An Astronomer’s Guide to the 2024 Total Solar Eclipse

[Visualization of a bright star in space, with a large planet orbiting in front of it and a tiny moon orbiting the planet.]

JACKIE FAHERTY (Senior Scientist, Department of Astrophysics): A solar eclipse is an alignment between– 

[A dotted line goes between the three orbs to show they are in alignment. Text labels appear indicating that the star is the Sun, the planet is Earth, and the moon is our Moon.]

FAHERTY: –the Sun, the Moon and the Earth in that order.

[Birds-eye view of the Solar System, we fly towards the Earth, which has a red orbit showing the Moon’s orbit around it.]

FAHERTY: So as the Earth is going around the Sun with the Moon going around the Earth, you can have occasionally a time–

[On the left of the screen, we see the Earth. On the right, the Moon is barely visible in the light of the Sun. A green cone shows the shadow that the Moon casts on the Earth.]

FAHERTY: –when the Moon lines up perfectly with the Sun's position,

[The counter-side to the previous shot: in the foreground is the Moon, and in the background distance is the Earth, with a shadow appearing on its surface. We fly quickly past the Moon to see the Earth closer up, and see the shadow in more detail.] 

FAHERTY: –thus blocking the light from the Sun and casting a shadow over Earth.

[FAHERTY appears on the screen, speaking to the audience.] 

FAHERTY: If you walk outside and you look at the Sun, which you should never do without protection, but if you did, you would find that you could cover it with your thumb.

[An almost-full Moon sits high in the sky, with the leaves of trees in the foreground.]

FAHERTY: If you do the same thing on a full moon night, you'll find you can also cover it with your thumb. 

[The footage of the Moon fades into a still image of the Sun, with solar flares around it’s edges. Text appears, pointing to the Sun: “400x larger.”] 

FAHERTY: While the Sun is 400 times larger than the Moon, 

[Barely visible beneath the huge size of the Sun, a circle draws around a tiny white speck in the corner of the screen. The speck and circle enlarge to reveal the Moon.] 

FAHERTY: the Moon is 400 times closer–

[Below the image of the Moon, the horizon of Earth from space appears. Text labels the Moon as “400x closer to Earth.”] 

FAHERTY: –than the Sun is.

[Next to the Moon, the same image of the Sun appears, and the two are the same size.] 

FAHERTY: So they can have the same apparent size in the sky. And when that happens,

[A timelapse of the Sun moving in the sky above a mountain.]

FAHERTY: –and they align, you can get the Moon completely blocking the Sun. 

[As the timelapse continues, the Sun darkens to a ring of light as the sky becomes completely dark. The logo for the American Museum of Natural History appears on screen, as the sky begins to lighten again and the Sun re-emerges to its full power.]

FAHERTY: My experience with–

[FAHERTY reappears on screen. Text appears: “Jackie Faherty, Senior Scientist, Department of Astrophysics.”]

FAHERTY: –a total solar eclipse goes back to 2017, where we had the Great American Eclipse. We had a total solar eclipse–

[A visualization of the Earth’s surface with North and South America visible, and an eclipse path projected onto the surface.]

FAHERTY: –that passed over the United States.

[Text appears over the eclipse path map: “August 21, 2017.”] 

FAHERTY: And I had my nephew with me at the time.

[A photo of FAHERTY and her young nephew, with bags packed at the airport.]

FAHERTY: He was seven, and we packed up and went to– 

[FAHERTY and her nephew look at the Sun through tinted solar eclipse glasses.]

FAHERTY: –Casper, Wyoming, which was in the path of totality.

[FAHERTY reappears on screen.] 

FAHERTY: I took a lot of care to try and find the place with the best weather because weather is going to make or break your day.

[A still image of people under a tent looking up at the sky.]

FAHERTY: So we were ready to go the moment that the Moon entered the disk of the Sun.

[A timelapse shows the orange disk of the Sun with a shadow slowly sliding over it until it’s almost a crescent.]

FAHERTY: And then we watched as it slowly crept across the disk of the Sun.

[FAHERTY reappears on screen.] 

FAHERTY: You see the last moments of light that are leaving the Sun, passing through these troughs of mountains on the Moon.

[An image of the Sun, moments before totality during an eclipse. There is a white ring around a dark circle of the Moon’s shadow, and at the bottom left are three small but bright white round circles of light. Text appears labelling the circles of light: “Baily’s beads.”]

FAHERTY: The sun gets covered with these tiny dots of light that are called Baily's beads. 

[FAHERTY reappears on screen.]

FAHERTY: And the very, very last one–

[Footage of a solar eclipse, where the Sun is mostly covered by the Moon’s silhouette. But in the top left, a bright white circle emerges in a flash. Text appears: “December 14, 2020.”]

FAHERTY: –creates a diamond ring effect with the corona of the Sun,

[A painting of the same effect–a lone orange circle of light on the edge of the Moon’s–appears with the text: “September 10, 1923.”]

FAHERTY: –this plasma that surrounds the Sun, for a second,

[FAHERTY reappears on screen.]

FAHERTY: and then all of a sudden in a moment that feels too epic to possibly give words to,

[Timelapse footage of the Sun suddenly being covered by a solar eclipse, as the sky goes from blue to deep purple. Text appears: “August 21, 2017.”] 

FAHERTY: –you go instantaneously from day to dusk with the Sun–

[On a baseball field, onlookers and players watch and [CHEER] as the Sun darkens high in the sky.] 

FAHERTY: –and the corona and the stars coming out.

[FAHERTY reappears on screen.]

FAHERTY: That to me is the most epic kind of immersion in an astronomical phenomenon you can get.

[Vertical footage of the back of a child as the person filming and the people around them [CHEER and YELL] in amazement.] 

[Oh my god – are you kidding me? Oh my god!]

[A still image of a total solar eclipse, where the Sun has been completely covered by the black circle of the Moon’s silhouette, and the hazy plasma corona surrounds the Sun like a cloud.] 

[The orb of the Hayden Planetarium at the American Museum of Natural History stands surrounded by models of the planets of the Solar System, as visitors walk by.] 

FAHERTY: The Earth is not the only planet in the solar system to have eclipses, and it's not the only one to have total solar eclipses.

[FAHERTY reappears on screen.]

FAHERTY: Mercury and Venus don't have moons, so they're out. 

[A visualization of Mars, with two red orbits around it representing its two moons, one of which flies by onscreen. Text reads: “Mars and its moons.”] 

FAHERTY: Mars has two moons, but Mars's moons are–

[A timelapse taken by NASA Perseverance rover (text reads: “April 20, 2022.”) shows Phobos, one of the moons of Mars, flying in front of the Sun. The shadow of Phobos never fully covers the Sun.] 

FAHERTY: –too small and too far away to give total solar eclipses.

[A visualization of Jupiter appears, with one of its moons in the foreground and tens of orange orbit lines from its many other moons surrounding the planet. Text appears: “Jupiter and its moons.”]

FAHERTY: Then there's the outer solar system: Jupiter, Saturn, Uranus, Neptune,

[In the center of the screen, small dark dwarf planet Pluto spins with a few moons surrounding it, with orbit lines in blue. Text appears: “Pluto and its moons.”] 

FAHERTY: even dwarf planet Pluto have moons that are really big and close enough– 

[A visualization of Saturn appears, with tens of red orbit lines from its many moons surrounding the planet. Text appears: “Saturn and its moons.”]

FAHERTY: –that they provide not just eclipses but total solar eclipses– 

[A photo of the surface of Jupiter taken from space appears. There is a big black shadow on one part, and text highlights this as an “eclipse shadow.”]

FAHERTY: –at some point during their year. 

[A photo of Earth taken from space appears, also with a big shadow over North America. Text highlights this as an eclipse shadow.]

FAHERTY: Back here on Earth, we get a total solar eclipse on average every 18 months.

[FAHERTY reappears on screen.]

FAHERTY: We do not get eclipses at the same time or the same place every year. We don't get them every month. And the reason for that is that the Moon's orbit, as it's going around Earth, is actually off by about five degrees. 

[The full orbit of the Moon is visible around the Earth, silhouetted by the Sun’s light in the background. It is clear that the Moon’s orbit is tilted slightly from the plane of Earth’s orbit. As the Moon moves, text highlights the “5° offset between orbits.”]

FAHERTY: Five degrees may not sound like a lot, but actually in space, that turns out to be quite a large number, at least large enough that it ensures that– 

[FAHERTY reappears on screen.]

FAHERTY: –every 28 or so days we're not getting an eclipse.

[A birds-eye view of the Earth orbiting around the Sun. Every so often, but irregularly, the Earth stops orbiting and text highlights that this is the time in it’s year when a solar eclipse happens. This happens at different places throughout the Earth’s orbit, thereby happening at different times in the year.]

FAHERTY: And then remember, Earth is spinning, Moon is spinning. And as those spins are happening, as they're both moving around the Sun,

[FAHERTY reappears on screen.]

FAHERTY: –they're constantly changing the positions they might be in at the time that the Moon lines up with the Sun.

[A solar eclipse path appears, with the shadow of the Moon passing over the North Pole and Greenland. Text reads: “August 12, 2026.”] 

FAHERTY: It changes where it is on the planet–

[Another solar eclipse path appears, with the shadow of the Moon passing over northern Africa and the Mediterranean Sea. Text reads: “August 2, 2027.”] 

FAHERTY: –and it changes the length of time that– 

[Another solar eclipse path appears, with the shadow of the Moon passing over the Indian Ocean between Africa and Australia. Text reads: “November 25, 2030.”]

FAHERTY: –it's going to happen on the planet, too.

[FAHERTY reappears on screen.]

FAHERTY: Staring at the Sun is never a good idea. It's not safe. There's a lot of harmful radiation that comes from the Sun.

[Two baseball players put on tinted and reflective solar eclipse viewing glasses.]

FAHERTY: So there are eclipse viewing glasses.

[Several adults and children look up at the Sun while wearing tinted solar eclipse viewing glasses.]

FAHERTY: They are certified–

[Hands show the interior of a pair of solar eclipse viewing glasses, where “Conforms to ISO 12312-2” is printed inside. A graphic circles this text, and text appears: “Look for ISO 12312-2.”] 

FAHERTY: –so that you know that standards have been put in place to make sure that your eyes are protected.

[FAHERTY reappears on screen.] 

FAHERTY: You also don't actually have to look at the Sun. You could project the Sun onto the ground, onto a cloth,

[Several still photos flash by of people using different telescopes and household objects to project an image of the Sun as the Moon is covering it onto the ground and pieces of paper.] 

FAHERTY: –onto something else, so that you're not actually looking at the Sun, but you're looking at the projection of the Sun and it unfolds like a movie in front of you with the Moon passing in front of it. 

[FAHERTY reappears on screen.]

FAHERTY: If this excites you and you want to go see it, then look up on an eclipse map the path of totality because it's narrow and you got to see if you can get there. But I encourage–

[Footage of a total solar eclipse on a lightly cloudy day.] 

FAHERTY: –everyone that can to participate in this awesome astronomical event.

[Credits roll.]