobsters. Mantis shrimp use armlike body parts to kill prey. They are often multicolored and have a very complex vision system.

Checking for the international standard isn't foolproof: It's possible for sellers with products who do not meet the standard to label their eyewear with it anyway. To avoid this, make sure you're ordering glasses from a reliable source.

polarization: (in physics) The condition — or creation of a condition — in which rays of wavelengths of light exhibit different properties when viewed from different directions.

refraction: The change in direction of light (or any other wave) as it passes through some material. For example, the path of light leaving water and entering air will bend, making partially submerged objects to appear to bend at the water’s surface.

Degree of polarization

Light can become polarized when reflecting off flat surfaces like puddles and pavement. Polarized sunglasses can then specifically block out those polarized light waves, reducing the glare that reaches a driver’s eyes.

Circular polarization

beetle: An order of insects known as Coleoptera, containing at least 350,000 different species. Adults tend to have hard and/or horn-like “forewings” which covers the wings used for flight.

Solar eclipse glasses can be used to safely view a total solar eclipse, but it's important to make sure they're of the right quality. Don't use sunglasses, smoked glass, an unfiltered telescope and magnifiers or polarized filters as a way to view the eclipse.

NASA recommends making a pinhole projector, which uses a small opening like a hole punched in an index card, to project an image of the sun onto a nearby surface. When using a pinhole projector, keep the sun at your back and view the projected image to safely see the eclipse. However, to do this safely, it's important to make sure to avoid actually looking at the sun itself.

Circularly polarizedlight

Edited By Allison Elyse Gualtieri, Alex Sundby

Light can also become polarized as it passes from one type of material into another. This is a process called refraction. And light can become polarized when it bounces, or scatters off atoms as it passes through a substance. This happens to moonlight and sunlight that travels through Earth’s atmosphere.

The organization maintains a list of reputable vendors of solar eclipse glasses. CBS News previously reported that NASA supports the American Astronomical Society's work, though the space agency does not maintain its own list of vendors.

molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

glare: Also called direct glare, it is light that travels directly from a light source and into someone’s eyes. It reduces the ability to see at night. Direct glare is one of three types of light pollution.

The only glasses that should be used to look at a partially eclipsed sun is with eclipse glasses that meet an international standard, ISO 12312-2, according to the American Optometric Association.

Another way to polarize light is to pass it through a filter. Such filters are made up of molecules that are all aligned the same way. This allows only light waves wiggling at specific angles to pass through. For example, some sunglasses contain polarizing filters. These glasses help reduce the amount of reflected light — or glare — that reaches a wearer’s eyes. That can block out glare from roadways or puddles to help protect drivers’ eyes and allow them to see more clearly.

polarization中文

Sunlight reflecting off water, for instance, can become polarized. The incoming light waves from the sun wiggle all different ways. But the light waves that bounce off the surface of the water are all mostly wiggling at the same angle. Pavement is another surface that can polarize reflected light.

Real eclipse glasses will have a note about the international standard somewhere on their body, according to the American Astronomical Society. Before buying, make sure the glasses are advertised as meeting this standard.

angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

Kerry Breen is a news editor at CBSNews.com. A graduate of New York University's Arthur L. Carter School of Journalism, she previously worked at NBC News' TODAY Digital. She covers current events, breaking news and issues including substance use.