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Meet Regulus, Leo the Lion’s Heart and brightest star

Star chart: animal-shaped constellation with head at right side and bright star, Regulus, in chest area.
Leo the Lion’s brightest star is Regulus, aka the Lion’s Heart. Regulus marks the bright dot at the bottom of a backward question mark that forms Leo’s head and shoulders. This pattern is called the Sickle. An easily identifiable triangle depicts the Lion’s hindquarters and tail, with the star Denebola marking the tail of the Lion. Chart via EarthSky.

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Regulus is the brightest star in the constellation Leo the Lion. Also known as Alpha Leonis, it ranks 21st in the list of brightest stars in our sky.

It’s located near the ecliptic, or sun’s path across our sky. So both Earth’s Northern and Southern Hemispheres see Regulus equally well.

Regulus is part of a backward question mark star pattern, and it marks the dot at the bottom of the question mark. This pattern, known as the Sickle, makes up the head and forequarters of Leo the Lion.

You’ll recognize Regulus for its brightness and blue-white color. It looks like one star to the eye, but it’s really four stars (that we know of so far).

Regulus is located about 79 light-years from Earth.

Star chart with stars in black on white and labeled, along with several labeled Messier objects.
A star chart showing the constellation Leo the Lion. On the right is a pattern that looks like a flipped question mark, the Sickle. This is the most recognizable pattern to look for when trying to locate Leo in the sky. Image via Torsten Bronger/ Wikimedia Commons.

Finding the Lion from the Northern Hemisphere

In the Northern Hemisphere, the star Regulus and its constellation Leo the Lion are harbingers of spring.

They crept higher in the sky with each passing day in March and April, as northern winter favorites – like Orion the Hunter – descended westward.

And now, in May, blue-white Regulus is brilliant in the eastern evening sky as soon as the sun goes down.

And a darker sky reveals the distinctive Sickle and the overall shape of the Lion.

From the Northern Hemisphere, Regulus is visible at some time of night throughout the year, except for about a month on either side of August 22. If you looked toward Regulus around that date, you’d see the sun.

In the Northern Hemisphere, Regulus is known as one of three bright stars making up the asterism of the Spring Triangle.

From the Southern Hemisphere, the Lion is upside down

Via Daniel Gaussen, Founder & Guide – Stargaze Mackenzie – New Zealand

From southern latitudes, the figure of the Lion – named long ago by stargazers on the northern part of Earth’s globe – appears upside down. Regulus traditionally marks Leo’s lower front paw. But Regulus appears as the highest of Leo’s stars from our southerly perspective.

And, from our latitudes on the south of Earth’s globe, the Sickle asterism appears as a mirrored upside-down question mark. This pattern is clearly recognizable for skywatchers tracing the inverted Lion across the northern sky.

As seen from either the Northern or Southern Hemisphere, Regulus more or less follows the sun and moon’s path across our sky. So those in the Northern Hemisphere face generally southward to see Regulus make its wide arc across the sky. But we in the Southern Hemisphere face generally northward to see it.

At a latitude of 35 degrees south, Regulus climbs to about 43 degrees above the northern horizon at its highest. It’s noticeably higher than other bright northern stars, such as Vega. In the Southern Hemisphere, Regulus is one of the easier northern stars to spot during the southern autumn and early winter evenings (May through August).

So, while Leo is a northern constellation, its most prominent marker – Regulus – remains a useful and reliable reference point from the Southern Hemisphere during the colder months.

Despite the constellation’s inverted appearance, the clarity of Regulus and the distinctive Sickle pattern make Leo surprisingly easy to identify once you know what to look for.

Planets and the moon pass near it

Regulus is the only 1st magnitude star to sit almost squarely on the ecliptic, or path of the sun, moon and planets across our sky.

So the moon sweeps past Regulus once a month when this star is visible. In some years, the moon occults – or passes in front of – Regulus as seen from Earth. We’re in a series of 20 lunar occultations of Regulus now, lasting from July 2025 to December 2026. During the December 2026 occultation, Mars and Jupiter will be nearby.

And bright planets also sometimes pass Regulus. Planets can even sometimes occult – or pass in front of – this star. The last planet to occult Regulus was Venus on July 7, 1959. Then on October 1, 2044, Venus will occult Regulus again.

Don’t miss a thing! Visit our monthly night sky guide.

A blue, egg-shaped star

Regulus is a multiple star system, consisting of at least four stars. The main star – Regulus A – is large and blue with a spectral type of B8 IVn. Its surface temperature averages about 12,460 kelvin (21,970 degrees F or 12,190 degrees C), which is much higher than our sun’s surface temperature. Regulus A is 3.8 times the mass of our sun, about 4 times as wide, and almost 300 times as bright.

Regulus A spins on its axis once every 16 hours. In contrast, our sun spins on its axis about once every 27 days. This fast rotation causes Regulus A to bulge at its equator, so it appears oblate, or egg-shaped. In fact, if Regulus rotated just a bit faster, it would fly apart!

And Regulus isn’t the only star with a fast spin. The stars Altair and Achernar are also fast spinners with flattened, oblate shapes.

An egg-shaped spheroid with a much smaller sphere at the lower right.
Georgia State University’s Center for High Angular Resolution Astronomy (CHARA) created this computer-generated model of Regulus in 2005. Next to it there is a model of our sun for scale. The high rotation rate of Regulus creates pronounced equatorial bulging, such that its diameter across its equator (running nearly vertically in this image) is 1/3 longer than its north-south diameter. Image via Wenjin Huang/ Georgia State University/ NOIRlab.

We can see 3 of Regulus’ 4 stars

Look through a small telescope using at least 50x magnification, and you will see Regulus as two objects separated by 177 arcseconds. The brighter of the pair is Regulus A.

The fainter one is Regulus B, a cool “orange” dwarf star with a spectral classification of K2 V. The B star has a mass that is 80% of the sun’s, and it’s half as bright. It has a surface temperature of 4,885 kelvin (8,300 F or 4,600 C), and it shines at magnitude 8.1.

Regulus B has its own companion: Regulus C. At magnitude 13.5, it’s only visible with powerful telescopes. With just 1/3 the mass of the sun, Regulus C is a red dwarf star with a spectral classification of M4 V. Regulus B and C are gravitationally bound to each other, and together they’re called Regulus BC. The distances between B and C ranged from 4.0 to 2.5 arcseconds between 1867 and 1943. There are no recently available measurements.

The 4th star in the system has never been directly resolved via imaging. But its presence is revealed by spectroscopic analysis of Regulus A. Astronomers think it may be a closely orbiting white dwarf star.

You might have heard of a star called Regulus D. This doesn’t refer to the spectroscopic companion of Regulus A, but to a 12th-magnitude star that sits 212 arcseconds from Regulus. For decades, people believed it to be a companion of Regulus, but recent studies from the Gaia satellite show this to be a background star not related to the Regulus system.

A rex by any other name

The name Regulus is from the diminutive form of the Latin rex, meaning little king.

Ancient Arab stargazers called Regulus by the name Qalb al-Asad, which means Heart of the Lion. It also bears the nickname Cor Leonis, again meaning Lion’s Heart. Fittingly, King Richard I of England was also famously known as the Lionheart, or more commonly Coeur de Lion in French.

There is a great deal of mythology associated with Leo, perhaps the most common tale being that Leo was the Nemean Lion of the Hercules story. Some Peruvians also knew these stars as the Mountain Lion, whereas in China it was sometimes seen as a horse, and at other times as part of a dragon. Christians in the Middle Ages sometimes referred to it as one of Daniel’s lions.

Antique colored etching of two yellow lions, one much larger, with the constellations' stars superimposed.
The larger lion is the constellation Leo, with the star Regulus at its heart, as depicted on a set of constellation cards, Urania’s Mirror, published in London in 1825. Above it is the faint constellation Leo Minor. Image via Library of Congress/ Wikimedia Commons.

A galaxy photobombs Regulus

Situated 1/3 degree north of Regulus is the galaxy Leo I. You can see it as a faint patch of light in the photo below. Leo I is difficult to see due to its proximity to Regulus. Albert George Wilson found it on photographic plates taken as part of the National Geographic Society-Palomar Observatory Sky Survey in 1950. It would be another 40 years before anyone viewed it.

Leo I is a dwarf galaxy, and a member of our local group. Amateur astronomers can view it, but this requires dark skies and a large telescope.

In a field of stars, a large, brilliant blue-white star. Above it is a faint horizontal oval smudge of light.
Regulus as photographed using a telescope. The faint smudge above it is the dwarf galaxy Leo I. Image via Fred Espenak. Used with permission.

Bottom line: Regulus, the brightest star in the constellation Leo the Lion, is associated with the arrival of spring and is prominent in May skies. It looks like a single point of light, but is really four stars.

Summer Triangle star: Altair is variable and spins fast!

What is the Sickle in Leo?

The post Meet Regulus, Leo the Lion’s Heart and brightest star first appeared on EarthSky.



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Star chart: animal-shaped constellation with head at right side and bright star, Regulus, in chest area.
Leo the Lion’s brightest star is Regulus, aka the Lion’s Heart. Regulus marks the bright dot at the bottom of a backward question mark that forms Leo’s head and shoulders. This pattern is called the Sickle. An easily identifiable triangle depicts the Lion’s hindquarters and tail, with the star Denebola marking the tail of the Lion. Chart via EarthSky.

Don’t miss the next unmissable night sky event. Sign up for our free newsletter for daily night sky updates, as well as the latest science news.

Regulus is the brightest star in the constellation Leo the Lion. Also known as Alpha Leonis, it ranks 21st in the list of brightest stars in our sky.

It’s located near the ecliptic, or sun’s path across our sky. So both Earth’s Northern and Southern Hemispheres see Regulus equally well.

Regulus is part of a backward question mark star pattern, and it marks the dot at the bottom of the question mark. This pattern, known as the Sickle, makes up the head and forequarters of Leo the Lion.

You’ll recognize Regulus for its brightness and blue-white color. It looks like one star to the eye, but it’s really four stars (that we know of so far).

Regulus is located about 79 light-years from Earth.

Star chart with stars in black on white and labeled, along with several labeled Messier objects.
A star chart showing the constellation Leo the Lion. On the right is a pattern that looks like a flipped question mark, the Sickle. This is the most recognizable pattern to look for when trying to locate Leo in the sky. Image via Torsten Bronger/ Wikimedia Commons.

Finding the Lion from the Northern Hemisphere

In the Northern Hemisphere, the star Regulus and its constellation Leo the Lion are harbingers of spring.

They crept higher in the sky with each passing day in March and April, as northern winter favorites – like Orion the Hunter – descended westward.

And now, in May, blue-white Regulus is brilliant in the eastern evening sky as soon as the sun goes down.

And a darker sky reveals the distinctive Sickle and the overall shape of the Lion.

From the Northern Hemisphere, Regulus is visible at some time of night throughout the year, except for about a month on either side of August 22. If you looked toward Regulus around that date, you’d see the sun.

In the Northern Hemisphere, Regulus is known as one of three bright stars making up the asterism of the Spring Triangle.

From the Southern Hemisphere, the Lion is upside down

Via Daniel Gaussen, Founder & Guide – Stargaze Mackenzie – New Zealand

From southern latitudes, the figure of the Lion – named long ago by stargazers on the northern part of Earth’s globe – appears upside down. Regulus traditionally marks Leo’s lower front paw. But Regulus appears as the highest of Leo’s stars from our southerly perspective.

And, from our latitudes on the south of Earth’s globe, the Sickle asterism appears as a mirrored upside-down question mark. This pattern is clearly recognizable for skywatchers tracing the inverted Lion across the northern sky.

As seen from either the Northern or Southern Hemisphere, Regulus more or less follows the sun and moon’s path across our sky. So those in the Northern Hemisphere face generally southward to see Regulus make its wide arc across the sky. But we in the Southern Hemisphere face generally northward to see it.

At a latitude of 35 degrees south, Regulus climbs to about 43 degrees above the northern horizon at its highest. It’s noticeably higher than other bright northern stars, such as Vega. In the Southern Hemisphere, Regulus is one of the easier northern stars to spot during the southern autumn and early winter evenings (May through August).

So, while Leo is a northern constellation, its most prominent marker – Regulus – remains a useful and reliable reference point from the Southern Hemisphere during the colder months.

Despite the constellation’s inverted appearance, the clarity of Regulus and the distinctive Sickle pattern make Leo surprisingly easy to identify once you know what to look for.

Planets and the moon pass near it

Regulus is the only 1st magnitude star to sit almost squarely on the ecliptic, or path of the sun, moon and planets across our sky.

So the moon sweeps past Regulus once a month when this star is visible. In some years, the moon occults – or passes in front of – Regulus as seen from Earth. We’re in a series of 20 lunar occultations of Regulus now, lasting from July 2025 to December 2026. During the December 2026 occultation, Mars and Jupiter will be nearby.

And bright planets also sometimes pass Regulus. Planets can even sometimes occult – or pass in front of – this star. The last planet to occult Regulus was Venus on July 7, 1959. Then on October 1, 2044, Venus will occult Regulus again.

Don’t miss a thing! Visit our monthly night sky guide.

A blue, egg-shaped star

Regulus is a multiple star system, consisting of at least four stars. The main star – Regulus A – is large and blue with a spectral type of B8 IVn. Its surface temperature averages about 12,460 kelvin (21,970 degrees F or 12,190 degrees C), which is much higher than our sun’s surface temperature. Regulus A is 3.8 times the mass of our sun, about 4 times as wide, and almost 300 times as bright.

Regulus A spins on its axis once every 16 hours. In contrast, our sun spins on its axis about once every 27 days. This fast rotation causes Regulus A to bulge at its equator, so it appears oblate, or egg-shaped. In fact, if Regulus rotated just a bit faster, it would fly apart!

And Regulus isn’t the only star with a fast spin. The stars Altair and Achernar are also fast spinners with flattened, oblate shapes.

An egg-shaped spheroid with a much smaller sphere at the lower right.
Georgia State University’s Center for High Angular Resolution Astronomy (CHARA) created this computer-generated model of Regulus in 2005. Next to it there is a model of our sun for scale. The high rotation rate of Regulus creates pronounced equatorial bulging, such that its diameter across its equator (running nearly vertically in this image) is 1/3 longer than its north-south diameter. Image via Wenjin Huang/ Georgia State University/ NOIRlab.

We can see 3 of Regulus’ 4 stars

Look through a small telescope using at least 50x magnification, and you will see Regulus as two objects separated by 177 arcseconds. The brighter of the pair is Regulus A.

The fainter one is Regulus B, a cool “orange” dwarf star with a spectral classification of K2 V. The B star has a mass that is 80% of the sun’s, and it’s half as bright. It has a surface temperature of 4,885 kelvin (8,300 F or 4,600 C), and it shines at magnitude 8.1.

Regulus B has its own companion: Regulus C. At magnitude 13.5, it’s only visible with powerful telescopes. With just 1/3 the mass of the sun, Regulus C is a red dwarf star with a spectral classification of M4 V. Regulus B and C are gravitationally bound to each other, and together they’re called Regulus BC. The distances between B and C ranged from 4.0 to 2.5 arcseconds between 1867 and 1943. There are no recently available measurements.

The 4th star in the system has never been directly resolved via imaging. But its presence is revealed by spectroscopic analysis of Regulus A. Astronomers think it may be a closely orbiting white dwarf star.

You might have heard of a star called Regulus D. This doesn’t refer to the spectroscopic companion of Regulus A, but to a 12th-magnitude star that sits 212 arcseconds from Regulus. For decades, people believed it to be a companion of Regulus, but recent studies from the Gaia satellite show this to be a background star not related to the Regulus system.

A rex by any other name

The name Regulus is from the diminutive form of the Latin rex, meaning little king.

Ancient Arab stargazers called Regulus by the name Qalb al-Asad, which means Heart of the Lion. It also bears the nickname Cor Leonis, again meaning Lion’s Heart. Fittingly, King Richard I of England was also famously known as the Lionheart, or more commonly Coeur de Lion in French.

There is a great deal of mythology associated with Leo, perhaps the most common tale being that Leo was the Nemean Lion of the Hercules story. Some Peruvians also knew these stars as the Mountain Lion, whereas in China it was sometimes seen as a horse, and at other times as part of a dragon. Christians in the Middle Ages sometimes referred to it as one of Daniel’s lions.

Antique colored etching of two yellow lions, one much larger, with the constellations' stars superimposed.
The larger lion is the constellation Leo, with the star Regulus at its heart, as depicted on a set of constellation cards, Urania’s Mirror, published in London in 1825. Above it is the faint constellation Leo Minor. Image via Library of Congress/ Wikimedia Commons.

A galaxy photobombs Regulus

Situated 1/3 degree north of Regulus is the galaxy Leo I. You can see it as a faint patch of light in the photo below. Leo I is difficult to see due to its proximity to Regulus. Albert George Wilson found it on photographic plates taken as part of the National Geographic Society-Palomar Observatory Sky Survey in 1950. It would be another 40 years before anyone viewed it.

Leo I is a dwarf galaxy, and a member of our local group. Amateur astronomers can view it, but this requires dark skies and a large telescope.

In a field of stars, a large, brilliant blue-white star. Above it is a faint horizontal oval smudge of light.
Regulus as photographed using a telescope. The faint smudge above it is the dwarf galaxy Leo I. Image via Fred Espenak. Used with permission.

Bottom line: Regulus, the brightest star in the constellation Leo the Lion, is associated with the arrival of spring and is prominent in May skies. It looks like a single point of light, but is really four stars.

Summer Triangle star: Altair is variable and spins fast!

What is the Sickle in Leo?

The post Meet Regulus, Leo the Lion’s Heart and brightest star first appeared on EarthSky.



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2026 name list for Atlantic hurricanes: Is yours among them?

Hurricanes: Satellite image of hurricane with 2026 hurricane names on top.
This is the list of tropical cyclone names for the 2026 Atlantic hurricane season. Read about the names of hurricanes below.

Read: NOAA’s hurricane season forecast for 2026

Atlantic hurricane names for 2026

NOAA’s Climate Prediction Center has just released its hurricane season outlook for 2026. But what are the names for the 2026 Atlantic tropical cyclones and hurricanes?

See the complete list of 2026 tropical cyclone and hurricane names in the image above. If any of these storms become truly destructive in 2026, the World Meteorological Organization, which is in charge of the list, retires and replaces the name. For example, in 2024, the World Meteorological Organization retired the names Beryl, Helene and Milton. Helene, in particular, became the deadliest storm in the U.S. since Katrina in 2005.

The 2026 Atlantic hurricane season officially starts June 1 and extends through November 30.

If you live near the Atlantic basin, you can keep up-to-date with forecasts from the National Hurricane Center.

Learn more about how to prepare for hurricane season.

How do hurricanes get their names?

Meteorologists long ago learned that naming tropical storms and hurricanes helps people remember the storms, communicate about them more effectively, and consequently stay safer if and when a particular storm strikes a coast.

These experts assign names to tropical storms according to an approved list before the start of each hurricane season. The U.S. National Hurricane Center started this practice in the early 1950s. Now, the World Meteorological Organization (WMO) generates and maintains the list of hurricane names.

Here are the hurricane names for 2026

Atlantic hurricane names (season runs from June 1 to November 30) are: Arthur, Bertha, Cristobal, Dolly, Edouard, Fay, Gonzalo, Hanna, Isaias, Josephine, Kyle. Leah, Marco, Nana, Omar. Paulette, Rene, Sally, Teddy, Vicky and Wilfred.

Eastern North Pacific hurricane names (season runs from May 15 to November 30) are: Amanda, Boris, Cristina, Douglas, Elida, Fausto, Genevieve, Hernan, Iselle, Julio, Karina, Lowell, Marie, Norbert, Odalys, Polo, Rachel, Simon, Trudy, Vance, Winnie. Xavier, Yolanda and Zeke.

If you’re interested, you can view those names, and names for upcoming years, at the U.S. National Hurricane Center.

Gif showing swirling white clouds over Florida's center moving northeast.
In 2022, Hurricane Ian devastated Florida’s Gulf Coast. It also brought flooding to central Florida, ripped roofs off on the Atlantic Coast and then menaced South Carolina. The name Ian will never again be used for a tropical cyclone or hurricane. Image via NOAA/ GOES.

The history of hurricane names

While people have been naming major storms for hundreds of years, most hurricanes originally had a designation using a system of latitude-longitude numbers. This was useful to meteorologists trying to track these storms. Unfortunately, this system confused people living on coasts seeking hurricane information.

In the early 1950s, the U.S. National Hurricane Center first developed a formal practice for storm naming for the Atlantic Ocean. At that time, storms got their names according to a phonetic alphabet (e.g., Able, Baker, Charlie) and the names used were the same for each hurricane season. In other words, the first hurricane of a season was always named “Able,” the second “Baker,” and so on.

In 1953, to avoid the repetitive use of names, the National Weather Service revised the system to give storms female names. By doing this, the National Weather Service was mimicking the habit of naval meteorologists, who named the storms after women, much as ships at sea traditionally had female names.

In 1978–1979, they revised the system again to include both female and male hurricane names.

See the complete history of naming hurricanes, including retired names, from NOAA.

When does a storm receive a name?

Tropical storms get a name when they display a rotating circulation pattern and wind speeds reach 39 miles per hour (63 kilometers per hour). A tropical storm develops into a hurricane when wind speeds go above 74 mph (119 km/h).

Experts have developed lists of hurricane names for many of the major ocean basins around the world. Today, there are six lists of hurricane names in use for Atlantic Ocean and Eastern North Pacific storms. These lists rotate, one each year. So that means the list of this year’s hurricane names for each basin will come up again six years from now.

However, there’s an exception to this practice. The World Meteorological Organization retires the names of extremely damaging hurricanes for legal, cultural sensitivity and historical reasons. For example, they retired the name Katrina in 2005 following the devastating impact that Hurricane Katrina had on New Orleans. In 2022, the World Meteorological Organization Hurricane Committee retired the names Fiona and Ian.

Large round white hurricane seen from above, with distinct spirals and eye, in Gulf of Mexico with green land areas visible.
Hurricane Katrina on August 28, 2005. Image via NASA.

Bottom line: The forecasts for Atlantic hurricanes and tropical storms is out. And the hurricane names for 2026 are ready. What’ll happen next?

Read: NOAA’s hurricane season forecast for 2026

Read more: What is a hurricane storm surge?

The post 2026 name list for Atlantic hurricanes: Is yours among them? first appeared on EarthSky.



from EarthSky https://ift.tt/0lK3YCe
Hurricanes: Satellite image of hurricane with 2026 hurricane names on top.
This is the list of tropical cyclone names for the 2026 Atlantic hurricane season. Read about the names of hurricanes below.

Read: NOAA’s hurricane season forecast for 2026

Atlantic hurricane names for 2026

NOAA’s Climate Prediction Center has just released its hurricane season outlook for 2026. But what are the names for the 2026 Atlantic tropical cyclones and hurricanes?

See the complete list of 2026 tropical cyclone and hurricane names in the image above. If any of these storms become truly destructive in 2026, the World Meteorological Organization, which is in charge of the list, retires and replaces the name. For example, in 2024, the World Meteorological Organization retired the names Beryl, Helene and Milton. Helene, in particular, became the deadliest storm in the U.S. since Katrina in 2005.

The 2026 Atlantic hurricane season officially starts June 1 and extends through November 30.

If you live near the Atlantic basin, you can keep up-to-date with forecasts from the National Hurricane Center.

Learn more about how to prepare for hurricane season.

How do hurricanes get their names?

Meteorologists long ago learned that naming tropical storms and hurricanes helps people remember the storms, communicate about them more effectively, and consequently stay safer if and when a particular storm strikes a coast.

These experts assign names to tropical storms according to an approved list before the start of each hurricane season. The U.S. National Hurricane Center started this practice in the early 1950s. Now, the World Meteorological Organization (WMO) generates and maintains the list of hurricane names.

Here are the hurricane names for 2026

Atlantic hurricane names (season runs from June 1 to November 30) are: Arthur, Bertha, Cristobal, Dolly, Edouard, Fay, Gonzalo, Hanna, Isaias, Josephine, Kyle. Leah, Marco, Nana, Omar. Paulette, Rene, Sally, Teddy, Vicky and Wilfred.

Eastern North Pacific hurricane names (season runs from May 15 to November 30) are: Amanda, Boris, Cristina, Douglas, Elida, Fausto, Genevieve, Hernan, Iselle, Julio, Karina, Lowell, Marie, Norbert, Odalys, Polo, Rachel, Simon, Trudy, Vance, Winnie. Xavier, Yolanda and Zeke.

If you’re interested, you can view those names, and names for upcoming years, at the U.S. National Hurricane Center.

Gif showing swirling white clouds over Florida's center moving northeast.
In 2022, Hurricane Ian devastated Florida’s Gulf Coast. It also brought flooding to central Florida, ripped roofs off on the Atlantic Coast and then menaced South Carolina. The name Ian will never again be used for a tropical cyclone or hurricane. Image via NOAA/ GOES.

The history of hurricane names

While people have been naming major storms for hundreds of years, most hurricanes originally had a designation using a system of latitude-longitude numbers. This was useful to meteorologists trying to track these storms. Unfortunately, this system confused people living on coasts seeking hurricane information.

In the early 1950s, the U.S. National Hurricane Center first developed a formal practice for storm naming for the Atlantic Ocean. At that time, storms got their names according to a phonetic alphabet (e.g., Able, Baker, Charlie) and the names used were the same for each hurricane season. In other words, the first hurricane of a season was always named “Able,” the second “Baker,” and so on.

In 1953, to avoid the repetitive use of names, the National Weather Service revised the system to give storms female names. By doing this, the National Weather Service was mimicking the habit of naval meteorologists, who named the storms after women, much as ships at sea traditionally had female names.

In 1978–1979, they revised the system again to include both female and male hurricane names.

See the complete history of naming hurricanes, including retired names, from NOAA.

When does a storm receive a name?

Tropical storms get a name when they display a rotating circulation pattern and wind speeds reach 39 miles per hour (63 kilometers per hour). A tropical storm develops into a hurricane when wind speeds go above 74 mph (119 km/h).

Experts have developed lists of hurricane names for many of the major ocean basins around the world. Today, there are six lists of hurricane names in use for Atlantic Ocean and Eastern North Pacific storms. These lists rotate, one each year. So that means the list of this year’s hurricane names for each basin will come up again six years from now.

However, there’s an exception to this practice. The World Meteorological Organization retires the names of extremely damaging hurricanes for legal, cultural sensitivity and historical reasons. For example, they retired the name Katrina in 2005 following the devastating impact that Hurricane Katrina had on New Orleans. In 2022, the World Meteorological Organization Hurricane Committee retired the names Fiona and Ian.

Large round white hurricane seen from above, with distinct spirals and eye, in Gulf of Mexico with green land areas visible.
Hurricane Katrina on August 28, 2005. Image via NASA.

Bottom line: The forecasts for Atlantic hurricanes and tropical storms is out. And the hurricane names for 2026 are ready. What’ll happen next?

Read: NOAA’s hurricane season forecast for 2026

Read more: What is a hurricane storm surge?

The post 2026 name list for Atlantic hurricanes: Is yours among them? first appeared on EarthSky.



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Ice volcanoes on Ganymede? New promising candidates found

Ice volcanoes on Ganymede: Cratered, moon-like dark and light gray sphere with one large, bright white crater with rays.
View larger. | Jupiter’s moon Ganymede is the largest moon in our solar system. Are there ice volcanoes on Ganymede? It’s possible, and now a new study has identified several good candidates. NASA’s Juno spacecraft captured this view of Ganymede on June 7, 2021. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Kalleheikki Kannisto.
  • Ganymede is Jupiter’s largest moon. It has a deep ocean beneath its outer icy surface. Does it also have ice volcanoes?
  • A new international study has identified several good candidates on Ganymede’s frozen surface.
  • These are depressions in the surface surrounded by flow-like formations, where water could have erupted to the surface from below.

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Possible ice volcanoes on Ganymede

Does Jupiter’s largest moon Ganymede have ice volcanoes? We don’t know for sure yet, but a new international study has identified some promising candidates.

Ganymede has a deep ocean hidden beneath its icy crust. That’s led scientists to speculate it could have ice volcanoes similar to the explosive geysers on Saturn’s ocean moon Enceladus. And on May 9, 2026, researchers said they have identified four primary locations where water and other volatile materials might have erupted to Ganymede’s surface.

Anezina Solomonidou at the Hellenic Space Center (HSC) in Greece led the new study. The study also includes researchers from France, Italy, Germany, the United States, the Czech Republic, ESA and NASA’s Jet Propulsion Laboratory.

The new peer-reviewed paper is accepted for publication in the Planetary Science Journal.

Gray landscape seen from above, with an oblong depression, craters and linear grooves.
Musa Patera, a depression on Ganymede some 43 miles (69 km) across. Scientists think it could have been left by an erupting ice volcano. NASA’s Galileo spacecraft captured this view on May 7, 1997. Image via NASA/ JPL/ Wikipedia.
Moon-like gray body with rayed crater and bright and dark patches.
View larger. | Another view of Jupiter’s largest moon Ganymede, from the Juno flyby on June 7, 2021. Image via NASA/ JPL-Caltech/ SwRI/ MSSS; image processing by Kevin M. Gill.

Most promising locations for ice volcanoes

Ganymede has unusual depressions – called paterae – and flow-like structures on its surface. Could upwelling water have formed them?

It certainly seems possible, since Ganymede has a deep, dark ocean beneath its outer icy crust. But it depends on whether the water could get through the crust in cracks or by other means. Scientists estimate Ganymede’s crust to be about 90-95 miles (145-153 km) thick. And they estimate the ocean below to be 60 miles (96 km) deep.

Intriguingly, the flow-like structures would have been formed by flowing icy watery material. And the paterae depressions would have been the volcanic vents. It’s similar to regular volcanism, but involving icy fluids rather than molten rock.

Sunlit edge of planet-like body, with geyser-like jets of vapor erupting upward against a black background.
View larger. | Saturn’s ocean moon Enceladus is famous for its geyser-like ice volcanoes. NASA’s Cassini spacecraft took this image on November 21, 2009. Does Ganymede have ice volcanoes too? Image via NASA/ JPL-Caltech/ Space Science Institute.

Implications for life

If there were – or perhaps still are – active ice volcanoes on Ganymede, that could provide clues about the conditions in the ocean below. And those conditions could determine whether Ganymede’s ocean might be habitable or not.

Solomonidou said:

Ganymede is one of the most fascinating worlds in the solar system. Understanding possible cryovolcanic activity can help us better understand how ocean worlds evolve and whether they may host conditions suitable for life.

Young woman with long, curly dark-gold hair standing with her arms folded.
Anezina Solomonidou at the Hellenic Space Center in Greece led the new study about ice volcanoes on Ganymede. Image via Hellenic Space Center.

Future observations by JUICE

The candidate ice volcanoes will be of great interest for the European Space Agency’s upcoming Jupiter Icy Moons Explorer (JUICE) mission. JUICE was launched in 2023 and will arrive at Jupiter in 2031. It will focus on exploring the largest moons of Jupiter: Ganymede, Callisto, Io and Europa. JUICE will use its MAJIS imaging spectrometer and the JANUS camera system to take a closer look at these potential ice volcanoes.

In 2023, scientists found that Ganymede is coated in salts and organics; and in 2021, they found water vapor in Ganymede’s thin atmosphere.

Also in 2021, NASA released new closeups of Ganymede from its Juno spacecraft. Juno obtained the images on June 7, 2021.

Bottom line: Are there ice volcanoes on Ganymede? A new international study reveals several good candidates on Jupiter’s large ocean moon.

Via Hellenic Space Center

Read more: Jupiter’s moon Ganymede is coated in salts and organics

Read more: Why do Jupiter’s large moons outnumber Saturn’s?

The post Ice volcanoes on Ganymede? New promising candidates found first appeared on EarthSky.



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Ice volcanoes on Ganymede: Cratered, moon-like dark and light gray sphere with one large, bright white crater with rays.
View larger. | Jupiter’s moon Ganymede is the largest moon in our solar system. Are there ice volcanoes on Ganymede? It’s possible, and now a new study has identified several good candidates. NASA’s Juno spacecraft captured this view of Ganymede on June 7, 2021. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Kalleheikki Kannisto.
  • Ganymede is Jupiter’s largest moon. It has a deep ocean beneath its outer icy surface. Does it also have ice volcanoes?
  • A new international study has identified several good candidates on Ganymede’s frozen surface.
  • These are depressions in the surface surrounded by flow-like formations, where water could have erupted to the surface from below.

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Possible ice volcanoes on Ganymede

Does Jupiter’s largest moon Ganymede have ice volcanoes? We don’t know for sure yet, but a new international study has identified some promising candidates.

Ganymede has a deep ocean hidden beneath its icy crust. That’s led scientists to speculate it could have ice volcanoes similar to the explosive geysers on Saturn’s ocean moon Enceladus. And on May 9, 2026, researchers said they have identified four primary locations where water and other volatile materials might have erupted to Ganymede’s surface.

Anezina Solomonidou at the Hellenic Space Center (HSC) in Greece led the new study. The study also includes researchers from France, Italy, Germany, the United States, the Czech Republic, ESA and NASA’s Jet Propulsion Laboratory.

The new peer-reviewed paper is accepted for publication in the Planetary Science Journal.

Gray landscape seen from above, with an oblong depression, craters and linear grooves.
Musa Patera, a depression on Ganymede some 43 miles (69 km) across. Scientists think it could have been left by an erupting ice volcano. NASA’s Galileo spacecraft captured this view on May 7, 1997. Image via NASA/ JPL/ Wikipedia.
Moon-like gray body with rayed crater and bright and dark patches.
View larger. | Another view of Jupiter’s largest moon Ganymede, from the Juno flyby on June 7, 2021. Image via NASA/ JPL-Caltech/ SwRI/ MSSS; image processing by Kevin M. Gill.

Most promising locations for ice volcanoes

Ganymede has unusual depressions – called paterae – and flow-like structures on its surface. Could upwelling water have formed them?

It certainly seems possible, since Ganymede has a deep, dark ocean beneath its outer icy crust. But it depends on whether the water could get through the crust in cracks or by other means. Scientists estimate Ganymede’s crust to be about 90-95 miles (145-153 km) thick. And they estimate the ocean below to be 60 miles (96 km) deep.

Intriguingly, the flow-like structures would have been formed by flowing icy watery material. And the paterae depressions would have been the volcanic vents. It’s similar to regular volcanism, but involving icy fluids rather than molten rock.

Sunlit edge of planet-like body, with geyser-like jets of vapor erupting upward against a black background.
View larger. | Saturn’s ocean moon Enceladus is famous for its geyser-like ice volcanoes. NASA’s Cassini spacecraft took this image on November 21, 2009. Does Ganymede have ice volcanoes too? Image via NASA/ JPL-Caltech/ Space Science Institute.

Implications for life

If there were – or perhaps still are – active ice volcanoes on Ganymede, that could provide clues about the conditions in the ocean below. And those conditions could determine whether Ganymede’s ocean might be habitable or not.

Solomonidou said:

Ganymede is one of the most fascinating worlds in the solar system. Understanding possible cryovolcanic activity can help us better understand how ocean worlds evolve and whether they may host conditions suitable for life.

Young woman with long, curly dark-gold hair standing with her arms folded.
Anezina Solomonidou at the Hellenic Space Center in Greece led the new study about ice volcanoes on Ganymede. Image via Hellenic Space Center.

Future observations by JUICE

The candidate ice volcanoes will be of great interest for the European Space Agency’s upcoming Jupiter Icy Moons Explorer (JUICE) mission. JUICE was launched in 2023 and will arrive at Jupiter in 2031. It will focus on exploring the largest moons of Jupiter: Ganymede, Callisto, Io and Europa. JUICE will use its MAJIS imaging spectrometer and the JANUS camera system to take a closer look at these potential ice volcanoes.

In 2023, scientists found that Ganymede is coated in salts and organics; and in 2021, they found water vapor in Ganymede’s thin atmosphere.

Also in 2021, NASA released new closeups of Ganymede from its Juno spacecraft. Juno obtained the images on June 7, 2021.

Bottom line: Are there ice volcanoes on Ganymede? A new international study reveals several good candidates on Jupiter’s large ocean moon.

Via Hellenic Space Center

Read more: Jupiter’s moon Ganymede is coated in salts and organics

Read more: Why do Jupiter’s large moons outnumber Saturn’s?

The post Ice volcanoes on Ganymede? New promising candidates found first appeared on EarthSky.



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Cumulonimbus clouds bring thunderstorms: How to spot them

Gigantic-looking anvil shaped cloud, rising above a puffy cloud layer.
Terry O’Leary of Virginia Beach, Virginia, captured the classic anvil shape of cumulonimbus clouds – out the window of an airplane – in early summer 2003 over central Virginia. Image via NASA GLOBE Clouds.

Love wildlife and the natural world? Get the latest animal stories – as well as space and night sky updates – delivered to your inbox.

What are cumulonimbus clouds?

Cumulonimbus clouds are among the most awe-inspiring of cloud formations. They might start as low as 0.6 miles (1,000 meters) above Earth’s surface. And their tops can reach up to 7 miles (12,000 meters) or more. So they can tower for miles into the sky, bumping into Earth’s stratosphere. Cumulonimbus clouds are known to flatten out into an anvil shape on top. They’re sometimes called thunderheads, because they’re the engines behind thunderstorms, severe weather and even tornadoes.

If you see a cumulonimbus cloud bubbling upward into the sky, get ready to take cover!

The word cumulonimbus comes from the Latin cumulo meaning heap or pile and nimbus meaning cloud. They begin as puffy white cumulus clouds that can rapidly grow under the right conditions.

How do they form?

As with cumulus clouds, which are fair-weather clouds, a cumulonimbus cloud begins with the process of convection. That’s what happens when warm air rises, because it’s less dense than the cooler air around it. Convection tends to happen on warm days when Earth’s surface heats unevenly, for example, in the afternoon over land. As the warm, moist air rises, it cools and condenses, forming puffy cumulus clouds.

If the rising air continues to be warmer than its surroundings, it’ll keep growing. That’s when it’ll form larger and taller clouds. When the atmosphere is particularly unstable – meaning that temperature decreases rapidly with height – this upward motion becomes more vigorous. In this case, a cumulus cloud can quickly grow into a cumulonimbus cloud.

Inside a developing cumulonimbus cloud, there are both updrafts and downdrafts. The winds of the updrafts can reach speeds of more than 100 mph (161 kph). These updrafts carry water vapor high into the atmosphere, where it condenses into water droplets or ice crystals. This process releases latent heat, fueling further cloud growth. The top of the cloud eventually flattens out when it hits the tropopause, the divider between the lower troposphere (the bottom layer of the atmosphere, where we live) and the higher stratosphere.


Watch this time lapse of cumulus clouds growing into a towering cumulonimbus cloud with an anvil top.

When and where do you see cumulonimbus clouds?

Cumulonimbus clouds can form anywhere in the world. But they’re most common in regions where warm, moist air is prevalent. In the United States, for instance, you can frequently see these clouds in the spring and summer months. That’s especially true if you live in the U.S. Great Plains, Midwest and Southeast, where warm, humid air from the Gulf of Mexico interacts with cooler air masses. But you can also see these clouds nearly every summer afternoon in central Florida, thanks to sea breezes and lots of tropical moisture.

And indeed – although they can also occur at other times of the day or night – afternoon and early evening are the best times to look for cumulonimbus clouds. That’s when surface heating from the sun is at its peak.

What kind of weather do cumulonimbus clouds bring?

Cumulonimbus clouds are synonymous with severe weather. They are the primary cloud type responsible for thunderstorms.

Depending on their intensity and the conditions around them, cumulonimbus clouds can produce:

  • Torrential rain: Localized downpours that can lead to flash flooding.
  • Hail: Ice particles carried in updrafts and downdrafts, growing larger before falling to the ground.
  • Strong winds: Often associated with downdrafts or microbursts, which can cause damage similar to weak tornadoes.
  • Tornadoes: In the most severe storms, rotating updrafts can spawn tornadoes.
  • Lightning: Electrical charges can trigger lightning within the cloud and also send bolts careening to the ground.

Due to all these hazards, airplanes fly around – and not through – cumulonimbus clouds.


In this video, you can see air traffic diverting around cumulonimbus clouds and then circling, waiting for the storms to clear the Atlanta airport before landing.

Stay safe

When you see a cumulonimbus cloud, think safety. The lightning from these clouds can strike miles away, far from where the cloud is producing rain. Hail can be dangerous for people and animals without shelter. Torrential rain can cause flash flooding, and strong winds and tornadoes can send objects flying.

Cumulonimbus clouds are awe-inspiring and formidable phenomena that remind us of nature’s raw power. Spotting a cumulonimbus cloud offers us a glimpse into the dynamic processes of the atmosphere. And it provides a warning of the powerful forces brewing above.

If you catch a great image of a cumulonimbus cloud, submit it to EarthSky’s community page.

Cumulonimbus clouds: Giant white cloud with a flat top rising much higher than a layer of lower clouds.
View at EarthSky Community Photos. | Ross Stone captured this image in California on July 31, 2024. Ross wrote: “When I saw this gigantic cumulonimbus cloud I had to pull off to the side of the road and take out my camera. I absolutely love the summertime clouds.” Thank you, Ross!

Bottom line: Cumulonimbus clouds, sometimes called thunderheads, are towering formations that can bring severe storms such as hail, lightning, flooding and tornadoes.

Read more:

Cloud shapes are a useful tool for predicting weather

Media we love: The book A Cloud a Day

Bumpy flight? Here’s how clouds affect air travel

The post Cumulonimbus clouds bring thunderstorms: How to spot them first appeared on EarthSky.



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Gigantic-looking anvil shaped cloud, rising above a puffy cloud layer.
Terry O’Leary of Virginia Beach, Virginia, captured the classic anvil shape of cumulonimbus clouds – out the window of an airplane – in early summer 2003 over central Virginia. Image via NASA GLOBE Clouds.

Love wildlife and the natural world? Get the latest animal stories – as well as space and night sky updates – delivered to your inbox.

What are cumulonimbus clouds?

Cumulonimbus clouds are among the most awe-inspiring of cloud formations. They might start as low as 0.6 miles (1,000 meters) above Earth’s surface. And their tops can reach up to 7 miles (12,000 meters) or more. So they can tower for miles into the sky, bumping into Earth’s stratosphere. Cumulonimbus clouds are known to flatten out into an anvil shape on top. They’re sometimes called thunderheads, because they’re the engines behind thunderstorms, severe weather and even tornadoes.

If you see a cumulonimbus cloud bubbling upward into the sky, get ready to take cover!

The word cumulonimbus comes from the Latin cumulo meaning heap or pile and nimbus meaning cloud. They begin as puffy white cumulus clouds that can rapidly grow under the right conditions.

How do they form?

As with cumulus clouds, which are fair-weather clouds, a cumulonimbus cloud begins with the process of convection. That’s what happens when warm air rises, because it’s less dense than the cooler air around it. Convection tends to happen on warm days when Earth’s surface heats unevenly, for example, in the afternoon over land. As the warm, moist air rises, it cools and condenses, forming puffy cumulus clouds.

If the rising air continues to be warmer than its surroundings, it’ll keep growing. That’s when it’ll form larger and taller clouds. When the atmosphere is particularly unstable – meaning that temperature decreases rapidly with height – this upward motion becomes more vigorous. In this case, a cumulus cloud can quickly grow into a cumulonimbus cloud.

Inside a developing cumulonimbus cloud, there are both updrafts and downdrafts. The winds of the updrafts can reach speeds of more than 100 mph (161 kph). These updrafts carry water vapor high into the atmosphere, where it condenses into water droplets or ice crystals. This process releases latent heat, fueling further cloud growth. The top of the cloud eventually flattens out when it hits the tropopause, the divider between the lower troposphere (the bottom layer of the atmosphere, where we live) and the higher stratosphere.


Watch this time lapse of cumulus clouds growing into a towering cumulonimbus cloud with an anvil top.

When and where do you see cumulonimbus clouds?

Cumulonimbus clouds can form anywhere in the world. But they’re most common in regions where warm, moist air is prevalent. In the United States, for instance, you can frequently see these clouds in the spring and summer months. That’s especially true if you live in the U.S. Great Plains, Midwest and Southeast, where warm, humid air from the Gulf of Mexico interacts with cooler air masses. But you can also see these clouds nearly every summer afternoon in central Florida, thanks to sea breezes and lots of tropical moisture.

And indeed – although they can also occur at other times of the day or night – afternoon and early evening are the best times to look for cumulonimbus clouds. That’s when surface heating from the sun is at its peak.

What kind of weather do cumulonimbus clouds bring?

Cumulonimbus clouds are synonymous with severe weather. They are the primary cloud type responsible for thunderstorms.

Depending on their intensity and the conditions around them, cumulonimbus clouds can produce:

  • Torrential rain: Localized downpours that can lead to flash flooding.
  • Hail: Ice particles carried in updrafts and downdrafts, growing larger before falling to the ground.
  • Strong winds: Often associated with downdrafts or microbursts, which can cause damage similar to weak tornadoes.
  • Tornadoes: In the most severe storms, rotating updrafts can spawn tornadoes.
  • Lightning: Electrical charges can trigger lightning within the cloud and also send bolts careening to the ground.

Due to all these hazards, airplanes fly around – and not through – cumulonimbus clouds.


In this video, you can see air traffic diverting around cumulonimbus clouds and then circling, waiting for the storms to clear the Atlanta airport before landing.

Stay safe

When you see a cumulonimbus cloud, think safety. The lightning from these clouds can strike miles away, far from where the cloud is producing rain. Hail can be dangerous for people and animals without shelter. Torrential rain can cause flash flooding, and strong winds and tornadoes can send objects flying.

Cumulonimbus clouds are awe-inspiring and formidable phenomena that remind us of nature’s raw power. Spotting a cumulonimbus cloud offers us a glimpse into the dynamic processes of the atmosphere. And it provides a warning of the powerful forces brewing above.

If you catch a great image of a cumulonimbus cloud, submit it to EarthSky’s community page.

Cumulonimbus clouds: Giant white cloud with a flat top rising much higher than a layer of lower clouds.
View at EarthSky Community Photos. | Ross Stone captured this image in California on July 31, 2024. Ross wrote: “When I saw this gigantic cumulonimbus cloud I had to pull off to the side of the road and take out my camera. I absolutely love the summertime clouds.” Thank you, Ross!

Bottom line: Cumulonimbus clouds, sometimes called thunderheads, are towering formations that can bring severe storms such as hail, lightning, flooding and tornadoes.

Read more:

Cloud shapes are a useful tool for predicting weather

Media we love: The book A Cloud a Day

Bumpy flight? Here’s how clouds affect air travel

The post Cumulonimbus clouds bring thunderstorms: How to spot them first appeared on EarthSky.



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Synchronous fireflies light up these national parks

Thousands of yellow dots among trees in a dark forest.
Have you heard of synchronous fireflies? It’s an amazing night spectacle where thousands of these glowing insects pulse in perfect rhythm across a forest, turning the darkness into a living wave of light. Image via P. Driessche/ National Park Service.

Love wildlife and the natural world? Get the latest animal stories – as well as space and night sky updates – delivered to your inbox.

Synchronous fireflies

It’s synchronous firefly season! Every year between mid-May and mid-June, locations such as the Great Smoky Mountains National Park in North Carolina and Tennessee, and Congaree in South Carolina, see fireflies flicker in harmony as night falls. The phenomenon happens as male fireflies seek mates. These fireflies – aka lightning bugs – flash with a distinct rhythm: a few quick bursts of light followed by a several-second pause, then more bursts. In person, the display looks like a wave of light passing over a hillside.

The demand to see the synchronous fireflies is high. So much so that the National Park Service has instituted a lottery system for some national parks. The lottery for Great Smoky Mountains has passed. But a lottery for guided viewing at Grandfather Mountain in North Carolina is just about to open.

And you don’t need to join a guided group to see synchronous fireflies. You don’t even have to be in these exact regions of the parks. In fact, people who live in the Smokies have been known to see synchronous fireflies in their backyard.

Just know that these insects prefer northern hardwood forest habitats such as the kind you find in Tennessee, North Carolina and South Carolina.

Fireflies are bioluminescent

Fireflies are bioluminescent. That means that – through a chemical reaction in the insects’ bodies – they’re able to emit light.

Luciferin is the key for creatures that emit this living light. Luciferin is a molecule that reacts in the presence of the enzyme luciferase to produce light. A chemical reaction between the two splits off a molecular fragment. That, in turn, produces an excited state that emits light.

Both words – luciferin and luciferase – come from the same root as lucifer. That word originates from Latin, combining lux (light) and ferre (to bring). It translates to “light-bringer” or “morning star.” It was the Roman name for Venus, when that brightest of planets is visible in the morning. It only later gained a darker association.

Thousands of yellow dots and many twisty dashed lines on a black background.
View larger. | Stacked photo of synchronous fireflies in Tennessee. Image via University of Colorado.

A landmark study on synchronous fireflies

A team of researchers from University of Colorado Boulder has been trying to understand how relatively simple insects manage to coordinate such feats of synchronization.

They published an important study about them on September 23, 2020, in the peer-reviewed Journal of the Royal Society Interface. This study suggests that – rather than flash according to some innate rhythm – the fireflies observe what their neighbors are doing. Then they adjust their behavior to match.

The researchers discovered that the fireflies don’t behave the same way when they’re alone as when they’re in a big group. For example, the team found that a single male firefly alone in the tent would flash without a good sense of rhythm, a few bursts here, a few bursts there. But with more fireflies in the tent, things began to change. Raphaël Sarfati, lead author of the study and a postdoctoral researcher at CU Boulder at the time, said:

When you start putting 20 fireflies together, that’s when you start observing what you see in the wild. You’ve got regular bursts of flashes, and they’re all synchronized.

That suggested to the researchers that the fireflies likely aren’t hardwired to flash with a particular pattern. Instead, their light displays seem to be more social. Bugs watch what their neighbors are doing and try to follow along.


A video of fireflies from the research team in the 2020 study.

More synchronous fireflies studies

Since that early study, these researchers have been busy:

Thousands of yellow dots among trees in a dark forest.
Have you heard of synchronous fireflies? It’s an amazing night spectacle where thousands of these glowing insects pulse in perfect rhythm across a forest, turning the darkness into a living wave of light. Image via P. Driessche/ National Park Service.

Love wildlife and the natural world? Get the latest animal stories – as well as space and night sky updates – delivered to your inbox.

Synchronous fireflies

It’s synchronous firefly season! Every year between mid-May and mid-June, locations such as the Great Smoky Mountains National Park in North Carolina and Tennessee, and Congaree in South Carolina, see fireflies flicker in harmony as night falls. The phenomenon happens as male fireflies seek mates. These fireflies – aka lightning bugs – flash with a distinct rhythm: a few quick bursts of light followed by a several-second pause, then more bursts. In person, the display looks like a wave of light passing over a hillside.

The demand to see the synchronous fireflies is high. So much so that the National Park Service has instituted a lottery system for some national parks. The lottery for Great Smoky Mountains has passed. But a lottery for guided viewing at Grandfather Mountain in North Carolina is just about to open.

And you don’t need to join a guided group to see synchronous fireflies. You don’t even have to be in these exact regions of the parks. In fact, people who live in the Smokies have been known to see synchronous fireflies in their backyard.

Just know that these insects prefer northern hardwood forest habitats such as the kind you find in Tennessee, North Carolina and South Carolina.

Fireflies are bioluminescent

Fireflies are bioluminescent. That means that – through a chemical reaction in the insects’ bodies – they’re able to emit light.

Luciferin is the key for creatures that emit this living light. Luciferin is a molecule that reacts in the presence of the enzyme luciferase to produce light. A chemical reaction between the two splits off a molecular fragment. That, in turn, produces an excited state that emits light.

Both words – luciferin and luciferase – come from the same root as lucifer. That word originates from Latin, combining lux (light) and ferre (to bring). It translates to “light-bringer” or “morning star.” It was the Roman name for Venus, when that brightest of planets is visible in the morning. It only later gained a darker association.

Thousands of yellow dots and many twisty dashed lines on a black background.
View larger. | Stacked photo of synchronous fireflies in Tennessee. Image via University of Colorado.

A landmark study on synchronous fireflies

A team of researchers from University of Colorado Boulder has been trying to understand how relatively simple insects manage to coordinate such feats of synchronization.

They published an important study about them on September 23, 2020, in the peer-reviewed Journal of the Royal Society Interface. This study suggests that – rather than flash according to some innate rhythm – the fireflies observe what their neighbors are doing. Then they adjust their behavior to match.

The researchers discovered that the fireflies don’t behave the same way when they’re alone as when they’re in a big group. For example, the team found that a single male firefly alone in the tent would flash without a good sense of rhythm, a few bursts here, a few bursts there. But with more fireflies in the tent, things began to change. Raphaël Sarfati, lead author of the study and a postdoctoral researcher at CU Boulder at the time, said:

When you start putting 20 fireflies together, that’s when you start observing what you see in the wild. You’ve got regular bursts of flashes, and they’re all synchronized.

That suggested to the researchers that the fireflies likely aren’t hardwired to flash with a particular pattern. Instead, their light displays seem to be more social. Bugs watch what their neighbors are doing and try to follow along.


A video of fireflies from the research team in the 2020 study.

More synchronous fireflies studies

Since that early study, these researchers have been busy:

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Constellations and signs: What’s the difference?


Maybe you associate the word zodiac with astrology. But it has an honored place in astronomy, too. Here’s why.

Guy Ottewell published this post on May 19, 2020, under the title The Difference Made by 2 Thousand Years. Reprinted here with permission. Updated by EarthSky editors.

Constellations and astrological signs

At 1 UTC on May 21, 2026, the sun will enter the astrological sign of Gemini. But – in the real sky – the sun doesn’t cross the official IAU constellation boundary into Gemini until a month later, around the June solstice (June 21).

Why is there a difference between signs as defined by astrologers, and constellations as defined by an international organization of astronomers?

The signs of Aries, Taurus, etc. – still used in astrology – are 30 degree-wide bands along the ecliptic, starting at longitude 0 degrees. This is also known as the First Point of Aries. The constellations are areas of the starry sky, defined since 1930 by specific lines and boundaries. The two coincided, somewhat over 2,000 years ago, when the system of astrological signs was defined. But precession – the wobbling of Earth’s spin axis over a cycle of 25,800 years – has made them increasingly divergent.

Don’t miss the next unmissable night sky event. Sign up to EarthSky’s free newsletter for daily night sky updates.

Chart showing the sun's movement through some constellations and stars.
Chart showing the sun’s movement through the constellations as defined by astronomers. You can see that the sun won’t enter Gemini until around June 21. Chart via Guy Ottewell’s 2026 Astronomical Calendar

The sun’s path through the sky

The chart above shows the sun’s travel from around March 20, 2026, (the spring or vernal equinox) to September 21, 2026. You can see that the sun does indeed enter Taurus around May 21. But this brings it to the beginning (roughly) of constellation Taurus, not Gemini. It will have to travel another 30 degrees – one month – to enter Gemini.

The stars and constellations stay fixed. What shifts over time is the celestial equator – the “belt,” you could say, of the spinning Earth – and the mapping system based on it.

Picturing constellations and signs

Mentally move them. Imagine the sun’s March-to-May track, and the celestial equator – the blue line on the chart above – slid 30 degrees to the left (east), while everything else stays in place. The crossing-point of equator and ecliptic – which is the zero point for longitude – is 30 degrees to the left: it is at what is now longitude 30 degrees, the beginning of Aries. So it really is then the First Point of Aries. In this mental projection, the sun is at the First Point of Aries in March, and arrives at the gates of Gemini at this time in May.

This was how things stood when the system of signs was agreed upon, around 2,000 years ago.

You can, with some imagination, see it in your sky, or on the chart above.

There is the sun (below the horizon) at its May 21, 2026, position where it enters the astrological sign of Gemini. If this were 150 BCE it would be 30 degrees on – at what is now longitude 90 degrees – the solstice point of our time, by the feet of Gemini.

Read more from Guy Ottewell.

Bottom line: What is the difference between the signs of the zodiac and the constellations of the zodiac? Astronomer Guy Ottewell illustrates and discusses this difference.

Read more: Planisphere: Your friend to find stars and constellations

Read more: What’s a constellation? What’s an asterism?

The post Constellations and signs: What’s the difference? first appeared on EarthSky.



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Maybe you associate the word zodiac with astrology. But it has an honored place in astronomy, too. Here’s why.

Guy Ottewell published this post on May 19, 2020, under the title The Difference Made by 2 Thousand Years. Reprinted here with permission. Updated by EarthSky editors.

Constellations and astrological signs

At 1 UTC on May 21, 2026, the sun will enter the astrological sign of Gemini. But – in the real sky – the sun doesn’t cross the official IAU constellation boundary into Gemini until a month later, around the June solstice (June 21).

Why is there a difference between signs as defined by astrologers, and constellations as defined by an international organization of astronomers?

The signs of Aries, Taurus, etc. – still used in astrology – are 30 degree-wide bands along the ecliptic, starting at longitude 0 degrees. This is also known as the First Point of Aries. The constellations are areas of the starry sky, defined since 1930 by specific lines and boundaries. The two coincided, somewhat over 2,000 years ago, when the system of astrological signs was defined. But precession – the wobbling of Earth’s spin axis over a cycle of 25,800 years – has made them increasingly divergent.

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Chart showing the sun's movement through some constellations and stars.
Chart showing the sun’s movement through the constellations as defined by astronomers. You can see that the sun won’t enter Gemini until around June 21. Chart via Guy Ottewell’s 2026 Astronomical Calendar

The sun’s path through the sky

The chart above shows the sun’s travel from around March 20, 2026, (the spring or vernal equinox) to September 21, 2026. You can see that the sun does indeed enter Taurus around May 21. But this brings it to the beginning (roughly) of constellation Taurus, not Gemini. It will have to travel another 30 degrees – one month – to enter Gemini.

The stars and constellations stay fixed. What shifts over time is the celestial equator – the “belt,” you could say, of the spinning Earth – and the mapping system based on it.

Picturing constellations and signs

Mentally move them. Imagine the sun’s March-to-May track, and the celestial equator – the blue line on the chart above – slid 30 degrees to the left (east), while everything else stays in place. The crossing-point of equator and ecliptic – which is the zero point for longitude – is 30 degrees to the left: it is at what is now longitude 30 degrees, the beginning of Aries. So it really is then the First Point of Aries. In this mental projection, the sun is at the First Point of Aries in March, and arrives at the gates of Gemini at this time in May.

This was how things stood when the system of signs was agreed upon, around 2,000 years ago.

You can, with some imagination, see it in your sky, or on the chart above.

There is the sun (below the horizon) at its May 21, 2026, position where it enters the astrological sign of Gemini. If this were 150 BCE it would be 30 degrees on – at what is now longitude 90 degrees – the solstice point of our time, by the feet of Gemini.

Read more from Guy Ottewell.

Bottom line: What is the difference between the signs of the zodiac and the constellations of the zodiac? Astronomer Guy Ottewell illustrates and discusses this difference.

Read more: Planisphere: Your friend to find stars and constellations

Read more: What’s a constellation? What’s an asterism?

The post Constellations and signs: What’s the difference? first appeared on EarthSky.



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Interstellar turbulence in the Milky Way distorts light

Artist illustration showing how light from a quasar gets distorted by turbulent gas in the interstellar medium.
Radio light from quasar TXS 2005+403 travels roughly 10 billion light-years to reach Earth. It passes through the Cygnus region, one of the most turbulent environments in our Milky Way Galaxy. On the left, this artist’s illustration shows the quasar as it truly appears. On the right, we see how turbulent gas distorts scientists’ view of the quasar in much the same way heat haze from a fire warps our view of the objects behind it. A new study has, for the 1st time, directly detected how this interstellar turbulence distorts light from distant objects. Image via Center for Astrophysics/ Melissa Weiss.
  • For the first time, astronomers have directly detected how turbulent gas between stars distorts light.
  • These turbulent structures occur at scales roughly the size of our solar system.
  • Understanding this distortion could help scientists “de-blur” images of the supermassive black hole at the center of our galaxy, Sagittarius A*.

The Center for Astrophysics published this original article on May 13, 2026. Edits by EarthSky.

Detecting interstellar turbulence

The space between stars in our galaxy, known as the interstellar medium, is churning with clouds of ionized gas and electrons. When waves of light from distant objects pass through this turbulent material, they are bent and distorted in the same way heat haze rising above a fire distorts our view of everything behind it. That distortion has long allowed astronomers to infer that the turbulence exists, but understanding its structure has remained out of reach … until now.

Now, astronomers say they have made the first direct detection of interstellar turbulence distorting light. And they say the findings will help us produce clearer images of the supermassive black hole at the center of the Milky Way Galaxy.

The researchers, led by the Harvard and Smithsonian’s Center for Astrophysics, published their peer-reviewed research in The Astrophysical Journal Letters on May 13, 2026.

An insightful quasar

To measure the interstellar turbulence, astronomers set their sights on quasar TXS 2005+403, a bright radio source powered by a supermassive black hole that is located roughly 10 billion light-years away from Earth, in the constellation Cygnus the Swan.

As radio light from the quasar travels toward Earth, it passes through the Cygnus region of the galaxy. That’s one of the most turbulent and strongly scattering environments in the Milky Way. The turbulence deflects and distorts the radio waves.

Alexander Plavin, an astronomer at the CfA’s Black Hole Initiative and lead author of the new paper, said:

Most of what we see in the radio data isn’t coming from the quasar itself, it’s coming from the scattering caused by the turbulence in this region of the Milky Way. That scattering and the distortions that come with it are what allows us to study the turbulence and better understand and infer its structure.

Imagery revealed light patterns consistent with turbulence

To get a better look at the effects of interstellar turbulence on light from the quasar, scientists analyzed nearly a decade of archival observations from the U.S. National Science Foundation’s Very Long Baseline Array (NSF VLBA). Operated by NSF’s National Radio Astronomy Observatory (NSF NRAO), the NSF VLBA is a network of ten radio telescopes spread across the country.

Scientists expected that when radio light from TXS 2005+403 passed though the Milky Way, it would spread out into a smooth blur and fade away. Instead, they found persistent, distinct patterns, producing structured, patchy distortions in the light that could only have come from turbulence. Pavin said:

The most distant pairs of telescopes should not have seen the quasar image, but to our surprise, they clearly detected its signal, or faint glow.

It can’t be explained by simple blurring or by the quasar itself, and it behaves the way turbulence is expected to, which is how we know we’re seeing the effects of interstellar turbulence.

Plavin added that the scattering properties along this line of sight through the galaxy remain persistent over time.

Understanding how gas behaves in our galaxy

The findings have significant implications for future astronomical research. The turbulence the researchers detected exists at scales roughly the size of our solar system. Understanding it helps explain how energy moves through the galaxy and how gas behaves before collapsing to form new stars.

The findings may also directly inform efforts to sharpen images of black holes. The Event Horizon Telescope’s images of Sagittarius A*, the supermassive black hole at the center of the Milky Way, are degraded by this same interstellar scattering. Studying how turbulence scatters radio light over time and different frequencies provides a path toward removing its effects from those images.

The team has begun a follow-up observing campaign with the NSF VLBA running through 2026. They aim to measure the specific properties of the screen created by this turbulence and track how it changes as the gas moves relative to Earth.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

Bottom line: For the first time, astronomers have directly detected how interstellar turbulence distorts the light from distant objects in our galaxy.

Source: Direct Very Long Baseline Interferometry Detection of Interstellar Turbulence Imprint on a Quasar: TXS 2005+403

Via Harvard and Smithsonian’s Center for Astrophysics

Read more: Why no radio signals from aliens? Is space weather to blame?

The post Interstellar turbulence in the Milky Way distorts light first appeared on EarthSky.



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Artist illustration showing how light from a quasar gets distorted by turbulent gas in the interstellar medium.
Radio light from quasar TXS 2005+403 travels roughly 10 billion light-years to reach Earth. It passes through the Cygnus region, one of the most turbulent environments in our Milky Way Galaxy. On the left, this artist’s illustration shows the quasar as it truly appears. On the right, we see how turbulent gas distorts scientists’ view of the quasar in much the same way heat haze from a fire warps our view of the objects behind it. A new study has, for the 1st time, directly detected how this interstellar turbulence distorts light from distant objects. Image via Center for Astrophysics/ Melissa Weiss.
  • For the first time, astronomers have directly detected how turbulent gas between stars distorts light.
  • These turbulent structures occur at scales roughly the size of our solar system.
  • Understanding this distortion could help scientists “de-blur” images of the supermassive black hole at the center of our galaxy, Sagittarius A*.

The Center for Astrophysics published this original article on May 13, 2026. Edits by EarthSky.

Detecting interstellar turbulence

The space between stars in our galaxy, known as the interstellar medium, is churning with clouds of ionized gas and electrons. When waves of light from distant objects pass through this turbulent material, they are bent and distorted in the same way heat haze rising above a fire distorts our view of everything behind it. That distortion has long allowed astronomers to infer that the turbulence exists, but understanding its structure has remained out of reach … until now.

Now, astronomers say they have made the first direct detection of interstellar turbulence distorting light. And they say the findings will help us produce clearer images of the supermassive black hole at the center of the Milky Way Galaxy.

The researchers, led by the Harvard and Smithsonian’s Center for Astrophysics, published their peer-reviewed research in The Astrophysical Journal Letters on May 13, 2026.

An insightful quasar

To measure the interstellar turbulence, astronomers set their sights on quasar TXS 2005+403, a bright radio source powered by a supermassive black hole that is located roughly 10 billion light-years away from Earth, in the constellation Cygnus the Swan.

As radio light from the quasar travels toward Earth, it passes through the Cygnus region of the galaxy. That’s one of the most turbulent and strongly scattering environments in the Milky Way. The turbulence deflects and distorts the radio waves.

Alexander Plavin, an astronomer at the CfA’s Black Hole Initiative and lead author of the new paper, said:

Most of what we see in the radio data isn’t coming from the quasar itself, it’s coming from the scattering caused by the turbulence in this region of the Milky Way. That scattering and the distortions that come with it are what allows us to study the turbulence and better understand and infer its structure.

Imagery revealed light patterns consistent with turbulence

To get a better look at the effects of interstellar turbulence on light from the quasar, scientists analyzed nearly a decade of archival observations from the U.S. National Science Foundation’s Very Long Baseline Array (NSF VLBA). Operated by NSF’s National Radio Astronomy Observatory (NSF NRAO), the NSF VLBA is a network of ten radio telescopes spread across the country.

Scientists expected that when radio light from TXS 2005+403 passed though the Milky Way, it would spread out into a smooth blur and fade away. Instead, they found persistent, distinct patterns, producing structured, patchy distortions in the light that could only have come from turbulence. Pavin said:

The most distant pairs of telescopes should not have seen the quasar image, but to our surprise, they clearly detected its signal, or faint glow.

It can’t be explained by simple blurring or by the quasar itself, and it behaves the way turbulence is expected to, which is how we know we’re seeing the effects of interstellar turbulence.

Plavin added that the scattering properties along this line of sight through the galaxy remain persistent over time.

Understanding how gas behaves in our galaxy

The findings have significant implications for future astronomical research. The turbulence the researchers detected exists at scales roughly the size of our solar system. Understanding it helps explain how energy moves through the galaxy and how gas behaves before collapsing to form new stars.

The findings may also directly inform efforts to sharpen images of black holes. The Event Horizon Telescope’s images of Sagittarius A*, the supermassive black hole at the center of the Milky Way, are degraded by this same interstellar scattering. Studying how turbulence scatters radio light over time and different frequencies provides a path toward removing its effects from those images.

The team has begun a follow-up observing campaign with the NSF VLBA running through 2026. They aim to measure the specific properties of the screen created by this turbulence and track how it changes as the gas moves relative to Earth.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

Bottom line: For the first time, astronomers have directly detected how interstellar turbulence distorts the light from distant objects in our galaxy.

Source: Direct Very Long Baseline Interferometry Detection of Interstellar Turbulence Imprint on a Quasar: TXS 2005+403

Via Harvard and Smithsonian’s Center for Astrophysics

Read more: Why no radio signals from aliens? Is space weather to blame?

The post Interstellar turbulence in the Milky Way distorts light first appeared on EarthSky.



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