The total solar eclipse is coming, and people are starting to prepare to watch the event. On August 17, the moon will completely cover the disc of the sun all the way from Oregon to South Carolina. The phenomenon, which has been dubbed the Great American Total Solar Eclipse, is expected to attract millions of viewers.
The total solar eclipse will be seen in states between Oregon and South Carolina, including Idaho, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, and North Carolina. Astronomers noted that the duration of the eclipse will depend on where you are.
It is important to take some precautions when viewing the total solar eclipse, and specialists say that anyone planning to watch the event should get a pair of solar viewing glasses, which are sold by several companies. NASA scientists were able to calculate exactly when and where the total solar eclipse will be seen.
NASA scientists predicted exactly where the Aug. 17 total solar eclipse will be seen
Ernie Wright, a NASA scientist that has been creating NASA’s visualizations of the event, spoke to Space.com to explain how satellites mapping the surface of the moon, along with advances in computing power made it possible for scientists to predict exactly where and for how long the total solar eclipse will be seen. NASA scientists were even able to predict the sites with a precision of around 100 meters (330 feet).
Wright explained that there is a 19th-century technique for predicting solar eclipses that involves scientists using a coordinate system aligned with the shadow of the moon on the Earth, which makes it easy to determine if a person on the ground was inside or outside the shadow’s circle. However, Wright believes that the method simplifies the sun-moon-Earth system, and it is only accurate within a few miles, depending on the location.
“That all assumes that the moon is perfectly smooth and that all the observers on the Earth are at sea level. These are simplifying assumptions; when you have to make these calculations with pencil and paper you need to simplify them a little bit,” said Wright, according to Space.com. “In the space age, we now have really excellent elevation maps of both the moon and the Earth, and elevations on the moon affect the limb of the moon – this is the edge of the moon’s disc as we see it from Earth – so it’s kind of bumpy, it’s jagged.”
Computing power allowed NASA to create models to predict precise viewing sites of total solar eclipse
The moon’s valleys and craters can allow glimmers of sunlight by when a simplified model would expect for the sun to be covered completely. Earth’s elevations also have a significant effect on the visibility of the eclipse, as scientists found.
Wright has been using elevation data from NASA’s Shuttle Radar Topography Mission, which can measure the elevation at 1,200 points between each line of longitude or latitude. He also considers the precise locations of the Earth, moon, and sun at each time to create his models, as well as the time the sunlight takes to travel to the moon and back down to Earth.
Wright first uses the 19th-century coordinate system as a starting point and then calculates the view for millions of potential observers by analyzing the profile of the moon, size, and angle of the sky, and elevations at points on the ground.
“It’s just been this confluence of large datasets from remote sensing and computing power that have allowed us to do this in the last 10 years,” told Wright to Space.com. “The animation that I did, that shows the shape of the umbra and all of that stuff, calculated the observer circumstances at half a trillion points – nobody’s going to do that by hand. They’d be happy if they could do 10 of them.”
He added that computers love to do things over and over again, as they never get tired.
Temperatures could drop about 10 degrees F during the ‘Great American Total Solar Eclipse’
Some people are wondering how much will the temperature drop during the total solar eclipse, as observers of these kinds of events have reported feeling sudden drops in temperature when the eclipse occurs.
Scientists say that the change in temperature varies based on the location and time of the year. The sudden drop is created by the loss of light from the sun’s disk, and it’s similar to the difference between the temperature at midday and the temperature after sunset, except on this occasion, the change will be quite sudden.
During a solar eclipse on December 9, 1834, the Gettysburg Republican Banner reported that in some locations, the eclipse caused temperatures to drop by as much as 28 degrees F, from 78 degrees F to 50 degrees F (25 degrees C to 10 degrees C). During another solar eclipse on the Norwegian island of Svalbard in Antarctica in March 2015, temperatures dropped from 8 degrees F to minus 7 degrees F (minus 13 degrees C to minus 21 degrees C). However, experts estimate that people can expect an average drop of around 10 degrees Fahrenheit (around 5 degrees Celsius) for this total solar eclipse.