Solar eclipse:

 Roughly 32 million Americans live along the route that the moon's shadow will take as it goes across the country. Millions more pouring into towns and cities in the path of totality to get a firsthand view of the total solar eclipse. And for more on the science behind what scientists will be able from it .

 What happens during a total solar eclipse?

Well,  we're taking advantage of a coincidence that we don't know of any other and moon combination has, which is the moon is 400 times smaller than the sun. And yet the sun is 400 times the distance away. So that cancels each other out. And so from where we sit on the surface of Earth, they appear to be the same diameter. Now the moon is on a tilted orbit so this doesn't happen every month whenever there's a new moon. But on occasion, relatively frequently, we get this occurrence where the moon passes right in front of the sun, eclipsing the sun and many times this happens over the ocean. So we don't know about it. In this case, what makes it extra is it's just going to rip across a huge population center, which is to say North America from Mexico through the continental United States, exiting Newfoundland, probably 30 to 40 million people just living under the so-called path of totality.

 So it's going to be a big event.?

Yeah, it sounds like it. And it's also a chance for scientists to learn more about our universe. NASA's going to launch rockets into the path of the eclipse. What makes this a unique research opportunity and what do you think they're hoping to learn?

Well, we want to know about the sun's corona. Looking at the sun with most instruments, there are some instruments which create artificial eclipses but most instruments are unable the corona, which is like a million times fainter than the sun itself. When the moon is eclipsing the sun, you see that outer edge, that crown the corona. Understanding its properties, what's in it? The chemical composition, that sort of thing just tells us more about the most important star we know of, which is to say our sun. So NASA's will fly some high altitude aircraft to gather that kind of spectroscopy information, infrared photography. They'll take a look at how the eclipse affects the ionosphere, the upper atmosphere. When you take away the sun briefly, it gives them an opportunity to see what the sun does to the atmosphere on the ground. They'll be testing some radars. They use to predict so-called space weather to refine their accuracy. So it does it it's nature's opportunity, a natural experiment which scientists always love to take advantage of.

What scientist doesn't love and nature's experiment. It sounds pretty great. It's also just an inspiring moment that we, as you mentioned, don't get to see that often. But in terms of safety, you know there's the thing. Don't look directly at the sun. Cover your eyes. 

Is that true

 What do people need to know about how to observe this safely?

Well, as we all know, we should never look at directly, ever. And unfortunately, during an eclipse, we're kind of tempted. Right? We want to see what's going on up there. So if you are in a situation where it is partial, a partial eclipse, either you're in a place where it's never going to become total or you're waiting for that 4 minutes or so when there's a total eclipse, you need to wear some of these eclipse glasses, these Mylar glasses, which block out enough of the sun's rays to safely look right at it. Now, if you're in the path of totality and you get to the point where the moon has completely covered over the sun, I would invite you to take those glasses off so you can see and marvel at the corona. The glasses are so dark that you might miss out. So be safe about it.

 But also don't forget to take them off when it's safe to do so, because that's the real thrill.

that's the really special It sounds like what will you be doing to watch the eclipse? I made plans to go to Dallas. I will be in the Cotton Bowl with about 30,000 young people. Unfortunately, the weather forecast is not looking fabulous for Dallas as you were just talking about. But I am heartened by the fact that this event is staged by the National Oceanic and Atmospheric Administration and who has more control over the weather than them. Right? Maybe maybe they'll part the clouds and give us all we need is 4 minutes at the right time. Let's just appeal to NOAA and see if they can get it done.