For more information about the total solar eclipse on April 8, including where to watch, start time and events happening around San Antonio, check out our guide.
The upcoming total solar eclipse will literally be a once-in-a-lifetime event for many San Antonians and others in the path of totality.
While residents and visitors were wowed by an annular solar eclipse just this past fall, the 210 hasn’t seen a total solar eclipse since 1397 — about 95 years before Christopher Columbus’ famous journey that would credit him for discovering the Americas and about 321 years before our city was founded. San Antonio won’t see another total solar eclipse until 2343 — about 319 years from now.
During the eclipse on April 8, the northwestern half of San Antonio will experience totality for roughly two to four minutes, depending on the exact location. For this small window of time, the moon will temporarily block out the sun completely, allowing viewers to catch a rare glimpse of the sun’s corona — the outermost part of the sun’s atmosphere.
In the United States, the eclipse will start in southwest Texas around 1:30 p.m. and will move northeast spanning parts of Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire and finishing in Maine around 4:30 p.m.
While day passes to Texas state parks for watching the eclipse were snapped up within hours of being released online, hundreds of viewing events are planned around the area and state, including the official Texas Eclipse Festival in Burnet and viewing parties at the Alamo, Witte Museum, Six Flags Fiesta Texas, SeaWorld and Natural Bridge Caverns.
Still have burning questions about the eclipse? Here’s everything you need to know before the show.
What is a total solar eclipse?
A total solar eclipse occurs when the moon passes between the Earth and the sun, completely blocking out the face of the sun as the moon casts a shadow onto the Earth. Those within the moon’s narrow shadow experience a total eclipse.
“If you want to see the total eclipse, you have to be under this tiny little spot here, which is approximately 100 miles across,” Angela Speck, professor of astrophysics and the chair of the Department of Physics and Astronomy at UTSA, told a room full of reporters last month while pointing at the blackest part of the moon’s shadow on a projected rendition.
Those within the gray portion of the moon’s shadow will only experience a partial solar eclipse — where the moon blocks out a portion of the sun but not all of it, Speck said.
“You can be somewhere that gets 99.9% coverage and you will still not experience totality, even with that tiny portion,” Speck said. “Close enough is not good enough. Get into the path of totality.”
What is the path of totality?
The path of totality is the narrow strip across the Earth where the moon will completely block out the sun for viewers within it. Only about 100 miles across, April 8’s path of totality will span 4,000 miles total across Mexico, 13 U.S. states and a very small portion of Canada.
About half of San Antonio lies within the path. Much of the Texas Hill Country is within this path, including the cities of Boerne, Kerrville, Fredericksburg and Castroville. The closer to the center of the path, the longer that location will experience totality. Kerrville, for example, almost completely at the path’s center, will experience almost 4.5 minutes of totality on April 8.
Will all of San Antonio be in the path of totality?
The path of totality will bisect the city roughly along the diagonal path of Interstate 35.
The northwestern half of the city will experience totality, whereas anyone outside this path — including those who choose to view the eclipse at the Alamo, Witte or San Antonio Zoo — will not. This is because even 0.01% of the sun’s brightness will outshine the moon, giving those outside the path a partial eclipse, Speck said.
“As [Professor Speck] said: 99.99% is a failing grade,” joked Patricia Reiff, a professor in the Department of Physics and Astronomy at Rice University and the founding director of the Rice Space Institute.
What is totality like?
According to research psychologist Sean Goldy, humans experiencing totality tend to have one common leading emotion: awe.
“People feel awe when they experience something mind-blowing and incredible, like eclipses,” said Goldy, a postdoc working at the Johns Hopkins Center for Psychedelic and Consciousness Research.
As the moon completely blocks out the sun, the sky will darken as if it were dawn or dusk, according to NASA. A total solar eclipse is the only type of solar eclipse where viewers can momentarily remove their eclipse glasses for the brief period of totality.
The sky will turn colors — shades of purple and orange and pink — as if there was a spectacular 360-degree sunset, said Speck, who has experienced three total eclipses.
The part of the sky closest to the eclipse will be dark, allowing viewers to see the sun’s corona as ghostlike wisps. These are rays of plasma — electrically charged gas — that radiate from the surface of the sun.
Sections of the sky close to the sun will be dark, allowing skygazers to see planets, stars and, if lucky, even comets they would not normally be able to see during the day, Speck said.
Why do I need special glasses or camera lenses?
Before and after totality, eclipse watchers will need to use certified eclipse glasses or a do-it-yourself pinhole projector to view the moon as it crosses the sun, Speck said. Staring directly at the sun — even during an eclipse when part of the sun is blocked — can cause damage to the human eye, she warned.
“With the glasses, the sun looks about as bright as the full moon,” she said. “You don’t want to look at the sun directly without the glasses.”
Eclipse glasses are special eyewear designed for direct viewing of the sun. These glasses are made of either a black polymer or silvery mylar that blocks 100% of infrared and ultraviolet light, filtering out eye-damaging radiation.
Make sure you get eclipse glasses certified by the International Organization for Standardization, said Randy Millican, emergency management coordinator of Kimble County in the Hill Country. Wearers should look for an ISO certification number on their glasses prior to using them. Find certified-safe eclipse glasses here.
“A welder’s helmet, one, two, three, four pairs of sunglasses — those do not work,” he said. “You must have the certified eclipse glasses.”
For those who want to watch the eclipse’s diamond-ring effect — the last flash of light that occurs as the sun slips completely behind the moon, and the first flash of light as it reappears on the other side — they should try to watch the one during re-emergence rather than the one as the sun disappears because the flash can affect how you view totality, Reiff said.
“Your cameras can capture those but don’t look at it with your eyes on the way in because it can ruin your night vision for the eclipse,” she said. “Instead, look for the diamond ring effect on the way out.”
How long will totality last?
How long you experience totality will depend on where you are, Speck said.
Those watching on the outermost edges of the path of totality will experience the phenomenon much more briefly than those in the path’s center. Cities at the path’s center, such as Kerrville and Fredericksburg, will experience almost 4.5 minutes of totality, while those in the northwestern half of San Antonio — including Speck, who will be watching from UTSA’s campus — will experience only about 2.5 minutes, she said.
How is this eclipse different from the one in October?
The moon’s orbit around the Earth is elliptical and not a perfect circle. This means the moon is closer to the Earth at certain times and farther away at others.
Last October’s solar eclipse was what is called an annular solar eclipse, or a “ring of fire” eclipse. While this type of eclipse also consists of the moon completely passing in front of the sun, it occurs at a time when the moon is at or near its farthest point from Earth (called “apogee”) and therefore appears smaller, meaning it does not completely block out the sun.
Instead, it creates the ring of fire effect, where a single ring of the sun’s light completely circles the moon. This is what many San Antonians got to experience this past fall.
A total solar eclipse occurs when the moon is closer to the Earth, appearing to those of us on Earth to be roughly the same size as the sun, allowing it to block out the sun’s light when it passes in front.
How rare are total solar eclipses?
When it comes to how often total solar eclipses grace a single spot on Earth with their presence, it’s only roughly every 375 years on average, Speck said.
That’s because of a few different factors.
For one, the moon’s elliptical orbit around the Earth is also at a tilt — meaning the moon’s shadow often misses Earth altogether when passing in front of the sun every month.
Another factor is the Earth’s shape, Speck said. The moon’s shadow does not move in a perfectly diagonal path along the Earth — it moves more in wavelike or circular paths, she said, depending on where the moon’s shadow is cast on our ellipsoid planet.
Why do scientists study total solar eclipses?
A lot can be learned about space, physics and nature during total solar eclipses, Reiff said.
For example, Albert Einstein’s theory of general relativity was first proven during a total solar eclipse in 1919. This theory states gravity is a curvature of time and space caused by mass and energy. If Einstein’s theory was right, the light from stars would be bent by the gravity of the sun and appear displaced during a total solar eclipse. A group of scientists, led by Sir Arthur Eddington, took measurements of stars during the 1919 eclipse in Africa, proving Einstein’s then-4-year-old predictions were correct.
During the 2017 total solar eclipse, scientists were able to, for the first time, establish how hot the sun’s corona is. Interestingly, they found that, at 2 million degrees Fahrenheit, the sun’s corona is roughly 200 times hotter than the surface of the star. Scientists plan to use next month’s eclipse to further study this effect, hoping to answer the question of why this is the case.
Space isn’t the only thing scientists can learn more about during a total solar eclipse. Animals have been proven time and time again to act bizarrely during solar eclipses, especially during total solar eclipses. Animal behaviorists, such as Adam Hartstone-Rose, a professor of biological sciences at North Carolina State University, use total solar eclipses as a chance to study this behavior, which ranges from assuming their nighttime sleeping positions to copulating, Hartstone-Rose said.
“The one behavior that all of the journalists seemed to be really excited to write about [after the 2017 eclipse] was what the Galapagos tortoises did,” he said. “You can watch them for three days prior to an eclipse and they are really very inactive animals, but as totality approached, they started moving around, and then at totality, they started breeding.”
Do I need to put eclipse glasses on my pet?
Our beloved furry friends do not need to wear eclipse glasses or protective eyewear during a solar eclipse, even if they are outside with us, Hartstone-Rose said.
“Animals don’t look at the sun,” he said with a chuckle. “If you want to put it on them as a fashion statement though, I mean sure, go ahead.”
When and where will the next total solar eclipse take place?
While the next total solar eclipse for San Antonio won’t be until 2343, there are other total solar eclipses in the U.S. to look forward to — albeit they’re about two decades away, Speck noted.
The next total solar eclipse that can be seen from the contiguous United States will be on Aug. 23, 2044 — although it will only be seen in Montana and North Dakota. Before that, there will be a smaller solar eclipse in 2033 that will be viewable only from Alaska.
The next total solar eclipse that will span the U.S. coast to coast will be in 2045. This one’s path of totality will barely clip the Texas Panhandle.
Will the eclipse affect traffic?
State agencies are warning residents and visitors to expect heavy traffic delays across the state April 7-9.
The Texas Department of Transportation has a webpage dedicated to the April eclipse in anticipation of this traffic. It warns drivers not to wear eclipse glasses while driving, to keep their headlights on while driving — even in the daylight — and to be on alert for distracted pedestrians looking to the sky.
“As people gear up for prime viewing of the eclipse, they should also prepare for busier-than-normal traffic on roads, especially on rural roads less accustomed to heavy travel,” media relations employee Laura Butterbrodt wrote in a recent TxDOT article. “Rural areas may see up to a 200% increase in people around the astronomical event. Drivers should fuel up on gas, snacks and water ahead of time and leave early in case of delays.”
TxDOT emergency management coordinator Matthew Heinze said it’s not the event but humans that are unpredictable.
“Much like a major weather event, we know the path, timing and duration, but we don’t know how many people will be on the road or how they will act,” he said.
TxDOT is encouraging residents and visitors to pull over in a safe, designated parking space before the eclipse if they want to view it. Parking or standing on road shoulders, medians or stopping in the middle of the road is not safe and “will not be permitted,” TxDOT said.
Where can I watch the eclipse?
In preparation for an influx of celestial tourism, Visit San Antonio, the local visitors bureau, has launched a webpage dedicated to “Fiesta del Sol,” giving locals and tourists alike the lowdown on the eclipse.
“San Antonio must be a great city — after all, Mother Nature picked it twice!” the page states cheekily. It includes safe viewing information, hotel advice and a list of organized watch parties.
Apart from the watch parties above, folks can watch the eclipse from a wide array of places. Here are some of the locations advertising their watch parties as April 8 draws nearer:
San Antonio parks
- Eisenhower Park
- Garza Community Center
- Gill Adult & Senior Center
- Granados Adult & Senior Center
- Medina River Natural Area
- Melendrez Community Center
- Phil Hardberger Park
- Ward Community Center
- Yates Community Center
San Antonio hotels and resorts
- La Cantera Resort
- Hyatt Hill Country Resort and Spa
- JW Marriott San Antonio Hill Country Resort and Spa
- Hilton San Antonio Hill Country Resort
