Figure caption: The left panel displays the CESSI prediction for the magnetic field structure of the Sun’s corona for the day of the eclipse, i.e., 8 April 2024. Closed magnetic loops which form arch-like structures in the corona (known as helmet streamers) are depicted in yellow. These coronal streamers generally appear as bright elongated petal-like structures in the corona when photographed in white light (or when seen directly during the eclipse through an eclipse glass). Positive and negative open magnetic field lines are depicted by green and magenta colors in the same image. These open field lines are not as bright in white light and do not form any large-scale visible structures. However, more advanced photographic techniques and post-processing of multiple images (which improve signal-to-noise) may reveal these fine structures. These magnetic field line structures are plotted within a region confined between the Sun’s surface and 2.5 times the solar radius. The middle panel displays a predicted “synthetic white-light" corona. The image on the extreme right is a result of further processing to render another synthetic white light solar corona which could be visible directly or through simple cameras and telescope setups. The (amateur) photographs of the eclipse are likely to be of such quality. We point out that our simulated images are oriented with solar north pole pointed up. Usually photographs taken at a certain latitude will have to be rotated by an angle corresponding to the latitude for comparison with these simulations.

On the day of the eclipse, our prediction indicates the presence of multiple large-scale petal-like structures. If this turns out to be close to reality, the 8 April 2024 eclipse corona would be quite complex and spectacular. Given the assumptions in our modeling technique, one expects the petal-like structures (coronal streamers) to be somewhat more elongated than what is predicted through our models.


Figure Caption: Using a data-driven Solar Surface Flux Transport (SFT) model, which can simulate the surface evolution of the Sun’s magnetic field, we predict the surface distribution of the Sun’s magnetic field for April 8, 2024. The latest solar active region assimilated into this model was on April 1, 2024. This predicted surface map serves as the input for our coronal field extrapolation model Similar SFT models have been utilized in previous studies by Nandy et. al. 2018, Astrophysical Journal, Vol 853, No 1 (, Bhowmik & Nandy 2018, Nature Communications, Vol 9, Article 5209 (, Dash et al 2019, Astrophysical Journal .


We utilize a novel approach that employs two distinct computational models, rooted in the theoretical framework proposed by Nandy et al. (2018), to predict the structure of the Sun's coronal magnetic field. To forecast the expected coronal field structure during an eclipse, we rely on two physics-based computational models, 1) the solar surface flux transport (SFT) model and 2) the potential field source surface (PFSS) model. To do this, we utilize a data-driven SFT model with built-in memory spanning multiple years. This model is run forward to April 8, 2024, to predict the Sun's surface magnetic field distribution on that day, incorporating the last solar active region observed on April 1, 2024. The SFT model is first calibrated from solar cycle 14 to solar cycle 25 ( till March 4, 2024) utilizing the sunspot characteristics driven from USAF/RGO-NOAA database. From March 5, 2024 onward, we consider the magnetic field strength of active regions according to the observed values from the Helioseismic Magnetic Imager (HMI) (properly scaled with USAF/RGO-NOAA database). Calibrating the SFT model for past solar cycles is essential to obtain accurate estimations of the polar field, particularly because observations suffer from projection effects away from the Sun’s disk centre. The predicted surface magnetic field distribution for April 8, 2024, serves as input for a potential field source surface model, which generates the coronal structure from the surface to 2.5 times solar radii, where we assume the magnetic field transitions to a radial configuration. This technique complements more computationally expensive full magnetohydrodynamic simulations and can be executed relatively quickly using modest resources available to us. We believe that utilizing the predictive solar surface flux transport model enhances the accuracy of surface magnetic field predictions, particularly at high latitudes by capturing the physics of surface plasma flux transport processes. Models that assimilate surface magnetic field data offer optimal boundary conditions for simulating and predicting the overall structure of the solar corona.

The synthetic white light corona is generated from the predicted coronal fields by assigning more weight to closed field lines relative to the open field lines and utilizing a combination of filters to approximately capture the density stratification of the corona. It is important to note that we are possibly near the peak of solar cycle 25. This means that there is a high probability of new sunspots emerging between the last assimilated data and the time of prediction. This can impact the predicted low-lying coronal field, especially if new sunspots emerge near the edges of the Sun. A large-scale solar magnetic storm or Coronal Mass Ejection (CME) can also result in rapid changes in the coronal structure, which would not be captured in such predictions. Therefore, we have limited our prediction to 7 days prior to the event, in order to minimize the impact of new sunspot emergence and other transient energetic events on our predictions.

References to relevant manuscripts:

  • "Prediction of the Sun's Coronal Magnetic Field and Forward-modeled Polarization Characteristics for the 2019 July 2 Total Solar Eclipse", Dash S., Bhowmik P., B S A., Ghosh N., Nandy D., ApJ, 2020, 890, 1, link
  • "Prediction of the Sun's Corona for the Total Solar Eclipse on 2019 July 2", Dash S., Bhowmik P., Nandy D., RNAAS, 2019, 3, 6, link
  • "The Large-scale Coronal Structure of the 2017 August 21 Great American Eclipse: An Assessment of Solar Surface Flux Transport Model Enabled Predictions and Observations", Nandy D., Bhowmik P., Yeates A. R., Panda S., Tarafder R., Dash S., The Astrophysical Journal, 2018, 853, 1, link
  • "Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions", Bhowmik P., Nandy D., Nature Communications, 2018, 9, 5209, link


This April 8, 2024, the United States will witness the Moon's shadow sweeping across its expanse, captivating millions with a total solar eclipse. This total solar eclipse could be even more exciting than those in the recent past including the Great American Total Solar Eclipse in 2017, due to its broader path of totality and extended duration.

Moreover, during the 2024 eclipse, the Sun will be at or near the maximum of its 11-year sunspot cycle – characterized by a highly tangled, complex magnetic field configuration. This state is likely to result in visible streamers extending across the corona. Moreover, observers will have an enhanced opportunity to witness prominences, manifesting vibrant loops emanating from the Sun's surface. With fortuitous timing, there may even be a possibility of witnessing a coronal mass ejection, a significant release of solar material, during the eclipse.

Expanse of the Path of Totality

The eclipse's trajectory across North America will span approximately 108 to 122 miles in width. This path will traverse various states and densely populated regions. It's estimated that around 31.6 million individuals reside within the totality path for this year's eclipse, with an additional 150 million people living within 200 miles of it. During April, approximately 99% of the U.S. population will have the opportunity to witness either a partial or total eclipse, depending on their location. All contiguous states of the U.S., as well as portions of Alaska and Hawaii, will experience at least a partial solar eclipse.


Duration of Totality

During the forthcoming eclipse, the period of totality will extend up to 4 minutes and 28 seconds, occurring approximately 25 minutes northwest of Torreón, Mexico. Upon entering Texas, the totality duration will be around 4 minutes and 26 seconds at the midpoint of the eclipse's path. Areas experiencing durations exceeding 4 minutes are situated as far north as Economy, Indiana. Even as the eclipse transitions out of the U.S. and enters Canada, it will still last up to 3 minutes and 21 seconds. It's a characteristic of any total solar eclipse that the duration of totality is longest near the center of the path widthwise and diminishes towards the edges.

Eclipse Stages WorldwideUTC TimeIndian Time
First location to see the partial eclipse begin8 Apr, 15:42:158 Apr, 21:12:15
First location to see the full eclipse begin8 Apr, 16:38:528 Apr, 22:08:52
Maximum Eclipse8 Apr, 18:17:218 Apr, 23:47:21
Last location to see the full eclipse end8 Apr, 19:55:359 Apr, 01:25:35
Last location to see the partial eclipse end8 Apr, 20:52:199 Apr, 02:22:19

Source:; NASA/Abbey Interrante

2024 Total Solar Eclipse: Through the Eyes of NASA


A total solar eclipse offers the best chance for ground-based coronal observations that can constrain theories and models of the Sun's corona. These models are essential in understanding the physics of coronal dynamics and the origin of solar storms. It is with the aim to understand the Sun's corona that scientists chase solar eclipses across countries and continents with their instruments. And it is with this same aim that theorists and modelers like us recreate the magic of the Sun using physics and computers. We will not get to see the eclipse, but we hope that our model prediction and the simulated data will on the one hand aid in interpreting the observations of the eclipse made by our American colleagues, and on the other hand, the eclipse observations by our American colleagues will teach us what we did right, and what we did wrong so that we can do better. Science sans frontiers!

The predictive capability of the procedure employed by CESSI for the upcoming eclipse has been tested multiple times in the past and has proven to be successful. A list of past solar eclipse predictions by CESSI are listed below,

The Great American Solar Eclipse
CESSI Prediction of South American Total Solar Eclipse 2019
CESSI Prediction of 2019 December 26 Solar Eclipse
CESSI Prediction of 2021 Solar Eclipse


The solar corona is very faint compared to the bright solar surface. Thus it is extremely hard to observe the corona unless any object occults the bright solar disk. This occulting object can be the Moon while passing in front of the Sun or an artificial disk mounted on a satellite (a coronagraph). Currently, the European Space Agency's Solar and Heliospheric Observatory has an instrument called LASCO which is a space-based coronagraph. India has recently deployed the Aditya-L1 satellite which is carrying multiple payloads onboard for observing the Sun's surface, chromosphere and corona. The Daniel K. Inouye Solar Telescope ( DIKIST ) and the Coronal Multichannel Polarimeter ( CoMP ) instruments are also expected to commission ground-based coronagraphs in the near future.

Apart from such instruments, solar eclipses during occultation by the Moon provide excellent opportunities to study the Sun's corona. But why do we need to study the corona at all and why do space agencies and countries make so much effort to deploy Sun observing instruments in space and on the ground?

The reason is that coronal magnetic field dynamics lead to solar flares, solar storms, and Coronal Mass Ejections (CMEs). The effect of the eruption of plasma and charged ions from the Sun during these events can be felt in the entire solar system. These events affect the Earth's outer atmosphere and our technologies leading to power outages and disruption of communication and GPS networks. They can also damage satellites and more importantly harm our astronauts orbiting around the Earth jeopardizing their health through doses of high radiation and energetic particles. As we get more and more dependent on space-reliant technologies with every passing day, it becomes imperative for us to study these solar phenomena and develop the understanding to be able to predict these events with a reasonable degree of accuracy.

Most of these eruptive events are associated with the magnetic field distribution of the corona. However, due to the scarcity of observation of the coronal magnetic field, scientists rely on computational models to constrain the magnetic nature of the corona. These scientific models, with an in-depth theoretical understanding of the dynamics of the solar corona can also provide a meaningful prediction of coronal magnetic field structures. Thus, observing the corona during an eclipse gives us an excellent opportunity to test the correctness of our models, and refine them leading to improved forecasting capabilities. The primary objective of CESSI is to develop advanced computational models for understanding solar activity and enabling space weather forecasting.

Coronal magnetic field dynamics lead to solar magnetic storms (flares and CMEs) which hurl vast amounts of magnetized plasma (charged particles) into interplanetary space creating hazardous space weather. Space weather impacts many of the technologies that we rely on today, including telecommunications, GPS navigational networks, electric power grids, air-traffic on polar routes and satellite operations. Observations of the solar corona during eclipses has the potential to constrain theoretical and computational models of coronal magnetic fields, which are expected to yield better forecasting capabilities for destructive space storms. These observations can also constrain the physical processes that heat the Sun’s corona to a super-hot million degrees and make it glow when the disk is shrouded by the dark side of the moon.


A solar eclipse occurs when the Moon is between the Sun and the Earth, so that the visible disk of the Sun, which is the photosphere, is 'occulted' or covered by the Moon. As is obvious, eclipses provide an excellent opportunity to study the Sun's 'crown'- its corona (otherwise invisible due to the blindingly bright photosphere), which has kept astrophysicists puzzled with its million-degree temperature for a long, long time! As the Moon comes between the Sun and the Earth only on a new moon day, a solar eclipse can only occur on a new moon day.

The reason why a solar eclipse doesn't occur on every new moon day is that the orbit of the Moon is 5 degrees inclined to the ecliptic, which is the plane in which the Earth revolves around the Sun. Thus, at least two and at the most five solar eclipses only can occur in a year. Solar eclipses can be observed from only a narrow strip on the Earth which falls in the shadow of the Moon, unlike lunar eclipses which can be observed from the entire hemisphere having night. Also, a total lunar eclipse can last up to 2 hours while the upper limit for any solar eclipse's totality is 8 minutes. This is because the Moon's shadow on the Earth is small. In fact, at least 92% of the sunlight usually received still reaches the Earth even during a solar eclipse. Seen from the Moon, the Earth would still look bright during a solar eclipse with only a small patch darkened by the shadow of the Moon.

Solar eclipses can be total, partial, or annular. In a total solar eclipse, the entire visible disk of the Sun is occulted, turning day into night for a few minutes. Only the partial disc of the Sun appears to be 'eaten' by the Moon in a partial eclipse as the name suggests. Annular solar eclipse, on the other hand, is one in which the Moon is too far away to cover the entire disc of the Sun, and so a thin ring of the photosphere is visible in this one. It's obvious that an annular eclipse occurs when the apparent size of the Sun is larger than the Moon, whereas the total one occurs when the apparent size of the Moon is bigger than the Sun.

People who chase eclipses around the globe and study them using astronomical tools are called 'umbraphiles'!


Eclipses have long been the subject of fantasies for humankind in a bid to understand the heavens. Interest in this phenomenon can be traced back to as early as 3340 BC in Ireland where petroglyphs exhibit a consistent understanding of tracks of the Sun and moon. Further records are obtained around 2134 BC in China where early philosophers recorded the event describing it as “an inharmonious meeting of the Sun and the Moon”. Descriptions of transitions in colors during solar eclipses have been recorded in ancient Indian texts such as Pancavimsa Bramhana. These vividly described color transitions match modern descriptions of solar eclipses. By 500 BC, the Babylonian and Greeks had already developed crude methods to predict the time of solar eclipses. However, the mysticism around eclipses remained till much into the middle ages. Confirmation bias fed to the belief that eclipses portended the death of emperors.

This mysticism, however, proved to be a windfall for astronomy as emperors concerned by this phenomena began to fund philosophers to study eclipses. It resulted in the first accurate sky maps and studies of the path of heavenly bodies. Around 130 BC, Hipparchus used observations of an eclipse from different locations to estimate the size of the moon. In 1715, Halley used Newton’s laws of gravity to predict the position and time of the next solar eclipse. Though Haley was slightly off, it cemented dominance of Newton’s theories in English science. More attention came his way as his laws were used to calculate the trajectories of planets.

It was soon identified that the observations and calculations for the orbits of Mercury and Uranus slightly varied. A bid to explain Mercury’s orbit would eventually lead Einstein to work out his revised theory of gravity. In a triumphant demonstration of the scientific method, the solar eclipse of 1919 would again help Arthur Eddington verify Einstein’s Theory of General Relativity.

The Great Eclipse of 1878. Magnificent pastel drawing by E.L. Trouvelot of the Sun's corona during the total solar eclipse of 1878 May 29. Credit: American expedition to Wyoming.

Total solar eclipses have historically provided us a unique opportunity to study the corona of the Sun. These observations are otherwise restricted due to the Sun’s bright photosphere. Observations during eclipses have therefore been the tools to understand the magnetic structuring, dynamics and physical construct of the Sun’s million degree corona.

Though the first reported reference of the corona can be traced back to Leo Diaconus of Constantinople in 968 AD, the first scientific ideas regarding the solar corona only emerged in the early 17th century. In 1605, Johannes Kepler suggested that the corona is light reflected due to the presence of material surrounding the moon. In 1724, Jose Jaoquin coined the term “Corona” and suggested that it is part of the Sun and not material surrounding the moon. More than a century later, the first wet plate photographs of the Sun’s corona were obtained in 1860 during a total solar eclipse. Currently, state of the art telescopes use occulting disks to create artificial eclipses to observe the solar corona.

One of the most historic solar eclipses was the total solar eclipse of 1919 May 29. By measuring the distance to background stars with and without the Sun, the gravitational lensing effect of the Sun as predicted by Einstein's General Theory of Relativity was confirmed by Arthur Eddington by taking down observations during this eclipse. Only a solar eclipse can facilitate the observation of stars with the Sun, making this eclipse a historic one!


Eclipses have fascinated human civilizations since ancient times. Naturally, lunar and solar eclipses have spawned various myths and superstitions among the general populace since ages. To read more click here.


The eclipse prediction campaign was conceived and led by Dibyendu Nandi at CESSI – a multi-institutional Center of Excellence established and funded by the Ministry of Education, Government of India under the Frontier Areas of Science and Technology Scheme. We acknowledge utilization of data from the NASA/SDO HMI instrument maintained by the HMI team and the Royal Greenwich Observatory/USAF-NOAA active region database compiled by David H. Hathaway. We are grateful to Prosenjit Lahiri for the design and maintenance of this website.

We acknowledge funding from the DST-INSPIRE program. We also acknowedge all our undergraduate and graduate students who have contributed over the years to the development of the CESSI solar corona prediction methodology.


Shaonwita Pal (CESSI, IISER Kolkata)
Soumyaranjan Dash (CESSI, IISER Kolkata)
Dibyendu Nandi (CESSI and Department of Physical Sciences, IISER Kolkata)
Chitradeep Saha (CESSI, IISER Kolkata)
Yoshita Baruah (CESSI and Department of Physical Sciences, IISER Kolkata)
Priyansh Jaswal (CESSI, IISER Kolkata)
Prosenjit Lahiri (CESSI, IISER Kolkata)


Prantika Bhowmik (CESSI, IISER Kolkata)
Anthony R. Yeates (Department of Mathematical Sciences, Durham University, UK)
Suman Panda (CESSI and Department of Physical Sciences, IISER Kolkata)
Rajashik Tarafder (CESSI and Department of Physical Sciences, IISER Kolkata)
Athira BS (CESSI, IISER Kolkata)
Souvik Roy (CESSI, IISER Kolkata)
Arnab Basak (CESSI, IISER Kolkata)


The images and data on this webpage have been uploaded for the usage of the community of interested scientists and the public who fund our research. It is free to use and disseminate, with due acknowledgment.


The above compilation of historical facts, anecdotes and scientific information has been collected from various sources which are referenced below.

1. Website for Paul Griffin:
2. Website:
3. Website:
4. Pasachoff, J. M. (1999), “Halley and his maps of the Total Eclipses of 1715 and 1724” Journal of Astronomical History and Heritage’ (ISSN 1440-2807), Vol. 2, No. 1, p. 39-54
5. Dyson, Frank W., Arthur S. Eddington, and Charles Davidson. “A determination of the deflection of light by the Sun's gravitational field, from observations made at the total eclipse of May 29, 1919”. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 220.571-581 (1920): 291-333.
6. Totality - Eclipses of the Sun (3rd edition) by Littmann, Espenak, and Willcox
7. “Images and Astronomy” by Kirit J. Sheth
8. Website:-
9. “Solar storm risk to the north American electric grid” - Llyod’s, and Atmospheric and Environmental Research
10. Website:
11. Schrijver, C.J. et al. (2015), “Understanding Space Weather to Shield Society: A Global Roadmap for 2015-2025 Commissioned by COSPAR and ILWS”, Advances in Space Research, Vol. 55, Page 2745
12. Vahia, M.N., and Subbarayappa, B.V. (2011), Eclipses in Ancient India.
13. Subbarayappa, B V, 2008, Traditions of Astronomy in India and Jyotishshastrs, Centre for Studies of Civilizations, Vol IV part 4, Centre for Studies of Civilisations, Viva Books
14. Mauna Loa Solar Observatory (MLSO)*

*We have been traditionally relying on solar coronagraph images from the Mauna Loa Solar Observatory (MLSO) for comparing SFT+PFSS simulation outcomes. Unfortunately, this was not possible this time, as MLSO ceased operations on November 22, 2022, following an eruption of Mauna Loa.


ISRO's Aditya L1 Mission
Coronal Multi-channel Polarimeter (CoMP)
Daniel K. Inouye Solar Telescope (DKIST)
Historical Eclipse Image Archive
Eclipse Photography by Miloslav Druckmüller
Website: The Great American Solar Eclipse


Dibyendu Nandi: dnandi @ iiserkol . ac . in

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