Astronomer Profile: Dr. Jeff Hall, Observatory Director


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.


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


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

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.


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
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

How To Know If Your Solar Glasses Are Certified

The Lowell Solar Eclipse Experience Solar GlassesIn our February 22 blog, we reviewed various methods of safely viewing the Sun during its partial phases of eclipse. One of these is by use of solar glasses (also called solar viewing glasses) that are simple to use, safe, and inexpensive.

Solar glasses usually consist of cardboard frames (more expensive ones are made of sturdier plastic) that hold a Mylar or, more typically, black polymer material that filters out harmful solar rays.

The International Organization of Standardization (ISO)—a worldwide body that sets standards for commercial and industrial products and processes—addresses safe viewing of the Sun in the

ISO 12312-2 standard (this is often listed more specifically as ISO 12312-2:2015). For solar eclipse glasses to be certified under this benchmark, they must block ultraviolet and infrared light as well as reduce visible light to safe and comfortable levels.

“If solar eclipse glasses are not marked as meeting the ISO standard, you’re better off not using them.”

Glasses that meet this standard should be marked as such (something like “Meets the requirement for ISO 12312-2:2015”). Safety is paramount with solar viewing, so if solar glasses are not marked as such, you’re better off not using them.

Rainbow Symphony is one company that has certified its solar glasses meet the ISO standard. This California-based manufacturer of 3D, eclipse, diffraction, and other varieties of glasses has produced the solar eclipse glasses that all participants at the Lowell Observatory Solar Experience will receive.

By Kevin Schindler, Lowell Observatory Historian

Stargazing During the Eclipse

Viewing planets and stars is usually a nighttime activity, experienced after the Sun has set and the ensuing darkness allows for these jewels to be seen. But the disappearance of sunlight during a total solar eclipse can result in a similar, albeit more short-lived, opportunity for stargazing. During this year’s August 21 eclipse, for instance, four different planets and several familiar constellations will shine ever-so- briefly during totality.

Eclipse Stargazing 2017
The eclipse view from Central Oregon. Made with Stellarium

During this year’s August 21 eclipse, four different planets and several familiar constellations will shine ever-so- briefly during totality.

Planets and Constellations

The brightest object to show itself, Venus, will become visible about 15 to 30 minutes before totality sets in. It will lie 34º west (to the right) of the darkening Sun (1º is about the width of your pinkie finger held at arm’s length, and 10º is the width of your fist held in the same way; thus, Venus will be a little more than three fist widths to the west of the Sun). It will stay visible until 15 to 30 minutes after totality ends.

Fainter Jupiter, located 52º east (to the left) of the Sun, should also become visible during the latter stages of partial eclipse for some observers east of Idaho, but it will be very low on the eastern horizon. It won’t have risen yet as seen west of Idaho so won’t be visible in that area. Some 30 seconds before and after totality, two other planets will be visible, though they will be more difficult to distinguish because of their faintness. Reddish Mars will be only 8º to the west of the Sun, while even fainter Mercury will be 11º southwest of the Sun.

As for constellations, the Sun will be in Leo during totality. Its brightest star, Regulus, may or may not be easy to see, depending on the glare from the nearby Sun’s corona during totality. Other bright stars that should be easier to see include Sirius (in Canis Major) and Rigel (in Orion), both to the west of the Sun; Capella (in Auriga and northwest of the Sun); and Arcturus (in Bootes and to the northeast of the Sun). The Big Dipper will also shine brightly, due north of the Sun.

By Kevin Schindler, Lowell Observatory Public Information Officer and Historian

What You’ll See During the Total Solar Eclipse

While totality will mark the crowning moment of the August 21 solar eclipse, several other phenomena leading up to this much-anticipated climax will be worth experiencing. The entire sequence will be an enchanting, multisensory encounter with one of nature’s sublime spectacles.

At the Lowell Observatory Solar Eclipse Experience in Madras, Oregon, the fun starts at 9:06:42 a.m., when the Moon takes its first bite out of the Sun in a moment called 1st contact; that signals the beginning of the eclipse. Using a filtered telescope, solar glasses, or other appropriate observing techniques, observers will be able to see more and more of the Sun covered during the approximately 73-minute transition from partial to total eclipse.

Totality of Solar EclipseAt about 10 a.m.—20 minutes before totality begins—the visible part of the Sun will have shriveled to almost a point (rather than a disc), resulting in sharper shadows. Soon, when about 85% of the Sun is covered, the sky will have darkened to the point that the planet Venus will be visible with the unaided eye, 34 degrees to the northwest of the Sun. At about 10:10 am, fainter Jupiter will be visible, a little more than 50 degrees southeast of the Sun.

Soon, the darkening sky will make those witnessing the eclipse feel like night is falling, though the darkest part of the sky will be toward the Sun, rather than at the distant horizon. Observers may notice that birds will stop singing and other daytime animals will cease activity, as if night has truly arrived. Just like at actual nightfall, this time of silence might then be followed by the sounds of crickets, cicadas, frogs, and other nocturnal critters. The temperature will also drop, perhaps up to 15 degrees or so.

At about 10:19:32 a.m.—two seconds before totality begins—the appearance of Bailey’s beads will quickly transition to the brief display of the diamond ring, and then totality begins, designated as 2nd contact. This will last until 10:21:36 (3 rd contact). During totality, the best view is with the unaided eye, looking at the totally eclipsed Sun and also at the so-called 360 degree sunset (all horizons will display sunset colors).

During the exciting buildup to totality, it’s easy to miss some of the features described above. Luckily, they will all be apparent, in opposite order, when totality ends and the Sun is again only partially eclipsed. Slowly, the Moon will move out of our line of sight with the Sun until 11:41:03 (4 th contact), when the eclipse ends.

By Kevin Schindler, Lowell Observatory Public Information Officer and Historian

Archaeological Evidence of a Total Solar Eclipse

Many observers of this year’s total solar eclipse will undoubtedly want to capture this extraordinary event by photographing or sketching it. Evidence at an archaeological site in New Mexico suggests that a witness to a similar event nearly a millennium ago did the same thing. The medium was rock, and that observer created a rock carving called a petroglyph by chipping away rock with a stone chisel.

Archaeological Petroglyphs in Chaco Canyon.

The petroglyph is on the south side of a free-standing rock in Chaco Canyon, just a few hundred yards from the Chaco Culture National Historical Park visitor center (this is some 102 miles northwest of Albuquerque, as the crow flies.) Scholars have referred to the rock as Piedra del Sol (“Sunstone”) because it contains several Sun-related features typically found in archaeological remains, including a spiral petroglyph apparently used to mark the location of the Sun on the summer solstice. But the alleged solar eclipse petroglyph is especially compelling because total solar eclipses are rare for any given location.

Eclipse Petroglyph Chaco Canyon
Petroglyph allegedly depicting a solar eclipse.

The petroglyph consists of a filled-in circle with curlicues shooting out from its perimeter. While other petroglyphs are nearby, a smaller, filled-in circle to its upper left has been

interpreted by some scientists as representing the planet Venus, which would have been visible once the Sun darkened during eclipse.

The curlicues may represent the Sun’s corona and, perhaps, coronal mass ejections (CMEs), which are abnormally large concentrations of plasma released from the corona. These CMEs are more common during times of peak solar activity, which generally follows an 11-year cycle.

eclipse sketch
Modern Day Sketch from the 1800s depicting the Corona and Corona Mass Ejection.

So, do the observations and inferences match the astronomical facts? Determining the time and location of past and present eclipses is fairly straightforward, and we know that a total solar eclipse was visible from Chaco Canyon on July 11, 1097, during the height of the Chaco culture. Research has also shown that this eclipse happened during peak solar activity. Finally, astronomers can easily ascertain the relative position of the planets and other celestial bodies in past years, and this circle is indeed in the proper position for Venus, relative to the Sun, for July 11, 1097.

We will likely never know for sure whether this petroglyph really does represent a total solar eclipse, but there is sufficient evidence to keep our curiosity alive.

By Kevin Schindler, Lowell Observatory Public Information Officer and Historian

Accessories of the 2017 Total Eclipse: Beads and Rings

During totality of the 2017 total solar eclipse, viewers will enjoy the rare opportunity to see the Sun’s corona, a complex region of extremely hot plasma extending far above the solar surface. But this won’t be the only unusual thing to see, as the first and last moments of the eclipse will be marked by two brief, spectacular phenomena— Baily’s Beads and the Diamond Ring Effect.

Leading up to totality, the Moon gradually moves in front of the Sun. Just before completely blocking it, a few rays of the Sun shine through valleys and other irregularities on the lunar limb (the edge of the Moon, as seen from Earth), resulting in a few bright beads of light called Baily’s beads. This feature is named after English astronomer Francis Baily, who in 1836 explained the nature of the phenomena. As with many cases in science, Baily was not the first person to observe or explain the effect; that honor goes to Baily’s countryman Edmond Halley in 1715.

The beads will be visible for only a short time; the last one glows brightly and looks like the diamond on a ring, and is thus known as the Diamond Ring Effect. Later, as the Sun comes out of eclipse, the Diamond Ring Effect and Bailey’s beads will again be visible. Both Baily’s beads and the Diamond Ring Effect are short-lived but dramatic and worth seeing.

By Kevin Schindler, Lowell Observatory Public Information Officer and Historian