Total solar eclipse: Astronomers uncover the science behind rare phenomenon

The last time the shadow of a total solar eclipse passed over the Lone Star State was in the summer of 1878. Rutherford B. Hayes was president and Texas Agricultural and Mechanical University had opened its doors to students just two years before his.

Much has changed since then, but the total solar eclipse on April 8 promises to be just as spectacular as the one that dazzled parts of Texas 146 years ago. For those lucky enough to see the eclipse in person, Texas A&M University astronomer Justin Spilker said the eclipse will offer “one of the most spectacular views nature can offer on Earth.” He said he would provide it.

If skies are clear, viewers of the solar eclipse within its total path, about 160 miles wide, will get a rare glimpse of the sun’s white, hot outer atmosphere, the corona, made up of an ever-changing wisp of plasma spread across space. You could do that.

“Normally this is completely invisible because the sun is so bright. You can actually see it for only a few minutes (when the moon covers the sun),” said Associate Professor in the Department of Physics and Astronomy said Spilker. Texas A&M College of Arts and Sciences.

During that brief moment, he says, things on Earth will begin to look and feel different. For those under the moon’s shadow, “the sun will appear to set in all directions around the horizon. You will see the perceived temperature drop by as much as 5 to 10 degrees. Birds will begin to go to nest. , the crickets think it’s night and start chirping. And about four minutes later the sun appears again.”

How rare are total solar eclipses?

Two conditions must be met for a total solar eclipse to occur, said Kevin Christians, associate professor emeritus of education. First, the moon must reach a point in its orbit where it appears perfectly aligned with the center of the sun when viewed from a particular location. spot. If the Moon comes between the Sun and Earth without this perfect alignment, only a partial solar eclipse will occur.

Second, the moon must be close enough to the Earth to block out the entire sun. Further away, an annular solar eclipse will occur where a thin ring of the sun’s surface will be visible.

“The moon’s orbit is roughly elliptical, so its distance from Earth is not always the same,” Kristunas said. “So when you have an alignment, sometimes you get an annular eclipse, and sometimes you get a total eclipse.”

Total solar eclipses, on the other hand, are not that rare, occurring approximately once every 1.5 years, Kristunas said. On the other hand, he said, the paths of these eclipses vary so widely that it is extremely rare for a totality event to occur in any particular location.

“The positions of the moon and sun have to be very precise, so searching for this usually requires traveling,” Kristunas explained. “If you just sit at home and wait for all the infection vectors to cover your home, on average in the Northern Hemisphere you have to wait 350 years between outbreaks. If you’re in the Southern Hemisphere, that’s about 450 years. Once every.”

Crissionas said the fact that Earth experiences a total solar eclipse is largely a “coincidence of fate.” For example, on Mars, both moons are too small and far away to cover the sun, so a solar eclipse seen from the Martian surface wouldn’t be all that surprising.

While Earth’s moon is about 400 times smaller than the sun, it is also about 400 times closer to Earth’s surface, meaning it can barely cover the entire sun during a total solar eclipse, Christunas explained. However, that’s not always the case, he said. The moon is moving away from the earth little by little. NASA estimates that it will be too far away for a total solar eclipse to occur in about 600 million years.

When is it safe to view a solar eclipse?

People observing the eclipse from outside total orbit should always protect their eyes when looking at the sun, Spilker said. Even when partially obscured, the visible surface of the sun, the photosphere, emits an overwhelming amount of light, including visible light as well as infrared and ultraviolet light, he said. Stated. For those on the path of totality, the only time it is safe to observe a solar eclipse with the naked eye is when the sun is completely covered and only the corona is visible.

“In the perfect moment, if you’re feeling lost, that’s when you can take off your glasses,” Spilker said. “Again, you can only take off the glasses if you enter the path of wholeness. I highly recommend it.”

Looking directly at the sun, even for short periods of time, can cause permanent damage to the retina, the layer of light-sensitive cells that lines the inner wall of the back of the eye. Importantly, this part of the body can’t sense pain, so damage to the retina can go unnoticed until later, Kristunas said.

Safe ways to observe a solar eclipse include indirect methods, such as a simple pinhole camera or a telescope that projects an image of the sun onto a piece of paper. If looking directly at the Sun, use eclipse glasses or similar viewing equipment that meet the ISO 12312-2 standard.

“If you have eclipse glasses, your number should be listed somewhere,” Spilker says. “When you wear this, you won’t be able to see anything but the sun.”

If you want to look directly through binoculars or a telescope, you will need to install similar special filters. The same goes for cameras and camera phones, Spilker says, but he argues that it’s best to experience the eclipse with as few distractions as possible.

“I don’t recommend trying to take pictures, especially at the moment of totality,” he says. “It’s a surreal and otherworldly experience, but it only lasts for a very short time. So unless you’re an expert in photography, I recommend living in the moment and experiencing it to the fullest.” I recommend it.”

prepare to be surprised

Spilker said eclipse viewers should also pay attention to the edge of the moon just before and after totality. For a brief period of time, sunlight penetrates the mountains and other features on the moon’s surface, causing a visual phenomenon known as “Bailey’s beads.”

“You’ll start to see a glow of sunlight, like a diamond ring. Outside of that, there will be a corona, and there will be bright flashes of light in certain places,” Spilker said.

Christunas said the experience of observing a total solar eclipse can be difficult to explain, but many people have tried it. One of the descriptions that best captures the “mystery of the whole,” he says, is a passage from the seventh century BC by the Greek poet Archilochus: My father, an Olympian, turned day into night. ”

Humanity’s understanding of the universe has evolved greatly since then, but those under the moon’s shadow on Monday are likely to experience the same sense of awe as the sky slowly darkens, Christunas said. Stated.

“I look up and the sun is like nothing I’ve ever seen before,” he said. “This is a natural phenomenon, so if you have a chance, I highly recommend you to see it at least once.”