August 21st…. The Great American Eclipse. Hundreds of thousands of people are expected to watch the celestial phenomenon take place as the Earth crosses the shadow of the moon.
Jared Brumbaugh has more on the science of total solar eclipses and what we can expect as the moon’s shadow passes by.
To better understand what a total solar eclipse is and what we can expect, I decided to go straight to the source of space science.
“My name is Noah Petro, I’m a research scientist here at the NASA Goddard Space Flight Center.”
Petro has been extra busy balancing the upcoming eclipse with other NASA projects he’s involved with.
“The Lunar Reconnaissance Orbiter, or LRO, is NASA’s mission orbiting the moon for the last eight years now. We have completely revolutionized our understanding of the lunar surface, its environment and how the moon changes on human time scales.”
The LRO mission has helped NASA identify new impact craters and landslides as well as quantify the presence and abundance of water and volatiles at or near the lunar surface. As exciting as the moon orbiting mission is, Petro is eagerly awaiting the second eclipse of the year. The first was a partial lunar eclipse that happened last week.
“During a total solar eclipse, the simplest explanation is the moon passes directly between Earth and the Sun, so the moon’s shadow gets cast upon the face of the earth. So on August 21st, those that will be along the path of totality will be standing, sitting, lying down in the shadow of moon.”
The path of totality is a 70 mile wide swath that stretches from Oregon to South Carolina, briefly passing over the far western tip of North Carolina. It will take approximately 94 minutes for the moon’s shadow to make the cross country trip.
Folks in the path of totality can see the moon completely block the sun for about 2 minutes. The sky will turn twilight-dark and the temperature could drop by as much as 10 degrees. Fortunately, people in eastern North Carolina can expect an awe-inspiring experience even though we are outside the path of totality.
“Folks in eastern North Carolina are going to get about a 90 percent obscuration of the sun by the moon depending on how close you are to the path of totality. So, in more southern eastern North Carolina, you’ll get a little bit more of an obscuration.”
The start of the partial eclipse, when the moon is first appearing to touch the sun, will occur around 1:21 in the afternoon. Over the next hour and a half, the moon will slowly move in front of the sun until it almost completely covers it.
“I would encourage folks to go out and try to pay attention to how dim it gets. It will not be quite as dark as dusk, but you’ll notice that the sunlight will be decreasing. It will still be bright, so you can’t look at the sun. And you might notice a very subtle temperature change.”
The maximum eclipse will occur around 2:48 in the afternoon. This is the point that the moon most obscures the sun. Birds may fall silent, crickets will chirp and nocturnal animals will believe – if only briefly – that night is falling.
“So I would suspect animals that are very light sensitive will start going about their bedtime routines. But I think for the most part, this is an area that we’ll learn a lot of what happens during an eclipse.”
The Great American Eclipse of 2017 may be the most observed eclipse in history. NASA researchers are taking advantage of the opportunity to try to answer a number of science questions.
“For example, one will be examining the precise timing of the eclipse. NASA, we’ve made predictions on when the eclipse will happen down to the tenth of a second. But any deviation from that timing will be attributable to our lack of understanding for the size of the sun. So just the basic measurement of when the eclipse is happening will help us refine our knowledge of the size of the sun.”
Measuring temperature perturbations during the eclipse will help NASA understand the dynamics of the Earth’s atmosphere. Petro says observations of the sun during totality will also allow scientists to study the solar corona.
“That’s the upper atmosphere of the sun, the super-heated millions of degrees in temperature atmosphere of the sun that we just really can’t measure. The sun’s surface is so bright, it blocks out the solar corona. During solar eclipses, we get an opportunity to make observations of the dynamics of the solar corona. They’re also the human response. I think people will be interested to see how people react to such a long eclipse.”
A handful of eclipse viewing parties and events are planned in eastern North Carolina. Craven Community College in New Bern is holding an event at 2:15 featuring an educational talk with astronomy instructor Dr. Robert Williams.
“We’re going to have telescopes with solar filters, we’ve ordered 250 pairs of solar glasses that are safe to observe. We’ll even have in the student center, we’ll have a live stream from NASA of what the eclipse looks like and that’s particularly good in case it gets cloudy.”
If you’re in the Kinston or Greenville area, A Time for Science in Grifton will host a solar eclipse party from 1 to 4 with solar telescope observing, planetarium shows, games and activities. There’s also a viewing party at Neuseway Planetarium in Kinston.
Whether you’re attending a public event or want to view the eclipse in solitude, Williams cautions people to be well equipped.
“You can get special glasses that should be certified. Or I have here a strip of material that I got from the Orion telescope company. If you have one of these, you can look at the eclipse. But you have to remember, we’re going to see a partial eclipse. We’re never going to get to totality. So the sun is much more dangerous in that situation than it would be ordinarily.”
It’s important to mention, not all solar eclipse glasses are created equal. Cheap knock-offs are being sold in stores and online. To make sure you’re safe, NASA recommends looking for glasses with the certified ISO 12312-2 safety standard. To help you out, NASA has a list of reputable vendors of solar filters and viewers on their website. We’ve posted a link at publicradioeast.org.
People across the country and here in eastern North Carolina are getting geared up for the highly anticipated eclipse. Solar glasses are flying off the shelves and many online retailers have them on backorder. If you are fortunate enough to find a pair, make sure to hang on to them for the next 28 years. That’s when the next total solar eclipse follows a similar path and should be visible here in eastern North Carolina.
For more information on the 2017 Total Solar Eclipse, go to: https://eclipse2017.nasa.gov/safety
For a a list of reputable vendors of solar filters and viewers, go to: https://eclipse.aas.org/resources/solar-filters
To see a visualization of the moon's shadow on Earth, go to: https://svs.gsfc.nasa.gov/Gallery/suneclipse2017.html