Bull sharks deliberately choose and maintain long-term social companions, defying the usual notion that sharks are solitary. Image via Wikipedia.
Bull sharks form specific social bonds instead of mixing randomly. That’s according to new research from more than six years at the Shark Reef Marine Reserve in Fiji. Researchers observed 184 bull sharks and discovered they actively choose companions and maintain long-term social connections. These findings challenge the common belief that sharks are solitary creatures.
The research team published its study in the peer-reviewed journal Animal Behaviour in April 2026.
Bull sharks show clear social preferences in the wild
The research showed bull sharks do not behave as solitary animals. They show distinct preferences for certain companions and deliberately choose who to associate with. Much like humans, they maintain different types of social relationships, ranging from close partners to more casual acquaintances. And, just like us, they actively avoid certain individuals. Lead author Natasha D. Marosi, an Exeter researcher and founder of Fiji Shark Lab, explained:
As humans we cultivate a range of social relationships — from casual acquaintances to our best friends — but we also actively avoid certain people — and these bull sharks are doing similar things.
Researchers from the University of Exeter, Lancaster University, Fiji Shark Lab and Beqa Adventure Divers observed the sharks over six years. They looked at broad associations and when sharks stayed close together. Plus they detailed interactions such as sharks following each other or swimming side by side. Social bonds were common among adult sharks, who also tended to associate with partners of similar size.
These images show different social interaction patterns: Lead–follow (a), parallel swim (b), lead–follow (c). Image via Animal Behaviour/ Marosi, N.D., Ellis, S., Jacoby, D.M.P., Brunnschweiler, J.M. & Croft, D.P. (CC BY-NC-ND 4.0).
Age groups and their social patterns
The study revealed clear differences in social behavior depending on life stage. Juvenile bull sharks live in rivers and estuaries. During this early stage they avoid predation, which includes avoiding adult bull sharks. Sub-adult sharks, which have not yet reached sexual maturity, usually remain in near-shore areas. Some of the braver sub-adults visit the Reserve, where they form social connections with adult sharks that may help them learn skills and integrate into the social network.
Adult sharks are highly social, frequently interacting with chosen partners. In contrast, older sharks are less socially active. Having accumulated years of experience in hunting and mating, these sharks rely less on social interactions for survival. Marosi explained:
Our results show that older sharks tend to be less social. These older individuals have many years of experience honing their skill sets, hunting and mating, and sociality may not be as integral to their survival as it is for an individual in their prime.
Benefits of social behavior
Social bonds offer multiple advantages. They help sharks learn new skills, find food and mates and avoid conflicts. Professor Darren Croft from Exeter’s Centre for Research in Animal Behaviour stated:
Contrary to commonly held perceptions of sharks, our study shows they have relatively rich and complex social lives.
Both males and females preferred female companions, but males had more social links overall. Marosi said:
Male bull sharks are physically smaller than females, thus one potential benefit they may gain is by being more socially integrated; they are buffered from aggressive confrontations with larger individuals.
A female bull shark at the Shark Reef Marine Reserve in Fiji. Video via Wikipedia.
Research and conservation relevance
Long-term observation allowed researchers to track individual sharks over many years. It also helped them understand how social patterns develop and persist. David Jacoby from Lancaster University emphasized that this approach provided valuable insights into shark behavior across different life stages:
This study capitalizes on data and knowledge from one of the longest running shark ecotourism dive sites in the world. This offered a unique opportunity to observe the detailed behavior of these individuals over many years, as they grow, develop and manage their social relationships.
Marosi added:
The Shark Reef Marine Reserve is a protected area where large numbers of sharks gather year round, giving us the ability to study individual sharks repeatedly over time.
Fiji Shark Lab is currently working alongside the Ministry of Fisheries, Fiji. By working closely with the Ministry of Fisheries, Shark Lab ensures that these insights are applied to safeguard bull shark populations effectively, helping shape conservation strategies that protect these sharks and their habitats for the long term.
Bottom line: Bull sharks form enduring social bonds, selecting preferred companions and sustaining strong, structured networks in the wild.
Bull sharks deliberately choose and maintain long-term social companions, defying the usual notion that sharks are solitary. Image via Wikipedia.
Bull sharks form specific social bonds instead of mixing randomly. That’s according to new research from more than six years at the Shark Reef Marine Reserve in Fiji. Researchers observed 184 bull sharks and discovered they actively choose companions and maintain long-term social connections. These findings challenge the common belief that sharks are solitary creatures.
The research team published its study in the peer-reviewed journal Animal Behaviour in April 2026.
Bull sharks show clear social preferences in the wild
The research showed bull sharks do not behave as solitary animals. They show distinct preferences for certain companions and deliberately choose who to associate with. Much like humans, they maintain different types of social relationships, ranging from close partners to more casual acquaintances. And, just like us, they actively avoid certain individuals. Lead author Natasha D. Marosi, an Exeter researcher and founder of Fiji Shark Lab, explained:
As humans we cultivate a range of social relationships — from casual acquaintances to our best friends — but we also actively avoid certain people — and these bull sharks are doing similar things.
Researchers from the University of Exeter, Lancaster University, Fiji Shark Lab and Beqa Adventure Divers observed the sharks over six years. They looked at broad associations and when sharks stayed close together. Plus they detailed interactions such as sharks following each other or swimming side by side. Social bonds were common among adult sharks, who also tended to associate with partners of similar size.
These images show different social interaction patterns: Lead–follow (a), parallel swim (b), lead–follow (c). Image via Animal Behaviour/ Marosi, N.D., Ellis, S., Jacoby, D.M.P., Brunnschweiler, J.M. & Croft, D.P. (CC BY-NC-ND 4.0).
Age groups and their social patterns
The study revealed clear differences in social behavior depending on life stage. Juvenile bull sharks live in rivers and estuaries. During this early stage they avoid predation, which includes avoiding adult bull sharks. Sub-adult sharks, which have not yet reached sexual maturity, usually remain in near-shore areas. Some of the braver sub-adults visit the Reserve, where they form social connections with adult sharks that may help them learn skills and integrate into the social network.
Adult sharks are highly social, frequently interacting with chosen partners. In contrast, older sharks are less socially active. Having accumulated years of experience in hunting and mating, these sharks rely less on social interactions for survival. Marosi explained:
Our results show that older sharks tend to be less social. These older individuals have many years of experience honing their skill sets, hunting and mating, and sociality may not be as integral to their survival as it is for an individual in their prime.
Benefits of social behavior
Social bonds offer multiple advantages. They help sharks learn new skills, find food and mates and avoid conflicts. Professor Darren Croft from Exeter’s Centre for Research in Animal Behaviour stated:
Contrary to commonly held perceptions of sharks, our study shows they have relatively rich and complex social lives.
Both males and females preferred female companions, but males had more social links overall. Marosi said:
Male bull sharks are physically smaller than females, thus one potential benefit they may gain is by being more socially integrated; they are buffered from aggressive confrontations with larger individuals.
A female bull shark at the Shark Reef Marine Reserve in Fiji. Video via Wikipedia.
Research and conservation relevance
Long-term observation allowed researchers to track individual sharks over many years. It also helped them understand how social patterns develop and persist. David Jacoby from Lancaster University emphasized that this approach provided valuable insights into shark behavior across different life stages:
This study capitalizes on data and knowledge from one of the longest running shark ecotourism dive sites in the world. This offered a unique opportunity to observe the detailed behavior of these individuals over many years, as they grow, develop and manage their social relationships.
Marosi added:
The Shark Reef Marine Reserve is a protected area where large numbers of sharks gather year round, giving us the ability to study individual sharks repeatedly over time.
Fiji Shark Lab is currently working alongside the Ministry of Fisheries, Fiji. By working closely with the Ministry of Fisheries, Shark Lab ensures that these insights are applied to safeguard bull shark populations effectively, helping shape conservation strategies that protect these sharks and their habitats for the long term.
Bottom line: Bull sharks form enduring social bonds, selecting preferred companions and sustaining strong, structured networks in the wild.
Observations of Comet 3I/ATLAS by the JANUS camera on ESA’s Juice mission. Juice caught the comet on November 5, 2025, when it was 64 million kilometers (40 million miles) away from the spacecraft. The length of the tail stretching away from the sun is about 6 million km (8 million miles) long here. Image via ESA/ Juice/ JANUS (CC BY-SA 3.0 IGO).
ESA’s JUpiter ICy Moons Explorer, aka Juice, is on a mission to the largest planet in our solar system. But in November 2025, it had a chance to observe interstellar comet 3I/ATLAS.
Juice observed Comet 3I/ATLAS releasing huge amounts of water vapor, mainly from its sun-facing side and surrounding dust coma.
The comet’s gas and dust extend over 5 million km (3 million miles), and images show typical comet behavior, much like ordinary solar system comets.
The Juice mission observes interstellar comet 3I/ATLAS
In November 2025, Juice was in the right place at the right time with the right equipment to observe interstellar comet 3I/ATLAS just after its closest approach to the sun. Our mission operations teams switched on five of Juice’s science instruments to collect information about how the active comet was behaving at the time.
Following a three-month wait to receive the data on Earth, scientists working on each of these instruments have spent the last few weeks delving into the photos, spectra and numbers. Results are still preliminary, work is still ongoing, but here are five things we’ve already learned.
1. 70 Olympic swimming pools of water vapor every day
On November 2, 2025, just four days after 3I/ATLAS had made its closest approach to the sun, Juice’s Moons And Jupiter Imaging Spectrometer (MAJIS) detected that the comet was spewing out 2,000 kg of water vapor every second. That’s equivalent to 70 Olympic swimming pools per day.
Comets – true to their ‘dirty snowball’ nickname – are mostly made of ice. As they approach the sun, this ice turns to gas and escapes the comet. The amount of water vapor leaving 3I/ATLAS is not exceptional. But it is on the high side of what we would expect from a comet close to the sun, based on what we have seen before in comets like 67P (300 kg per second) and Halley (20,000 kg per second).
These numbers depend a lot on the size of a comet and its distance from the sun. MAJIS detected 3I/ATLAS again on November 12 and 19, as it was moving away from the sun. By November 12, the amount of water vapor being released by the comet did not seem to have reduced significantly. The instrument team is planning to analyze the data from November 19 in the coming weeks.
MAJIS infrared observations of 3I/ATLAS in infrared light, overlaid on an image from Juice’s navigation camera. The instrument detected water vapor and carbon dioxide being released by the comet. Image via ESA/ Juice/ MAJIS (CC BY-SA 3.0 IGO).
2. Water vapor released in the direction of the sun
Juice’s Submillimeter Wave Instrument (SWI) also detected water vapor from 3I/ATLAS. It revealed that most of it was coming from the sun-facing side of the comet. It also appears that a lot of this water vapor is not actually coming directly from the solid part of the comet (its nucleus). Instead, it’s coming from icy dust grains that have escaped into a surrounding halo of dust and gas (its coma).
The SWI team are continuing to look into the data to determine how much ‘light’ water (normal H2O) 3I/ATLAS is releasing. It is interesting to compare this to the amount of ‘semiheavy’ water (HDO) from the comet, which has been measured by the ALMA and Webb telescopes. This ratio is a really important number in our studies of the universe. It gives a kind of ‘fingerprint’ that describes how and where an object formed.
ALMA and Webb found this ratio to be unexpectedly and extremely high for 3I/ATLAS. This may possibly be because the comet was born in a very cold and very ancient environment, where it was exposed to a lot of ultraviolet radiation from young stars. The SWI team is investigating whether the Juice data back up these findings.
3. Gas and dust stretch for 5 million km
Juice’s Ultraviolet Imaging Spectrograph (UVS) captured light coming from oxygen, hydrogen and carbon atoms in the gas and dust surrounding and trailing behind the comet. Oxygen, hydrogen, carbon and dust emit photons of light at specific wavelengths, which UVS recorded as counts per second.
UVS saw these gas elements and dust stretching up to more than 5 million km (3.1 million miles) from 3I/ATLAS’s nucleus. Gas and dust are common around active comets, with tails sometimes reaching up to 10 million km (6.2 million miles) long.
Counts of oxygen, hydrogen, carbon and dust measured by Juice’s UVS instrument from Comet 3I/ATLAS. Image via ESA (CC BY-SA 3.0 IGO).
4. This interstellar comet looks just like a normal comet!
Juice’s high-resolution science camera, JANUS (short for ‘Jovis Amorum ac Natorum Undique Scrutator’ – or ‘Scrutiniser of Jupiter, and all his loves and descendants’) also saw 3I/ATLAS spewing gas and dust.
Despite being over 60 million km (37 million miles) from 3I/ATLAS, JANUS clearly reveals the coma in which the nucleus is hiding, as well as two tails. One tail stretches away from the sun. And the other follows the path taken by the comet through the solar system. We can also see fainter shapes within the coma and tails that indicate various processes and interactions with the radiation, particles and magnetic field from the sun. The JANUS team is currently investigating these shapes in more detail.
Overall, JANUS shows that, despite its interstellar origin, Comet 3I/ATLAS was behaving like a typical comet from the solar system during a close approach to the sun.
Comet 3I/ATLAS through red and violet filters. In the red filter, the bright center of the coma is more compact and there are two tails: one straight down, and a fuzzier one going to the lower left. In the violet filter, the coma is bigger but fainter, and only one tail stands out clearly. The differences arise because different gas and dust particles release or reflect light at different wavelengths. Image via ESA (CC BY-SA 3.0 IGO).
5. 3I/ATLAS is supporting our planetary defense efforts
Juice’s Navigation Camera (NavCam) is specially designed to help Juice navigate around Jupiter’s icy moons following arrival in 2031. The encounter with 3I/ATLAS enabled us to do something totally unexpected with it.
We have already used telescopes on and around Earth to estimate the location and path of Comet 3I/ATLAS through the solar system. It seems to come from the direction of the Milky Way’s disk. Therefore, it was likely created more than 10 billion years ago.
NavCam had a much closer view of 3I/ATLAS, from a different angle as from Earth-based telescopes, during a period when the comet was not visible from Earth. This meant that ESA’s Planetary Defence team could line up NavCam images from throughout November to get a better idea of the comet’s changing position and trajectory.
In this way, the team – which usually tracks potentially hazardous asteroids – showed how powerful observations from deep-space missions can be to precisely calculate the orbits of comets or asteroids that cannot immediately be seen from Earth.
What’s more, because a comet’s trajectory is affected slightly by the release of dust and gas, the team is starting to use the trajectory measurements based on NavCam images to understand what materials – and how much of them – the comet is leaving in its wake.
Juice’s NavCam had a much closer view of 3I/ATLAS from a different angle as from Earth-based telescopes, during a period when the comet was not visible from Earth. This meant that NavCam images from throughout November 2025 could be lined up to get a better idea of the comet’s changing position and trajectory. Image via ESA/ Juice/ NavCam (CC BY-SA 3.0 IGO).
What’s next for Juice?
Instrument teams will continue to study the data, with many teams planning to publish papers on their results in the coming months. Olivier Witasse, ESA Juice Project Scientist, said:
3I/ATLAS is a rare and unexpected visitor. Its arrival came as a complete surprise. But when we realized that Juice would be close to the comet around its closest approach to the sun, we realized what a unique opportunity this was to collect a once-in-a-lifetime dataset.
Observing the comet was challenging, with no guarantee of success. But in the end, it turned into a great bonus for Juice during its journey to Jupiter.
The closest Juice came to 3I/ATLAS was about 60 million km (37 million miles), whereas it will see Jupiter’s moons from just a few hundred kilometers away. Even so, being designed and equipped to study icy moons, Juice’s instruments were a great match for the icy interstellar comet.
We still have five years to wait before Juice arrives at Jupiter in 2031. But all its instruments will be switched on once again in September 2026 when Juice returns to Earth for another gravity assist. Co-Project Scientist Claire Vallat said:
The data we are already seeing from Juice’s instruments is really promising. We are getting more excited about how well they work and how much we will reveal about Jupiter and its icy moons in the 2030s.
Bottom line: Juice reveals Comet 3I/ATLAS is highly active, with a vast gas and dust cloud. It behaves like solar system comets while offering clues to its interstellar origins.
Observations of Comet 3I/ATLAS by the JANUS camera on ESA’s Juice mission. Juice caught the comet on November 5, 2025, when it was 64 million kilometers (40 million miles) away from the spacecraft. The length of the tail stretching away from the sun is about 6 million km (8 million miles) long here. Image via ESA/ Juice/ JANUS (CC BY-SA 3.0 IGO).
ESA’s JUpiter ICy Moons Explorer, aka Juice, is on a mission to the largest planet in our solar system. But in November 2025, it had a chance to observe interstellar comet 3I/ATLAS.
Juice observed Comet 3I/ATLAS releasing huge amounts of water vapor, mainly from its sun-facing side and surrounding dust coma.
The comet’s gas and dust extend over 5 million km (3 million miles), and images show typical comet behavior, much like ordinary solar system comets.
The Juice mission observes interstellar comet 3I/ATLAS
In November 2025, Juice was in the right place at the right time with the right equipment to observe interstellar comet 3I/ATLAS just after its closest approach to the sun. Our mission operations teams switched on five of Juice’s science instruments to collect information about how the active comet was behaving at the time.
Following a three-month wait to receive the data on Earth, scientists working on each of these instruments have spent the last few weeks delving into the photos, spectra and numbers. Results are still preliminary, work is still ongoing, but here are five things we’ve already learned.
1. 70 Olympic swimming pools of water vapor every day
On November 2, 2025, just four days after 3I/ATLAS had made its closest approach to the sun, Juice’s Moons And Jupiter Imaging Spectrometer (MAJIS) detected that the comet was spewing out 2,000 kg of water vapor every second. That’s equivalent to 70 Olympic swimming pools per day.
Comets – true to their ‘dirty snowball’ nickname – are mostly made of ice. As they approach the sun, this ice turns to gas and escapes the comet. The amount of water vapor leaving 3I/ATLAS is not exceptional. But it is on the high side of what we would expect from a comet close to the sun, based on what we have seen before in comets like 67P (300 kg per second) and Halley (20,000 kg per second).
These numbers depend a lot on the size of a comet and its distance from the sun. MAJIS detected 3I/ATLAS again on November 12 and 19, as it was moving away from the sun. By November 12, the amount of water vapor being released by the comet did not seem to have reduced significantly. The instrument team is planning to analyze the data from November 19 in the coming weeks.
MAJIS infrared observations of 3I/ATLAS in infrared light, overlaid on an image from Juice’s navigation camera. The instrument detected water vapor and carbon dioxide being released by the comet. Image via ESA/ Juice/ MAJIS (CC BY-SA 3.0 IGO).
2. Water vapor released in the direction of the sun
Juice’s Submillimeter Wave Instrument (SWI) also detected water vapor from 3I/ATLAS. It revealed that most of it was coming from the sun-facing side of the comet. It also appears that a lot of this water vapor is not actually coming directly from the solid part of the comet (its nucleus). Instead, it’s coming from icy dust grains that have escaped into a surrounding halo of dust and gas (its coma).
The SWI team are continuing to look into the data to determine how much ‘light’ water (normal H2O) 3I/ATLAS is releasing. It is interesting to compare this to the amount of ‘semiheavy’ water (HDO) from the comet, which has been measured by the ALMA and Webb telescopes. This ratio is a really important number in our studies of the universe. It gives a kind of ‘fingerprint’ that describes how and where an object formed.
ALMA and Webb found this ratio to be unexpectedly and extremely high for 3I/ATLAS. This may possibly be because the comet was born in a very cold and very ancient environment, where it was exposed to a lot of ultraviolet radiation from young stars. The SWI team is investigating whether the Juice data back up these findings.
3. Gas and dust stretch for 5 million km
Juice’s Ultraviolet Imaging Spectrograph (UVS) captured light coming from oxygen, hydrogen and carbon atoms in the gas and dust surrounding and trailing behind the comet. Oxygen, hydrogen, carbon and dust emit photons of light at specific wavelengths, which UVS recorded as counts per second.
UVS saw these gas elements and dust stretching up to more than 5 million km (3.1 million miles) from 3I/ATLAS’s nucleus. Gas and dust are common around active comets, with tails sometimes reaching up to 10 million km (6.2 million miles) long.
Counts of oxygen, hydrogen, carbon and dust measured by Juice’s UVS instrument from Comet 3I/ATLAS. Image via ESA (CC BY-SA 3.0 IGO).
4. This interstellar comet looks just like a normal comet!
Juice’s high-resolution science camera, JANUS (short for ‘Jovis Amorum ac Natorum Undique Scrutator’ – or ‘Scrutiniser of Jupiter, and all his loves and descendants’) also saw 3I/ATLAS spewing gas and dust.
Despite being over 60 million km (37 million miles) from 3I/ATLAS, JANUS clearly reveals the coma in which the nucleus is hiding, as well as two tails. One tail stretches away from the sun. And the other follows the path taken by the comet through the solar system. We can also see fainter shapes within the coma and tails that indicate various processes and interactions with the radiation, particles and magnetic field from the sun. The JANUS team is currently investigating these shapes in more detail.
Overall, JANUS shows that, despite its interstellar origin, Comet 3I/ATLAS was behaving like a typical comet from the solar system during a close approach to the sun.
Comet 3I/ATLAS through red and violet filters. In the red filter, the bright center of the coma is more compact and there are two tails: one straight down, and a fuzzier one going to the lower left. In the violet filter, the coma is bigger but fainter, and only one tail stands out clearly. The differences arise because different gas and dust particles release or reflect light at different wavelengths. Image via ESA (CC BY-SA 3.0 IGO).
5. 3I/ATLAS is supporting our planetary defense efforts
Juice’s Navigation Camera (NavCam) is specially designed to help Juice navigate around Jupiter’s icy moons following arrival in 2031. The encounter with 3I/ATLAS enabled us to do something totally unexpected with it.
We have already used telescopes on and around Earth to estimate the location and path of Comet 3I/ATLAS through the solar system. It seems to come from the direction of the Milky Way’s disk. Therefore, it was likely created more than 10 billion years ago.
NavCam had a much closer view of 3I/ATLAS, from a different angle as from Earth-based telescopes, during a period when the comet was not visible from Earth. This meant that ESA’s Planetary Defence team could line up NavCam images from throughout November to get a better idea of the comet’s changing position and trajectory.
In this way, the team – which usually tracks potentially hazardous asteroids – showed how powerful observations from deep-space missions can be to precisely calculate the orbits of comets or asteroids that cannot immediately be seen from Earth.
What’s more, because a comet’s trajectory is affected slightly by the release of dust and gas, the team is starting to use the trajectory measurements based on NavCam images to understand what materials – and how much of them – the comet is leaving in its wake.
Juice’s NavCam had a much closer view of 3I/ATLAS from a different angle as from Earth-based telescopes, during a period when the comet was not visible from Earth. This meant that NavCam images from throughout November 2025 could be lined up to get a better idea of the comet’s changing position and trajectory. Image via ESA/ Juice/ NavCam (CC BY-SA 3.0 IGO).
What’s next for Juice?
Instrument teams will continue to study the data, with many teams planning to publish papers on their results in the coming months. Olivier Witasse, ESA Juice Project Scientist, said:
3I/ATLAS is a rare and unexpected visitor. Its arrival came as a complete surprise. But when we realized that Juice would be close to the comet around its closest approach to the sun, we realized what a unique opportunity this was to collect a once-in-a-lifetime dataset.
Observing the comet was challenging, with no guarantee of success. But in the end, it turned into a great bonus for Juice during its journey to Jupiter.
The closest Juice came to 3I/ATLAS was about 60 million km (37 million miles), whereas it will see Jupiter’s moons from just a few hundred kilometers away. Even so, being designed and equipped to study icy moons, Juice’s instruments were a great match for the icy interstellar comet.
We still have five years to wait before Juice arrives at Jupiter in 2031. But all its instruments will be switched on once again in September 2026 when Juice returns to Earth for another gravity assist. Co-Project Scientist Claire Vallat said:
The data we are already seeing from Juice’s instruments is really promising. We are getting more excited about how well they work and how much we will reveal about Jupiter and its icy moons in the 2030s.
Bottom line: Juice reveals Comet 3I/ATLAS is highly active, with a vast gas and dust cloud. It behaves like solar system comets while offering clues to its interstellar origins.
The constellation Chamaeleon is a Southern Hemisphere target for April evenings. Chart via EarthSky.
The constellation of the Chamaeleon lies deep in the Southern Hemisphere sky. You have to be south of the equator to spot it. As a south circumpolar constellation, it circles closely around the south celestial pole. So, from most of the Southern Hemisphere, it never sets. And that’s why, if you’re in the Southern Hemisphere, you can see it on any night of the year.
The origin of the Chamaeleon
Pieter Dirkszoon Keyser and Frederick de Houtman created the Chamaeleon, along with 11 other Southern Hemisphere constellations, in the late 1500s. These Dutch navigators explored the Southern Hemisphere and took astronomical observations, naming the new constellations after creatures they met on their travels. The chameleon is a type of lizard, and the northern sky has its own lizard constellation: Lacerta.
Locating the constellation of the Chameleon
You can find the constellation Chamaeleon any time of year in the Southern Hemisphere between the south celestial pole and the flowing river of the Milky Way. Also, if you can find the Southern Hemisphere’s prominent constellation of the Southern Cross, or Crux, and draw a line to the south celestial pole, you’ll pass through Chamaeleon.
The dim stars of the Chamaeleon lie near the south celestial pole. Image via IAU/ Sky and Telescope/ Wikipedia. CC BY 3.0.
The stars of the Chamaeleon
The stars of the constellation are all 4th magnitude and dimmer. Alpha Chamaeleontis and Theta Chamaeleontis lie a mere 1/2 degree from each other, with Alpha at magnitude 4.06 and Theta at magnitude 4.35. They lie 63 and 155 light-years away, respectively.
Delta Chamaeleontis is a double star near the center of the constellation. Its two components, four arcminutes apart, are magnitude 4.45 and 5.46, averaging 350 light-years distant. Then two degrees away is Gamma Chamaeleontis, magnitude 4.12 and 413 light-years away. Lastly is Beta Chamaeleontis at magnitude 4.24 and 271 light-years distant, found at the opposite end of the constellation as Alpha.
The constellation is supposed to represent the type of lizard known as the chameleon. Shown here is the panther chameleon from Madagascar. Image via Wikimedia Commons.
Bottom line: The constellation Chamaeleon is a dark patch of sky that lies deep in the Southern Hemisphere and is visible any night of the year.
The constellation Chamaeleon is a Southern Hemisphere target for April evenings. Chart via EarthSky.
The constellation of the Chamaeleon lies deep in the Southern Hemisphere sky. You have to be south of the equator to spot it. As a south circumpolar constellation, it circles closely around the south celestial pole. So, from most of the Southern Hemisphere, it never sets. And that’s why, if you’re in the Southern Hemisphere, you can see it on any night of the year.
The origin of the Chamaeleon
Pieter Dirkszoon Keyser and Frederick de Houtman created the Chamaeleon, along with 11 other Southern Hemisphere constellations, in the late 1500s. These Dutch navigators explored the Southern Hemisphere and took astronomical observations, naming the new constellations after creatures they met on their travels. The chameleon is a type of lizard, and the northern sky has its own lizard constellation: Lacerta.
Locating the constellation of the Chameleon
You can find the constellation Chamaeleon any time of year in the Southern Hemisphere between the south celestial pole and the flowing river of the Milky Way. Also, if you can find the Southern Hemisphere’s prominent constellation of the Southern Cross, or Crux, and draw a line to the south celestial pole, you’ll pass through Chamaeleon.
The dim stars of the Chamaeleon lie near the south celestial pole. Image via IAU/ Sky and Telescope/ Wikipedia. CC BY 3.0.
The stars of the Chamaeleon
The stars of the constellation are all 4th magnitude and dimmer. Alpha Chamaeleontis and Theta Chamaeleontis lie a mere 1/2 degree from each other, with Alpha at magnitude 4.06 and Theta at magnitude 4.35. They lie 63 and 155 light-years away, respectively.
Delta Chamaeleontis is a double star near the center of the constellation. Its two components, four arcminutes apart, are magnitude 4.45 and 5.46, averaging 350 light-years distant. Then two degrees away is Gamma Chamaeleontis, magnitude 4.12 and 413 light-years away. Lastly is Beta Chamaeleontis at magnitude 4.24 and 271 light-years distant, found at the opposite end of the constellation as Alpha.
The constellation is supposed to represent the type of lizard known as the chameleon. Shown here is the panther chameleon from Madagascar. Image via Wikimedia Commons.
Bottom line: The constellation Chamaeleon is a dark patch of sky that lies deep in the Southern Hemisphere and is visible any night of the year.
The EarthSky community has many talented astrophotographers who capture stunning images of the deep sky. We gathered some of our favorite deep-sky photos we received in March 2026 for you to enjoy. Do you have images of your own to share? You can submit them to us here. We would love to see them!
View at EarthSky Community Photos. | Jelieta Walinski at Desert Bloom Observatory in St. David, Arizona, used more than 100 hours of exposures to image this emerald nebula. Jelieta wrote: “In a quiet region of the constellation Serpens, this emission nebula reveals itself as a cosmic bloom. This deep image transforms faint hydrogen gas into a luminous structure resembling a flower unfolding in green radiance.” Thank you, Jelieta!View at EarthSky Community Photos. | Mohammed Ahmed in Suez, Egypt, used a telephoto lens to capture this view of the Horsehead Nebula in the constellation Orion on March 22, 2026. Mohammed wrote: “I wanted to say goodbye to winter with this shot. This is the famous Horsehead Nebula, a dark nebula located in Orion near the star Alnitak. It’s one of the hidden gems of the winter sky, and now we will have to wait for next winter for Orion to come back.” Thank you, Mohammed!View at EarthSky Community Photos. | Kueng Cornelia in Lake Zurich, Switzerland, captured this telescopic view of the Seagull Nebula, in the constellation Monoceros, on March 18, 2025. Kueng wrote: “I am on the way to collect nebulae with animal names for my lovely grandchildren. Just now in my backyard toward the south, IC 2177 – the Seagull Nebula – is in good position.” Thank you, Kueng!
View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, captured this telescopic view of Messier 82, the Starburst Galaxy in Ursa Major, on March 10, 2026. Steven wrote: “M82 had a gravitational interaction with its larger neighbor, galaxy M81. This, in turn, funneled large amounts of gas toward the core of M82, which then triggered intense star formation at a rate 10 times faster than in our Milky Way.” Thank you, Steven!View at EarthSky Community Photos. | Steven Bellavia in Scottsburg, Virginia, captured these exposures of the Leo Triplet of Galaxies on March 19, 2026. Steven wrote: “I have always enjoyed images of the Leo Triplet of galaxies. But I have also always wanted to capture them close up, one at a time, as each one is beautiful and full of intricate colors and details, often missed in the wide-field images. So on my recent astro-camping trip to the Staunton River Star Party, I captured 2 of the 3, close up, with the 3rd from a year ago, also from the same star party.” Thank you, Steven!
Bottom line: Without a doubt, you’ll enjoy this gallery of deep-sky photos for March 2026 from our EarthSky community. If you have a great photo to share, send it in, too. We love to see them!
The EarthSky community has many talented astrophotographers who capture stunning images of the deep sky. We gathered some of our favorite deep-sky photos we received in March 2026 for you to enjoy. Do you have images of your own to share? You can submit them to us here. We would love to see them!
View at EarthSky Community Photos. | Jelieta Walinski at Desert Bloom Observatory in St. David, Arizona, used more than 100 hours of exposures to image this emerald nebula. Jelieta wrote: “In a quiet region of the constellation Serpens, this emission nebula reveals itself as a cosmic bloom. This deep image transforms faint hydrogen gas into a luminous structure resembling a flower unfolding in green radiance.” Thank you, Jelieta!View at EarthSky Community Photos. | Mohammed Ahmed in Suez, Egypt, used a telephoto lens to capture this view of the Horsehead Nebula in the constellation Orion on March 22, 2026. Mohammed wrote: “I wanted to say goodbye to winter with this shot. This is the famous Horsehead Nebula, a dark nebula located in Orion near the star Alnitak. It’s one of the hidden gems of the winter sky, and now we will have to wait for next winter for Orion to come back.” Thank you, Mohammed!View at EarthSky Community Photos. | Kueng Cornelia in Lake Zurich, Switzerland, captured this telescopic view of the Seagull Nebula, in the constellation Monoceros, on March 18, 2025. Kueng wrote: “I am on the way to collect nebulae with animal names for my lovely grandchildren. Just now in my backyard toward the south, IC 2177 – the Seagull Nebula – is in good position.” Thank you, Kueng!
View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, captured this telescopic view of Messier 82, the Starburst Galaxy in Ursa Major, on March 10, 2026. Steven wrote: “M82 had a gravitational interaction with its larger neighbor, galaxy M81. This, in turn, funneled large amounts of gas toward the core of M82, which then triggered intense star formation at a rate 10 times faster than in our Milky Way.” Thank you, Steven!View at EarthSky Community Photos. | Steven Bellavia in Scottsburg, Virginia, captured these exposures of the Leo Triplet of Galaxies on March 19, 2026. Steven wrote: “I have always enjoyed images of the Leo Triplet of galaxies. But I have also always wanted to capture them close up, one at a time, as each one is beautiful and full of intricate colors and details, often missed in the wide-field images. So on my recent astro-camping trip to the Staunton River Star Party, I captured 2 of the 3, close up, with the 3rd from a year ago, also from the same star party.” Thank you, Steven!
Bottom line: Without a doubt, you’ll enjoy this gallery of deep-sky photos for March 2026 from our EarthSky community. If you have a great photo to share, send it in, too. We love to see them!
This is the elegant crested tinamou (Eudromia elegans). Many bird species that are closely related will lay eggs that are similar in color. But tinamou birds, which live in habitats ranging from Mexico down through South America, lay eggs that come in a variety of colors. Image via Scott Hecker/ Flickr (CC BY 2.0).
Why do tinamou birds lay such colorful eggs?
The myriad egg colors that tinamou birds lay – which range from brilliant pinks and blues to rich purples and greens – have long fascinated scientists. Why do similar species under the same habitat pressures produce different egg colors? Scientists think the diverse colors might be a social mating signal. The latest research shows that various colors could help these ground-nesting birds differentiate their eggs from those of closely related species.
A team of researchers published their findings on Tinamou egg color in the peer-reviewed journal Evolution in May of 2023.
The tinamou bird lays a variety of colors of eggs. Top: The chocolate-colored eggs are from the spotted nothura species of tinamou. Bottom: The turquoise eggs are from the white-throated tinamou. Images via Manuel Anastácio/ (Wikimedia CommonsCC BY 3.0).
Scientists have a decent grasp on the broad factors that influence what color eggs a bird will have. These factors include nesting location and habitat, competition and predation by other species, and mating and incubation cues. Ground-nesting birds, such as killdeers and piping plovers, typically lay pale, speckled eggs that provide camouflage from predators. Meanwhile, birds that are cavity nesters, such as red-bellied woodpeckers and barred owls, lay white eggs. That’s because color would have little benefit in the dark and not be worth the energy investment. Then there are birds that lay brightly colored eggs, such as American robins. The robin’s-egg-blue pigment – or biliverdin – is thought to protect the developing embryo from harmful ultraviolet light.
Tinamou birds, which are native to Mexico, Central America and South America, use an assortment of vibrant egg colors. These colors may seem perplexing at first glance. Because these birds are ground nesters, we might expect cryptic (camouflaging) egg coloration to fool predators. But tinamou birds have a well-camouflaged mottled plumage, and they sit on the nests, guarding and incubating the eggs. Thus, the eggs are not readily visible to predators. So other evolutionary driving forces must be at play.
Tinamou egg color as a mating cue
The hypothesis proposed by the team of scientists – Qin Li, Dahong Chen and Silu Wang – in the 2023 study is that egg color serves as a mating signal that contributes to tinamou speciation, which is the process by which new species are formed. They collected data on egg color of 32 tinamou species, using both community science databases and museum collections.
The findings showed that divergent egg colors were more common among species living in the same ecoregions.
Their conclusion was that egg colors evolved partly to help species recognize each other and avoid mating mistakes in areas where similar species live. In the wild, a female would see eggs already in a nest when she approaches a male to mate. The color of the eggs help her determine which species the nest belongs to. Thus, she can decide whether or not to lay eggs with that male and avoid breeding with the wrong species.
In tinamou birds, the females mate with multiple males, and it is the male (not the female) that sits on the nest to incubate the eggs. The nests may contain eggs from multiple females of the same species but not eggs from different species. Possibly, the egg colors could also serve as a cue to the male to incubate only those eggs from his species.
Tinamou birds appear to be displaying a phenomenon that biologists call character displacement. In character displacement, species living in the same habitat evolve to have different traits to avoid competition. The classic example of character displacement is Darwin’s beloved Galapagos finches. They evolved to have divergent beak shapes, allowing each species to specialize in eating different types of seeds.
Additional reasons for varying egg colors
There might not be only one reason for why tinamou birds lay various colored eggs. Besides helping females find the nests of their own species, predation could still play a role.
Evolutionary biologist Patricia Brennan conducted an earlier study in which she proposed that tinamou egg color may be a signal to other female birds promoting synchronous laying. The idea is that if multiple females can find a nest easily because of the colorful eggs, they may be compelled to lay their eggs at the same time in the same nest as a form of communal nesting. Then, at least some of the eggs would likely survive attacks by predators, such as snakes, foxes and hawks, because there’s safety in numbers. In other words, the sheer number of eggs produced at once increases the odds that at least some will survive.
As egg color expert Dan Ardia, in an interview in the Cornell Laboratory of Ornithology’s Living Bird magazine, said:
There are many competing hypotheses to explain egg coloration and they’re not all mutually exclusive. Pigment function is almost surely a complicated combination of factors depending on the idiosyncrasies of each species.
If you plan to decorate eggs for Easter, you can sneak in some science lessons on how egg color can be used by ground-nesting birds for camouflage and for finding nests. Do you think kids will have a hard time finding camouflaged eggs? EarthSky would love to see science-themed Easter egg photos. Submit them to us!
Bottom line: Why do tinamou birds lay such colorful eggs? Scientists think the many egg colors evolved in part to help closely related species recognize each other and avoid competition from other species at their nest sites.
This is the elegant crested tinamou (Eudromia elegans). Many bird species that are closely related will lay eggs that are similar in color. But tinamou birds, which live in habitats ranging from Mexico down through South America, lay eggs that come in a variety of colors. Image via Scott Hecker/ Flickr (CC BY 2.0).
Why do tinamou birds lay such colorful eggs?
The myriad egg colors that tinamou birds lay – which range from brilliant pinks and blues to rich purples and greens – have long fascinated scientists. Why do similar species under the same habitat pressures produce different egg colors? Scientists think the diverse colors might be a social mating signal. The latest research shows that various colors could help these ground-nesting birds differentiate their eggs from those of closely related species.
A team of researchers published their findings on Tinamou egg color in the peer-reviewed journal Evolution in May of 2023.
The tinamou bird lays a variety of colors of eggs. Top: The chocolate-colored eggs are from the spotted nothura species of tinamou. Bottom: The turquoise eggs are from the white-throated tinamou. Images via Manuel Anastácio/ (Wikimedia CommonsCC BY 3.0).
Scientists have a decent grasp on the broad factors that influence what color eggs a bird will have. These factors include nesting location and habitat, competition and predation by other species, and mating and incubation cues. Ground-nesting birds, such as killdeers and piping plovers, typically lay pale, speckled eggs that provide camouflage from predators. Meanwhile, birds that are cavity nesters, such as red-bellied woodpeckers and barred owls, lay white eggs. That’s because color would have little benefit in the dark and not be worth the energy investment. Then there are birds that lay brightly colored eggs, such as American robins. The robin’s-egg-blue pigment – or biliverdin – is thought to protect the developing embryo from harmful ultraviolet light.
Tinamou birds, which are native to Mexico, Central America and South America, use an assortment of vibrant egg colors. These colors may seem perplexing at first glance. Because these birds are ground nesters, we might expect cryptic (camouflaging) egg coloration to fool predators. But tinamou birds have a well-camouflaged mottled plumage, and they sit on the nests, guarding and incubating the eggs. Thus, the eggs are not readily visible to predators. So other evolutionary driving forces must be at play.
Tinamou egg color as a mating cue
The hypothesis proposed by the team of scientists – Qin Li, Dahong Chen and Silu Wang – in the 2023 study is that egg color serves as a mating signal that contributes to tinamou speciation, which is the process by which new species are formed. They collected data on egg color of 32 tinamou species, using both community science databases and museum collections.
The findings showed that divergent egg colors were more common among species living in the same ecoregions.
Their conclusion was that egg colors evolved partly to help species recognize each other and avoid mating mistakes in areas where similar species live. In the wild, a female would see eggs already in a nest when she approaches a male to mate. The color of the eggs help her determine which species the nest belongs to. Thus, she can decide whether or not to lay eggs with that male and avoid breeding with the wrong species.
In tinamou birds, the females mate with multiple males, and it is the male (not the female) that sits on the nest to incubate the eggs. The nests may contain eggs from multiple females of the same species but not eggs from different species. Possibly, the egg colors could also serve as a cue to the male to incubate only those eggs from his species.
Tinamou birds appear to be displaying a phenomenon that biologists call character displacement. In character displacement, species living in the same habitat evolve to have different traits to avoid competition. The classic example of character displacement is Darwin’s beloved Galapagos finches. They evolved to have divergent beak shapes, allowing each species to specialize in eating different types of seeds.
Additional reasons for varying egg colors
There might not be only one reason for why tinamou birds lay various colored eggs. Besides helping females find the nests of their own species, predation could still play a role.
Evolutionary biologist Patricia Brennan conducted an earlier study in which she proposed that tinamou egg color may be a signal to other female birds promoting synchronous laying. The idea is that if multiple females can find a nest easily because of the colorful eggs, they may be compelled to lay their eggs at the same time in the same nest as a form of communal nesting. Then, at least some of the eggs would likely survive attacks by predators, such as snakes, foxes and hawks, because there’s safety in numbers. In other words, the sheer number of eggs produced at once increases the odds that at least some will survive.
As egg color expert Dan Ardia, in an interview in the Cornell Laboratory of Ornithology’s Living Bird magazine, said:
There are many competing hypotheses to explain egg coloration and they’re not all mutually exclusive. Pigment function is almost surely a complicated combination of factors depending on the idiosyncrasies of each species.
If you plan to decorate eggs for Easter, you can sneak in some science lessons on how egg color can be used by ground-nesting birds for camouflage and for finding nests. Do you think kids will have a hard time finding camouflaged eggs? EarthSky would love to see science-themed Easter egg photos. Submit them to us!
Bottom line: Why do tinamou birds lay such colorful eggs? Scientists think the many egg colors evolved in part to help closely related species recognize each other and avoid competition from other species at their nest sites.
Star-hopping is the art of navigating around the sky using bright stars. On April evenings, you can look west after sunset to star-hop from the constellation Orion to Sirius. Chart via EarthSky.
One very easy constellation to find at this time of the year is the magnificent Orion the Hunter, now descending in the west after sunset. It’s easy because Orion contains a very noticeable pattern of three medium-bright stars in a short straight row. These stars are known as Orion’s Belt. Find Orion, and continue the line of his belt to star-hop to Sirius. Found in the constellation Canis Major, this is the night sky’s brightest star!
As Earth revolves around the sun, both the constellation Orion and the star Sirius are about to disappear for a while. They always drop into the sun’s glare shortly after this time of the year, as Earth’s motion brings the sun between us and them. So be sure to look for them while you can, soon after the sun goes down. We’ll see them again in the east before dawn, beginning around late July or early August.
Try it for yourself
People learning to recognize the stars often use star-hopping – going from stars they know to objects that are fainter or less easily identifiable – to find and recognize new stars and constellations. The use of Orion’s Belt to find Sirius is one of the best-known star-hops in the sky, because the stars are so bright and the pattern is so definite.
Another great star-hop to try is using the Big Dipper to find Polaris, the North Star. If you’re in the Northern Hemisphere, this star-hop will allow you to always find north!
Look for the Big and Little Dipper high in the northern sky on spring evenings. This view is for the Northern Hemisphere. The 2 outer stars in the bowl of the Dipper point to Polaris, the North Star. Polaris marks the end of the handle of the Little Dipper. Chart via EarthSky.View at EarthSky Community Photos. | Cecille Kennedy in Oregon shared this image with us on March 13, 2024. Cecille wrote: “Before midnight, pointing the camera straight up into the night sky, there is the Big Dipper and the Little Dipper. When you are looking at Polaris, you are facing north. While other constellations move around, Polaris stays still as it’s found at the north celestial pole. Thus Polaris is a very useful star for navigators and sailors. The 2 front stars in the asterism of the Big Dipper are called Pointers because they point to the North Star or Polaris.” Thank you, Cecille!
Bottom line: Star-hopping is going from stars you know to stars you don’t know. Star-hop from the constellation Orion the Hunter to Sirius, the night sky’s brightest star, before they’re gone!
Star-hopping is the art of navigating around the sky using bright stars. On April evenings, you can look west after sunset to star-hop from the constellation Orion to Sirius. Chart via EarthSky.
One very easy constellation to find at this time of the year is the magnificent Orion the Hunter, now descending in the west after sunset. It’s easy because Orion contains a very noticeable pattern of three medium-bright stars in a short straight row. These stars are known as Orion’s Belt. Find Orion, and continue the line of his belt to star-hop to Sirius. Found in the constellation Canis Major, this is the night sky’s brightest star!
As Earth revolves around the sun, both the constellation Orion and the star Sirius are about to disappear for a while. They always drop into the sun’s glare shortly after this time of the year, as Earth’s motion brings the sun between us and them. So be sure to look for them while you can, soon after the sun goes down. We’ll see them again in the east before dawn, beginning around late July or early August.
Try it for yourself
People learning to recognize the stars often use star-hopping – going from stars they know to objects that are fainter or less easily identifiable – to find and recognize new stars and constellations. The use of Orion’s Belt to find Sirius is one of the best-known star-hops in the sky, because the stars are so bright and the pattern is so definite.
Another great star-hop to try is using the Big Dipper to find Polaris, the North Star. If you’re in the Northern Hemisphere, this star-hop will allow you to always find north!
Look for the Big and Little Dipper high in the northern sky on spring evenings. This view is for the Northern Hemisphere. The 2 outer stars in the bowl of the Dipper point to Polaris, the North Star. Polaris marks the end of the handle of the Little Dipper. Chart via EarthSky.View at EarthSky Community Photos. | Cecille Kennedy in Oregon shared this image with us on March 13, 2024. Cecille wrote: “Before midnight, pointing the camera straight up into the night sky, there is the Big Dipper and the Little Dipper. When you are looking at Polaris, you are facing north. While other constellations move around, Polaris stays still as it’s found at the north celestial pole. Thus Polaris is a very useful star for navigators and sailors. The 2 front stars in the asterism of the Big Dipper are called Pointers because they point to the North Star or Polaris.” Thank you, Cecille!
Bottom line: Star-hopping is going from stars you know to stars you don’t know. Star-hop from the constellation Orion the Hunter to Sirius, the night sky’s brightest star, before they’re gone!
View at EarthSky Community Photos. | Steve Price of Draper, Utah, posted this photo on March 30, 2024. Steve wrote: “These are some of the Ukrainian Pysanky Easter eggs I made. We display them each Easter season.” Thanks, Steve!
Here’s the rule for Easter Sunday. It generally falls on the first Sunday after the first full moon on or after the vernal equinox.
And so Easter is a movable feast. Its date is different from year to year. The 2026 equinox was March 20. It marked an unofficial beginning of spring for the Northern Hemisphere and autumn for the Southern Hemisphere. The first full moon after the March equinox arrives overnight on April 1-2, 2026. Voilà! In 2026, Easter is April 5.
And then Eastern Orthodox Easter falls on April 12, 2026. Generally, that date is a little different because it follows the Julian calendar.
How is Easter determined?
The Council of Nicaea – first ecumenical council of the Christian church – established the date of Easter when it met in Turkey in the year 325 CE. By ecclesiastical rules set centuries ago, there are 35 dates on which Easter can take place.
The earliest possible date for Easter is March 22 and the latest possible date is April 25.
Easter can never come as early as March 21, though. That’s because, by ecclesiastical rules, the vernal equinox is fixed on March 21. That’s in spite of the fact that in the 21st century (2001 to 2100) every March equinox after the year 2007 will fall on March 19 or March 20.
The last time Easter fell on March 22 (earliest possible date) was in 1818, and the next time will be in 2285. The most recent time an Easter came in March was March 27, 2016.
Easter eggs from the Czech Republic. Image via svajcr/ Wikipedia.
More details and dates
The earliest Easter in the 21st century came in the year 2008 (March 23, 2008). Another March 23 Easter won’t come again until the year 2160.
The century’s latest Easter will occur in the year 2038 (April 25, 2038). After that, it will next fall on April 25 in the year 2190.
One last detail. Most of us celebrate Easter Sunday via a combination of ecclesiastical rules set long ago and real events in our night sky. But these don’t always coincide. For example, an ecclesiastical full moon doesn’t usually happen on the same date as the full moon you see at night. Ecclesiastical full moons are formally fixed as the 14th day of the ecclesiastical lunar month.
So it’s possible for an ecclesiastical Easter and an astronomical Easter to occur on different dates, as well.
View at EarthSky Community Photos. | Steve Price of Draper, Utah, posted this photo on March 30, 2024. Steve wrote: “These are some of the Ukrainian Pysanky Easter eggs I made. We display them each Easter season.” Thanks, Steve!
Here’s the rule for Easter Sunday. It generally falls on the first Sunday after the first full moon on or after the vernal equinox.
And so Easter is a movable feast. Its date is different from year to year. The 2026 equinox was March 20. It marked an unofficial beginning of spring for the Northern Hemisphere and autumn for the Southern Hemisphere. The first full moon after the March equinox arrives overnight on April 1-2, 2026. Voilà! In 2026, Easter is April 5.
And then Eastern Orthodox Easter falls on April 12, 2026. Generally, that date is a little different because it follows the Julian calendar.
How is Easter determined?
The Council of Nicaea – first ecumenical council of the Christian church – established the date of Easter when it met in Turkey in the year 325 CE. By ecclesiastical rules set centuries ago, there are 35 dates on which Easter can take place.
The earliest possible date for Easter is March 22 and the latest possible date is April 25.
Easter can never come as early as March 21, though. That’s because, by ecclesiastical rules, the vernal equinox is fixed on March 21. That’s in spite of the fact that in the 21st century (2001 to 2100) every March equinox after the year 2007 will fall on March 19 or March 20.
The last time Easter fell on March 22 (earliest possible date) was in 1818, and the next time will be in 2285. The most recent time an Easter came in March was March 27, 2016.
Easter eggs from the Czech Republic. Image via svajcr/ Wikipedia.
More details and dates
The earliest Easter in the 21st century came in the year 2008 (March 23, 2008). Another March 23 Easter won’t come again until the year 2160.
The century’s latest Easter will occur in the year 2038 (April 25, 2038). After that, it will next fall on April 25 in the year 2190.
One last detail. Most of us celebrate Easter Sunday via a combination of ecclesiastical rules set long ago and real events in our night sky. But these don’t always coincide. For example, an ecclesiastical full moon doesn’t usually happen on the same date as the full moon you see at night. Ecclesiastical full moons are formally fixed as the 14th day of the ecclesiastical lunar month.
So it’s possible for an ecclesiastical Easter and an astronomical Easter to occur on different dates, as well.
