You might have heard that Earth recently gained an extra moon. Apparently, though, this isn’t enough disruption for our solar system for some scientists’ tastes. Now they want to get rid of the sun as well. More specifically, a group of researchers at the European Space Agency are planning to launch a pair of satellites into orbit around Earth, with the aim of creating a solar eclipse on command.

Why would anyone want to trigger an artificial solar eclipse? To slow down global warming? To protect us from apocalyptic solar storms? As a backlash against solar power? To force us to use fossil fuels, like Mr Burns in that one episode of The Simpsons? We’ve tried to answer all of these important questions, and more, below.

THE MISSION IS SET TO LAUNCH BEFORE THE END OF 2024

You might think that blocking out the sun sounds like a distant sci-fi dream (or nightmare) but the two satellites that will undertake the mission are scheduled to be launched before the year is out, maybe even as soon as the next few weeks. Together, they’re known as Proba-3, and can fly in sync – to the tune of a single millimetre – thanks to lasers and light sensors that communicate their exact location. For the mission, they’ll orbit Earth at a distance of 144 metres apart, functioning as a single observatory.

WHAT WILL PROBA-3 ACTUALLY DO?

During their precise orbit, one of the Proba-3 spacecraft will block the view of the sun as seen from the other craft using a disc or “occulter”. Essentially, this will create an eclipse that can last several hours, during which the second craft can take measurements and take a look at the sun’s corona (the bit that bleeds around the edge of an object during an eclipse) in unprecedented detail.

In a dazzling first, two European spacecraft —flying in millimeter-perfect formation — have created an artificial solar eclipse in space, capturing the clearest images of the Sun’s elusive corona yet.

The European Space Agency’s Proba-3 mission has released its first set of solar corona images, offering a rare glimpse into one of the Sun’s most mysterious layers that holds clues to solar storms and space weather.

The breakthrough comes after the twin satellites, carrying Coronagraph and Occulter, achieved the remarkable feat of flying 150 meters apart in near-perfect sync, creating an orbiting total eclipse for scientific study.

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Unlike traditional coronagraphs, which must contend with stray light and Earth’s atmosphere, Proba-3 performed this delicate maneuver entirely in space.

Precision in outer space

The Occulter blocked out the Sun’s bright disk with a 1.4-meter shield, casting an 8-centimeter-wide shadow onto the Coronagraph’s optical instrument, ASPIICS, which then captured the faint, ghostly halo of the corona.

With its 5-centimeter aperture, ASPIICS is able to see much closer to the Sun’s surface and with greater clarity than ever before.

Proba-3 Occulter eclipsing Sun for Coronagraph spacecraft. Credit -ESA

“Each full image – covering the area from the occulted Sun all the way to the edge of the field of view – is actually constructed from three images. The difference between those is only the exposure time, which determines how long the coronagraph’s aperture is exposed to light. Combining the three images gives us the full view of the corona,” said Andrei Zhukov, Principal Investigator for ASPIICS at the Royal Observatory of Belgium.

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This artificial eclipse can be generated every 19.6 hours and held for up to six hours, a vast improvement over the fleeting minutes of natural eclipses, which occur barely once or twice a year.

The solar corona, mysteriously hotter than the surface beneath it, is central to understanding the solar wind and coronal mass ejections. These violent bursts of particles can spark auroras or disrupt communications and power grids on Earth.

Proba-3’s early observations are already helping refine solar models, especially with the support of ESA’s Virtual Space Weather Modelling Centre and KU Leuven’s COCONUT software.

Proba-3’s artificial solar eclipse. Credit-ESA

“Seeing the first data from ASPIICS is incredibly exciting. Together with the measurements made by another instrument on board, DARA, ASPIICS will contribute to unraveling long-lasting questions about our home star,” says Joe Zender, ESA’s Proba-3 project scientist.

Aiming for autonomy

Proba-3’s formation flying relies on a suite of advanced positioning systems developed under ESA’s General Support Technology Programme.

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Mission manager Damien Galano said that the satellites achieved their first precise alignment autonomously, with ground control ready to step in, though future operations aim for full autonomy.

“Having two spacecraft form one giant coronagraph in space allowed us to capture the inner corona with very low levels of stray light in our observations, exactly as we expected.,” Galano said.

“Although we are still in the commissioning phase, we have already achieved precise formation flying with unprecedented accuracy. This is what allowed us to capture the mission’s first images, which will no doubt be of high value to the scientific community.

The mission also carried two other scientific instruments including the Digital Absolute Radiometer (DARA), which measures the Sun’s total energy output, and the 3D Energetic Electron Spectrometer (3DEES), which studies electron activity in Earth’s radiation belts.

The Sun and its corona viewed by Proba-2, Proba-3 and SOHO. Credit-ESA

Built by a 14-country consortium led by Spain’s Sener, with key input from Belgium and India, Proba-3 launched aboard a PSLV-XL rocket from Sriharikota in December 2024.

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Scientists are now working to extend the eclipse observation window and feed the data into models that could forecast solar activity with greater accuracy.

“Current coronagraphs are no match for Proba-3, which will observe the Sun’s corona down almost to the edge of the solar surface. So far, this was only possible during natural solar eclipses,” says Jorge Amaya, Space Weather Modelling Coordinator at ESA.

“This huge flow of observations will help refine computer models further as we compare and adjust variables to match the real images. Together with the team at KU Leuven, which is behind one such model, we have been able to create a simulation of Proba-3’s first observations.”

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An illustration showing the artificial eclipse captured by the ESA’s Proba-3 mission. | Credit: Daisy Dobrijevic

Total solar eclipses are rare, but exactly how rare is now up for debate after the European Space Agency debuted the first images today (June 16) from two new satellites that together operate as an “eclipse machine.”

Total solar eclipses currently occur 14 times every 18 years and 11 days somewhere on Earth, which is one every 16 months, on average. According to NASA, they occur once every 366 years in any specific place.

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Requiring neither lucky geography nor patience, the European Space Agency (ESA) Proba-3 mission, which launched on a PSLV-XL rocket from India’s Satish Dhawan Space Centre on Dec. 5, 2024, has just sent back its first images that are sure to impress eclipse chasers across the world. The mission is the first to see two satellites orbit in a “precision formation,” with one acting as the moon to eclipse the sun in front of the other, which points a telescope at the sun to capture its elusive corona.

A decade in the making, these first images — from the mission’s first successful formation flying demo on May 23 — are a glimpse of what’s to come.

The sun’s inner corona appears green in this visible-light image taken on May 23, 2025, by the ASPIICS coronagraph aboard Proba-3. | Credit: ESA/Proba-3/ASPIICS/WOW algorithm

The sun’s corona

The solar corona, the sun’s outer atmosphere, is a mystery. The sun’s photosphere, its surface, is about 10,000 degrees Fahrenheit (5,500 degrees Celsius), but the corona is two million degrees Fahrenheit (over 1,1 million degrees C) — about 200 times hotter. Scientists need to know why and how this is the case, mainly because the corona is where the solar wind is generated.

The coronal green line — the hottest part of the sun’s inner corona — and a loop following a solar flare, in an image taken on May 23, 2025, by the ASPIICS coronagraph aboard Proba-3. | Credit: ESA/Proba-3/ASPIICS

“As well as being an amazing thing to see, the corona is also a laboratory for plasma physics and the main source of space weather,” said Andrei Zhukov, Principal Investigator for the Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun (ASPIICS) at the Royal Observatory of Belgium, speaking at the Solar Eclipse Conference in Leuven, Belgium.

A prominence in the sun’s inner corona — as often seen during a total solar eclipse — appears faint yellow in this image of helium atoms taken on March 23, 2025, by the ASPIICS coronagraph aboard Proba-3. | Credit: ESA/Proba-3/ASPIICS

Capturing a prominence

Observations of the corona are crucial to understanding phenomena such as solar wind and coronal mass ejections, which can disrupt Earth’s power and communication systems and produce spectacular displays of the northern lights. However, Proba-3’s images will also help solar physicists see features in the corona that are sometimes visible to observers of total solar eclipses. “Sometimes, clouds of relatively cold plasma are observed near the sun, creating what we call a prominence,” said Zhukov. Prominences are much colder than the surrounding million-degree hot plasma in the corona, though still around 10,000 degrees Celsius. “We are very happy to have been able to capture one such structure in one of the first ASPIICS images,” said Zhukov.

The sun’s inner corona in violet to show polarised white light, in an image taken on May 23, 2025, by the ASPIICS coronagraph aboard Proba-3. | Credit: ESA/Proba-3/ASPIICS

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Coronagraphs in space

But there’s a problem. The sun’s disk is a million times brighter than the corona and completely overwhelms the human eye. The only time the corona can be seen is during a total solar eclipse. “They’re inconvenient, they’re rare and last only a few minutes,” said Zhukov.”The last total solar eclipse in Belgium was in 1406, and the next is in 2090. That’s why we have coronagraphs.”

A coronagraph is a device attached to a telescope that blocks out the direct light from a star — in this case, the sun — so that whatever is around it can be seen. Sometimes it’s exoplanets. In this case, it’s the corona. Unfortunately, Earth’s atmosphere scatters that light. In short, they work much better in space. “Current coronagraphs are no match for Proba-3, which will observe the sun’s corona down almost to the edge of the solar surface,” says Jorge Amaya, Space Weather Modelling Coordinator at ESA. “So far, this was only possible during natural solar eclipses.”

A mash-up of three images: the sun’s disc in ultraviolet (yellow) light from Proba-2, the outer corona (in red) from the LASCO C2 coronagraph on NASA’s SOHO Observatory, and the inner corona (in green) from Proba-3’s ASPIICS coronagraph. | Credit: ESA/Proba-3/ASPIICS

Proba-3’s first images

In March, Proba-3’s two spacecraft — the Coronagraph satellite and the Occulter satellite — aligned 500 feet (150 meters) apart with millimeter accuracy for several hours without ground intervention. The Occulter successfully blocked the sun’s disk to cast a shadow onto ASPIICS — the coronagraph’s sensitive optical instrument that captures the corona. “Having two spacecraft form one giant coronagraph in space allowed us to capture the inner corona with very low levels of stray light in our observations, exactly as we expected,” said Damien Galano, Proba-3 mission manager. “I was absolutely thrilled to see the images, especially since we got them on the first try,” said Zhukov. “It’s just a teaser because we are still in the commissioning phase.”

How Proba-3’s images are created

Proba-3 is ESA’s — and the world’s — first precision formation flying mission. | Credit: ESA-F. Zonno

The images themselves were processed by scientists and engineers at the ASPIICS Science Operations Centre at the Royal Observatory of Belgium. Each complete image — covering the area from the occulted sun to the edge of the field of view — is constructed from three images. “The difference between those is only the exposure time, which determines how long the coronagraph’s aperture is exposed to light. Combining the three images gives us the full view of the corona,” said Zhukov. “Our ‘artificial eclipse’ images are comparable with those taken during a natural eclipse — the difference is that we can create our eclipse once every 19.6-hour orbit.”

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Proba-3 will create about 1,000 hours of images of the corona over its two-year mission — and anyone will be able to download the data. “We have an open data policy — the uncalibrated data will be published immediately so everyone will be able to calibrate their own data,” said Zhukov.

Proba-3’s orbit

The paired Proba-3 satellites will have a highly elliptical orbit. | Credit: ESA – P. Carril, 2013

The solar-powered Proba-3 satellites have an elliptical orbit with a perigee (closest point) of 373 miles (600 kilometers) and an apogee of 37,000 miles (60,000 kilometers). They only fly in formation when close to apogee because that’s when Earth’s gravity, its magnetic field and atmospheric drag are at their weakest. That allows the satellites to use minimal propellant to attempt formation flying. The coronagraph satellite positions itself 492 feet (150 meters) behind the occulter satellite — two orders of magnitude farther than any other space-based coronagraph — with the formation flying performed down to a single millimeter in precision. The 4.4 feet (1.4 meters) occulter casts a 3.15 inch (8 centimeters) shadow onto the coronagraph. Remarkably, it’s all done autonomously, with Proba standing for “Project for onboard autonomy”.

“The precision achieved is extraordinary,” said Dietmar Pilz, ESA Director of Technology, Engineering and Quality. “It validates our years of technological development and positions ESA at the forefront of formation flying missions.”

The first artificial solar eclipse

Artificial solar eclipse produced by NASA’s Apollo spacecraft in 1975, observed from a Russian Soyuz spacecraft during the Apollo-Soyuz Test Project. | Credit: NASA

Proba-3 is not unique. A joint mission between the U.S. and the Soviet Union, the Apollo-Soyuz Test Project in 1975 saw the first coronal observation using formation flying, with the Apollo spacecraft acting as an improvised coronagraph, allowing the Soyuz crew to photograph the solar corona. “It was all done by hand — the image was taken through a window of a Soyuz spacecraft,” said Zhukov. The results were disappointing, mainly because the thruster gases around the spacecraft scattered the light.

With Proba-3, the concept has become a reality, and artificial solar eclipses will be possible, revealing the inner solar corona without the need to wait for a total solar eclipse. Will that deter eclipse chasers? Absolutely not!

CAPE CANAVERAL, Fla. (AP) — A pair of European satellites have created the first artificial solar eclipses by flying in precise and fancy formation, providing hours of on-demand totality for scientists.

The European Space Agency released the eclipse pictures at the Paris Air Show on Monday. Launched late last year, the orbiting duo have churned out simulated solar eclipses since March while zooming tens of thousands of miles (kilometers) above Earth.

Flying 492 feet (150 meters) apart, one satellite blocks the sun like the moon does during a natural total solar eclipse as the other aims its telescope at the corona, the sun’s outer atmosphere that forms a crown or halo of light.

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It’s an intricate, prolonged dance requiring extreme precision by the cube-shaped spacecraft, less than 5 feet (1.5 meters) in size. Their flying accuracy needs to be within a mere millimeter, the thickness of a fingernail. This meticulous positioning is achieved autonomously through GPS navigation, star trackers, lasers and radio links.

Dubbed Proba-3, the $210 million mission has generated 10 successful solar eclipses so far during the ongoing checkout phase. The longest eclipse lasted five hours, said the Royal Observatory of Belgium’s Andrei Zhukov, the lead scientist for the orbiting corona-observing telescope. He and his team are aiming for a wondrous six hours of totality per eclipse once scientific observations begin in July.

Scientists already are thrilled by the preliminary results that show the corona without the need for any special image processing, said Zhukov.

“We almost couldn’t believe our eyes,” Zhukov said in an email. “This was the first try, and it worked. It was so incredible.”

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Zhukov anticipates an average of two solar eclipses per week being produced for a total of nearly 200 during the two-year mission, yielding more than 1,000 hours of totality. That will be a scientific bonanza since full solar eclipses produce just a few minutes of totality when the moon lines up perfectly between Earth and the sun — on average just once every 18 months.

The sun continues to mystify scientists, especially its corona, which is hotter than the solar surface. Coronal mass ejections result in billions of tons of plasma and magnetic fields being hurled out into space. Geomagnetic storms can result, disrupting power and communication while lighting up the night sky with auroras in unexpected locales.

While previous satellites have generated imitation solar eclipses — including the European Space Agency and NASA’s Solar Orbiter and Soho observatory — the sun-blocking disk was always on the same spacecraft as the corona-observing telescope. What makes this mission unique, Zhukov said, is that the sun-shrouding disk and telescope are on two different satellites and therefore far apart.

The distance between these two satellites will give scientists a better look at the part of the corona closest to the limb of the sun.

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“We are extremely satisfied by the quality of these images, and again this is really thanks to formation flying” with unprecedented accuracy, ESA’s mission manager Damien Galano said from the Paris Air Show.

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AP journalist John Leicester contributed to this report from Paris.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.

1. What’s happening?

The Moon will cross directly between Earth and the Sun, temporarily blocking the Sun from view along a narrow path across Mexico, the United States, and Canada. Viewers across the rest of the United States will see a partial eclipse, with the Moon covering only part of the Sun’s disk.

2. When will it happen?

The eclipse takes place on April 8. It will get underway at 10:42 a.m. CDT, when the Moon’s shadow first touches Earth’s surface, creating a partial eclipse. The Big Show—totality—begins at about 11:39 a.m., over the south-central Pacific Ocean. The shadow will first touch North America an hour and a half later, on the Pacific coast of Mexico. Moving at more than 1,600 miles (2,575 km) per hour, the path of totality will enter the United States at Eagle Pass, Texas, at 1:27 p.m. CDT. The lunar shadow will exit the United States and enter the Canadian province of New Brunswick near Houlton, Maine, at 2:35 p.m. (3:35 p.m. EDT).

3. How long will totality last?

The exact timing depends on your location. The maximum length is 4 minutes, 27 seconds near Torreon, Mexico. In the United States, several towns in southwestern Texas will see 4 minutes, 24 seconds of totality. The closer a location is to the centerline of the path of totality, the longer the eclipse will last.

4. What will it look like?

Eclipse veterans say there’s nothing quite like a total solar eclipse. In the last moments before the Sun disappears behind the Moon, bits of sunlight filter through the lunar mountains and canyons, forming bright points of light known as Baily’s beads. The last of the beads provides a brief blaze known as a diamond ring effect. When it fades away, the sky turns dark and the corona comes into view— million-degree plasma expelled from the Sun’s surface. It forms silvery filaments that radiate away from the Sun. Solar prominences, which are fountains of gas from the surface, form smaller, redder streamers on the rim of the Sun’s disk.

5. What safety precautions do I need to take?

It’s perfectly safe to look at the total phase of the eclipse with your eyes alone. In fact, experts say it’s the best way to enjoy the spectacle. The corona, which surrounds the intervening Moon with silvery tendrils of light, is only about as bright as a full Moon.

During the partial phases of the eclipse, however, including the final moments before and first moments after totality, your eyes need protection from the Sun’s blinding light. Even a 99-percent-eclipsed Sun is thousands of times brighter than a full Moon, so even a tiny sliver of direct sunlight can be dangerous!

To stay safe, use commercially available eclipse viewers, which can look like eyeglasses or can be embedded in a flat sheet that you hold in front of your face. Make sure your viewer meets the proper safety standards, and inspect it before you use it to make sure there are no scratches to let in unfiltered sunlight.

You also can view the eclipse through a piece of welder’s glass (No. 14 or darker), or stand under a leafy tree and look at the ground; the gaps between leaves act as lenses, projecting a view of the eclipse on the ground. With an especially leafy tree you can see hundreds of images of the eclipse at once. (You can also use a colander or similar piece of gear to create the same effect.)

One final mode of eclipse watching is with a pinhole camera. You can make one by poking a small hole in an index card, file folder, or piece of stiff cardboard. Let the Sun shine through the hole onto the ground or a piece of paper, but don’t look at the Sun through the hole! The hole projects an image of the eclipsed Sun, allowing you to follow the entire sequence, from the moment of first contact through the Moon’s disappearance hours later.

6. Where can I see the eclipse?

In the United States, the path of totality will extend from Eagle Pass, Texas, to Houlton, Maine. It will cross 15 states: Texas, Oklahoma, Arkansas, Missouri, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, New York, Vermont, New Hampshire, Maine, Tennessee, and Michigan (although it barely nicks the last two).

In Texas, the eclipse will darken the sky over Austin, Waco, and Dallas—the most populous city in the path, where totality (the period when the Sun is totally eclipsed) will last 3 minutes, 51 seconds.

Other large cities along the path include Little Rock; Indianapolis; Dayton, Toledo, and Cleveland, Ohio; Erie, Pennsylvania; Buffalo and Rochester, New York; and Burlington, Vermont.

Outside the path of totality, American skywatchers will see a partial eclipse, in which the Sun covers only part of the Sun’s disk. The sky will grow dusky and the air will get cooler, but the partially eclipsed Sun is still too bright to look at without proper eye protection. The closer to the path of totality, the greater the extent of the eclipse. From Memphis and Nashville, for example, the Moon will cover more than 95 percent of the Sun’s disk. From Denver and Phoenix, it’s about 65 percent. And for the unlucky skywatchers in Seattle, far to the northwest of the eclipse centerline, it’s a meager 20 percent.

The total eclipse path also crosses Mexico, from the Pacific coast, at Mazatlán, to the Texas border. It also crosses a small portion of Canada, barely including Hamilton, Ontario. Eclipse Details for Locations Around the United States • aa.usno.navy.mil/data/Eclipse2024 • eclipse.aas.org • GreatAmericanEclipse.com

7. What causes solar eclipses?

These awe-inspiring spectacles are the result of a pleasant celestial coincidence: The Sun and Moon appear almost exactly the same size in Earth’s sky. The Sun is actually about 400 times wider than the Moon but it’s also about 400 times farther, so when the new Moon passes directly between Earth and the Sun—an alignment known as syzygy—it can cover the Sun’s disk, blocking it from view.

8. Why don’t we see an eclipse at every new Moon?

The Moon’s orbit around Earth is tilted a bit with respect to the Sun’s path across the sky, known as the ecliptic. Because of that angle, the Moon passes north or south of the Sun most months, so there’s no eclipse. When the geometry is just right, however, the Moon casts its shadow on Earth’s surface, creating a solar eclipse. Not all eclipses are total. The Moon’s distance from Earth varies a bit, as does Earth’s distance from the Sun. If the Moon passes directly between Earth and the Sun when the Moon is at its farthest, we see an annular eclipse, in which a ring of sunlight encircles the Moon. Regardless of the distance, if the SunMoon-Earth alignment is off by a small amount, the Moon can cover only a portion of the Sun’s disk, creating a partial eclipse.

9. How often do solar eclipses happen?

Earth sees as least two solar eclipses per year, and, rarely, as many as five. Only three eclipses per two years are total. In addition, total eclipses are visible only along narrow paths. According to Belgian astronomer Jean Meuss, who specializes in calculating such things, any given place on Earth will see a total solar eclipse, on average, once every 375 years. That number is averaged over many centuries, so the exact gap varies. It might be centuries between succeeding eclipses, or it might be only a few years. A small region of Illinois, Missouri, and Kentucky, close to the southeast of St. Louis, for example, saw the total eclipse of 2017 and will experience this year’s eclipse as well. Overall, though, you don’t want to wait for a total eclipse to come to you. If you have a chance to travel to an eclipse path, take it!

10. What is the limit for the length of totality?

Astronomers have calculated the length of totality for eclipses thousands of years into the future. Their calculations show that the greatest extent of totality will come during the eclipse of July 16, 2186, at 7 minutes, 29 seconds, in the Atlantic Ocean, near the coast of South America. The eclipse will occur when the Moon is near its closest point to Earth, so it appears largest in the sky, and Earth is near its farthest point from the Sun, so the Sun appears smaller than average. That eclipse, by the way, belongs to the same Saros cycle as this year’s.

11. When will the next total eclipse be seen from the United States?

The next total eclipse visible from anywhere in the United States will take place on March 30, 2033, across Alaska. On August 22, 2044, a total eclipse will be visible across parts of Montana, North Dakota, and South Dakota. The next eclipse to cross the entire country will take place on August 12, 2045, streaking from northern California to southern Florida. Here are the other total solar eclipses visible from the contiguous U.S. this century:

March 30, 2052 Florida, Georgia, tip of South Carolina May 11, 2078 From Louisiana to North Carolina May 1, 2079 From Philadelphia up the Atlantic coast to Maine September 14, 2099 From North Dakota to the Virginia-North Carolina border

12. What is the origin of the word ‘eclipse?’

The word first appeared in English writings in the late 13th century. It traces its roots, however, to the Greek words “ecleipsis” or “ekleipein.” According to various sources, the meaning was “to leave out, fail to appear,” “a failing, forsaking,” or “abandon, cease, die.”

13. Do solar eclipses follow any kind of pattern?

The Moon goes through several cycles. The best known is its 29.5-day cycle of phases, from new through full and back again. Other cycles include its distance from Earth (which varies by about 30,000 miles (50,000 km) over 27.5 days) and its relationship to the Sun’s path across the sky, known as the ecliptic (27.2 days), among others. These three cycles overlap every 6,585.3 days, which is 18 years, 11 days, and 8 hours.

This cycle of cycles is known as a Saros (a word created by Babylonians). The circumstances for each succeeding eclipse in a Saros are similar—the Moon is about the same distance from Earth, for example, and they occur at the same time of year. Each eclipse occurs one-third of the way around Earth from the previous one, however; the next eclipse in this Saros, for example, will be visible from parts of the Pacific Ocean.

Each Saros begins with a partial eclipse. A portion of the Moon just nips the northern edge of the Sun, for example, blocking only a fraction of the Sun’s light. With each succeeding eclipse in the cycle, the Moon covers a larger fraction of the solar disk, eventually creating dozens of total eclipses. The Moon then slides out of alignment again, this time in the opposite direction, creating more partial eclipses. The series ends with a grazing partial eclipse on the opposite hemisphere (the southern tip, for example).

Several Saros cycles churn along simultaneously (40 are active now), so Earth doesn’t have to wait 18 years between eclipses. They can occur at intervals of one, five, six, or seven months.

The April 8 eclipse is the 30th of Saros 139, a series of 71 events that began with a partial eclipse, in the far north, and will end with another partial eclipse, this time in the far southern hemisphere. The next eclipse in this Saros, also total, will take place on April 20, 2042.

SAROS 139

First eclipse

May 17, 1501

First total eclipse

December 21, 1843

Final total eclipse

March 26, 2601

Longest total eclipse

July 16, 2186, 7 minutes, 29 seconds

Final partial eclipse

July 3, 2763

All eclipses

71 (43 total, 16 partial, 12 hybrid)

Source: NASA Catalog of Solar Eclipses: eclipse.gsfc.nasa.gov/SEsaros/SEsaros139.html

14. What about eclipse seasons?

Eclipses occur in “seasons,” with two or three eclipses (lunar and solar) in a period of about five weeks. Individual eclipses are separated by two weeks: a lunar eclipse at full Moon, a solar eclipse at new Moon (the sequence can occur in either order). If the first eclipse in a season occurs during the first few days of the window, then the season will have three eclipses. When one eclipse in the season is poor, the other usually is much better.

That’s certainly the case with the season that includes the April 8 eclipse. It begins with a penumbral lunar eclipse on the night of March 24, in which the Moon will pass through Earth’s outer shadow. The eclipse will cover the Americas, although the shadow is so faint that most skywatchers won’t notice it.