The Moon covers the Sun. What's the big deal?
Given the hype surrounding Monday's total eclipse, astrophysicist Dr. Angela Speck has faced that question many times. Speck is director of the astronomy department at the University of Missouri and chairs the American Astronomical Society's Total Solar Eclipse Task Force.
During a recent visit to Fulton, Speck walked listeners through the science of the eclipse - and why they should care.
"There are some things people just ought to see," she said. "It would be a pity if people missed it."
Reason 1: It's a rarely seen phenomenon
Eclipses aren't actually that rare, Speck said.
"The eclipse is what happens when the new moon is in front of the Sun," she said.
As the Earth orbits the Sun, the Moon circle Earth. However, the Moon's path is tilted relative to the Earth and Sun's orbital plane. Also, the Moon's distance from the Earth changes; its orbit isn't a perfect circle.
Occasionally everything lines up just right so the Moon is directly between the Earth and the Sun. But the Moon has to be at the right distance, too. If it's too far from Earth, it'll only block the Sun's middle, resulting in an "annular" eclipse (where you can see a ring of Sun around the Moon).
"We get a solar eclipse somewhere on the planet nearly once a year," Speck said.
The key phrase there is "somewhere on the planet." Because the Moon is smaller than the Earth and far away, it casts a relatively small shadow, only about 70 miles wide. Only the people who happen to be inside that shadow as the Earth turns get to see the total eclipse.
Large parts of the planet are covered in water or have few inhabitants. The 2015 total solar eclipse happened near the North Pole, and the few astronomers there to see it got chased by polar bears, Speck said.
"The chance of whether your bit of the planet gets to see it is very slim," she added.
The last time an eclipse happened over Fulton was in the 1400s, Speck said. She added people often tell her they saw eclipses while growing up, but m ost have only seen a partial or annular eclipse.
"We had one of those over Missouri in 1994," she said.
Reason 2: It's highly accessible
Speck said other recent eclipses over land have been in places that are difficult to access or unsafe. Scientists had difficulty getting permission to bring equipment to China for its 2009 total solar eclipse.
"This one crosses over land for such a long time - over places with scientific equipment that are relatively safe," Speck said.
This eclipse enters the U.S. in Oregon and exits by way of South Carolina.
"About 12 million people don't need to go anywhere (to see the total eclipse)," she said.
Another 50 million live within 100 miles of the path of totality. Additionally, no matter where you are in the U.S. you'll at least see a partial eclipse, she said.
"Northern Maine gets 50 percent (of the Sun covered)," she said.
Reason 3: It's scientifically important
Many scientists are taking advantage of the eclipse. While a point at the center of the path of totality will only see totality for about two and a half minutes, the shadow will take about 90 minutes to cross America. That's a lot of time to collect data at many spots across the map, Speck said.
"NASA has seven observation bases along the path, including in Jefferson City," Speck said.
NASA has also coordinated weather balloon launches across the United States. The balloons will lift instruments high into the atmosphere to collect data. In Fulton, Arkansas State University's BalloonSAT will study air temperature and pressure during the eclipse.
Over in Columbia, scientists at the University of Missouri will study animal behavior during the eclipse, Speck said.
The American Astronomical Society is also promoting citizen science during the eclipse. Visit this site to learn about experiments can be done at home: eclipse.aas.org/resources/citizen-science.
Reason 4: It's going to look amazing
Speck made it clear the eclipse is safe to observe with proper equipment.
"I want to make sure that you are reassured and you spread the word that this is not scary," she said.
As long as you use eclipse-viewing glasses during the lead-up to totality, your eyes will be safe, she said.
While the Moon's shadow approaches, the temperature will drop by about 10 degrees, creating an area of low air pressure.
"There's a wind that's flowing into the path of totality," she said. "The wind will blow away any wispy clouds."
For about 90 minutes, the temperature will steadily drop and more and more of the Sun will be covered. However, the Sun's so bright that not much difference will be visible until it's about 75 percent covered, she said.
"Toward the horizon, you will see colors like just after a sunset, except all around you," Speck said.
Animals may behave as if the sun is actually setting, with birds swooping around and singing.
Right before the Moon covers the sun, a single bright spot will peek out around it, making what looks like a diamond ring in the sky. After the "diamond" vanishes, it'll be safe to remove your eclipse glasses, Speck said.
Totality will begin at 1:13 p.m. and last about two minutes and 34 seconds in Fulton.
"It's only going to be two and a half minutes, but it's still gong to be an impressive two and a half minutes," she said. "Possibly the most impressive two and a half minutes of your life."
With the main body of the Sun covered, watchers will be able to see the solar corona (the Sun's outermost layer).
"This isn't like anything you've seen before," Speck said.
Giant jets of burning plasma will trace bright lines around the Moon.
"You'll be able to see winter stars," Speck added - that is, if you can tear your eyes away from the Sun.
Even if clouds obscure the eclipse, viewers will still see the sky go dark and feel the temperature drop. The National Weather Service predicted Monday will be partly cloudy with a 20 percent chance of precipitation.