Get ready for the April 2024 total solar eclipse. Learn about the science behind solar eclipses, how to watch safely, and how to engage students in NASA science.
On April 8, 2024, a total solar eclipse will be visible across much of the central and northeastern United States, as well as parts of Mexico and Canada.
Whether you are traveling to the path of the total eclipse or will be able to step outside and watch the eclipse where you live, here's everything you need to know, including what to expect, how to watch safely, and how to engage in scientific observations and discovery with NASA.
What Are Solar Eclipses?
Solar eclipses occur when the Sun, the Moon, and Earth align. For this alignment to happen, two things need to be true. First, the Moon needs to be in the new moon phase, which is when the Moon’s orbit brings it between Earth and the Sun. Second, eclipses can only happen during eclipse seasons, which last about 34 days and occur just shy of every six months. An eclipse season is the time period when the Sun, the Moon, and Earth can line up on the same plane as Earth's orbit during a new or full moon. If a new moon happens during an eclipse season, the shadow cast by the Moon will land on Earth, resulting in a solar eclipse. Most of the time, because the Moon’s orbit is slightly tilted, the Moon’s shadow falls above or below Earth, and we don't get a solar eclipse.
Not all solar eclipses look the same. The distance between the Sun, the Moon, and Earth plays an important role in what we see during a solar eclipse. Even though the Moon is much smaller than the Sun (about 400 times smaller in diameter), the Sun and Moon look about the same size from Earth. This is because the Sun is about 400 times farther away than the Moon. But as the Moon travels its elliptical orbit around Earth, its size appears slightly larger when it is closer to Earth and slightly smaller when it is farther from Earth. This contributes to the different kinds of solar eclipses you might have heard about. For example:
- During a total solar eclipse, the Moon is closer to Earth in its orbit and appears larger, completely blocking the Sun's disk. This allows viewers in the path of totality to see the Sun’s corona, which is usually obscured by the bright light of the Sun’s surface.
- An annular solar eclipse occurs when the Sun, Moon, and Earth are properly aligned, but the Moon is farther away in its orbit, so it does not completely cover the Sun's disk from our perspective. Annular eclipses are notable for the "ring of fire," a thin ring of the Sun’s disk that's still visible around the Moon during annularity. The name annular eclipse comes from the world of mathematics, where a ring shape is known as an annulus.
- Partial eclipses can happen for two reasons. First, viewers outside the path of totality during a total solar eclipse – or the path of annularity during an annular eclipse – will see only part of the Sun’s surface covered by the Moon. The other time a partial eclipse can occur is when the Moon is nearly above or below Earth in its orbit so only part of the Moon’s shadow falls on Earth. In this case, only part of the Sun’s surface will appear covered by the Moon.
How to Watch the Upcoming Solar Eclipse
First, an important safety note: Do not look directly at the Sun or view any part of the partial solar eclipse without certified eclipse glasses or a solar filter. Read more below about when you can safely view the total solar eclipse without eclipse glasses or a solar filter. Visit the NASA Eclipse website for more information on safe eclipse viewing.
When following proper safety guidelines, witnessing an eclipse is an unparalleled experience. Many “eclipse chasers” have been known to travel the world to see solar eclipses. Here's what to expect on April 8, 2024:
The start time and visibility of the eclipse will depend on your location. You can use this map to find detailed eclipse information, including the start time, by clicking on your location.
The eclipse begins when the edge of the Moon first crosses in front of the disk of the Sun. This is called a partial eclipse and might look as if a bite has been taken out of the Sun.
It is important to keep your eclipse glasses on during all parts of the partial solar eclipse. The visible part of the Sun is tens of thousands of times brighter than what you see during totality. You can also use a pinhole camera to view the eclipse.
An approximately 115-mile-wide strip known as the path of totality is where the shadow of the Moon, or umbra, will fall on Earth. Inside this path, totality will be visible starting about 65 to 75 minutes after the eclipse begins.
If you are in the path of totality, it is safe to take off your eclipse glasses and look at the total eclipse only during totality. Be sure to put your glasses back on before the total phase ends and the surface of the Sun becomes visible again. Your viewing location during the eclipse will determine how long you can see the eclipse in totality. In the U.S., viewers can expect to see 3.5 to 5.5 minutes of totality.
After totality ends, a partial eclipse will continue for 60 to 80 minutes, ending when the edge of the Moon moves off of the disk of the Sun.
For more information about the start of the partial eclipse, the start and duration of totality, and the percentage of the Sun eclipsed outside the path of totality, find your location on this eclipse map.
On April 8, NASA Television will host a live broadcast featuring views from telescopes along the path of totality.
What Solar Eclipses Mean for Science
Solar eclipses provide a unique opportunity for scientists to study the Sun and Earth from land, air, and space, plus allow the public to engage in citizen science!
Scientists measure incoming solar radiation, also known as insolation, to better understand Earth’s radiation budget – the energy emitted, reflected, and absorbed by our planet. Just as clouds block sunlight and reduce insolation, eclipses create a similar phenomenon, providing a great opportunity to study how increased cloud cover can impact weather and climate.
Solar eclipses can also help scientists study solar radiation in general and the structure of the Sun. On a typical day, the bright surface of the Sun, called the photosphere, is the only part of the Sun we can see. During a total solar eclipse, the photosphere is completely blocked by the Moon, leaving the outer atmosphere of the Sun (corona) and the thin lower atmosphere (chromosphere) visible. Studying these regions of the Sun’s atmosphere can help scientists understand solar radiation, why the corona is hotter than the photosphere, and the process by which the Sun sends a steady stream of material and radiation into space. Annular solar eclipses provide opportunities for scientists to practice their observation methods so that they'll be ready when a total solar eclipse comes around.
Citizen scientists can get involved in collecting data and participating in the scientific process, too, through NASA’s GLOBE program. During the eclipse, anyone in the path of the eclipse and in partial eclipse areas can act as citizen scientists by measuring temperature and cloud cover data and report it using the GLOBE Observer app to help further the study of how eclipses affect Earth’s atmosphere.
Visit NASA's Eclipse Science page to learn more about the many ways scientists are using the eclipse to improve their understanding of Earth, the Moon, and the Sun.
Solar Eclipse Lessons and Projects
Use these standards-aligned lessons and related activities to get your students excited about the eclipse and the science that will be conducted during the eclipse.
- Student Project
How to Make a Pinhole Camera
Learn how to make your very own pinhole camera to safely see a solar eclipse in action from anywhere the eclipse is visible, partial or full!
Time < 30 mins
Students learn about the phases of the Moon by acting them out. In 30 minutes, they will act out one complete, 30-day, Moon cycle.
Time 30-60 mins
- Math Problem
Model a Solar Eclipse
Students use simple materials to model a partial, annular, and total solar eclipse.
Time 30-60 mins
Measuring Solar Energy During an Eclipse
Students use mobile devices to measure the impact a solar eclipse has on the energy received at Earth’s surface.
Time 1-2 hrs
Modeling the Earth-Moon System
Students learn about scale models and distance by creating a classroom-size Earth-Moon system.
Time 30-60 mins
- Math Problem
Students use the mathematical constant pi to approximate the area of land covered by the Moon’s shadow during the eclipse.
Time < 30 mins
- Math Problem
Students use pi to figure out how much of the Sun’s disk will be covered by the Moon during an eclipse and whether it’s a total or annular eclipse.
Time < 30 mins
- Mobile App
NASA GLOBE Observer App
Students can become citizen scientists and collect data for NASA’s GLOBE Program using this app available for iOS and Android devices.