How can we visualize ourselves in our home galaxy, the Milky Way? Join EarthSky’s Deborah Byrd and Marcy Curran as they discuss seeing the Milky Way in our sky, and how to understand your place in it.
Which spiral arm of the Milky Way is ours?
Our Milky Way galaxy is the island of stars we call home. If you imagine it as a disk with spiral arms emanating from the center, our sun is approximately halfway from the center to the visible edge. Our solar system lies between two prominent spiral arms: the Perseus Arm and the Scutum-Centaurus Arm. But we aren’t quite free floating in empty space. We lie on the edge of a relatively minor spiral arm, the Orion-Cygnus Arm, or simply, the Orion Arm or Local Arm.
Our location in the galaxy is significant, as it appears that – like planetary systems – galaxies have habitable zones.
An astonishing 95% of the Milky Way’s suns may not be able to sustain habitable planets, because many orbit the galaxy in paths that carry them through the deadly spiral arms. Any star that passes through one of these starry swarms is subject to deadly radiation from the congested stars. Our own solar system orbits far enough from the center to keep it in sync with the rotation of the rest of the galaxy, so that it remains in the quieter space between the spiral arms. The Earth and its planetary siblings are well placed in a quiet, resource-rich niche of a vast and complex galaxy.
The structure of the Milky Way
The Milky Way is a barred spiral galaxy, which means it has a central bar. There’s still a lot we don’t know about the structure of our galaxy. According to the best current knowledge, the Milky Way is about 100,000 light-years across, about 2,000 light-years deep, and has 100 to 400 billion stars. Astronomers once thought that our spiral galaxy had four major arms, but now they say we have just two major arms and many minor arms.
Where, within this vast spiral structure, do our sun and its planets reside? We’re about 26,000 light-years from the center of the galaxy, on the inner edge of the Orion-Cygnus Arm.
View larger. | Artist’s concept of our Milky Way galaxy. Astronomers now believe the Milky Way galaxy has 2 major arms and many minor arms. Our sun is about halfway from the galactic center, on a minor arm that’s sometimes called the Orion Spur. Image via NASA.
The Orion Arm
The Orion Arm of the Milky Way is probably some 3,500 light-years wide. Initially, astronomers thought it was about 10,000 light-years in length. But a study from 2016 suggests it’s more than 20,000 light-years long.
Astronomers continue to piece together the structure of the Milky Way by painstakingly measuring the positions and distances to many stars and gas clouds. Telescopes on the ground and in space determine distances from parallax measurements. For example, the Gaia Space Telescope’s goal is to provide a 3-dimensional map of our Milky Way.
The Orion Arm gets its name from the constellation Orion the Hunter, which is one of the most prominent constellations of the Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of this constellation (Betelgeuse, Rigel, the stars of Orion’s Belt, the Orion nebula) are neighbors to our sun. The reason we see so many bright objects within the constellation Orion is because when we look at it, we’re looking into our own local spiral arm.
View larger. | Artist’s concept of our galactic neighborhood. Some of the best-known astronomical objects in our sky lie in the Orion Arm, along with our sun. Image via R. Hurt/ Wikimedia Commons (public domain).
Bottom line: Where do we live in the Milky Way galaxy? We lie between the major arms in a smaller spiral arm known as the Orion Arm.
How can we visualize ourselves in our home galaxy, the Milky Way? Join EarthSky’s Deborah Byrd and Marcy Curran as they discuss seeing the Milky Way in our sky, and how to understand your place in it.
Which spiral arm of the Milky Way is ours?
Our Milky Way galaxy is the island of stars we call home. If you imagine it as a disk with spiral arms emanating from the center, our sun is approximately halfway from the center to the visible edge. Our solar system lies between two prominent spiral arms: the Perseus Arm and the Scutum-Centaurus Arm. But we aren’t quite free floating in empty space. We lie on the edge of a relatively minor spiral arm, the Orion-Cygnus Arm, or simply, the Orion Arm or Local Arm.
Our location in the galaxy is significant, as it appears that – like planetary systems – galaxies have habitable zones.
An astonishing 95% of the Milky Way’s suns may not be able to sustain habitable planets, because many orbit the galaxy in paths that carry them through the deadly spiral arms. Any star that passes through one of these starry swarms is subject to deadly radiation from the congested stars. Our own solar system orbits far enough from the center to keep it in sync with the rotation of the rest of the galaxy, so that it remains in the quieter space between the spiral arms. The Earth and its planetary siblings are well placed in a quiet, resource-rich niche of a vast and complex galaxy.
The structure of the Milky Way
The Milky Way is a barred spiral galaxy, which means it has a central bar. There’s still a lot we don’t know about the structure of our galaxy. According to the best current knowledge, the Milky Way is about 100,000 light-years across, about 2,000 light-years deep, and has 100 to 400 billion stars. Astronomers once thought that our spiral galaxy had four major arms, but now they say we have just two major arms and many minor arms.
Where, within this vast spiral structure, do our sun and its planets reside? We’re about 26,000 light-years from the center of the galaxy, on the inner edge of the Orion-Cygnus Arm.
View larger. | Artist’s concept of our Milky Way galaxy. Astronomers now believe the Milky Way galaxy has 2 major arms and many minor arms. Our sun is about halfway from the galactic center, on a minor arm that’s sometimes called the Orion Spur. Image via NASA.
The Orion Arm
The Orion Arm of the Milky Way is probably some 3,500 light-years wide. Initially, astronomers thought it was about 10,000 light-years in length. But a study from 2016 suggests it’s more than 20,000 light-years long.
Astronomers continue to piece together the structure of the Milky Way by painstakingly measuring the positions and distances to many stars and gas clouds. Telescopes on the ground and in space determine distances from parallax measurements. For example, the Gaia Space Telescope’s goal is to provide a 3-dimensional map of our Milky Way.
The Orion Arm gets its name from the constellation Orion the Hunter, which is one of the most prominent constellations of the Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of this constellation (Betelgeuse, Rigel, the stars of Orion’s Belt, the Orion nebula) are neighbors to our sun. The reason we see so many bright objects within the constellation Orion is because when we look at it, we’re looking into our own local spiral arm.
View larger. | Artist’s concept of our galactic neighborhood. Some of the best-known astronomical objects in our sky lie in the Orion Arm, along with our sun. Image via R. Hurt/ Wikimedia Commons (public domain).
Bottom line: Where do we live in the Milky Way galaxy? We lie between the major arms in a smaller spiral arm known as the Orion Arm.
View larger. | Is there an atmosphere on rocky exoplanet 55 Cancri e? This is an artist’s concept of 55 Cancri e, 41 light-years from Earth. Analysis by the Webb Space Telescope shows that it likely has a substantial atmosphere of carbon dioxide or carbon monoxide. Image via NASA/ ESA/ CSA/ Ralf Crawford (STScI).
An international team of astronomers studied rocky exoplanet 55 Cancri e for evidence of an atmosphere. Scientists have long debated whether an atmosphere of any kind existed.
They found that the planet likely does have a substantial atmosphere of either carbon dioxide or carbon monoxide.
55 Cancri e is a super-Earth about twice the size of Earth. It is only 41 light-years away, and extremely hot. In fact, its entire surface is probably covered by molten lava.
Potential atmosphere on rocky exoplanet
For the first time, astronomers say that they have detected a possible atmosphere on a rocky exoplanet. The researchers said on May 8, 2024, that they used the James Webb Space Telescope to make the discovery. Atmospheres have been found and analyzed on a large and growing number of gas giant planets, but those are much easier to detect. This smaller rocky world, 55 Cancri e, is nearby in galactic terms, only 41 light-years from Earth. It is a super-Earth, almost twice the size of Earth. But unlike our planet, it is extremely hot and likely has a molten surface. So while it may be rocky with an atmosphere, it is not like the Earth.
This potential discovery is a new milestone for Webb. Finding rocky exoplanets with atmospheres is a major goal for astronomers. Lead author Renyu Hu at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, said:
Webb is pushing the frontiers of exoplanet characterization to rocky planets. It is truly enabling a new type of science.
Atmosphere or no atmosphere?
Astronomers discovered 55 Cancri e in 2011. Since then, scientists have continued to debate if the planet had an atmosphere or not. And if it did, how dense was it? It was possible that 55 Cancri e didn’t have any atmosphere at all. That’s because it orbits only 1.4 million miles (2.3 million km) from its sun-like star. That’s only 1/25 the distance that Mercury is from our sun. Radiation from the star would likely strip the atmosphere away. Also, the planet is probably tidally locked to its star, so that the same side always faces the star. And, it’s extremely hot, about 2,800 degrees Fahrenheit, or 1,540 degrees Celsius. Therefore, its entire surface is likely molten lava.
2 possibilities
If it did have an atmosphere, then scientists said there were two likely possibilities. One was a substantial atmosphere of oxygen, nitrogen and carbon dioxide. The other was a more tenuous atmosphere of vaporized rock, rich in silicon, iron, aluminum and calcium. Now, Webb might finally help answer these questions. As co-author Diana Dragomir, an exoplanet researcher at the University of New Mexico, noted:
I’ve worked on this planet for more than a decade. It’s been really frustrating that none of the observations we’ve been getting have robustly solved these mysteries. I am thrilled that we’re finally getting some answers!
Co-author Yamila Miguel at the Leiden Observatory and the Netherlands Institute for Space Research (SRON) added:
We’ve spent the last 10 years modeling different scenarios, trying to imagine what this world might look like. Finally getting some confirmation of our work is priceless!
View larger. | Secondary eclipse light curve of 55 Cancri e from the MIRI instrument on Webb. The decrease in brightness occurred when the planet moved behind its star, as seen from Earth. Image via NASA/ ESA/ CSA/ Joseph Olmsted (STScI)/ Aaron Bello-Arufe (JPL).
A substantial atmosphere (probably) on rocky exoplanet 55 Cancri e
Webb observed 55 Cancri e with its Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), using the secondary eclipse spectroscopy method. It looked for subtle changes in the mid-infrared and near-infrared light coming from the planet. The researchers subtracted the brightness of the star itself during the secondary eclipse – when the planet was behind the star – from when the planet was beside the star (light from both the star and planet), as seen from Earth.
Cooler than expected, but still hot
Interestingly, Webb found that the planet is a bit cooler than had been expected. If it had no atmosphere, or only a thin one from vaporized rock, then the temperature on the dayside of the planet would be about 4,000 degrees Fahrenheit (2,200 degrees Celsius). However, with its MIRI instrument, Webb measured a temperature of 2,800 degrees F (1,540 degrees C). That indicated a thicker atmosphere, probably composed of carbon dioxide or carbon monoxide and other volatiles. As Hu said:
Instead, the MIRI data showed a relatively low temperature of about 2,800 degrees Fahrenheit [~1540 degrees Celsius]. This is a very strong indication that energy is being distributed from the dayside to the nightside, most likely by a volatile-rich atmosphere.
The NIRCam instrument provided similar results. Co-author Aaron Bello-Arufe at NASA JPL said:
We see evidence of a dip in the spectrum between 4 and 5 microns; less of this light is reaching the telescope. This suggests the presence of an atmosphere containing carbon monoxide or carbon dioxide, which absorb these wavelengths of light.
View larger. | Emission spectrum of 55 Cancri e, from the MIRI and NIRCam instruments on Webb. The results indicate that the planet likely has a substantial atmosphere of carbon dioxide or carbon monoxide and other volatiles, not just vaporized rock. Image via NASA/ ESA/ CSA/ Joseph Olmsted (STScI)/ Renyu Hu (JPL)/ Aaron Bello-Arufe (JPL)/ Michael Zhang (University of Chicago)/ Mantas Zilinskas (SRON Netherlands Institute for Space Research).
A magma ocean world
Unfortunately for the prospects of life, 55 Cancri e is quite inhospitable. It is so hot that scientists think its surface is a vast magma ocean instead of being solid. Consequently, the atmosphere is likely coming from the interior of the planet, instead of being the original primordial atmosphere from when it first formed. The magma ocean would help to replenish the atmosphere. Bello-Arufe said:
The primary atmosphere would be long gone because of the high temperature and intense radiation from the star. This would be a secondary atmosphere that is continuously replenished by the magma ocean. Magma is not just crystals and liquid rock; there’s a lot of dissolved gas in it, too.
However, the finding shows that rocky planets outside our solar system can indeed maintain atmospheres. If it can happen on 55 Cancri e, then it should also occur on other rocky worlds, including ones more potentially habitable, as Hu noted:
Ultimately, we want to understand what conditions make it possible for a rocky planet to sustain a gas-rich atmosphere: a key ingredient for a habitable planet.
Bottom line: NASA’s Webb telescope has tentatively detected an atmosphere on rocky exoplanet 55 Cancri e, a hot super-Earth world only 41 light-years away.
View larger. | Is there an atmosphere on rocky exoplanet 55 Cancri e? This is an artist’s concept of 55 Cancri e, 41 light-years from Earth. Analysis by the Webb Space Telescope shows that it likely has a substantial atmosphere of carbon dioxide or carbon monoxide. Image via NASA/ ESA/ CSA/ Ralf Crawford (STScI).
An international team of astronomers studied rocky exoplanet 55 Cancri e for evidence of an atmosphere. Scientists have long debated whether an atmosphere of any kind existed.
They found that the planet likely does have a substantial atmosphere of either carbon dioxide or carbon monoxide.
55 Cancri e is a super-Earth about twice the size of Earth. It is only 41 light-years away, and extremely hot. In fact, its entire surface is probably covered by molten lava.
Potential atmosphere on rocky exoplanet
For the first time, astronomers say that they have detected a possible atmosphere on a rocky exoplanet. The researchers said on May 8, 2024, that they used the James Webb Space Telescope to make the discovery. Atmospheres have been found and analyzed on a large and growing number of gas giant planets, but those are much easier to detect. This smaller rocky world, 55 Cancri e, is nearby in galactic terms, only 41 light-years from Earth. It is a super-Earth, almost twice the size of Earth. But unlike our planet, it is extremely hot and likely has a molten surface. So while it may be rocky with an atmosphere, it is not like the Earth.
This potential discovery is a new milestone for Webb. Finding rocky exoplanets with atmospheres is a major goal for astronomers. Lead author Renyu Hu at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, said:
Webb is pushing the frontiers of exoplanet characterization to rocky planets. It is truly enabling a new type of science.
Atmosphere or no atmosphere?
Astronomers discovered 55 Cancri e in 2011. Since then, scientists have continued to debate if the planet had an atmosphere or not. And if it did, how dense was it? It was possible that 55 Cancri e didn’t have any atmosphere at all. That’s because it orbits only 1.4 million miles (2.3 million km) from its sun-like star. That’s only 1/25 the distance that Mercury is from our sun. Radiation from the star would likely strip the atmosphere away. Also, the planet is probably tidally locked to its star, so that the same side always faces the star. And, it’s extremely hot, about 2,800 degrees Fahrenheit, or 1,540 degrees Celsius. Therefore, its entire surface is likely molten lava.
2 possibilities
If it did have an atmosphere, then scientists said there were two likely possibilities. One was a substantial atmosphere of oxygen, nitrogen and carbon dioxide. The other was a more tenuous atmosphere of vaporized rock, rich in silicon, iron, aluminum and calcium. Now, Webb might finally help answer these questions. As co-author Diana Dragomir, an exoplanet researcher at the University of New Mexico, noted:
I’ve worked on this planet for more than a decade. It’s been really frustrating that none of the observations we’ve been getting have robustly solved these mysteries. I am thrilled that we’re finally getting some answers!
Co-author Yamila Miguel at the Leiden Observatory and the Netherlands Institute for Space Research (SRON) added:
We’ve spent the last 10 years modeling different scenarios, trying to imagine what this world might look like. Finally getting some confirmation of our work is priceless!
View larger. | Secondary eclipse light curve of 55 Cancri e from the MIRI instrument on Webb. The decrease in brightness occurred when the planet moved behind its star, as seen from Earth. Image via NASA/ ESA/ CSA/ Joseph Olmsted (STScI)/ Aaron Bello-Arufe (JPL).
A substantial atmosphere (probably) on rocky exoplanet 55 Cancri e
Webb observed 55 Cancri e with its Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), using the secondary eclipse spectroscopy method. It looked for subtle changes in the mid-infrared and near-infrared light coming from the planet. The researchers subtracted the brightness of the star itself during the secondary eclipse – when the planet was behind the star – from when the planet was beside the star (light from both the star and planet), as seen from Earth.
Cooler than expected, but still hot
Interestingly, Webb found that the planet is a bit cooler than had been expected. If it had no atmosphere, or only a thin one from vaporized rock, then the temperature on the dayside of the planet would be about 4,000 degrees Fahrenheit (2,200 degrees Celsius). However, with its MIRI instrument, Webb measured a temperature of 2,800 degrees F (1,540 degrees C). That indicated a thicker atmosphere, probably composed of carbon dioxide or carbon monoxide and other volatiles. As Hu said:
Instead, the MIRI data showed a relatively low temperature of about 2,800 degrees Fahrenheit [~1540 degrees Celsius]. This is a very strong indication that energy is being distributed from the dayside to the nightside, most likely by a volatile-rich atmosphere.
The NIRCam instrument provided similar results. Co-author Aaron Bello-Arufe at NASA JPL said:
We see evidence of a dip in the spectrum between 4 and 5 microns; less of this light is reaching the telescope. This suggests the presence of an atmosphere containing carbon monoxide or carbon dioxide, which absorb these wavelengths of light.
View larger. | Emission spectrum of 55 Cancri e, from the MIRI and NIRCam instruments on Webb. The results indicate that the planet likely has a substantial atmosphere of carbon dioxide or carbon monoxide and other volatiles, not just vaporized rock. Image via NASA/ ESA/ CSA/ Joseph Olmsted (STScI)/ Renyu Hu (JPL)/ Aaron Bello-Arufe (JPL)/ Michael Zhang (University of Chicago)/ Mantas Zilinskas (SRON Netherlands Institute for Space Research).
A magma ocean world
Unfortunately for the prospects of life, 55 Cancri e is quite inhospitable. It is so hot that scientists think its surface is a vast magma ocean instead of being solid. Consequently, the atmosphere is likely coming from the interior of the planet, instead of being the original primordial atmosphere from when it first formed. The magma ocean would help to replenish the atmosphere. Bello-Arufe said:
The primary atmosphere would be long gone because of the high temperature and intense radiation from the star. This would be a secondary atmosphere that is continuously replenished by the magma ocean. Magma is not just crystals and liquid rock; there’s a lot of dissolved gas in it, too.
However, the finding shows that rocky planets outside our solar system can indeed maintain atmospheres. If it can happen on 55 Cancri e, then it should also occur on other rocky worlds, including ones more potentially habitable, as Hu noted:
Ultimately, we want to understand what conditions make it possible for a rocky planet to sustain a gas-rich atmosphere: a key ingredient for a habitable planet.
Bottom line: NASA’s Webb telescope has tentatively detected an atmosphere on rocky exoplanet 55 Cancri e, a hot super-Earth world only 41 light-years away.
Here’s devastating and deadly Hurricane Katrina on August 28, 2005. For this upcoming Atlantic hurricane season, we’ll be transitioning from El Niño conditions to La Niña conditions. What will that mean for hurricane season in 2024? Find out here. Image via NASA.
Whether that’s a relief or not depends in part on where you live. Above-normal temperatures are still forecast across the U.S. in summer 2024. And if you live along the U.S. Atlantic or Gulf Coasts, La Niña can contribute to the worst possible combination of climate conditions for fueling hurricanes.
Pedro DiNezio, an atmosphere and ocean scientist at the University of Colorado who studies El Niño and La Niña, explains why and what’s ahead.
La Niña and El Niño are the two extremes of a recurring climate pattern that can affect weather around the world.
Forecasters know La Niña has arrived when temperatures in the eastern Pacific Ocean along the equator west of South America cool by at least half a degree Celsius (0.9 Fahrenheit) below normal. During El Niño, the same region warms instead.
Those temperature fluctuations might seem small, but they can affect the atmosphere in ways that ripple across the planet.
How La Nina and El Nino form. NOAA.
Atmospheric circulation
The tropics have an atmospheric circulation pattern called the Walker Circulation, named after Sir Gilbert Walker, an English physicist in the early 20th century. The Walker Circulation is basically giant loops of air rising and descending in different parts of the tropics.
Normally, air rises over the Amazon and Indonesia because moisture from the tropical forests makes the air more buoyant there, and it comes down in East Africa and the eastern Pacific. During La Niña, those loops intensify, generating stormier conditions where they rise and drier conditions where they descend. And during El Niño, ocean heat in the eastern Pacific instead shifts those loops, so the eastern Pacific gets stormier.
During La Niña, the Walker Circulation intensifies, triggering stronger storms where the air rises. Image via Fiona Martin/ NOAA/ Climate.gov. During El Niño, the Walker Circulation shifts eastward, so more storms form off California as warm air rises over the warmer waters of the eastern Pacific. Image via Fiona Martin, NOAA Climate.gov.
— NWS Climate Prediction Center (@NWSCPC) May 9, 2024
The jet stream
EL Niño and La Niña also affect the jet stream, a strong current of air that blows from west to east across the U.S. and other mid-latitude regions.
During El Niño, the jet stream tends to push storms toward the subtropics, making these typically dry areas wetter. Conversely, mid-latitude regions that normally would get the storms become drier because storms shift away.
This year, forecasters expect a fast transition to La Niña, likely by late summer. After a strong El Niño, like the world saw in late 2023 and early 2024, conditions tend to swing fairly quickly to La Niña. How long it will stick around is an open question. This cycle tends to swing from extreme to extreme every three to seven years on average. But while El Niños tend to be short-lived, La Niñas can last two years or longer.
How does La Niña affect hurricanes?
Temperatures in the tropical Pacific also control wind shear over large parts of the Atlantic Ocean.
Wind shear is a difference in wind speeds at different heights or direction. Hurricanes have a harder time holding their column structure during strong wind shear because stronger winds higher up push the column apart.
La Niña produces less wind shear, removing a brake on hurricanes. That’s not good news for people living in hurricane-prone regions like Florida. In 2020, during the last La Niña, the Atlantic saw a record 30 tropical storms and 14 hurricanes, and 2021 had 21 tropical storms and seven hurricanes.
Forecasters are already warning that this year’s Atlantic storm season could rival 2021, due in large part to La Niña. The tropical Atlantic has also been exceptionally warm, with sea surface temperature-breaking records for over a year. That warmth affects the atmosphere, causing more atmospheric motion over the Atlantic, fueling hurricanes.
Some of the online discourse around mainstream coverage of outlooks for a very active Atlantic hurricane season has been along the lines of "they say that every year".
Comparing all April-issued CSU hurricane season outlooks, this is the most active forecast they've made yet: pic.twitter.com/vLFYE0yMMx
Comparing March 2024 SST's in the Tropical Atlantic with other active hurricane seasons. SST's can change quickly – and we will still see changes as we head into hurricane season – but these years ultimately produced large numbers of storms. (Season named storm # on right). pic.twitter.com/QxhqQkw5NW
The U.S. Southwest’s water supplies will probably be okay for the first year of La Niña because of all the rain over the past winter. But the second year tends to become problematic. A third year, as the region saw in 2022, can lead to severe water shortages.
During La Niña, the jet stream tends to be farther north, causing drier conditions across the U.S. Southwest. Image via NOAA/ Climate.gov.
What happens in the Southern Hemisphere during La Niña?
The impacts of El Niño and La Niña are almost a mirror image in the Southern Hemisphere.
Chile and Argentina tend to get drought during La Niña, while the same phase leads to more rain in the Amazon. Australia had severe flooding during the last La Niña. La Niña also favors the Indian monsoon, meaning above-average rainfall. The effects aren’t immediate, however. In South Asia, for example, the changes tend to show up a few months after La Niña has officially appeared.
Typical La Niña climate impacts, though conditions aren’t always like this. Image via NOAA/ Climate.gov.
What about climate change?
El Niño and La Niña are now happening on top of the effects of global warming. That can exacerbate temperatures, as the world saw in 2023, and precipitation can go off the charts.
La Niña should cool things a bit, but greenhouse gas emissions that drive global warming are still rising in the background. So while fluctuations between El Niño and La Niña can cause short-term temperature swings, the overall trend is toward a warming world.
The image is a little outdated, here’s the up to date data, which is unchanged. pic.twitter.com/3GCsf9l8f6
Here’s devastating and deadly Hurricane Katrina on August 28, 2005. For this upcoming Atlantic hurricane season, we’ll be transitioning from El Niño conditions to La Niña conditions. What will that mean for hurricane season in 2024? Find out here. Image via NASA.
Whether that’s a relief or not depends in part on where you live. Above-normal temperatures are still forecast across the U.S. in summer 2024. And if you live along the U.S. Atlantic or Gulf Coasts, La Niña can contribute to the worst possible combination of climate conditions for fueling hurricanes.
Pedro DiNezio, an atmosphere and ocean scientist at the University of Colorado who studies El Niño and La Niña, explains why and what’s ahead.
La Niña and El Niño are the two extremes of a recurring climate pattern that can affect weather around the world.
Forecasters know La Niña has arrived when temperatures in the eastern Pacific Ocean along the equator west of South America cool by at least half a degree Celsius (0.9 Fahrenheit) below normal. During El Niño, the same region warms instead.
Those temperature fluctuations might seem small, but they can affect the atmosphere in ways that ripple across the planet.
How La Nina and El Nino form. NOAA.
Atmospheric circulation
The tropics have an atmospheric circulation pattern called the Walker Circulation, named after Sir Gilbert Walker, an English physicist in the early 20th century. The Walker Circulation is basically giant loops of air rising and descending in different parts of the tropics.
Normally, air rises over the Amazon and Indonesia because moisture from the tropical forests makes the air more buoyant there, and it comes down in East Africa and the eastern Pacific. During La Niña, those loops intensify, generating stormier conditions where they rise and drier conditions where they descend. And during El Niño, ocean heat in the eastern Pacific instead shifts those loops, so the eastern Pacific gets stormier.
During La Niña, the Walker Circulation intensifies, triggering stronger storms where the air rises. Image via Fiona Martin/ NOAA/ Climate.gov. During El Niño, the Walker Circulation shifts eastward, so more storms form off California as warm air rises over the warmer waters of the eastern Pacific. Image via Fiona Martin, NOAA Climate.gov.
— NWS Climate Prediction Center (@NWSCPC) May 9, 2024
The jet stream
EL Niño and La Niña also affect the jet stream, a strong current of air that blows from west to east across the U.S. and other mid-latitude regions.
During El Niño, the jet stream tends to push storms toward the subtropics, making these typically dry areas wetter. Conversely, mid-latitude regions that normally would get the storms become drier because storms shift away.
This year, forecasters expect a fast transition to La Niña, likely by late summer. After a strong El Niño, like the world saw in late 2023 and early 2024, conditions tend to swing fairly quickly to La Niña. How long it will stick around is an open question. This cycle tends to swing from extreme to extreme every three to seven years on average. But while El Niños tend to be short-lived, La Niñas can last two years or longer.
How does La Niña affect hurricanes?
Temperatures in the tropical Pacific also control wind shear over large parts of the Atlantic Ocean.
Wind shear is a difference in wind speeds at different heights or direction. Hurricanes have a harder time holding their column structure during strong wind shear because stronger winds higher up push the column apart.
La Niña produces less wind shear, removing a brake on hurricanes. That’s not good news for people living in hurricane-prone regions like Florida. In 2020, during the last La Niña, the Atlantic saw a record 30 tropical storms and 14 hurricanes, and 2021 had 21 tropical storms and seven hurricanes.
Forecasters are already warning that this year’s Atlantic storm season could rival 2021, due in large part to La Niña. The tropical Atlantic has also been exceptionally warm, with sea surface temperature-breaking records for over a year. That warmth affects the atmosphere, causing more atmospheric motion over the Atlantic, fueling hurricanes.
Some of the online discourse around mainstream coverage of outlooks for a very active Atlantic hurricane season has been along the lines of "they say that every year".
Comparing all April-issued CSU hurricane season outlooks, this is the most active forecast they've made yet: pic.twitter.com/vLFYE0yMMx
Comparing March 2024 SST's in the Tropical Atlantic with other active hurricane seasons. SST's can change quickly – and we will still see changes as we head into hurricane season – but these years ultimately produced large numbers of storms. (Season named storm # on right). pic.twitter.com/QxhqQkw5NW
The U.S. Southwest’s water supplies will probably be okay for the first year of La Niña because of all the rain over the past winter. But the second year tends to become problematic. A third year, as the region saw in 2022, can lead to severe water shortages.
During La Niña, the jet stream tends to be farther north, causing drier conditions across the U.S. Southwest. Image via NOAA/ Climate.gov.
What happens in the Southern Hemisphere during La Niña?
The impacts of El Niño and La Niña are almost a mirror image in the Southern Hemisphere.
Chile and Argentina tend to get drought during La Niña, while the same phase leads to more rain in the Amazon. Australia had severe flooding during the last La Niña. La Niña also favors the Indian monsoon, meaning above-average rainfall. The effects aren’t immediate, however. In South Asia, for example, the changes tend to show up a few months after La Niña has officially appeared.
Typical La Niña climate impacts, though conditions aren’t always like this. Image via NOAA/ Climate.gov.
What about climate change?
El Niño and La Niña are now happening on top of the effects of global warming. That can exacerbate temperatures, as the world saw in 2023, and precipitation can go off the charts.
La Niña should cool things a bit, but greenhouse gas emissions that drive global warming are still rising in the background. So while fluctuations between El Niño and La Niña can cause short-term temperature swings, the overall trend is toward a warming world.
The image is a little outdated, here’s the up to date data, which is unchanged. pic.twitter.com/3GCsf9l8f6
When we think of carnivorous beings, images of large fangs and sharp claws come to mind. But what about carnivorous plants? Even though their name indicates that they are carnivorous, the vast majority only feed on insects.
There are around 700 species of carnivorous plants and some of them can hunt animals larger than insects, such as rats, frogs, or lizards. You might wonder, how can these plants trap prey? The surface of their leaves is extremely sensitive. Therefore, any pressure triggers a change in the water pressure of the leaf cells. That change translates into movement. The cells expand or contract and cause motion. That’s how their mouths open and close, or how their tentacles extend and trap their prey.
The Venus flytrap is one of the most famous carnivorous plants. Image via Rapha Wilde/ Unsplash.
They are classified into five groups depending on the way they capture their prey.
Snap traps close their “mouths.” They are probably the most well-known type of carnivorous plant. Snap trap plants have leaves for mouths that release nectar on their edges to attract prey. When the prey approaches and touches the hairs or filaments inside the mouth, it closes, trapping the prey.
The Venus flytrap is one of the most famous carnivorous plants and is a snap trap plant. It has sensory hairs or filaments inside the mouth – between three and six on the surface of each leaf – that indicate to the leaf when to close. So, yes! Plants also produce electrical signals even though they lack a nervous system. The mouth only closes when the prey touches the filaments at least twice in less than 20 seconds, so as not to confuse it with a drop of water.
A Venus flytrap. The “mouth” has from 3 to 6 filaments on the surface of each leaf. Image via Rapha Wilde/ Unsplash.
Sticky traps
Sticky traps (or flypaper traps) have leaves with hairs or filaments that produce nectar – that looks like dew or water drops at the top of the hairs – to attract prey. But this nectar is also sticky like glue. When the prey, attracted by the nectar, gets to the plant, it is trapped by the glue. Some plants have tentacle-like leaves that not only have the sticky filaments, but that can also wrap around the prey like an octopus.
Sticky traps seduce and kill with a sweet, sticky nectar. Image via Dean Erasmus/ Unsplash.
Pitcher plants
Pitcher plants (or pitfall traps) are jug-shaped and possess an incredible structure. Some of them have tendrils that fall down, then turn back up and transform into leaves that are completely closed at the bottom. The bottom of the jug fills with sweet, delicious nectar to attract prey. And it also fills with digestive enzymes to decompose prey. Also, these plants have a lid at the top. When they are digesting their prey, the lid closes.
Pitcher plants have a liquid at the bottom to drown its prey. image via JeremiahsCPs/ Wikipedia (public domain).
Light trap
A light trap (or lobster trap) plant also attracts prey with nectar, which is located at the bottom. In this case, the prey enters the plant, that has sort of a window that allows light to enter the plant. The prey gets deeper into the plant, following the light and the nectar, and can’t find the way back to the dark entry.
Inward hairs
Inward hairs (or pigeon traps) have hairs where the prey enters. Once inside the trap, the prey can’t escape past the hairs.
How is prey digested?
Carnivorous plants produce nectar to attract prey, then use acids to dissolve their victims, and enzymes to digest them. Enzymes are a type of protein that act as catalysts and regulators of chemical reactions.
Once the plant begins to produce digestive enzymes to decompose and digest the prey, there are other glands in the plant that begin to function. They absorb the solution that has been produced, and with it, the nutrients that the plant needs. Not a drop is wasted in the entire process.
How long does it take to digest its prey?
The most curious thing about these plants is that it can take more than two weeks for them to digest any insect, while humans only need about two days to completely digest food.
But even if their digestion is slow, the mouths and lids are quite fast! According to a study from the National Institute of Health:
It was shown using high-speed video under ultraviolet light that the fast closure of Venus flytrap starts at about 40 milliseconds after mechanical stimulation and completes in 0.3–0.7 s.
This is a type of pitcher plant. Carnivorous plants produce nectar to attract prey, acids to dissolve their victims, and enzymes to digest them. Image via Rapha Wilde/ Unsplash.
How did they become carnivorous?
Let’s not forget that, in the end, these carnivorous plants are still plants. So, yes, they do go through a normal photosynthesis process, which converts light into chemical energy. This process requires not only sunlight, but also water, carbon dioxide, and nutrients such as nitrogen. But carnivorous plants usually live in swampy places, such as bogs and wetlands, areas that have little nitrogen and an acidic pH. That’s why they evolved into carnivores.
Plants get nutrients from the soil through their roots. But if the soil quality isn’t good enough, with areas low in nitrogen, then the carnivorous plants need to supplement nitrogen by eating insects or animals.
But trapping and digesting prey require energy, which leaves less energy for photosynthesis. Consequently, carnivorous plants photosynthesize at significantly lower rates than regular plants. Still, these plants need ample sunlight.
Curious things about them
Most carnivorous plants respect pollinating insects. Like many other plants, carnivorous plants need pollinators, though some carnivorous plants can self-pollinate. If carnivorous plants feed on insects, how do they differentiate pollinators from non-pollinators? That’s where the magic of nature comes in to play.
Logically, the plants don’t know which insect is approaching. So, they grow a very long stem, far away from their traps, and right at the top, there is an attractive flower for the beloved pollinators.
Many carnivorous plants avoid trapping the much appreciated pollinators with a flower that is far away from their traps. Image via Juliana Barquero/ Unsplash.
Some even hibernate
Some carnivorous plants of tropical origin hibernate during winter. Although their behavior varies depending on the species, they usually shed their leaves to sprout again with the arrival of spring. This is a protective mechanism that enables the plant to survive in various climates. So, if you have one and it stops growing in winter, now you know why.
There are some species that live submerged in water. In this case, the base of the plant is submerged while the stems with traps are on the surface. How cool! This is how they feed.
Can you grow them at home?
Although they are wild plants, if you replicate the conditions in which they live, they can be grown at home. Study the type of plant and its needs before purchasing one. These plants are delicate and require specific care. You should know that some carnivorous plants survive well in cold climates, but the vast majority live in tropical and humid climates.
The soil for carnivorous plants should have few nutrients and not be fertilized. Make sure the plant has enough humidity and plenty of sunlight. If you live in a cold place, it is advisable to keep the plant indoors and create a small greenhouse to maintain humidity and warmth.
Instead of watering it from the top, place a deep container of water under the pot and let it absorb water. When the surface of the pot is wet, you can remove the container. Use distilled water or rainwater to avoid any additives found in tap water.
The plant’s feeding habits depend on the type of plant. Keep in mind that some species ONLY need sunlight and water to live.
When the plant moves, like when closing its mouths, it uses a lot of energy. So don’t play with your plant to make it close its mouths on purpose, it will lose a lot of energy and won’t receive any nutrients. It needs that energy to survive.
In many cases, you won’t have to feed it because the plant has its own system for attracting insects. If your plant is indoors and doesn’t have access to any insects, you can feed it, but take into account that it may take up to two weeks for your plant to digest the insect you offer it.
Bottom line: Beware of carnivorous plants! There are hundreds of species and they are deadly, but mostly to insects. The structure of their traps is foolproof.
When we think of carnivorous beings, images of large fangs and sharp claws come to mind. But what about carnivorous plants? Even though their name indicates that they are carnivorous, the vast majority only feed on insects.
There are around 700 species of carnivorous plants and some of them can hunt animals larger than insects, such as rats, frogs, or lizards. You might wonder, how can these plants trap prey? The surface of their leaves is extremely sensitive. Therefore, any pressure triggers a change in the water pressure of the leaf cells. That change translates into movement. The cells expand or contract and cause motion. That’s how their mouths open and close, or how their tentacles extend and trap their prey.
The Venus flytrap is one of the most famous carnivorous plants. Image via Rapha Wilde/ Unsplash.
They are classified into five groups depending on the way they capture their prey.
Snap traps close their “mouths.” They are probably the most well-known type of carnivorous plant. Snap trap plants have leaves for mouths that release nectar on their edges to attract prey. When the prey approaches and touches the hairs or filaments inside the mouth, it closes, trapping the prey.
The Venus flytrap is one of the most famous carnivorous plants and is a snap trap plant. It has sensory hairs or filaments inside the mouth – between three and six on the surface of each leaf – that indicate to the leaf when to close. So, yes! Plants also produce electrical signals even though they lack a nervous system. The mouth only closes when the prey touches the filaments at least twice in less than 20 seconds, so as not to confuse it with a drop of water.
A Venus flytrap. The “mouth” has from 3 to 6 filaments on the surface of each leaf. Image via Rapha Wilde/ Unsplash.
Sticky traps
Sticky traps (or flypaper traps) have leaves with hairs or filaments that produce nectar – that looks like dew or water drops at the top of the hairs – to attract prey. But this nectar is also sticky like glue. When the prey, attracted by the nectar, gets to the plant, it is trapped by the glue. Some plants have tentacle-like leaves that not only have the sticky filaments, but that can also wrap around the prey like an octopus.
Sticky traps seduce and kill with a sweet, sticky nectar. Image via Dean Erasmus/ Unsplash.
Pitcher plants
Pitcher plants (or pitfall traps) are jug-shaped and possess an incredible structure. Some of them have tendrils that fall down, then turn back up and transform into leaves that are completely closed at the bottom. The bottom of the jug fills with sweet, delicious nectar to attract prey. And it also fills with digestive enzymes to decompose prey. Also, these plants have a lid at the top. When they are digesting their prey, the lid closes.
Pitcher plants have a liquid at the bottom to drown its prey. image via JeremiahsCPs/ Wikipedia (public domain).
Light trap
A light trap (or lobster trap) plant also attracts prey with nectar, which is located at the bottom. In this case, the prey enters the plant, that has sort of a window that allows light to enter the plant. The prey gets deeper into the plant, following the light and the nectar, and can’t find the way back to the dark entry.
Inward hairs
Inward hairs (or pigeon traps) have hairs where the prey enters. Once inside the trap, the prey can’t escape past the hairs.
How is prey digested?
Carnivorous plants produce nectar to attract prey, then use acids to dissolve their victims, and enzymes to digest them. Enzymes are a type of protein that act as catalysts and regulators of chemical reactions.
Once the plant begins to produce digestive enzymes to decompose and digest the prey, there are other glands in the plant that begin to function. They absorb the solution that has been produced, and with it, the nutrients that the plant needs. Not a drop is wasted in the entire process.
How long does it take to digest its prey?
The most curious thing about these plants is that it can take more than two weeks for them to digest any insect, while humans only need about two days to completely digest food.
But even if their digestion is slow, the mouths and lids are quite fast! According to a study from the National Institute of Health:
It was shown using high-speed video under ultraviolet light that the fast closure of Venus flytrap starts at about 40 milliseconds after mechanical stimulation and completes in 0.3–0.7 s.
This is a type of pitcher plant. Carnivorous plants produce nectar to attract prey, acids to dissolve their victims, and enzymes to digest them. Image via Rapha Wilde/ Unsplash.
How did they become carnivorous?
Let’s not forget that, in the end, these carnivorous plants are still plants. So, yes, they do go through a normal photosynthesis process, which converts light into chemical energy. This process requires not only sunlight, but also water, carbon dioxide, and nutrients such as nitrogen. But carnivorous plants usually live in swampy places, such as bogs and wetlands, areas that have little nitrogen and an acidic pH. That’s why they evolved into carnivores.
Plants get nutrients from the soil through their roots. But if the soil quality isn’t good enough, with areas low in nitrogen, then the carnivorous plants need to supplement nitrogen by eating insects or animals.
But trapping and digesting prey require energy, which leaves less energy for photosynthesis. Consequently, carnivorous plants photosynthesize at significantly lower rates than regular plants. Still, these plants need ample sunlight.
Curious things about them
Most carnivorous plants respect pollinating insects. Like many other plants, carnivorous plants need pollinators, though some carnivorous plants can self-pollinate. If carnivorous plants feed on insects, how do they differentiate pollinators from non-pollinators? That’s where the magic of nature comes in to play.
Logically, the plants don’t know which insect is approaching. So, they grow a very long stem, far away from their traps, and right at the top, there is an attractive flower for the beloved pollinators.
Many carnivorous plants avoid trapping the much appreciated pollinators with a flower that is far away from their traps. Image via Juliana Barquero/ Unsplash.
Some even hibernate
Some carnivorous plants of tropical origin hibernate during winter. Although their behavior varies depending on the species, they usually shed their leaves to sprout again with the arrival of spring. This is a protective mechanism that enables the plant to survive in various climates. So, if you have one and it stops growing in winter, now you know why.
There are some species that live submerged in water. In this case, the base of the plant is submerged while the stems with traps are on the surface. How cool! This is how they feed.
Can you grow them at home?
Although they are wild plants, if you replicate the conditions in which they live, they can be grown at home. Study the type of plant and its needs before purchasing one. These plants are delicate and require specific care. You should know that some carnivorous plants survive well in cold climates, but the vast majority live in tropical and humid climates.
The soil for carnivorous plants should have few nutrients and not be fertilized. Make sure the plant has enough humidity and plenty of sunlight. If you live in a cold place, it is advisable to keep the plant indoors and create a small greenhouse to maintain humidity and warmth.
Instead of watering it from the top, place a deep container of water under the pot and let it absorb water. When the surface of the pot is wet, you can remove the container. Use distilled water or rainwater to avoid any additives found in tap water.
The plant’s feeding habits depend on the type of plant. Keep in mind that some species ONLY need sunlight and water to live.
When the plant moves, like when closing its mouths, it uses a lot of energy. So don’t play with your plant to make it close its mouths on purpose, it will lose a lot of energy and won’t receive any nutrients. It needs that energy to survive.
In many cases, you won’t have to feed it because the plant has its own system for attracting insects. If your plant is indoors and doesn’t have access to any insects, you can feed it, but take into account that it may take up to two weeks for your plant to digest the insect you offer it.
Bottom line: Beware of carnivorous plants! There are hundreds of species and they are deadly, but mostly to insects. The structure of their traps is foolproof.
Aftermath of an earthquake on Japan’s Noto Peninsula that took place on January 1, 2024. A new study from MIT, focused on earthquakes in Japan, suggests that heavy snowfall and rainfall can contribute to triggering swarms of earthquakes. Image via Japan Ministry of Defense/ Wikimedia Commons (CC BY 4.0).
Researchers looked for patterns in an earthquake swarm that started on the Noto Peninsula of Japan in late 2020.
They found a correlation between the earthquakes and seasonal periods of heavy snow and rain.
The snow and rain increase fluid pressure in cracks and fissures in subsurface bedrock, contributing to regular earthquake triggers and producing earthquake swarms.
Can intense weather trigger earthquakes?
Earthquakes happen when movement below Earth’s surface – such as shifting tectonic plates and faults – occurs. But could other factors also be at play? On May 8, 2024, researchers at the Massachusetts Institute of Technology (MIT) said climate and certain intense weather events may also help trigger earthquakes. In particular, heavy snowfall and rain can play a role. The new report focuses on a swarm of earthquakes in Japan over the past few years.
The researchers, led by former MIT research associate Qing-Yu Wang (now at Grenoble Alpes University), published their peer-reviewed findings in Science Advances on May 8, 2024.
Snowfall and rain contributed to earthquakes in Japan
The researchers focused on a series of earthquakes that have been occurring on the Noto Peninsula in Japan since 2020. The paper stated:
Since late 2020, a swarm of crustal earthquakes in the northeastern region of the Noto Peninsula, Japan, far from the plate boundaries of the subducting Pacific and Philippine plates, has been responsible for hundreds of earthquakes per day. Unlike typical subduction zone interplate earthquakes, inland crustal earthquakes in Japan islands predominantly take place at relatively shallow depths … Earthquake locations show that the Noto earthquake swarm started at a depth of about 15 km (9 mi), deeper than typical crustal earthquakes, and has since slowly migrated northeast toward the surface. This suggests that … there is an underlying forcing that is driving the earthquakes.
Connection between earthquakes and precipitation events
What is the underlying forcing? The new study suggests heavy snowfall and rain are at least part of the reason. The researchers found the start of the earthquake swarm matched up with strong precipitation events of heavy snow or rain. Study co-author William Frank at MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) said:
We see that snowfall and other environmental loading at the surface impacts the stress state underground, and the timing of intense precipitation events is well-correlated with the start of this earthquake swarm. So, climate obviously has an impact on the response of the solid earth, and part of that response is earthquakes.
The changes in underground pressure also correlate with seasonal patterns of snowfall and rainfall. Moreover, this pattern may occur elsewhere as well, not just in Japan.
Earthquake swarm and seismic velocity
The earthquakes in Japan – hundreds since late 2020 – are what scientists call an earthquake swarm. Instead of one big initial earthquake, followed by aftershocks, these are ongoing swarms of earthquakes without an initial bigger earthquake to trigger them. The research team at MIT, as well as scientists in Japan, looked for patterns in the swarms. Using the Japanese Meteorological Agency’s catalog of earthquakes, they examined earthquakes on Noto Peninsula over the past 11 years.
And indeed, they found something interesting. Before 2020, the recorded earthquakes were sporadic in nature. But after 2020, the earthquakes became more intense. They also began to cluster, which was the beginning of the swarm. To check this further, the researchers compared those results with another dataset from monitoring stations during the same 11-year period. The researchers wanted to check the speed, or the “seismic velocity,” of the seismic events, as in how fast a seismic wave traveled between monitoring stations.
The speed depends on the structure of the subsurface. The results supported the earlier findings. The seismic velocities changed when the earthquake swarm started and were also synchronized with the changing seasons. That was a big clue. Frank said:
We then had to explain why we were observing this seasonal variation.
Weight from snow and rain
So there was a demonstrated connection to the changing seasons. But why, exactly? Could changes in the environment somehow affect the subsurface where the earthquakes occurred? The answer had to do with seasonal precipitation. Snow or rain could affect the pore fluid pressure beneath the surface. This is the pressure from fluids in cracks and fissures in bedrock. As Frank explained:
When it rains or snows, that adds weight, which increases pore pressure, which allows seismic waves to travel through slower. When all that weight is removed, through evaporation or runoff, all of a sudden, that pore pressure decreases and seismic waves are faster.
So how could Wang and the team test this further? They created a hydromechanical model of the Noto Peninsula to simulate the underlying pore pressure over the last 11 years in response to seasonal changes in precipitation. The data included measurements of daily snow, rainfall and sea-level changes. The team used the data to track changes in excess pore pressure. Again, the results matched up with previous findings, as Frank noted:
We had seismic velocity observations, and we had the model of excess pore pressure, and when we overlapped them, we saw they just fit extremely well.
Noto Peninsula, Japan, as seen from the space shuttle in 2005. Image via Wikimedia Commons (public domain).
Snowfall the biggest contributor
Snowfall in particular had the strongest effect. So the periods of heavy snowfall helped to trigger the earthquake swarm. Frank added:
We can see that the timing of these earthquakes lines up extremely well with multiple times where we see intense snowfall. It’s well-correlated with earthquake activity. And we think there’s a physical link between the two.
The researchers note that while heavy snowfall and rain can contribute to producing an earthquake swarm, the original trigger is, as usual, in the subsurface. The climate and events simply enhance the effects. Frank said:
When we first want to understand how earthquakes work, we look to plate tectonics, because that is and will always be the number one reason why an earthquake happens. But, what are the other things that could affect when and how an earthquake happens? That’s when you start to go to second-order controlling factors, and the climate is obviously one of those.
Bottom line: A new study from MIT shows that climate and intense weather events like heavy snowfall and rain helped produce a swarm of earthquakes in Japan starting in 2020.
Aftermath of an earthquake on Japan’s Noto Peninsula that took place on January 1, 2024. A new study from MIT, focused on earthquakes in Japan, suggests that heavy snowfall and rainfall can contribute to triggering swarms of earthquakes. Image via Japan Ministry of Defense/ Wikimedia Commons (CC BY 4.0).
Researchers looked for patterns in an earthquake swarm that started on the Noto Peninsula of Japan in late 2020.
They found a correlation between the earthquakes and seasonal periods of heavy snow and rain.
The snow and rain increase fluid pressure in cracks and fissures in subsurface bedrock, contributing to regular earthquake triggers and producing earthquake swarms.
Can intense weather trigger earthquakes?
Earthquakes happen when movement below Earth’s surface – such as shifting tectonic plates and faults – occurs. But could other factors also be at play? On May 8, 2024, researchers at the Massachusetts Institute of Technology (MIT) said climate and certain intense weather events may also help trigger earthquakes. In particular, heavy snowfall and rain can play a role. The new report focuses on a swarm of earthquakes in Japan over the past few years.
The researchers, led by former MIT research associate Qing-Yu Wang (now at Grenoble Alpes University), published their peer-reviewed findings in Science Advances on May 8, 2024.
Snowfall and rain contributed to earthquakes in Japan
The researchers focused on a series of earthquakes that have been occurring on the Noto Peninsula in Japan since 2020. The paper stated:
Since late 2020, a swarm of crustal earthquakes in the northeastern region of the Noto Peninsula, Japan, far from the plate boundaries of the subducting Pacific and Philippine plates, has been responsible for hundreds of earthquakes per day. Unlike typical subduction zone interplate earthquakes, inland crustal earthquakes in Japan islands predominantly take place at relatively shallow depths … Earthquake locations show that the Noto earthquake swarm started at a depth of about 15 km (9 mi), deeper than typical crustal earthquakes, and has since slowly migrated northeast toward the surface. This suggests that … there is an underlying forcing that is driving the earthquakes.
Connection between earthquakes and precipitation events
What is the underlying forcing? The new study suggests heavy snowfall and rain are at least part of the reason. The researchers found the start of the earthquake swarm matched up with strong precipitation events of heavy snow or rain. Study co-author William Frank at MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) said:
We see that snowfall and other environmental loading at the surface impacts the stress state underground, and the timing of intense precipitation events is well-correlated with the start of this earthquake swarm. So, climate obviously has an impact on the response of the solid earth, and part of that response is earthquakes.
The changes in underground pressure also correlate with seasonal patterns of snowfall and rainfall. Moreover, this pattern may occur elsewhere as well, not just in Japan.
Earthquake swarm and seismic velocity
The earthquakes in Japan – hundreds since late 2020 – are what scientists call an earthquake swarm. Instead of one big initial earthquake, followed by aftershocks, these are ongoing swarms of earthquakes without an initial bigger earthquake to trigger them. The research team at MIT, as well as scientists in Japan, looked for patterns in the swarms. Using the Japanese Meteorological Agency’s catalog of earthquakes, they examined earthquakes on Noto Peninsula over the past 11 years.
And indeed, they found something interesting. Before 2020, the recorded earthquakes were sporadic in nature. But after 2020, the earthquakes became more intense. They also began to cluster, which was the beginning of the swarm. To check this further, the researchers compared those results with another dataset from monitoring stations during the same 11-year period. The researchers wanted to check the speed, or the “seismic velocity,” of the seismic events, as in how fast a seismic wave traveled between monitoring stations.
The speed depends on the structure of the subsurface. The results supported the earlier findings. The seismic velocities changed when the earthquake swarm started and were also synchronized with the changing seasons. That was a big clue. Frank said:
We then had to explain why we were observing this seasonal variation.
Weight from snow and rain
So there was a demonstrated connection to the changing seasons. But why, exactly? Could changes in the environment somehow affect the subsurface where the earthquakes occurred? The answer had to do with seasonal precipitation. Snow or rain could affect the pore fluid pressure beneath the surface. This is the pressure from fluids in cracks and fissures in bedrock. As Frank explained:
When it rains or snows, that adds weight, which increases pore pressure, which allows seismic waves to travel through slower. When all that weight is removed, through evaporation or runoff, all of a sudden, that pore pressure decreases and seismic waves are faster.
So how could Wang and the team test this further? They created a hydromechanical model of the Noto Peninsula to simulate the underlying pore pressure over the last 11 years in response to seasonal changes in precipitation. The data included measurements of daily snow, rainfall and sea-level changes. The team used the data to track changes in excess pore pressure. Again, the results matched up with previous findings, as Frank noted:
We had seismic velocity observations, and we had the model of excess pore pressure, and when we overlapped them, we saw they just fit extremely well.
Noto Peninsula, Japan, as seen from the space shuttle in 2005. Image via Wikimedia Commons (public domain).
Snowfall the biggest contributor
Snowfall in particular had the strongest effect. So the periods of heavy snowfall helped to trigger the earthquake swarm. Frank added:
We can see that the timing of these earthquakes lines up extremely well with multiple times where we see intense snowfall. It’s well-correlated with earthquake activity. And we think there’s a physical link between the two.
The researchers note that while heavy snowfall and rain can contribute to producing an earthquake swarm, the original trigger is, as usual, in the subsurface. The climate and events simply enhance the effects. Frank said:
When we first want to understand how earthquakes work, we look to plate tectonics, because that is and will always be the number one reason why an earthquake happens. But, what are the other things that could affect when and how an earthquake happens? That’s when you start to go to second-order controlling factors, and the climate is obviously one of those.
Bottom line: A new study from MIT shows that climate and intense weather events like heavy snowfall and rain helped produce a swarm of earthquakes in Japan starting in 2020.
Crux, the Southern Cross, and its major stars. Mimosa is on the left near the Jewel Box Cluster. This is the view from a southerly latitude (around 25 degrees north parallel, close to Miami, Florida) in the Northern Hemisphere around midnight in the spring.
A star named Mimosa
Crux, the Southern Cross constellation, lies deep in southern skies. Its 2nd-brightest star, Beta Crucis, bears a couple of nicknames, including Mimosa and Becrux. (The constellation’s brightest star, Alpha Crucis, has the nickname Acrux.) German astronomer Johann Bayer (1572-1625) may have been the one to call it Mimosa. Bayer’s reasoning is unclear, but it might be related to this star’s blue-white color. It could also be in honor of the mimosa flower, although most of those are pink, red or yellow.
View at EarthSky Community Photos. | Prateek Pandey in Bhopal, India, caught the Southern Cross while at its highest point around midnight (its midnight culmination) on March 6, 2021. In April and May, the Southern Cross reaches its highest point in the sky earlier in the evening. Thank you, Prateek!
How to see Beta Crucis
Blue-white Mimosa is the 20th brightest star in all the heavens. It’s the 2nd-brightest star in the constellation Crux the Southern Cross. The Cross is a Southern Hemisphere constellation, and you will not see Mimosa north of 30 degrees north latitude. Some cities near 30 degrees north latitude are Austin, Texas; Cairo, Egypt; and New Delhi, India. Southern Hemisphere observers know and love Mimosa, though, and it is circumpolar for latitudes of about 30 degrees south and higher.
A midnight culmination occurs when a star is roughly opposite the sun. It ensures that the star will be above the horizon a maximum amount of time. This occurs for Mimosa on or about April 2 each year.
It stays above the horizon year-round for observers in the Southern Hemisphere, but it can be seen by those in the southern reaches of the Northern Hemisphere for a short time each year. For example, observers in southerly latitudes around Miami, Florida (around 26 degrees north latitude and farther south), can view the Southern Cross and Mimosa on May evenings as it appears just above the southern horizon.
The nearer the observer is to the northern observation limit of about 30 degrees, the lower the star will climb into the sky and the shorter the time it will be visible. For example, from Austin, the star barely skirts the horizon for about a half hour at most. Often it can’t be seen at all due to the dimming affects of Earth’s atmosphere. From Miami it rises almost 5 degrees above the horizon and stays up more than four hours.
From Northern Hemisphere locations such as Hawaii, where Mimosa can be seen more easily, it rises in the late evening in late winter, far to the south-southeast, and sets in the predawn hours to the south-southwest. By early June it rises before sundown and sets by midnight.
History and mythology of Mimosa
Because of its southerly location, Crux and Mimosa were essentially unknown in classical western mythology. Of course, these stars were well known to the Australian Aboriginal peoples as well as the islanders of Polynesia and the people of southern Africa.
In Australia, for example, one Aboriginal story is that the stars of the Southern Cross are a reminder of the time and place where death first came to mankind. Two of the stars are the glowing eyes of the spirit of death, and the other two are the eyes of the first man to die.
The main stars of Crux, including Mimosa, appear on the flags of both Australia and New Zealand. Mimosa appears as the left side of the crossbar, and Acrux as the bottom of the Cross.
View at EarthSky Community Photos. | Kannan A in Woodlands, Singapore, captured this photo of the Southern Cross – and the star Mimosa – on March 8, 2021. He wrote: “The Southern Cross constellation seen here in the morning in Singapore looking south. On the left of this cross are the 2 pointer stars, Alpha Centauri (Rigel Kentaurus) and Beta Centauri (Hadar). They point to the Southern Cross.” Thanks, Kannan!
The science of Beta Crucis
Mimosa lies about 350 light-years from Earth, according to data obtained by the Hipparcos mission. It has a visual magnitude of 1.25. Mimosa is a giant (or subgiant) blue star, more than 3,000 times brighter than our sun in visible light.
Mimosa is blue and very hot. Astronomer James Kaler has estimated its temperature at nearly 28,000 kelvin (about 50,000 degrees F or 27,700 degrees C) at the surface. Such high temperatures demand that much of the the star’s energy be radiated in ultraviolet and higher frequencies invisible to the human eye. So, when you take this into account, Mimosa is about 34,000 times more energetic than the sun, according to Kaler.
Mimosa has a radius about eight times that of the sun, with a mass 14 times greater. However, these figures are uncertain. The reason? Mimosa has a small stellar companion about which little is known. Since all we can observe is the combined light of both, it’s difficult to be precise on the details. The star also is a complex variable star with three short periodicities in its light, which varies less than a 20th of a magnitude over several hours.
Position of Mimosa (Beta Crucis) is RA: 12h 47m 44s, dec: -59° 41′ 19″.
Bottom line: Mimosa is the 2nd-brightest star in Crux, the Southern Cross. Always visible from the Southern Hemisphere, Mimosa can be seen from southerly Northern Hemisphere locations.
Crux, the Southern Cross, and its major stars. Mimosa is on the left near the Jewel Box Cluster. This is the view from a southerly latitude (around 25 degrees north parallel, close to Miami, Florida) in the Northern Hemisphere around midnight in the spring.
A star named Mimosa
Crux, the Southern Cross constellation, lies deep in southern skies. Its 2nd-brightest star, Beta Crucis, bears a couple of nicknames, including Mimosa and Becrux. (The constellation’s brightest star, Alpha Crucis, has the nickname Acrux.) German astronomer Johann Bayer (1572-1625) may have been the one to call it Mimosa. Bayer’s reasoning is unclear, but it might be related to this star’s blue-white color. It could also be in honor of the mimosa flower, although most of those are pink, red or yellow.
View at EarthSky Community Photos. | Prateek Pandey in Bhopal, India, caught the Southern Cross while at its highest point around midnight (its midnight culmination) on March 6, 2021. In April and May, the Southern Cross reaches its highest point in the sky earlier in the evening. Thank you, Prateek!
How to see Beta Crucis
Blue-white Mimosa is the 20th brightest star in all the heavens. It’s the 2nd-brightest star in the constellation Crux the Southern Cross. The Cross is a Southern Hemisphere constellation, and you will not see Mimosa north of 30 degrees north latitude. Some cities near 30 degrees north latitude are Austin, Texas; Cairo, Egypt; and New Delhi, India. Southern Hemisphere observers know and love Mimosa, though, and it is circumpolar for latitudes of about 30 degrees south and higher.
A midnight culmination occurs when a star is roughly opposite the sun. It ensures that the star will be above the horizon a maximum amount of time. This occurs for Mimosa on or about April 2 each year.
It stays above the horizon year-round for observers in the Southern Hemisphere, but it can be seen by those in the southern reaches of the Northern Hemisphere for a short time each year. For example, observers in southerly latitudes around Miami, Florida (around 26 degrees north latitude and farther south), can view the Southern Cross and Mimosa on May evenings as it appears just above the southern horizon.
The nearer the observer is to the northern observation limit of about 30 degrees, the lower the star will climb into the sky and the shorter the time it will be visible. For example, from Austin, the star barely skirts the horizon for about a half hour at most. Often it can’t be seen at all due to the dimming affects of Earth’s atmosphere. From Miami it rises almost 5 degrees above the horizon and stays up more than four hours.
From Northern Hemisphere locations such as Hawaii, where Mimosa can be seen more easily, it rises in the late evening in late winter, far to the south-southeast, and sets in the predawn hours to the south-southwest. By early June it rises before sundown and sets by midnight.
History and mythology of Mimosa
Because of its southerly location, Crux and Mimosa were essentially unknown in classical western mythology. Of course, these stars were well known to the Australian Aboriginal peoples as well as the islanders of Polynesia and the people of southern Africa.
In Australia, for example, one Aboriginal story is that the stars of the Southern Cross are a reminder of the time and place where death first came to mankind. Two of the stars are the glowing eyes of the spirit of death, and the other two are the eyes of the first man to die.
The main stars of Crux, including Mimosa, appear on the flags of both Australia and New Zealand. Mimosa appears as the left side of the crossbar, and Acrux as the bottom of the Cross.
View at EarthSky Community Photos. | Kannan A in Woodlands, Singapore, captured this photo of the Southern Cross – and the star Mimosa – on March 8, 2021. He wrote: “The Southern Cross constellation seen here in the morning in Singapore looking south. On the left of this cross are the 2 pointer stars, Alpha Centauri (Rigel Kentaurus) and Beta Centauri (Hadar). They point to the Southern Cross.” Thanks, Kannan!
The science of Beta Crucis
Mimosa lies about 350 light-years from Earth, according to data obtained by the Hipparcos mission. It has a visual magnitude of 1.25. Mimosa is a giant (or subgiant) blue star, more than 3,000 times brighter than our sun in visible light.
Mimosa is blue and very hot. Astronomer James Kaler has estimated its temperature at nearly 28,000 kelvin (about 50,000 degrees F or 27,700 degrees C) at the surface. Such high temperatures demand that much of the the star’s energy be radiated in ultraviolet and higher frequencies invisible to the human eye. So, when you take this into account, Mimosa is about 34,000 times more energetic than the sun, according to Kaler.
Mimosa has a radius about eight times that of the sun, with a mass 14 times greater. However, these figures are uncertain. The reason? Mimosa has a small stellar companion about which little is known. Since all we can observe is the combined light of both, it’s difficult to be precise on the details. The star also is a complex variable star with three short periodicities in its light, which varies less than a 20th of a magnitude over several hours.
Position of Mimosa (Beta Crucis) is RA: 12h 47m 44s, dec: -59° 41′ 19″.
Bottom line: Mimosa is the 2nd-brightest star in Crux, the Southern Cross. Always visible from the Southern Hemisphere, Mimosa can be seen from southerly Northern Hemisphere locations.
View at EarthSky Community Photos. | Julie Lanter in Claryville, Kentucky, caught the aurora on May 10, 2024. Julie wrote: “The aurora borealis? In Kentucky? What a rare, unexpected sight!” Thank you, Julie!
Auroras last night!
On Friday, May 10, 2024, space weather forecasters began predicting a “severe” solar storm. When it came, it was even stronger than predicted, at “extreme” levels. So many people saw amazing displays of auroras last night from places at latitudes as low as Mexico, the Bahamas, western Africa, New Zealand, Australia, Chile and Argentina. Wonderful that so many got to see it! And the images came pouring in. The ones on this page are just a taste of what we received at EarthSky Community Photos, and in our social media feeds. Thank you to all who submitted photos! What a night!
Marty Curran in Cheyenne, Wyoming captured this stunning view of the auroras last night (night of May 10-11, 2024) from an extreme solar storm. Thank you, Marty!View at EarthSky Community Photos. | Aurora as seen from Cheyenne, Wyoming, early on May 11, 2024, by Marcy Curran. Marcy wrote: “What an incredible geomagnetic storm. This is with my cell phone from our deck. I am glad my husband woke me up and said, ‘You need to see this.'” Thank you, Marcy.View at EarthSky Community Photos. | Roy Trugler captured the aurora from Little Sebago Lake, Gray, Maine, on May 10, 2024. Roy wrote: “Northern lights in Maine.” Thank you, Roy!Paul Scott Anderson caught the aurora on May 10, 2024, from Vancouver, Canada. Paul wrote: “I’m starting to see the auroras more easily by eye, too. Even better in iPhone night mode!” Thank you, Paul.View at EarthSky Community Photos. | Patricia Evans caught the aurora over Nubble Lighthouse in Cape Neddick, Maine, on May 10, 2024. Patricia wrote: “I watched as the ripples of color changed and danced across the sky. It was so much fun to hear all the ‘oooohs’ and ‘ahhhhs’ and oh wows from fellow onlookers!” Thank you, Patricia!Marcy Curran captured the aurora on May 10, 2024, from Cheyenne, Wyoming. Thank you, Marcy!View at EarthSky Community Photos. | David Hawkes in Sheffield, UK, caught the aurora on May 11, 2024. David wrote: “I had read about possible Aurora tonight in the UK due to the various CMEs hitting earth and thought maybe there was a chance of seeing something. Not something I’ve witnessed before, so one off the bucket list! What a light show!” Thank you, David.View at EarthSky Community Photos. | Daniel Wiegert caught this view of the May 10-11, 2024, aurora from Glommen, Sweden. Daniel wrote: “I have never experienced auroras towards the south at this latitude before. Most action was in the southwestern direction (and straight up).” Thank you, Daniel!View at EarthSky Community Photos. | Chuck Reinhart in Vincennes, Indiana, caught the aurora on May 10, 2024. Chuck wrote: “This is a view of the Northern Lights from my yard in Vincennes, Indiana. The camera’s sensor records colors the eye can’t see.” Thank you, Chuck!EarthSky’s Will Triggs captured this photo of the aurora from just east of London, UK on May 10, 2024. Thanks, Will!EarthSky’s Will Triggs captured this photo of the aurora from just east of London, UK on May 10, 2024. Thanks, Will!EarthSky’s Will Triggs captured this photo of the aurora from just east of London, UK on May 10, 2024. Thanks, Will!EarthSky’s Theresa Wiegert captured this photo from Brockville, Canada, on March 10, 2024. Thanks, Theresa!EarthSky’s Kelly Kizer Whitt captured this photo of the aurora just in front of a lightning storm in Madison, Wisconsin. Thanks, Kelly!EarthSky’s Theresa Wiegert captured this photo from Brockville, Canada, on March 10, 2024. Thanks, Theresa!EarthSky’s Raúl Cortes captured this image from Zacatecas, Mexico on May 10, 2024. Thanks. Raúl!EarthSky’s Theresa Wiegert captured this photo from Brockville, Canada, on March 10, 2024. Thanks, Theresa!
Bottom line: Auroras last night (night of May 10-11, 2024) from “extreme” geomagnetic storming – which came after a week of very high activity on the sun – wowed millions around the globe.
View at EarthSky Community Photos. | Julie Lanter in Claryville, Kentucky, caught the aurora on May 10, 2024. Julie wrote: “The aurora borealis? In Kentucky? What a rare, unexpected sight!” Thank you, Julie!
Auroras last night!
On Friday, May 10, 2024, space weather forecasters began predicting a “severe” solar storm. When it came, it was even stronger than predicted, at “extreme” levels. So many people saw amazing displays of auroras last night from places at latitudes as low as Mexico, the Bahamas, western Africa, New Zealand, Australia, Chile and Argentina. Wonderful that so many got to see it! And the images came pouring in. The ones on this page are just a taste of what we received at EarthSky Community Photos, and in our social media feeds. Thank you to all who submitted photos! What a night!
Marty Curran in Cheyenne, Wyoming captured this stunning view of the auroras last night (night of May 10-11, 2024) from an extreme solar storm. Thank you, Marty!View at EarthSky Community Photos. | Aurora as seen from Cheyenne, Wyoming, early on May 11, 2024, by Marcy Curran. Marcy wrote: “What an incredible geomagnetic storm. This is with my cell phone from our deck. I am glad my husband woke me up and said, ‘You need to see this.'” Thank you, Marcy.View at EarthSky Community Photos. | Roy Trugler captured the aurora from Little Sebago Lake, Gray, Maine, on May 10, 2024. Roy wrote: “Northern lights in Maine.” Thank you, Roy!Paul Scott Anderson caught the aurora on May 10, 2024, from Vancouver, Canada. Paul wrote: “I’m starting to see the auroras more easily by eye, too. Even better in iPhone night mode!” Thank you, Paul.View at EarthSky Community Photos. | Patricia Evans caught the aurora over Nubble Lighthouse in Cape Neddick, Maine, on May 10, 2024. Patricia wrote: “I watched as the ripples of color changed and danced across the sky. It was so much fun to hear all the ‘oooohs’ and ‘ahhhhs’ and oh wows from fellow onlookers!” Thank you, Patricia!Marcy Curran captured the aurora on May 10, 2024, from Cheyenne, Wyoming. Thank you, Marcy!View at EarthSky Community Photos. | David Hawkes in Sheffield, UK, caught the aurora on May 11, 2024. David wrote: “I had read about possible Aurora tonight in the UK due to the various CMEs hitting earth and thought maybe there was a chance of seeing something. Not something I’ve witnessed before, so one off the bucket list! What a light show!” Thank you, David.View at EarthSky Community Photos. | Daniel Wiegert caught this view of the May 10-11, 2024, aurora from Glommen, Sweden. Daniel wrote: “I have never experienced auroras towards the south at this latitude before. Most action was in the southwestern direction (and straight up).” Thank you, Daniel!View at EarthSky Community Photos. | Chuck Reinhart in Vincennes, Indiana, caught the aurora on May 10, 2024. Chuck wrote: “This is a view of the Northern Lights from my yard in Vincennes, Indiana. The camera’s sensor records colors the eye can’t see.” Thank you, Chuck!EarthSky’s Will Triggs captured this photo of the aurora from just east of London, UK on May 10, 2024. Thanks, Will!EarthSky’s Will Triggs captured this photo of the aurora from just east of London, UK on May 10, 2024. Thanks, Will!EarthSky’s Will Triggs captured this photo of the aurora from just east of London, UK on May 10, 2024. Thanks, Will!EarthSky’s Theresa Wiegert captured this photo from Brockville, Canada, on March 10, 2024. Thanks, Theresa!EarthSky’s Kelly Kizer Whitt captured this photo of the aurora just in front of a lightning storm in Madison, Wisconsin. Thanks, Kelly!EarthSky’s Theresa Wiegert captured this photo from Brockville, Canada, on March 10, 2024. Thanks, Theresa!EarthSky’s Raúl Cortes captured this image from Zacatecas, Mexico on May 10, 2024. Thanks. Raúl!EarthSky’s Theresa Wiegert captured this photo from Brockville, Canada, on March 10, 2024. Thanks, Theresa!
Bottom line: Auroras last night (night of May 10-11, 2024) from “extreme” geomagnetic storming – which came after a week of very high activity on the sun – wowed millions around the globe.
