Total Solar Eclipse (April 2024)
Overview | Total Solar Eclipse in Texas | April Weather in Texas | Eye Safety | Solar Filters for Optics | Resources | Photography
Martin Bernetti/AFP/Getty Images
Overview
On April 8, 2024, a total solar eclipse, known as the "Great North American Eclipse," will carve a narrow path of totality from southwest to northeast across 13 U.S. states. The duration of totality will be up to 4 minutes and 27 seconds, almost double that of The Great American Eclipse of August 21, 2017.
The centerline of the eclipse enters Texas, and the United States, as it crosses the Rio Grande River at the Mexico-U.S. border at approximately 12:10PM CDT, with totality beginning in that location at about 1:27PM CDT.
Remember that since the Moon never entirely covers the Sun during an annular, or "ring of fire," solar eclipse, you must use special eclipse safety glasses or viewers at all times. Unlike during a total solar eclipse, during an annular eclipse there is never a time when it's safe to look with unprotected eyes.
To determine the precise start time, end time, and duration of annularity for your exact location on eclipse day, use the interactive Google eclipse maps developed by Xavier Jubier.
Total Solar Eclipse in Texas
As it exits Mexico and enters the U.S., traveling through the Texas Hill Country, the eclipse will have already reached its "point of greatest duration," that singular spot along every total solar eclipse centerline where the duration of totality is longer than anywhere else. That point is also the duration of totality "tipping point," meaning that the duration gradually increases along the centerline up until that point and then starts to decrease on the other side. In other words, for the 2024 eclipse, the duration of totality is all downhill in the U.S., with the longest durations in Texas and the shortest in Maine. Therefore, the path of totality in Texas will be considered a prime viewing destination on April 8. And since the point of greatest duration in Mexico is only a little more than 300 miles to the south of where the path of totality enters the U.S., the duration of totality on the centerline will only be a few seconds short of the eclipse maximum of 4 minutes and 28 seconds even a couple of hundred miles north of the border.
If the longest durations of totality in the U.S. wasn't enough, Texas is also widely considered to have the best eclipse-day weather prospects in the country. More specifically, eclipse weather forecasting site eclipsophile.com points out that, in Texas, "the north [or west] side of the track has a notably sunnier April climate than the south [or east]." In general, the farther south you are for this eclipse, the better your weather odds. And you can't get any farther south along the path of totality in the U.S. than Texas.
Texas will also be the place where perhaps more people will witness totality than anywhere else in the U.S., not only because Texas is such a large state and the path of totality covers so much ground here, but also because Texas is where the path happens to cross the three largest cities—San Antonio, Dallas, and Austin—it will encounter during its journey across the country. In fact, not long after the eclipse enters the U.S., the 120-mile-wide path of totality crosses over the most populous city along its path in the U.S. Unfortunately, though, San Antonio sits right on the eastern edge of the path of totality with about half of the city inside the path and half outside. Downtown attractions like the River Walk and the Alamo are outside the path of totality and you'll need to be in the northwestern part of the city to see a total eclipse—although totality durations will be relatively short here along the edge of the path. If you're at SeaWorld San Antonio, for example, you'll witness totality for about 2 minutes and 3 seconds, with the duration steadily decreasing to the south and east. If you're in the San Antonio area and want to more than double your totality viewing time, drive west on Interstate 10 to reach the eclipse centerline about 60 miles away.
Just a bit farther north, the eclipse crosses over the Texas state capital, Austin. As with San Antonio, Austin lies along the eastern edge of the eclipse path where durations of totality will be relatively short. Luckily, though, totality will be seen within most of Austin's city limits, with just a few areas in the southeastern part of the city outside the path. Downtown Austin will get about 1 minute and 44 seconds of totality, with durations dropping off as you go south and east. By early April, Austin's famous Congress Avenue Bridge bats should have arrived from their winter grounds in Mexico. It will be an interesting experiment in animal behavior to see if the bats emerge from under the bridge during the eclipse.
The sprawling Dallas-Fort Worth Metroplex area spreads out from the western limit of the eclipse path all the way to the centerline, offering residents and visitors plenty of places to view totality. For the cities themselves, Dallas is centered about halfway between the centerline and the western limit of the eclipse path while Fort Worth is closer to the western edge. In downtown Dallas, you'll enjoy about 3 minutes and 51 seconds of totality. Fort Worth will get about 2 minutes and 33 seconds of totality downtown, with durations decreasing as you go north and west and with a few areas outside the path of totality in the far northwestern part of the city. On the other, less heavily populated, side of the centerline from the Dallas-Fort Worth area, interstates 45, 20, and 30 can be used to reach the maximum durations found near the centerline. Houston is relatively close on the eastern side of the eclipse path. Drive west on I-10 to reach the path in under three hours or north on I-45 to reach totality in under two. Shreveport, Louisiana, is within easy striking distance via Interstate 49 or I-20 and can make a good basecamp for eclipse expeditions.
The centerline of the eclipse exits the state as it crosses the Red River at approximately 3:06pm CDT, with totality coming to an end in that location at about 1:49pm CDT. From the Mexico-Texas border to the Texas-Oklahoma border, the Moon's shadow travels approximately 478 miles along the centerline in 17 minutes and 29 seconds at an average speed of 1,641 miles per hour.
Source: NationalEclipse.com
April Weather in Texas
When the Moon’s shadow crosses the Rio Grande and moves into the United States, it traverses the floodplain of the Rio Grande River where elevations are between 200 and 300 m above sea level (please see the topographical map at right). Immediately afterward, the shadow meets the Balcones Escarpment and rises up onto the Edwards Plateau, an increase of about 400 m in elevation. After passing San Antonio and Austin, the track descends onto the Gulf Coastal Plain and later, the Mississippi floodplain, passing Dallas and Fort Worth on its way to the Oklahoma and Arkansas borders.
One of the surprises of the graph of centerline cloud cover is the seeming lack of strong responses to the topography beneath the shadow track, even though there are some significant mountain heights to cross in Arkansas and Missouri. Usually, we expect to see an increase in gloomy weather when the terrain rises and a lower amount of cloud where the terrain descends, but in Texas, where the high plains derive part of their climatology from the Southwestern Deserts, this relationship does not hold. For this part of the eclipse, the centre-line cloudiness responds only weakly to the underlying along-track topology. However, when we look at the map of cloud cover (Figure 11), we see that there are significant terrain-induced modifications to the cloud cover, but they are off to the north or south side of the central line and don’t appear in Figure 10’s graph. The variation in south side-north side cloud cover is reflected in the station plots in Figure 10, however, as they lie both above and below the centerline trace depending on their distance from the shadow axis.
One of the surprises of the graph of centerline cloud cover in is the seeming lack of strong responses to the topography beneath the shadow track, even though there are some significant mountain heights to cross in Arkansas and Missouri. Usually, we expect to see an increase in gloomy weather when the terrain rises and a lower amount of cloud where the terrain descends, but in Texas, where the high plains derive part of their climatology from the Southwestern Deserts, this relationship does not hold. For this part of the eclipse, the centerline cloudiness responds only weakly to the underlying along-track topology.
However, when we look at the map of cloud cover (please see the April Media Cloud Amount graphic at left), we see that there are significant terrain-induced modifications to the cloud cover, but they are off to the north or south side of the central line.
Across Texas, the north side of the track has a notably sunnier April climate than the south. The best of Texas weather prospects—in fact, the best prospects in the United States and Canada—lies on the Edwards Plateau, where median cloud amounts are as much as 15 percent lower than those south of the centre line on the Coastal Plain. We can be even more specific: according to the satellite data, the best climatological prospects lie between Junction and Brady, both in Texas. Brady is perilously close to the north limit but Junction, 28 km inside the track, has an eclipse duration of 3m 7s, generous, but significantly shorter than the 4m 26s at the centerline near Kerrville. Satellite measurements show an median April cloud fraction of 39 percent (0.39 on the map) in the area. Junction is connected with Kerrville and San Antonio by Interstate 10, which provides a convenient cross-track route to better weather from those locations if movement is necessary on eclipse day. Don’t leave it to the last minute—the 2017 eclipse taught us that even Interstates will come to a halt when the eclipse is imminent!
Source: Eclipsophile.com
Eye Safety During A Total Solar Eclipse
Except during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun’s bright face, it is not safe to look directly at the Sun without specialized eye protection for solar viewing.
Viewing any part of the bright Sun through a camera lens, binoculars, or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury.
When watching the partial phases of the solar eclipse directly with your eyes, which happens before and after totality, you must look through safe solar viewing glasses (“eclipse glasses”) or a safe handheld solar viewer at all times. Eclipse glasses are NOT regular sunglasses; regular sunglasses, no matter how dark, are not safe for viewing the Sun. Safe solar viewers are thousands of times darker and must comply with the ISO 12312-2 international standard.
Always inspect your eclipse glasses or handheld viewer before use; if torn, scratched, or otherwise damaged, discard the device. Always supervise children using solar viewers.
Do NOT look at the Sun through a camera lens, telescope, binoculars, or any other optical device while wearing eclipse glasses or using a handheld solar viewer — the concentrated solar rays will burn through the filter and cause serious eye injury.
Do NOT use eclipse glasses or handheld viewers with cameras, binoculars, or telescopes. Those require different types of solar filters. When viewing a partial or annular eclipse through cameras, binoculars, or telescopes equipped with proper solar filters, you do not need to wear eclipse glasses. (The solar filters do the same job as the eclipse glasses to protect your eyes.)
Here are some important safety guidelines to follow during a total solar eclipse:
- View the Sun through eclipse glasses or a handheld solar viewer during the partial eclipse phases before and after totality.
- You can view the eclipse directly without proper eye protection only when the Moon completely obscures the Sun’s bright face – during the brief and spectacular period known as totality. (You’ll know it’s safe when you can no longer see any part of the Sun through eclipse glasses or a solar viewer.)
- As soon as you see even a little bit of the bright Sun reappear after totality, immediately put your eclipse glasses back on or use a handheld solar viewer to look at the Sun.
Source: NASA
Solar Filters For Optics
With one notable exception, it is never safe to look directly at the Sun through a telescope, binoculars, or camera lens without a solar filter. That exception is during totality, when the dazzlingly bright solar surface is completely blocked by the Moon. But totality is fleeting. Most of the time during an eclipse you’ll be watching the partial phases, during which filters are always required.
Telescopes, binoculars, and cameras need solar filters for two reasons: to protect them from intense sunlight and to ensure that you don’t accidentally look at the Sun through an unfiltered instrument. In every case, the solar filter must be attached to the front of your telescope, binoculars, or camera lens. This ensures that the Sun’s light and heat are kept out of the optics.
Make sure the filter is attached securely so it won’t pop off if your instrument is bumped or the wind suddenly gusts — but not so securely that you can't remove it easily at the beginning of totality!
If your telescope has a small auxiliary finder scope or other aiming device, make sure that it is capped, removed, or safely filtered just like the main telescope.
Solar filters provided with inexpensive telescopes, usually designed to thread into an eyepiece at the back end of the telescope, are dangerous. If the filter is attached to the spot where you place your eye, sunlight concentrated by your optics will burn right though it. This is also why looking through unfiltered optics while wearing eclipse viewers is extremely dangerous and a recipe for serious eye injury. We'll say it again: a solar filter must be attached to the front of your telescope, binoculars, or camera lens.
You’ll generally encounter three types of solar filters: metal on glass (usually the most durable and expensive), aluminized polyester film (frequently referred to as aluminized Mylar), and black polymer (sometimes with a layer of aluminized polyester on one side). Some render the Sun white, while others impart a yellow, orange, or bluish tint. All are effective, so choose the type that best suits your preference and budget.
Source: American Astronomical Society
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If you have any questions about this event, please contact Club President David Swinney.