Updated Safety Advice for Viewing the August 21st Solar Eclipse

In response to alarming reports of potentially unsafe eclipse viewers flooding the market as the coast-to-coast solar eclipse of August 21st draws near, the American Astronomical Society (AAS) has revised some of its safety advice to the public.

safety-adviceHow can you tell if your “eclipse glasses” or handheld solar viewers are safe? It is no longer sufficient to look for the logo of the International Organization for Standardization (ISO) and a label indicating that the product meets the ISO 12312-2 international safety standard for filters for direct viewing of the Sun’s bright face. Why not? Because it now appears that some companies are printing the ISO logo and certification label on fake eclipse glasses and handheld solar viewers made with materials that do not block enough of the Sun’s ultraviolet, visible, and infrared radiation to make them truly safe. Some sellers are even displaying fake test results on their websites to support their bogus claim of compliance with the ISO safety standard.

Given this unfortunate situation, the only way you can be sure your solar viewer is safe is to verify that it comes from a reputable manufacturer or one of their authorized dealers. The AAS Solar Eclipse Task Force has been working diligently to compile a list of such vendors, now posted on its Reputable Vendors of Solar Filters & Viewers page. Task-force members have checked manufacturers’ ISO paperwork to make sure it is complete and that it comes from an accredited testing facility, and they’ve asked manufacturers to identify their authorized resellers and dealers to identify the source of the products they’re selling. Only when everything checks out does the AAS add a vendor to its listing.

“If we don’t list a supplier, that doesn’t mean their products are unsafe,” says AAS Press Officer and task-force representative Rick Fienberg. “It just means that we have no knowledge of them or that we haven’t convinced ourselves they’re safe.”

How can you tell if your solar viewer is NOT safe? The only thing you can see through a safe solar filter from a reputable vendor is the Sun itself. If you can see ordinary household lights through your eclipse glasses or handheld viewer, it’s no good. Safe solar filters produce a view of the Sun that is comfortably bright (like the full Moon), in focus, and surrounded by black sky. If you glance at the Sun through your solar filter and find it uncomfortably bright, out of focus, and surrounded by a murky haze, it’s no good. You should contact the seller and demand a refund or credit for return of the product, then obtain a replacement from one of the sources listed on the AAS’s reputable-vendors page.

What if you received eclipse glasses or a handheld solar viewer from a relative, friend, neighbor, or acquaintance? If that person is an amateur or professional astronomer — and astronomers have been handing out eclipse viewers like Halloween candy lately — they’re almost certainly ISO-compliant, because astronomers get their solar filters from sources they know and trust (in other words, from the ones listed on the AAS’s reputable-vendors page). Ditto for professional astronomical organizations, including college and university physics and astronomy departments, and amateur-astronomy clubs.

If you bought or were given eclipse viewers at a science museum or planetarium, or at an astronomy trade show, again you’re almost certainly in possession of ISO-compliant filters. As long as you can trace your filters to a reputable vendor or other reliable source, and as long as they have the ISO logo and a statement attesting to their ISO 12312-2 compliance, you should have nothing to worry about. What you absolutely should NOT do is search for eclipse glasses on the internet and buy whatever pops up in the ads or search results. Check the AAS list of reputable vendors and buy from one of them.

The AAS continues to emphasize that it is perfectly safe to look directly at the Sun during the brief total phase of the solar eclipse (“totality”), when the Moon entirely blocks the Sun’s bright face. On August 21stthis will occur only within a roughly 70-mile-wide path spanning the country from Oregon to South Carolina, and only for up to 2 minutes 40 seconds. Before and after totality, or throughout the entire eclipse if you’re outside the path (in which case you’ll see only a partial eclipse, which is nowhere near as exciting or magnificent as a total one), the only safe way to look directly at the Sun is through special-purpose solar filters. These are commonly sold as paper- or plastic-framed eclipse glasses or cardboard solar viewers that you hold in your hand. Ordinary sunglasses, even very dark ones, are not safe for looking directly at the Sun; they transmit many thousands of times too much sunlight.

Here are the AAS’s instructions for the safe use of eclipse glasses and handheld solar viewers (https://eclipse.aas.org/eye-safety):

* Always inspect your solar filter before use; if scratched, punctured, torn, or otherwise damaged, discard it. Read and follow any instructions printed on or packaged with the filter.

* Always supervise children using solar filters.

* If you normally wear eyeglasses, keep them on. Put your eclipse glasses on over them, or hold your handheld viewer in front of them.

* Stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright Sun. After looking at the Sun, turn away and remove your filter — do not remove it while looking at the Sun.

* Do not look at the uneclipsed or partially eclipsed Sun through an unfiltered camera, telescope, binoculars, or other optical device.

* Similarly, do not look at the Sun through a camera, a telescope, binoculars, or any other optical device while using your eclipse glasses or handheld solar viewer — the concentrated solar rays could damage the filter and enter your eye(s), causing serious injury.

* Seek expert advice from an astronomer before using a solar filter with a camera, telescope, binoculars, or any other optical device; note that solar filters must be attached to the front of any telescope, binoculars, camera lens, or other optics.

* If you are inside the path of totality, remove your solar filter only when the Moon completely covers the Sun’s bright face and it suddenly gets quite dark. Experience totality, then, as soon as the bright Sun begins to reappear, replace your solar viewer to look at the remaining partial phases.

* Outside the path of totality, you must always use a safe solar filter to view the Sun directly.

Some eclipse glasses and solar viewers are printed with warnings stating that you shouldn’t look through them for more than 3 minutes at a time and that you should discard them if they are more than 3 years old. Such warnings are outdated and do not apply to eclipse viewers compliant with the ISO 12312-2 international safety standard, which was adopted in 2015. If your eclipse glasses or viewers are relatively new and are ISO 12312-2 compliant, you may look at the uneclipsed or partially eclipsed Sun through them for as long as you wish. Furthermore, if the filters aren’t scratched, punctured, or torn, you may reuse them indefinitely.

What about welding filters? The only ones that are safe for direct viewing of the Sun with your eyes are those of Shade 12, 13, or 14. These are much darker than the filters used for most kinds of welding. If you have an old welder’s helmet around the house and are thinking of using it to view the Sun, make sure you know the filter’s shade number. If it’s less than 12 (and it probably is), don’t even think about using it to look at the Sun. Many people find the Sun too bright even in a Shade 12 filter, and some find the Sun too dim in a Shade 14 filter — but Shade 13 filters are uncommon and can be hard to find. The AAS’s Reputable Vendors of Solar Filters & Viewers page doesn’t list any suppliers of welder’s filters, only suppliers of special-purpose filters made for viewing the Sun.

An alternative method for safe viewing of the partially eclipsed Sun is indirectly via pinhole projection. For example, cross the outstretched, slightly open fingers of one hand over the outstretched, slightly open fingers of the other, creating a waffle pattern. With your back to the Sun, look at your hands’ shadow on the ground. The little spaces between your fingers will project a grid of small images on the ground, showing the Sun as a crescent during the partial phases of the eclipse. Or just look at the shadow of a leafy tree during the partial eclipse; you’ll see the ground dappled with crescent Suns projected by the tiny spaces between the leaves.

Press Release by the American Astronomical Society (AAS)

SWRI Team to Use Airborne Telescopes to Study Sun and Mercury During Total Solar Eclipse

EclipseA team led by the Southwest Research Institute (SwRI) will use airborne telescopes aboard NASA research aircraft to study the solar corona and Mercury’s surface during this summer’s total solar eclipse. The August 21 observations will provide the clearest images to date of the Sun’s outer atmosphere and attempt the first-ever “thermal images” of surface temperature variations on Mercury.

Total solar eclipses are unique opportunities for scientists to study the hot atmosphere above the Sun’s visible surface. The faint light from the corona is usually overpowered by intense emissions from the Sun itself. During a total eclipse, however, the Moon blocks the glare from the bright solar disk and darkens the sky, allowing the weaker coronal emissions to be observed.

“By looking for high-speed motion in the solar corona, we hope to understand what makes it so hot. It’s millions of degrees Celsius, hundreds of times hotter than the visible surface below,” said Dr. Amir Caspi, principal investigator of the project and a senior research scientist in SwRI’s Boulder, Colorado, office. “In addition, the corona is one of the major sources of electromagnetic storms here at Earth. These phenomena damage satellites, cause power grid blackouts, and disrupt communication and GPS signals, so it’s important to better understand them.”

Why is the Sun’s outer atmosphere so much hotter than its surface? Perhaps the Sun’s magnetic field carries energy into the corona and converts it into heat. Or perhaps nanoflares or nanojets — explosions or eruptions too small and numerous to see individually — are constantly releasing small amounts of energy that combine to heat the entire corona. The team will use high-speed, high-definition video of the corona to look for fast, coherent motions that could help solve this puzzle. The project may also shed light on another question: why the magnetic structures in the corona are relatively smooth and stable.

“The magnetic field forms well organized loops and arcades in the lower corona, as well as large, fan-shaped structures extending out to many solar radii,” said Dr. Craig DeForest, a co-investigator also from SwRI’s Boulder office. “These structures are constantly being churned and tangled by the motion of the solar surface itself. So why does the corona always appear well organized, like a recently-coiffed head of hair, and not snarled or matted?”

From two of NASA’s WB-57 research aircraft, the team will observe the corona during the eclipse using stabilized telescopes with sensitive, high-speed, visible-light and infrared cameras at 50,000 feet. This high altitude provides distinct advantages over ground-based observations.

“Being above the weather guarantees perfect observing conditions, while being above more than 90 percent of Earth’s atmosphere gives us much better image quality than on the ground,” said another SwRI co-investigator, Dr. Constantine Tsang. “This mobile platform also allows us to chase the eclipse shadow, giving us over 7 minutes of totality between the two planes, compared to just 2 minutes and 40 seconds for a stationary observer on the ground.”

These are the first astronomical observations for the WB-57s. Southern Research, which is located in Birmingham, Alabama, built the Airborne Imaging and Recording Systems onboard and is working with the scientific team to upgrade its DyNAMITE telescopes on both planes with solar filters and improved data recorders.

“This airborne platform also provides us with higher-quality, higher-speed images than are achievable from current or previous space-borne instruments,” said Caspi. “It highlights the potential of the WB-57 platform for future astronomical observations.”

Eclipse observations also give the team a unique opportunity to study Mercury, the planet closest to the Sun. Mercury is difficult to observe because it is usually washed out by the bright daytime sky, or distorted by the atmosphere near the horizon at twilight.

“We plan to measure Mercury in the infrared, in near darkness, and through very little atmosphere,” Tsang said. Scientists hope to use infrared measurements to calculate surface temperatures over the planet’s entire night side. “How the temperature changes across the surface gives us information about the thermophysical properties of Mercury’s soil, down to depths of about a few centimeters, something that has never been measured before.”

The SwRI-led team includes scientists from the University of Colorado, the National Center for Atmospheric Research High Altitude Observatory, and the Smithsonian Astrophysical Observatory, as well as international colleagues at Trinity College Dublin in Ireland and the Royal Observatory of Belgium. The team will make its data available to the public after the event. The team’s work will also be featured in two documentaries to air on eclipse day and in the fall of 2017.

Press Release from Southwest Research Institute

Media Invitation: Lowell Observatory Solar Eclipse Experience in Madras, Oregon

What: Lowell Observatory invites members of the media to attend the Lowell Observatory Solar Eclipse Experience (LOSEE), a two-day event celebrating the August 21 total solar eclipse.

When: LOSEE will take place on August 20 and 21, 2017.

Where: The Lowell Observatory Eclipse Expedition will take place at the Madras High School football field and adjoining Performing Arts Center in Madras, Oregon.

Event Description: This will be the first total solar eclipse to stretch across the United States, from the Pacific to Atlantic oceans, since 1918. To celebrate, Lowell Observatory astronomers and educators are hosting this two-day, education-focused event that includes presentations by astronomers and a star party on the evening of August 21, and eclipse viewing, science demonstrations, and astronomer presentations on August 21. Plus, the Science Channel will be broadcasting live from our event to its worldwide network of tens of millions of followers on television, social media, and its website.

Complimentary Press Registration: Lowell Observatory offers complimentary press registration to working journalists, broadcasters, PIOs, and other media professionals. While press registration is available at the event, we recommend pre-registering. This will not only allow us to better plan, but also gives you the opportunity to receive relevant information that we will periodically share up until eclipse day.

To register contact Molly Baker via email at mbaker@lowell.edu

By Kevin Schindler, Lowell Observatory Historian

Astronomer Profile: Dr. Dave Schleicher

Note: Seven Lowell Observatory astronomers will participate in the 2017 Lowell Observatory Solar Eclipse Experience in Madras, Oregon on August 20-21. We will profile each in separate blogs. Today, we introduce Dr. Dave Schleicher.

Schleicher_Dave
Education

Dave Schleicher earned a bachelor’s degree from the University of Michigan and a Ph.D. from the University of Maryland in 1983.

Research Interests

Dr. Schleicher’s major research interests include the physical properties, chemical composition, and behavior of comets. He began using Lowell telescopes in 1979 while a graduate student at Arizona State University and joined the Lowell staff in 1985.

Dr. Schleicher uses a variety of observational tools and theoretical modeling in his studies. In 1986, he co-discovered the periodic variability of Comet Halley—a discovery that profoundly affected the interpretation of other measurements of Halley, including those from the Giotto and Vega spacecraft. He has since obtained support observations for all other comets visited by the spacecraft.

Fun Fact

Dr. Schleicher’s interest in astronomy began before second grade while looking through a neighbor’s small telescope. This soon became his hobby but when he chose astronomy as a career, he realized he needed another hobby and took up photography. Today he is an accomplished photographer and has taken pictures around the world while traveling for telescope observing sessions or professional astronomy meetings.

Lowell Observatory Solar Eclipse Experience Activities

Dr. Schleicher will be on hand to talk about astronomy and answer questions about the cosmos.

By Kevin Schindler, Lowell Observatory Historian

 

Astronomer Profile: Dr. Deidre Hunter

Note: Seven Lowell Observatory astronomers will participate in the 2017 Lowell Observatory Solar Eclipse Experience in Madras, Oregon on August 20-21. We will profile each in separate blogs. Today, we introduce Dr. Deidre Hunter.

Education

Deidre Hunter earned a bachelor’s degree from the University of Arizona in 1975 and a Ph.D. in astronomy from the University of Illinois in 1982.

Research Interests

Dr. Deidre HunterDr. Hunter’s primary scientific interest is tiny irregular galaxies—how they originate, evolve, and produce stars and star clusters, and how they are shaped. She held postdoctoral fellowships at the Kitt Peak National Observatory and the Department of Terrestrial Magnetism of the Carnegie Institution of Washington before coming to Lowell Observatory in 1986.

Dr. Hunter also runs Lowell’s Navajo-Hopi Astronomy Outreach Program. This is a science enrichment and outreach program for 5 th – 8 th grade Navajo and Hopi teachers and their classes. The program pairs astronomers with teachers for one year. The astronomer visits the classroom throughout the year, leading astronomy discussions and hands-on activities in collaboration with the teacher. Largely due to her commitment to this long-running and innovative program, Hunter was awarded the American Astronomical Society’s prestigious Education Prize in 2014.

Fun Fact

Dr. Deidre HunterDr. Hunter and her husband (fellow Lowell astronomer Dr. Phil Massey) have backpacked in the Grand Canyon 21 times, the last three with their daughter. They have also rafted down the Colorado River on commercial trips twice, paddling the entire way, and will be taking their daughter on her first trip in the summer of 2017.

Lowell Observatory Solar Eclipse Experience Presentation

Date: Monday, August 21, 11 a.m.

Title: Tiny Galaxies and Baby Stars

Description: Dwarf irregular galaxies are the tiniest galaxies in the universe. Yet, they pose a problem by doing what people say they shouldn’t be able to do: make new stars.

By Kevin Schindler, Lowell Observatory Historian

Astronomer Profile: Dr. Jeff Hall, Observatory Director

jeffrrey-hall-astronomer

Note: Seven Lowell Observatory astronomers will participate in the 2017 Lowell Observatory Solar Eclipse Experience in Madras, Oregon on August 20-21. We will profile each in separate blogs. Today, we introduce Jeff Hall, who also serves as Observatory director.

Education

Jeff Hall earned a BA in physics from Johns Hopkins University in 1986 and a Ph.D. in astronomy and astrophysics from Pennsylvania State University in 1991.

Research Interests

Dr. Jeff Hall joined the Lowell Observatory staff in 1992 as a postdoctoral research fellow. He works with a team of other scientists on Lowell’s Solar-Stellar Spectrograph project, a long-term program involving monitoring of solar and stellar activity cycles, with the goal of lending an astronomical perspective to solar influences on terrestrial climate.

Dr. Hall has served as Lowell’s director since June 2010. He is the incoming chair of the American Astronomical Society’s standing committee on light pollution, space debris, and radio interference, and has played a leading role in dark-sky preservation efforts around Arizona.

In the Community

In the community, he serves as a member of Flagstaff’s leadership group, the Northern Arizona Leadership Alliance, and is former president of the Governing Board of Northland Preparatory Academy, a college-prep charter school, as well as of the Board of Directors of the Flagstaff Symphony Orchestra. His principal avocation is music and he has been the substitute organist for the Episcopal Church of the Epiphany as long as he has lived in Flagstaff.

Fun Fact

jeffrey-hall-astronomer

Dr. Hall is an avid bicyclist and for years has tracked his cycling progress by a system named after early 20th century astrophysicist and biking enthusiast Arthur Eddington, who devised the scheme. The so-called Eddington Number (which Eddington was far too modest to call it himself) is defined as “the largest integer n, such that one had cycled at least n miles on n different days”. Hall’s current Eddington Number is 36.

Lowell Observatory Solar Eclipse Experience Presentations

Date: Sunday, August 20, 6 p.m.; Monday, August 21, 7 a.m.

Title: What to Expect When You’re Expecting an Eclipse

Description: Circumstances of eclipses, what we see when one happens, what we learn about the Sun (and other stars) from eclipses.

Astronomer Profile: Dr. Gerard van Belle

astronomer-gerard-van-belle
Andrew Holt Frazier

Note: Seven Lowell Observatory astronomers will participate in the 2017 Lowell Observatory Solar Eclipse Experience in Madras, Oregon on August 20-21. We will profile each in separate blogs. Today, we introduce Dr. Gerard van Belle.

Education

Gerard van Belle received a bachelor’s degree in physics from Whitman College in 1990, a master’s in physics from The Johns Hopkins University in 1993, and a Ph.D. in physics from the University of Wyoming in 1996.

Research Interests
astronomer-gerard-van-belle
Andrew Holt Frazier

Dr. van Belle has been on the Lowell Observatory faculty since August of 2011. He builds and uses the highest-resolution optical telescopes available on the planet to learn about the sizes, shapes, and surfaces of stars. These parameters tell us about the internal structure and evolution of stars, information which is essential to understanding new planets being discovered around nearby stars. Dr. van Belle has also applied high-resolution, high-precision astronomical techniques to detect such planets and map the surfaces of stars.

He was recently named the director of the Navy Precision Optical Interferometer (NPOI), a project operated in partnership by Lowell, the Naval Research Lab (NRL), and the U.S. Naval Observatory (USNO). Before working at Lowell, he served as an instrument scientist for the European Southern Observatory’s Very Large Telescope Interferometer (VLTI) facility in Chile and an instrument architect for NASA’s Keck Interferometer in Hawaii.

Fun Fact

In the August 12, 2014 issue of Esquire magazine, Dr. van Belle was featured as one of 22 men who are redefining style across America.

Lowell Observatory Solar Eclipse Experience Presentations

Date: Sunday, August 20, 8 p.m.

Title: An Explosion of Exoplanets: How Microscopic Eclipses have led to Detections of Nearby Worlds

Description: Twenty years of detecting planets orbiting other stars will be discussed, with the

vast majority of them being found to date via shadows in the light.

Date: Monday, August 21, 2 p.m.

Title: The Pluto Vote: One Astronomer’s Personal Story.

Description: While Dr. van Belle does not study Pluto, he was on hand at the International Astronomical Union’s 2006 meeting during which Pluto was kicked out of the Sun’s family of planets. His accidental involvement makes for an amusing story.

By Kevin Schindler, Lowell Observatory Historian

Total Eclipse of the Sun to be Commemorated on a Forever Stamp

The U.S. Postal Service will soon release a first-of-its-kind stamp that changes when you touch it. The Total Solar Eclipse Forever stamp, which commemorates the August 21 eclipse, transforms into an image of the Moon from the heat of a finger. The public is asked to share the news on social media using the hashtag #EclipseStamps.

Eclipse Stamp

Tens of millions of people in the United States hope to view this rare event, which has not been seen on the U.S. mainland since 1979. The eclipse will travel a narrow path across the entire country for the first time since 1918. The path will run west to east from Oregon to South Carolina and will include portions of 14 states.

The June 20, 1:30 p.m. MT First-Day-of-Issue ceremony will take place at the Art Museum of the University of Wyoming (UW) in Laramie. The University is celebrating the summer solstice on June 20. Prior to the event, visitors are encouraged to arrive at 11:30 a.m. to witness a unique architectural feature where a single beam of sunlight shines on a silver dollar embedded in the floor, which occurs at noon on the summer solstice in the UW Art Museum’s Rotunda Gallery.

The back of the stamp pane provides a map of the August 21 eclipse path and times it may appear in some locations.

Thermochromic Ink

The stamp image is a photograph taken by astrophysicist Fred Espenak, aka Mr. Eclipse, of Portal, AZ, that shows a total solar eclipse seen from Jalu, Libya, on March 29, 2006.

In the first U.S. stamp application of thermochromic ink, the total solar eclipse stamps will reveal a second image. Using the body heat of your thumb or fingers and rubbing the eclipse image will reveal an underlying image of the Moon (Espenak also took the photograph of the full Moon). The image reverts back to the eclipse once it cools.

Thermochromic inks are vulnerable to UV light and should be kept out of direct sunlight as much as possible to preserve this special effect. To help ensure longevity, the Postal Service will be offering a special envelope to hold and protect the stamp pane for a nominal fee.

A total eclipse of the Sun occurs when the Moon completely blocks the visible solar disk from view, casting a shadow on Earth. The 70-mile-wide shadow path of the eclipse, known as the “path of totality,” will traverse the country diagonally, appearing first in Oregon (mid-morning local time) and exiting some 2,500 miles east and 90 minutes later off the coast of South Carolina (mid-afternoon local time).

A total solar eclipse provides us with the only chance to see the Sun’s corona — its extended outer atmosphere — without specialized instruments. During the total phase of an eclipse the corona appears as a gossamer white halo around the black disk of the Moon, resembling the petals of a flower reaching out into space.

Art director Antonio Alcalá of Alexandria, VA, designed the stamp.

The Total Eclipse of the Sun stamp is being issued as a Forever stamp, which is always equal in value to the current First-Class Mail 1-ounce price.

Press Release by the United States Postal Service

Science Channel to Broadcast Live Coverage of Lowell Eclipse Event

 

The Lowell Observatory Solar Eclipse Experience is an excellent opportunity to witness Lowell carrying out its dual mission of astronomical research and public education. During the eight-hour eclipse event on August 21 in Madras, Oregon, Lowell astronomers and educators will be on hand to teach, inspire, and share in the excitement of the total solar eclipse. Typical of Lowell’s long tradition of spreading scientific enlightenment, mass media will also play a vital role in reaching people across the globe.

Since the early days of educational science programming on television, the research of Lowell Observatory has been featured on various programs. In 1957, Walt Disney’s Disneyland series included the episode Mars and Beyond, which featured rocket scientist Werner von Braun discussing the problem of traveling to the red planet, as well as Lowell astronomer and Mars expert E.C. Slipher discussing his Mars research.


Two decades later, in 1980, astronomer/science popularizer Carl Sagan appeared at Lowell on Episode 5 of his Cosmos series, Blues for a Red Planet. In 1996, Bill Nye came to Lowell and filmed an episode of Bill Nye the Science Guy, “Pseudoscience”, and a year later Leonard Nimoy interviewed comet hunter Carolyn Shoemaker for a show. In addition to these, numerous other science programs have been filmed at Lowell for the History Channel, Discovery Channel, and many other outlets. Discovery’s sister station, the Science Channel, will soon get in on the act as it will carry a live broadcast of Lowell’s eclipse event. This means that millions of people across the world will be able to listen to Lowell astronomers and educators and experience totality, all from the comfort of their homes as they watch on their computers and televisions.

By Kevin Schindler, Lowell Observatory Historian

A Pinhole Viewer by any Other Name

Colander Pinhole Viwer

As we discussed in the February 22 blog, solar eclipses may be indirectly viewed in a variety of ways. One of the simplest and least expensive (often coming at no cost) is to create a projected image of the Sun through a pinhole viewer. This may be accomplished by simply poking a small hole in a piece of cardboard, and then holding the cardboard such that the sunlight passes through the hole and falls onto a viewing surface (a white piece of paper, sidewalk, garage door, etc.) To focus the image, the observer simply moves the cardboard farther or nearer from the viewing surface.

Eclipse Pinhole Viewer
Jenny Oh/KQED

Observers can get pretty creative with such pinhole viewers, devising a pattern of holes that spells out a word or forms a familiar shape like a heart.

 

“One of the simplest and least expensive ways to view an eclipse is to create a projected image of the Sun through a pinhole viewer.”

Colander Pinhole Viewer
Frederic of Attic Self-Storage Blog

Another version of a pinhole viewer, one that needs no preparation, may be found in most kitchens. This is a colander, whose numerous holes are usually a perfect size to project the sun’s image.

While pinhole viewers are not useful during totality (you want to be looking at the eclipsed sun at this time anyway) they are perfect for easily seeing the partial phases of a solar eclipse.

By Kevin Schindler, Lowell Observatory Historian