Orion Nebula is a place where new stars are born

Many people are familiar with Orion, the most noticeable of all constellations. The three stars of Orion’s Belt jump out at you midway between Orion’s two brightest stars, Betelgeuse and Rigel, which are two of the brightest stars in the sky. Once you find the Belt stars, you can also locate the Orion Nebula, otherwise known as M42, a stellar nursery where new stars are being born. Follow th links below to learn more about the Orion Nebula.

How to locate the Orion Nebula.

What science says about the Orion Nebula.

View larger. | Three medium-bright stars in a short, straight row represent Orion’s Belt. A curved line of stars extending from the Belt represents Orion’s Sword. The Orion Nebula lies about midway down in the Sword of Orion. Photo by EarthSky Facebook friend Marian McGaffney.

Orion ascending over Normandy, France as seen by EarthSky Facebook friend Mohamed Laaifat. Thank you, Mohamed. Click here to expand image.

How to locate the Orion Nebula. If you want to find this famous nebula, first you have to locate the constellation Orion. Fortunately, that’s easy, if you’re looking at the right time of year. The Northern Hemisphere winter months (Southern Hemisphere summer months) are the perfect time to come to know Orion. The constellation is noticeable for three medium-bright stars in a short, straight row. These stars represent Orion’s Belt.

If you look closely, you’ll notice a curved line of stars “hanging” from the three Belt stars. These stars represent Orion’s Sword. Look for the Orion Nebula about midway down in the Sword of Orion.

As a general rule, the higher the constellation Orion is in the sky, the easier it is to see the Orion Nebula. Orion is due south and highest in the sky around midnight in middle December. The stars return to the same place in the sky some 4 minutes earlier each night, or 2 hours earlier each month. So look for Orion to be highest up around 10 p.m. in mid-January and 8 p.m. in mid-February.

Another time people notice Orion is around the months of August and September, when this constellation appears in the east before dawn.

Most nebulae – clouds of interstellar gas and dust – are difficult if not impossible to see with the unaided eye or even binoculars. But the Orion Nebula is in a class nearly all by itself. It’s visible to the unaided eye on a dark, moonless night. To me, it looks like a star encased in a globe of luminescent fog. The dark-sky aficionado Stephen James O’Meara described it as:

… angel’s breath against a frosted sky.

In a dark country sky, observe the Orion Nebula for yourself to see what it looks like. A backyard telescope, or even binoculars do wonders to showcase one of the greatest celestial treasures in the winter sky.

The Orion Nebula. Image via NASA/ESA

What science says about the Orion Nebula. According to modern astronomers, the Orion Nebula is an enormous cloud of gas and dust, one of many in our Milky Way galaxy. It lies roughly 1,300 light-years from Earth.

At some 30 to 40 light-years in diameter, this great big nebulous cocoon is giving birth to perhaps a thousand stars. A young open star cluster, whose stars were born at the same time from a portion of the nebula and are still loosely bound by gravity, can be seen within the nebula. It is sometimes called the Orion Nebula Star Cluster. In 2012, an international team of astronomers suggested this cluster in the Orion Nebula might have a black hole at its heart.

The four brightest stars in the Orion Nebula can be seen through amateur astronomers’ telescopes and are affectionately known as The Trapezium. The light of the young, hot Trapezium stars illuminate the Orion Nebula. These stars are only a million or so years old – mere babes in the lifetime of a star.

But most of the stars in this emerging cluster are veiled behind the Orion Nebula itself, the great stellar nursery in Orion’s Sword.

Orion Nebula’s position is Right Ascension: 5h 35.4m; Declination: 5^o 27′ south

Bottom line: Everything you need to know about the Orion Nebula. How to find it. Science of the Orion Nebula.

from EarthSky http://ift.tt/1whINEC

Many people are familiar with Orion, the most noticeable of all constellations. The three stars of Orion’s Belt jump out at you midway between Orion’s two brightest stars, Betelgeuse and Rigel, which are two of the brightest stars in the sky. Once you find the Belt stars, you can also locate the Orion Nebula, otherwise known as M42, a stellar nursery where new stars are being born. Follow th links below to learn more about the Orion Nebula.

How to locate the Orion Nebula.

What science says about the Orion Nebula.

View larger. | Three medium-bright stars in a short, straight row represent Orion’s Belt. A curved line of stars extending from the Belt represents Orion’s Sword. The Orion Nebula lies about midway down in the Sword of Orion. Photo by EarthSky Facebook friend Marian McGaffney.

Orion ascending over Normandy, France as seen by EarthSky Facebook friend Mohamed Laaifat. Thank you, Mohamed. Click here to expand image.

How to locate the Orion Nebula. If you want to find this famous nebula, first you have to locate the constellation Orion. Fortunately, that’s easy, if you’re looking at the right time of year. The Northern Hemisphere winter months (Southern Hemisphere summer months) are the perfect time to come to know Orion. The constellation is noticeable for three medium-bright stars in a short, straight row. These stars represent Orion’s Belt.

If you look closely, you’ll notice a curved line of stars “hanging” from the three Belt stars. These stars represent Orion’s Sword. Look for the Orion Nebula about midway down in the Sword of Orion.

As a general rule, the higher the constellation Orion is in the sky, the easier it is to see the Orion Nebula. Orion is due south and highest in the sky around midnight in middle December. The stars return to the same place in the sky some 4 minutes earlier each night, or 2 hours earlier each month. So look for Orion to be highest up around 10 p.m. in mid-January and 8 p.m. in mid-February.

Another time people notice Orion is around the months of August and September, when this constellation appears in the east before dawn.

Most nebulae – clouds of interstellar gas and dust – are difficult if not impossible to see with the unaided eye or even binoculars. But the Orion Nebula is in a class nearly all by itself. It’s visible to the unaided eye on a dark, moonless night. To me, it looks like a star encased in a globe of luminescent fog. The dark-sky aficionado Stephen James O’Meara described it as:

… angel’s breath against a frosted sky.

In a dark country sky, observe the Orion Nebula for yourself to see what it looks like. A backyard telescope, or even binoculars do wonders to showcase one of the greatest celestial treasures in the winter sky.

The Orion Nebula. Image via NASA/ESA

What science says about the Orion Nebula. According to modern astronomers, the Orion Nebula is an enormous cloud of gas and dust, one of many in our Milky Way galaxy. It lies roughly 1,300 light-years from Earth.

At some 30 to 40 light-years in diameter, this great big nebulous cocoon is giving birth to perhaps a thousand stars. A young open star cluster, whose stars were born at the same time from a portion of the nebula and are still loosely bound by gravity, can be seen within the nebula. It is sometimes called the Orion Nebula Star Cluster. In 2012, an international team of astronomers suggested this cluster in the Orion Nebula might have a black hole at its heart.

The four brightest stars in the Orion Nebula can be seen through amateur astronomers’ telescopes and are affectionately known as The Trapezium. The light of the young, hot Trapezium stars illuminate the Orion Nebula. These stars are only a million or so years old – mere babes in the lifetime of a star.

But most of the stars in this emerging cluster are veiled behind the Orion Nebula itself, the great stellar nursery in Orion’s Sword.

Orion Nebula’s position is Right Ascension: 5h 35.4m; Declination: 5^o 27′ south

Bottom line: Everything you need to know about the Orion Nebula. How to find it. Science of the Orion Nebula.

from EarthSky http://ift.tt/1whINEC

Tapping nature to clean wastewater

In the WaterHub's 2,200-square-foot greenhouse, campus wasterwater is filtered and circulated among plant roots, where microbes naturally consume organic material.



By Kimber Williams, Emory Report



A new Emory facility, called the WaterHub, uses adaptive ecological technology to naturally break down organic matter in wastewater. The WaterHub is projected to help Emory reclaim some 300,000 gallons of campus wastewater daily, cutting potable water consumption as much as 35 percent and saving the university millions in water utility costs over a 20-year period, according to Matthew Early, vice president for Campus Services.



"Emory is a leader in sustainability," Early says. "With this facility, we’re taking a major step forward in becoming one of the first in the nation with this technology for cleaning our own wastewater."



Even as the facility was being constructed last semester, it was being put into service — Emory students used it for research by monitoring the changing microbiology of wastewater samples as the new project was ramping up.



Read more about the WaterHub.



from eScienceCommons http://ift.tt/1CH7Ylj

In the WaterHub's 2,200-square-foot greenhouse, campus wasterwater is filtered and circulated among plant roots, where microbes naturally consume organic material.



By Kimber Williams, Emory Report



A new Emory facility, called the WaterHub, uses adaptive ecological technology to naturally break down organic matter in wastewater. The WaterHub is projected to help Emory reclaim some 300,000 gallons of campus wastewater daily, cutting potable water consumption as much as 35 percent and saving the university millions in water utility costs over a 20-year period, according to Matthew Early, vice president for Campus Services.



"Emory is a leader in sustainability," Early says. "With this facility, we’re taking a major step forward in becoming one of the first in the nation with this technology for cleaning our own wastewater."



Even as the facility was being constructed last semester, it was being put into service — Emory students used it for research by monitoring the changing microbiology of wastewater samples as the new project was ramping up.



Read more about the WaterHub.



from eScienceCommons http://ift.tt/1CH7Ylj

Super Bowl Athletes Are Scientists At Work [Uncertain Principles]

I wrote up another piece about football for the Conversation, this time drawing on material from Eureka, explaining how great football players are using scientific thinking:

Seattle Seahawks cornerback Richard Sherman gets called a lot of things. He calls himself the greatest cornerback in the NFL (and Seattle fans tend to agree). Sportswriters and some other players call him a loudmouth and a showboater. Fans of other teams call him a lot of things that shouldn’t see print (even on the internet). One thing you’re not likely to hear anyone on ESPN call Sherman, though, is “scientist.”

And yet, an elite professional athlete like Richard Sherman is, in fact, extremely adept at doing science. Not the white-lab-coat, equations-on-a-blackboard sort of science, but the far older and universal process of observing, making and testing models of the universe.

I wrote something similar last year, but with more words and less detail. This goes on to make a specific science analogy, between the rapidly repeated process of testing and refining models you see in sports and the rapid repetition of test and measurement used for precision timekeeping.

I don’t expect this one to generate as much buzz as my previous piece over there, because it doesn’t directly ruffle as many feathers. But it’s a new audience for this stuff, and I’m pretty happy with how the piece came out. So, go over there and read the whole thing.

from ScienceBlogs http://ift.tt/15P54y3

I wrote up another piece about football for the Conversation, this time drawing on material from Eureka, explaining how great football players are using scientific thinking:

Seattle Seahawks cornerback Richard Sherman gets called a lot of things. He calls himself the greatest cornerback in the NFL (and Seattle fans tend to agree). Sportswriters and some other players call him a loudmouth and a showboater. Fans of other teams call him a lot of things that shouldn’t see print (even on the internet). One thing you’re not likely to hear anyone on ESPN call Sherman, though, is “scientist.”

And yet, an elite professional athlete like Richard Sherman is, in fact, extremely adept at doing science. Not the white-lab-coat, equations-on-a-blackboard sort of science, but the far older and universal process of observing, making and testing models of the universe.

I wrote something similar last year, but with more words and less detail. This goes on to make a specific science analogy, between the rapidly repeated process of testing and refining models you see in sports and the rapid repetition of test and measurement used for precision timekeeping.

I don’t expect this one to generate as much buzz as my previous piece over there, because it doesn’t directly ruffle as many feathers. But it’s a new audience for this stuff, and I’m pretty happy with how the piece came out. So, go over there and read the whole thing.

from ScienceBlogs http://ift.tt/15P54y3

In My Earbuds Lately [Aardvarchaeology]

Country Funk — Country Funk (1970)

Here are some good albums that I’ve been listening to lately.

• Country Funk — Country Funk (1970). Not country and not funk: folk psych.


• GOAT — Commune (2014). Eclectic psychedelia with screamy female vocals and bongos!


• Opeth — Pale Communion (2014). When black metal ages into virtuoso prog rock.


• Pixies — Indie Cindy (2014). Eclectic alt-rock, does not look back.


• Teenage Fanclub — Shadows (2010). Fannies doing what they do best.


• Wooden Shjips — West (2011). Drony stony spacey.

from ScienceBlogs http://ift.tt/1ByMcfD

Country Funk — Country Funk (1970)

Here are some good albums that I’ve been listening to lately.

• Country Funk — Country Funk (1970). Not country and not funk: folk psych.


• GOAT — Commune (2014). Eclectic psychedelia with screamy female vocals and bongos!


• Opeth — Pale Communion (2014). When black metal ages into virtuoso prog rock.


• Pixies — Indie Cindy (2014). Eclectic alt-rock, does not look back.


• Teenage Fanclub — Shadows (2010). Fannies doing what they do best.


• Wooden Shjips — West (2011). Drony stony spacey.

from ScienceBlogs http://ift.tt/1ByMcfD

This date in science: First modern suspension bridge completed

January 30, 1826. Workers completed construction of the first modern suspension bridge on this date. It was the Menai Bridge between Wales on the island of Great Britain and the smaller island of Anglesey, to the west. According to local reports about the bridge from nearly 200 years ago, travel in the strait between Wales and Anglesey was hazardous, due to shifting currents and unpredictable weather patterns. But the island of Anglesey had the Atlantic Ocean and Irish Sea to its west, and, especially after Ireland joined the United Kingdom in 1800, people increasingly wanted to use Anglesey as a jumping off point to reach the Emerald Isle by ferry boat.

The Menai Bridge between Wales and Anglesey is considered the first modern suspension bridge in the world. Image credit: Ingy the Wingy/Flickr

Menai Bridge – marked the the red letter A – between Wales on the island of Great Britain and the smaller island of Anglesey. Map via Google.

A Scottish civil engineer, architect and stonemason named Thomas Telford designed the Menai Bridge. It’s a suspension bridge, with its deck (load-bearing portion) hung below suspension cables on vertical suspenders. Examples of this type of bridge were built in 15th century Tibet and Bhutan, but the Menai Bridge was heralded as the first modern suspension bridge in the world.

The Menai Bridge reportedly stands 100 feet (about 30 meters) above the waters. It’s tall enough to allow sailing ships to pass underneath. It spans 579 feet (about 175 meters) from the Wales coast to the coast of Anglesey, and it’s supported by 16 large chains.

The chains has been changed out over the years to allow heavier truck traffic to pass through.

The Menai Bridge is still in use today.

Menai Bridge on an evening in 2010. Via Wikimedia Commons.

Bottom line: On January 30, 1826, workers completed the Menai Bridge between Wales and Anglesey, the first modern suspension bridge in the world.

from EarthSky http://ift.tt/1uIBeBA

January 30, 1826. Workers completed construction of the first modern suspension bridge on this date. It was the Menai Bridge between Wales on the island of Great Britain and the smaller island of Anglesey, to the west. According to local reports about the bridge from nearly 200 years ago, travel in the strait between Wales and Anglesey was hazardous, due to shifting currents and unpredictable weather patterns. But the island of Anglesey had the Atlantic Ocean and Irish Sea to its west, and, especially after Ireland joined the United Kingdom in 1800, people increasingly wanted to use Anglesey as a jumping off point to reach the Emerald Isle by ferry boat.

The Menai Bridge between Wales and Anglesey is considered the first modern suspension bridge in the world. Image credit: Ingy the Wingy/Flickr

Menai Bridge – marked the the red letter A – between Wales on the island of Great Britain and the smaller island of Anglesey. Map via Google.

A Scottish civil engineer, architect and stonemason named Thomas Telford designed the Menai Bridge. It’s a suspension bridge, with its deck (load-bearing portion) hung below suspension cables on vertical suspenders. Examples of this type of bridge were built in 15th century Tibet and Bhutan, but the Menai Bridge was heralded as the first modern suspension bridge in the world.

The Menai Bridge reportedly stands 100 feet (about 30 meters) above the waters. It’s tall enough to allow sailing ships to pass underneath. It spans 579 feet (about 175 meters) from the Wales coast to the coast of Anglesey, and it’s supported by 16 large chains.

The chains has been changed out over the years to allow heavier truck traffic to pass through.

The Menai Bridge is still in use today.

Menai Bridge on an evening in 2010. Via Wikimedia Commons.

Bottom line: On January 30, 1826, workers completed the Menai Bridge between Wales and Anglesey, the first modern suspension bridge in the world.

from EarthSky http://ift.tt/1uIBeBA

Ancient skull offers clues to humans’ migration out of Africa

Views of a human skull, with a missing jaw, found in northern Isreal and estimated at 55,000 years old. Photograph via Tel Aviv University and University of Vienna

Location of Manot Cave in northern Israel. Map via Nature.

In 2008, a bulldozer clearing land for a development near the Sea of Galilee in northern Israel revealed the opening to a limestone cave. The cave entrance had apparently been blocked for 15,000 years. Later, amateur speleologists found a partial skull in the cave, which researchers recognized as an important find. An international team of researchers now says the partial skull is some 55,000 years old. They say it sheds light on the interbreeding of our ancestors with Neanderthals and provides new insights into the migration of modern humans out of Africa. The Israeli, North American and European researchers reported the rare find and their analysis of it in the journal Nature on January 28, 2015.

Anthropologists believe that modern humans (Homo sapiens) walked out of Africa at least 60,000 years ago. At that time, the climate in parts of Europe was cold and harsh, and so modern humans spread only slowly across the continent until about 45,000 years ago.

Spread they did, however, eventually replacing all other forms of hominin (humans and their predecessors). And yet, because human fossils from this important period in human history are scarce, the details of our ancestors’ initial migration from Africa and subsequent spread across Europe has remained largely mysterious.

Prof. Israel Hershkovitz of Tel Aviv University led the anthropological study of the skull, and led the excavation together with archaeologists Dr. Ofer Marder of Ben-Gurion University, and Dr. Omry Barzilai of the Israel Antiquities Authority. Hershkovitz was quoted in an article in Nature as saying:

… the Manot people are probably the forefathers of the early Palaeolithic populations of Europe.

A distinctive bun-shaped occipital region at the back of the partial skull suggests its connection with modern humans.

The shape of the skull is what suggests this connection. The researchers say it has a distinctive bun-shaped occipital region at the back. In this way, its shape resembles modern African and European skulls.

The specimen also provides evidence that both modern humans and Neanderthals inhabited this region during the late Pleistocene, close in time to the likely interbreeding event between modern humans and Neanderthals. Interbreeding has been suggested by earlier genome studies of Neanderthals and of both ancient and contemporary Homo sapiens. The Nature article explained:

The Manot people are also a leading candidate for the humans that bred with Neanderthals — exploits that have given all of today’s non-African humans a sliver of Neanderthal heritage. The Manot Cave is not far from two other sites that held Neanderthal remains of a similar age.

The researchers suggest that the population from which this skull is derived had recently migrated out of Africa and established itself in the Levantine corridor – the relatively narrow strip between the Mediterranean Sea to the northwest and deserts to the southeast which connects Africa to Eurasia – during a time span that was favorable for human migration, due to a warmer and wetter climate over the Northern Sahara and the Mediterranean.

Inside the Manot Cave in Israel’s Galilee, where a 55,000-year-old skull sheds new light on human migration patterns. Photo via Amos Frumkin / Hebrew University Cave Research Center

Bottom line: A partial skull found in a cave in northern Israel sheds light on the interbreeding of our ancestors with Neanderthals and provides new insights into the migration of modern humans out of Africa.

Via Alpha Galileo and Nature

from EarthSky http://ift.tt/1uIBelb

Views of a human skull, with a missing jaw, found in northern Isreal and estimated at 55,000 years old. Photograph via Tel Aviv University and University of Vienna

Location of Manot Cave in northern Israel. Map via Nature.

In 2008, a bulldozer clearing land for a development near the Sea of Galilee in northern Israel revealed the opening to a limestone cave. The cave entrance had apparently been blocked for 15,000 years. Later, amateur speleologists found a partial skull in the cave, which researchers recognized as an important find. An international team of researchers now says the partial skull is some 55,000 years old. They say it sheds light on the interbreeding of our ancestors with Neanderthals and provides new insights into the migration of modern humans out of Africa. The Israeli, North American and European researchers reported the rare find and their analysis of it in the journal Nature on January 28, 2015.

Anthropologists believe that modern humans (Homo sapiens) walked out of Africa at least 60,000 years ago. At that time, the climate in parts of Europe was cold and harsh, and so modern humans spread only slowly across the continent until about 45,000 years ago.

Spread they did, however, eventually replacing all other forms of hominin (humans and their predecessors). And yet, because human fossils from this important period in human history are scarce, the details of our ancestors’ initial migration from Africa and subsequent spread across Europe has remained largely mysterious.

Prof. Israel Hershkovitz of Tel Aviv University led the anthropological study of the skull, and led the excavation together with archaeologists Dr. Ofer Marder of Ben-Gurion University, and Dr. Omry Barzilai of the Israel Antiquities Authority. Hershkovitz was quoted in an article in Nature as saying:

… the Manot people are probably the forefathers of the early Palaeolithic populations of Europe.

A distinctive bun-shaped occipital region at the back of the partial skull suggests its connection with modern humans.

The shape of the skull is what suggests this connection. The researchers say it has a distinctive bun-shaped occipital region at the back. In this way, its shape resembles modern African and European skulls.

The specimen also provides evidence that both modern humans and Neanderthals inhabited this region during the late Pleistocene, close in time to the likely interbreeding event between modern humans and Neanderthals. Interbreeding has been suggested by earlier genome studies of Neanderthals and of both ancient and contemporary Homo sapiens. The Nature article explained:

The Manot people are also a leading candidate for the humans that bred with Neanderthals — exploits that have given all of today’s non-African humans a sliver of Neanderthal heritage. The Manot Cave is not far from two other sites that held Neanderthal remains of a similar age.

The researchers suggest that the population from which this skull is derived had recently migrated out of Africa and established itself in the Levantine corridor – the relatively narrow strip between the Mediterranean Sea to the northwest and deserts to the southeast which connects Africa to Eurasia – during a time span that was favorable for human migration, due to a warmer and wetter climate over the Northern Sahara and the Mediterranean.

Inside the Manot Cave in Israel’s Galilee, where a 55,000-year-old skull sheds new light on human migration patterns. Photo via Amos Frumkin / Hebrew University Cave Research Center

Bottom line: A partial skull found in a cave in northern Israel sheds light on the interbreeding of our ancestors with Neanderthals and provides new insights into the migration of modern humans out of Africa.

Via Alpha Galileo and Nature

from EarthSky http://ift.tt/1uIBelb

What causes the aurora borealis or northern lights?

Aurora just west of Saskatoon, by Colin Chatfield. He said, “We were just about to leave as the Aurora was just a dull band, then it came alive for about an hour or so. This was taken at 2:02am today [January 27, 2015] … It is not very visible, but I caught Comet Lovejoy at centre left of this photo.”

Those who live at or visit high latitudes might at times experience colored lights shimmering across the night sky. Some Inuit believed that the spirits of their ancestors could be seen dancing in the flickering aurora. In Norse mythology, the aurora was a fire bridge to the sky built by the gods. This ethereal display – the aurora borealis or aurora australis, the northern or southern lights – is beautiful. What causes these lights to appear?

Our sun is 93 million miles away. But its effects extend far beyond its visible surface. Great storms on the sun send gusts of charged solar particles hurtling across space. If Earth is in the path of the particle stream, our planet’s magnetic field and atmosphere react.

When the charged particles from the sun strike atoms and molecules in Earth’s atmosphere, they excite those atoms, causing them to light up.

What does it mean for an atom to be excited? Atoms consist of a central nucleus and a surrounding cloud of electrons encircling the nucleus in an orbit. When charged particles from the sun strike atoms in Earth’s atmosphere, electrons move to higher-energy orbits, further away from the nucleus. Then when an electron moves back to a lower-energy orbit, it releases a particle of light or photon.

What happens in an aurora is similar to what happens in the neon lights we see on many business signs. Electricity is used to excite the atoms in the neon gas within the glass tubes of a neon sign. That’s why these signs give off their brilliant colors. The aurora works on the same principle – but at a far more vast scale.

When charged particles from the sun strike air molecules in Earth's magnetic field, they cause those molecules' atoms to become excited. The molecules give off light as they calm down. Image Credit: NASA

The aurora often appears as curtains of lights, but they can also be arcs or spirals, often following lines of force in Earth’s magnetic field. Most are green in color but sometimes you’ll see a hint of pink, and strong displays might also have red, violet and white colors. The lights typically are seen in the far north – the nations bordering the Arctic Ocean – Canada and Alaska, Scandinavian countries, Iceland, Greenland and Russia. But strong displays of the lights can extend down into more southerly latitudes in the United States. And of course, the lights have a counterpart at Earth’s south polar regions.

The colors in the aurora were also a source of mystery throughout human history. But science says that different gases in Earth’s atmosphere give off different colors when they are excited. Oxygen gives off the green color of the aurora, for example. Nitrogen causes blue or red colors.

So today the mystery of the aurora is not so mysterious as it used to be. Yet people still travel thousands of miles to see the brilliant natural light shows in Earth’s atmosphere. And even though we know the scientific reason for the aurora, the dazzling natural light show can still fire our imaginations to visualize fire bridges, gods or dancing ghosts.

“This photo was captured a couple of hours ago in Nordreisa, Norway. I was dressed in my very best winter clothes and I can easily admit that I was freezing most of the time anyways, 22 below (-7.6 fahrenheit) kinda has that effect.” January, 2015. © 2015 Tor-Ivar Næss

Aurora in Vesterlålen, Norway, January 2015 by Stig Hansen

Mike Taylor in Maine caught this photo in September, 2014. More about Mike and this photo.

Photo © 2014 Tor-Ivar Næss

Aurora borealis over Norway’s Steinvikholmen Castle on April 3, 2014 by Hallvor Hobbyfotograf Lillebo.View larger. | Photo credit: Hallvor Hobbyfotograf Lillebo

Reisafjorden, Norway bathing in auroras on January 2, 2014. When charged particles from the sun strike atoms in Earth’s atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light. This process creates the beautiful aurora, or northern lights. Image copyright 2014 Tor-Ivar Næss. Via WaitForIt on Facebook.

View larger. | Mike Taylor calls this photo Moonlight Aurora II. He captured it on February 19, 2014. Visit Taylor Photography

View larger. | Aurora over Mt. Hood in Oregon as captured by Ben Coffman Photography during the night of May 31-June 1, 2013. Visit Ben’s photography page on G+ or visit Ben on Facebook.

Aurora on January 1, 2014 by Geir-Inge Bushmann. The lights typically are seen in the far north – the nations bordering the Arctic Ocean – Canada and Alaska, Scandinavian countries, Iceland, Greenland and Russia. See more photos from Geir-Inge Bushmann

View larger. | Aurora seen by EarthSky Facebook friend Colin Chatfield in Saskatchewan, Canada on May 19, 2012.

View larger. | Spectacular aurora, or northern lights, seen by EarthSky Facebook friend Colin Chatfield in Saskatchewan, Canada on October 24, 2011.

Bottom line: When charged particles from the sun strike atoms in Earth’s atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light. This process creates the beautiful aurora, or northern lights.

from EarthSky http://ift.tt/1tDXph8

Aurora just west of Saskatoon, by Colin Chatfield. He said, “We were just about to leave as the Aurora was just a dull band, then it came alive for about an hour or so. This was taken at 2:02am today [January 27, 2015] … It is not very visible, but I caught Comet Lovejoy at centre left of this photo.”

Those who live at or visit high latitudes might at times experience colored lights shimmering across the night sky. Some Inuit believed that the spirits of their ancestors could be seen dancing in the flickering aurora. In Norse mythology, the aurora was a fire bridge to the sky built by the gods. This ethereal display – the aurora borealis or aurora australis, the northern or southern lights – is beautiful. What causes these lights to appear?

Our sun is 93 million miles away. But its effects extend far beyond its visible surface. Great storms on the sun send gusts of charged solar particles hurtling across space. If Earth is in the path of the particle stream, our planet’s magnetic field and atmosphere react.

When the charged particles from the sun strike atoms and molecules in Earth’s atmosphere, they excite those atoms, causing them to light up.

What does it mean for an atom to be excited? Atoms consist of a central nucleus and a surrounding cloud of electrons encircling the nucleus in an orbit. When charged particles from the sun strike atoms in Earth’s atmosphere, electrons move to higher-energy orbits, further away from the nucleus. Then when an electron moves back to a lower-energy orbit, it releases a particle of light or photon.

What happens in an aurora is similar to what happens in the neon lights we see on many business signs. Electricity is used to excite the atoms in the neon gas within the glass tubes of a neon sign. That’s why these signs give off their brilliant colors. The aurora works on the same principle – but at a far more vast scale.

When charged particles from the sun strike air molecules in Earth's magnetic field, they cause those molecules' atoms to become excited. The molecules give off light as they calm down. Image Credit: NASA

The aurora often appears as curtains of lights, but they can also be arcs or spirals, often following lines of force in Earth’s magnetic field. Most are green in color but sometimes you’ll see a hint of pink, and strong displays might also have red, violet and white colors. The lights typically are seen in the far north – the nations bordering the Arctic Ocean – Canada and Alaska, Scandinavian countries, Iceland, Greenland and Russia. But strong displays of the lights can extend down into more southerly latitudes in the United States. And of course, the lights have a counterpart at Earth’s south polar regions.

The colors in the aurora were also a source of mystery throughout human history. But science says that different gases in Earth’s atmosphere give off different colors when they are excited. Oxygen gives off the green color of the aurora, for example. Nitrogen causes blue or red colors.

So today the mystery of the aurora is not so mysterious as it used to be. Yet people still travel thousands of miles to see the brilliant natural light shows in Earth’s atmosphere. And even though we know the scientific reason for the aurora, the dazzling natural light show can still fire our imaginations to visualize fire bridges, gods or dancing ghosts.

“This photo was captured a couple of hours ago in Nordreisa, Norway. I was dressed in my very best winter clothes and I can easily admit that I was freezing most of the time anyways, 22 below (-7.6 fahrenheit) kinda has that effect.” January, 2015. © 2015 Tor-Ivar Næss

Aurora in Vesterlålen, Norway, January 2015 by Stig Hansen

Mike Taylor in Maine caught this photo in September, 2014. More about Mike and this photo.

Photo © 2014 Tor-Ivar Næss

Aurora borealis over Norway’s Steinvikholmen Castle on April 3, 2014 by Hallvor Hobbyfotograf Lillebo.View larger. | Photo credit: Hallvor Hobbyfotograf Lillebo

Reisafjorden, Norway bathing in auroras on January 2, 2014. When charged particles from the sun strike atoms in Earth’s atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light. This process creates the beautiful aurora, or northern lights. Image copyright 2014 Tor-Ivar Næss. Via WaitForIt on Facebook.

View larger. | Mike Taylor calls this photo Moonlight Aurora II. He captured it on February 19, 2014. Visit Taylor Photography

View larger. | Aurora over Mt. Hood in Oregon as captured by Ben Coffman Photography during the night of May 31-June 1, 2013. Visit Ben’s photography page on G+ or visit Ben on Facebook.

Aurora on January 1, 2014 by Geir-Inge Bushmann. The lights typically are seen in the far north – the nations bordering the Arctic Ocean – Canada and Alaska, Scandinavian countries, Iceland, Greenland and Russia. See more photos from Geir-Inge Bushmann

View larger. | Aurora seen by EarthSky Facebook friend Colin Chatfield in Saskatchewan, Canada on May 19, 2012.

View larger. | Spectacular aurora, or northern lights, seen by EarthSky Facebook friend Colin Chatfield in Saskatchewan, Canada on October 24, 2011.

Bottom line: When charged particles from the sun strike atoms in Earth’s atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light. This process creates the beautiful aurora, or northern lights.

from EarthSky http://ift.tt/1tDXph8