Space rock hit moon at 38,000 mph

Observers watching the January 20-20, 2019. total eclipse of the moon saw a rare event, a short-lived flash as a meteorite hit the lunar surface.

Astronomers say it’s the first time an event of its kind has been filmed.

A new analysis by Spanish astronomers says the space rock collided with the moon at 38,000 miles per hour (61,000 km/hour) excavating a crater 33-50 feet (10-15 meters) across. The study was published April 27, 2019, in the peer-reviewed journal Monthly Notices of the Royal Astronomical Society.

The January 20-21 total lunar eclipse was the last one until May 2021, with observers in North and South America and western Europe enjoying the best view. At 4:41 UTC, just after the total phase of the eclipse began, there was a flash on the lunar surface. Widespread reports from amateur astronomers indicated the flash – attributed to a meteorite impact – was bright enough to be seen with the naked eye.

Meanwhile, researchers at the Moon Impacts Detection and Analysis System (MIDAS) in the south of Spain used eight telescopes to monitor the lunar surface. Video footage from MIDAS recorded the moment of impact. The impact flash lasted 0.28 seconds and is the first ever filmed during a lunar eclipse, despite a number of earlier attempts. MIDAS telescopes observed the impact flash at multiple wavelengths (different colors of light), improving the analysis of the event.

The MIDAS researchers concluded that the incoming rock had a mass of 99 lb (45 kg), measured 12-24 inches (30-60 cm) across, and hit the surface close to the crater close to the crater Lagrange H at 38,000 miles per hour (61,000 km/hour).

The scientists assessed the impact energy as equivalent to 1.5 tonnes (1.7 tons) of TNT, enough, they said, to create a crater about the size of two double decker buses side by side. They estimated that the debris that was ejected when the rock hit reached a peak temperature of 9,800 degrees F (5,400 degrees C), roughly the same temperature as the surface of the sun.

The flash from the impact of the meteorite on the eclipsed moon, seen as the dot at top left (indicated by the arrow), as recorded by two of the telescopes operating in the framework of the MIDAS Survey from Sevilla (Spain) on January 21. 2019. Image via J.M. Madiedo/MIDAS.

Unlike Earth, the moon has no atmosphere to protect it and so even small space rocks can hit its surface. Since these impacts take place at huge speeds, the rocks instantaneously vaporize upon impact, producing a glowing plume of debris that can be detected from Earth as short-duration flashes. Jose Maria Madiedo of the University of Huelva is a study co-author. He said in a statement:

It would be impossible to reproduce these high-speed collisions in a lab on Earth. Observing flashes is a great way to test our ideas on exactly what happens when a meteorite collides with the moon.

Here at EarthSky, we heard from one of our community members, Greg Hogan in Kathleen, Georgia, after eclipse night. He wrote:

I reviewed my images from the other night, and I am showing in the news reports that the impact happened at 11:41 eastern time … I’m pretty excited!

You can see two of Greg’s photos below, with the meteorite flash marked by an arrow.

View larger at EarthSky Community Photos. | This flash on the red, eclipsed moon came from a meteorite strike! EarthSky friend Greg Hogan in Kathleen, Georgia, was one of the first to notice he’d caught the flash on film. Thanks for the heads up, Greg!

View larger at EarthSky Community Photos. | Another shot from Greg Hogan of the meteorite flash on the moon, January 20, 2019, at 11:41 eastern time (January 21 at 4:41 UTC).

Bottom line: Astronomers say that a meteorite that hit the moon during the January 20-21 lunar eclipse created a crater 33-50 feet (10-15 meters) across.

Source: Multiwavelength observations of a bright impact flash during the 2019 January total lunar eclipse

Via Royal Astronomical Society

from EarthSky http://bit.ly/2PDZcjG

Observers watching the January 20-20, 2019. total eclipse of the moon saw a rare event, a short-lived flash as a meteorite hit the lunar surface.

Astronomers say it’s the first time an event of its kind has been filmed.

A new analysis by Spanish astronomers says the space rock collided with the moon at 38,000 miles per hour (61,000 km/hour) excavating a crater 33-50 feet (10-15 meters) across. The study was published April 27, 2019, in the peer-reviewed journal Monthly Notices of the Royal Astronomical Society.

The January 20-21 total lunar eclipse was the last one until May 2021, with observers in North and South America and western Europe enjoying the best view. At 4:41 UTC, just after the total phase of the eclipse began, there was a flash on the lunar surface. Widespread reports from amateur astronomers indicated the flash – attributed to a meteorite impact – was bright enough to be seen with the naked eye.

Meanwhile, researchers at the Moon Impacts Detection and Analysis System (MIDAS) in the south of Spain used eight telescopes to monitor the lunar surface. Video footage from MIDAS recorded the moment of impact. The impact flash lasted 0.28 seconds and is the first ever filmed during a lunar eclipse, despite a number of earlier attempts. MIDAS telescopes observed the impact flash at multiple wavelengths (different colors of light), improving the analysis of the event.

The MIDAS researchers concluded that the incoming rock had a mass of 99 lb (45 kg), measured 12-24 inches (30-60 cm) across, and hit the surface close to the crater close to the crater Lagrange H at 38,000 miles per hour (61,000 km/hour).

The scientists assessed the impact energy as equivalent to 1.5 tonnes (1.7 tons) of TNT, enough, they said, to create a crater about the size of two double decker buses side by side. They estimated that the debris that was ejected when the rock hit reached a peak temperature of 9,800 degrees F (5,400 degrees C), roughly the same temperature as the surface of the sun.

The flash from the impact of the meteorite on the eclipsed moon, seen as the dot at top left (indicated by the arrow), as recorded by two of the telescopes operating in the framework of the MIDAS Survey from Sevilla (Spain) on January 21. 2019. Image via J.M. Madiedo/MIDAS.

Unlike Earth, the moon has no atmosphere to protect it and so even small space rocks can hit its surface. Since these impacts take place at huge speeds, the rocks instantaneously vaporize upon impact, producing a glowing plume of debris that can be detected from Earth as short-duration flashes. Jose Maria Madiedo of the University of Huelva is a study co-author. He said in a statement:

It would be impossible to reproduce these high-speed collisions in a lab on Earth. Observing flashes is a great way to test our ideas on exactly what happens when a meteorite collides with the moon.

Here at EarthSky, we heard from one of our community members, Greg Hogan in Kathleen, Georgia, after eclipse night. He wrote:

I reviewed my images from the other night, and I am showing in the news reports that the impact happened at 11:41 eastern time … I’m pretty excited!

You can see two of Greg’s photos below, with the meteorite flash marked by an arrow.

View larger at EarthSky Community Photos. | This flash on the red, eclipsed moon came from a meteorite strike! EarthSky friend Greg Hogan in Kathleen, Georgia, was one of the first to notice he’d caught the flash on film. Thanks for the heads up, Greg!

View larger at EarthSky Community Photos. | Another shot from Greg Hogan of the meteorite flash on the moon, January 20, 2019, at 11:41 eastern time (January 21 at 4:41 UTC).

Bottom line: Astronomers say that a meteorite that hit the moon during the January 20-21 lunar eclipse created a crater 33-50 feet (10-15 meters) across.

Source: Multiwavelength observations of a bright impact flash during the 2019 January total lunar eclipse

Via Royal Astronomical Society

from EarthSky http://bit.ly/2PDZcjG

Will the Higgs boson help scientists trap dark matter?

A visualization of dark matter. Image via Zarija Lukic/Berkeley Lab.

This story appeared originally as “Scientists Invent Way to Trap Mysterious ‘Dark World’ Particle at Large Hadron Collider” by Louis Lerner of UChicgo News

Now that they’ve identified the Higgs boson, scientists at the Large Hadron Collider (LHC) – the world’s largest and most powerful particle accelerator – have set their sights on an even more elusive target.

What exactly is the Higgs boson?

All around us is dark matter and dark energy — the invisible stuff that binds the galaxy together, but which no one has been able to directly detect. LianTao Wang is a University of Chicago professor of physics who studies how to find signals in large particle accelerators like the LHC. Wang said:

We know for sure there’s a dark world, and there’s more energy in it than there is in ours.

Wang, along with scientists from the University of Chicago and affiliated Fermilab, think they may be able to lead us to its tracks; in a paper published April 3, 2019, in Physical Review Letters, they laid out an innovative method for stalking dark matter in the LHC by exploiting a potential particle’s slightly slower speed.

The Large Hadron Collider (LHC) is the largest machine in the world. It lies in a tunnel 575 feet (175 meters) beneath the France–Switzerland border. Image via CERN.

While the dark world makes up more than 95 percent of the universe, scientists only know it exists from its effects — like a poltergeist you can only see when it pushes something off a shelf. For example, we know there’s dark matter because we can see gravity acting on it — it helps keep our galaxies from flying apart.

Theorists think there’s one particular kind of dark particle that only occasionally interacts with normal matter. It would be heavier and longer-lived than other known particles, with a lifetime up to one tenth of a second. A few times in a decade, researchers believe, this particle can get caught up in the collisions of protons that the LHC is constantly creating and measuring. Wang said:

One particularly interesting possibility is that these long-lived dark particles are coupled to the Higgs boson in some fashion — that the Higgs is actually a portal to the dark world.

Wang is referring to the Higgs boson – the last holdout particle in physicists’ grand theory of how the universe works, discovered at the LHC in 2012. He said:

It’s possible that the Higgs could actually decay into these long-lived particles.

The only problem is sorting out these events from the rest; there are more than a billion collisions per second in the 27-kilometer LHC, and each one of these sends subatomic chaff spraying in all directions.

Wang, University of Chicago postdoctoral fellow Jia Liu and Fermilab scientist Zhen Liu (now at the University of Maryland) proposed a new way to search by exploiting one particular aspect of such a dark particle. Liu, the first author on the study, said:

If it’s that heavy, it costs energy to produce, so its momentum would not be large – it would move more slowly than the speed of light.

That time delay would set it apart from all the rest of the normal particles. Scientists would only need to tweak the system to look for particles that are produced and then decay a bit more slowly than everything else.

The difference is on the order of a nanosecond — a billionth of a second — or smaller. But the LHC already has detectors sophisticated enough to catch this difference; a recent study using data collected from the last run found the method should work, plus the detectors will get even more sensitive as part of the upgrade that is currently underway. Liu said:

We anticipate this method will increase our sensitivity to long-lived dark particles by more than an order of magnitude – while using capabilities we already have at the LHC.

Experimentalists are already working to build the trap: When the LHC turns back on in 2021, after boosting its luminosity by tenfold, all three of the major detectors will be implementing the new system, the scientists said. Liu said:

We think it has great potential for discovery.

Wang added:

If the particle is there, we just have to find a way to dig it out. Usually, the key is finding the question to ask.

Bottom line: Now that they’ve identified the Higgs boson, Large Hadron Collider scientists have set their sights on an even more elusive target – dark matter and dark energy.

Source: Enhancing Long-Lived Particles Searches at the LHC with Precision Timing Information

from EarthSky http://bit.ly/2GVyIYm

A visualization of dark matter. Image via Zarija Lukic/Berkeley Lab.

This story appeared originally as “Scientists Invent Way to Trap Mysterious ‘Dark World’ Particle at Large Hadron Collider” by Louis Lerner of UChicgo News

Now that they’ve identified the Higgs boson, scientists at the Large Hadron Collider (LHC) – the world’s largest and most powerful particle accelerator – have set their sights on an even more elusive target.

What exactly is the Higgs boson?

All around us is dark matter and dark energy — the invisible stuff that binds the galaxy together, but which no one has been able to directly detect. LianTao Wang is a University of Chicago professor of physics who studies how to find signals in large particle accelerators like the LHC. Wang said:

We know for sure there’s a dark world, and there’s more energy in it than there is in ours.

Wang, along with scientists from the University of Chicago and affiliated Fermilab, think they may be able to lead us to its tracks; in a paper published April 3, 2019, in Physical Review Letters, they laid out an innovative method for stalking dark matter in the LHC by exploiting a potential particle’s slightly slower speed.

The Large Hadron Collider (LHC) is the largest machine in the world. It lies in a tunnel 575 feet (175 meters) beneath the France–Switzerland border. Image via CERN.

While the dark world makes up more than 95 percent of the universe, scientists only know it exists from its effects — like a poltergeist you can only see when it pushes something off a shelf. For example, we know there’s dark matter because we can see gravity acting on it — it helps keep our galaxies from flying apart.

Theorists think there’s one particular kind of dark particle that only occasionally interacts with normal matter. It would be heavier and longer-lived than other known particles, with a lifetime up to one tenth of a second. A few times in a decade, researchers believe, this particle can get caught up in the collisions of protons that the LHC is constantly creating and measuring. Wang said:

One particularly interesting possibility is that these long-lived dark particles are coupled to the Higgs boson in some fashion — that the Higgs is actually a portal to the dark world.

Wang is referring to the Higgs boson – the last holdout particle in physicists’ grand theory of how the universe works, discovered at the LHC in 2012. He said:

It’s possible that the Higgs could actually decay into these long-lived particles.

The only problem is sorting out these events from the rest; there are more than a billion collisions per second in the 27-kilometer LHC, and each one of these sends subatomic chaff spraying in all directions.

Wang, University of Chicago postdoctoral fellow Jia Liu and Fermilab scientist Zhen Liu (now at the University of Maryland) proposed a new way to search by exploiting one particular aspect of such a dark particle. Liu, the first author on the study, said:

If it’s that heavy, it costs energy to produce, so its momentum would not be large – it would move more slowly than the speed of light.

That time delay would set it apart from all the rest of the normal particles. Scientists would only need to tweak the system to look for particles that are produced and then decay a bit more slowly than everything else.

The difference is on the order of a nanosecond — a billionth of a second — or smaller. But the LHC already has detectors sophisticated enough to catch this difference; a recent study using data collected from the last run found the method should work, plus the detectors will get even more sensitive as part of the upgrade that is currently underway. Liu said:

We anticipate this method will increase our sensitivity to long-lived dark particles by more than an order of magnitude – while using capabilities we already have at the LHC.

Experimentalists are already working to build the trap: When the LHC turns back on in 2021, after boosting its luminosity by tenfold, all three of the major detectors will be implementing the new system, the scientists said. Liu said:

We think it has great potential for discovery.

Wang added:

If the particle is there, we just have to find a way to dig it out. Usually, the key is finding the question to ask.

Bottom line: Now that they’ve identified the Higgs boson, Large Hadron Collider scientists have set their sights on an even more elusive target – dark matter and dark energy.

Source: Enhancing Long-Lived Particles Searches at the LHC with Precision Timing Information

from EarthSky http://bit.ly/2GVyIYm

Tackling side effects in head and neck cancer treatment – the end of the road for hyperbaric oxygen?

Some side effects appear years after cancer treatment. That’s the case for one side effect of radiotherapy for head and neck cancer, called osteoradionecrosis.

This painful condition results from damage to the jaw bone, which often doesn’t heal properly and can cause bone fractures or even bone death.

It can develop without an obvious trigger, but it’s often linked to dental work like tooth extractions or implants. And it can happen even if the dental work is carried out 20 years after radiotherapy.

Professor Richard Shaw, a Cancer Research UK-funded head and neck surgeon at the University of Liverpool, treats the difficult condition quite frequently through reconstructive surgery.

Shaw says that these procedures are often bigger and harder than patients’ original cancer surgery, because they’ve already had so much treatment in that area.

For that reason, researchers have looked for ways to prevent osteoradionecrosis from developing. And that’s where hyperbaric oxygen comes in. It started with a small trial in the 80s, which has influenced the way doctors prepare patients for dental surgery ever since.

But new trial data, led by Shaw and published in the International Journal of Radiation Oncology, shows the hyperbaric oxygen hype may have been a bit premature.

The trial of hyperbaric oxygen

Back in the 1980s, a small trial in the US showed that giving hyperbaric oxygen before dental surgery could reduce the risk of osteoradionecrosis developing.

What is hyperbaric oxygen therapy?

Hyperbaric oxygen treatment involves sitting in a chamber where the oxygen is at a higher pressure than the air we normally breathe. It’s thought the increase in oxygen can help to promote healing. Sessions typically last 60-90 minutes.

“Prevention is obviously a very good idea, but I think there was concern around whether hyperbaric oxygen was the answer,” says Shaw.

A big question that lingered around the treatment was how applicable the 34-year-old trial results were to patient’s today. Radiotherapy has become a lot more targeted than it was a few decades ago, which may affect the risk of someone developing osteoradionecrosis.

“There really was no recent, good evidence for hyperbaric oxygen,” says Shaw.

No one wants to take the risk with our patients who, after all, had been cured of head and neck cancer and saw themselves as long-term survivors.

– Professor Richard Shaw

Adding to that, hyperbaric oxygen treatment takes time. Patients have to travel to a centre with a specialised chamber every day for 30 days.

And finally, the cost. According to Shaw, the NHS is spending somewhere between £5K and £10K per patient on hyperbaric oxygen treatment.

Expensive, intensive and based on potentially shaky evidence. The feeling was that it was time for hyperbaric oxygen to be put back to the test.

The verdict’s in

Shaw and his team ran a trial testing hyperbaric oxygen treatment in 144 patients who’d had head and neck cancer and now needed dental surgery. Half the patients had a course of hyperbaric oxygen before surgery, the other half didn’t.
Patients were then monitored after dental treatment to see who developed osteoradionecrosis, as well as monitoring pain levels and quality of life.

Professor Richard Shaw (left) and one of the trial team in a hyperbaric chamber

The first thing the team learnt was that osteoradionecrosis is a lot less common now than it was in the 80s.

“We can now say that with modern radiotherapy, someone’s risk of having this jaw problem is about 1 in 20. Which is a lot lower than the previous trial, which had shown it was around 1 in 3,” says Shaw.

The other big finding was that hyperbaric oxygen had no impact on the number of people developing osteoradionecrosis – the numbers were pretty much the same in each side of the trial.

And although people who had hyperbaric oxygen reported fewer short-term side effects and less pain immediately after surgery, there was no difference in long-term pain or quality of life between the two groups.

“It’s very clear that in our health system, hyperbaric oxygen is no longer justified,” says Shaw. “In some ways it could be reported as a negative finding, because hyperbaric oxygen didn’t work. But I think it has given us a definitive change of practice.”

What’s next?

As well as changing practice, the trial leaves another legacy: patient samples. Shaw is planning to use these to understand more about who develops osteoradionecrosis.

“What you’ll deduce with 6% of patients developing osteoradionecrosis in this trial is that 94% of people didn’t, even though they were considered high risk,” he says.

Right now, risk is assessed based on where the radiotherapy was aimed, as well as the type of follow-up dental work that’s being done. But Shaw believes risk could be predicted more precisely. The team will now study the patient samples to look if there are any differences in the DNA of patients who went on to develop osteoradionecrosis.

“We’re looking for a genetic signal or a ‘fingerprint’ that identifies people at high risk of osteoradionecrosis that we could validate in future trials,” says Shaw.

For now, Shaw says doctors can help to reduce the risk of osteoradionecrosis by making sure patients’ teeth are in the best possible condition before and after radiotherapy.

This, Shaw says, could help make sure “these conditions that require surgery don’t arise in the first place.”

Katie

Reference

Shaw RJ, et al. (2019) HOPON (Hyperbaric Oxygen for the Prevention of Osteoradionecrosis): A Randomized Controlled Trial of Hyperbaric Oxygen to Prevent Osteoradionecrosis of the Irradiated Mandible After Dentoalveolar Surgery. Int J Radiat Oncol Biol Phys. DOI: 10.1016/j.ijrobp.2019.02.044.

from Cancer Research UK – Science blog http://bit.ly/2PFNLrT

Some side effects appear years after cancer treatment. That’s the case for one side effect of radiotherapy for head and neck cancer, called osteoradionecrosis.

This painful condition results from damage to the jaw bone, which often doesn’t heal properly and can cause bone fractures or even bone death.

It can develop without an obvious trigger, but it’s often linked to dental work like tooth extractions or implants. And it can happen even if the dental work is carried out 20 years after radiotherapy.

Professor Richard Shaw, a Cancer Research UK-funded head and neck surgeon at the University of Liverpool, treats the difficult condition quite frequently through reconstructive surgery.

Shaw says that these procedures are often bigger and harder than patients’ original cancer surgery, because they’ve already had so much treatment in that area.

For that reason, researchers have looked for ways to prevent osteoradionecrosis from developing. And that’s where hyperbaric oxygen comes in. It started with a small trial in the 80s, which has influenced the way doctors prepare patients for dental surgery ever since.

But new trial data, led by Shaw and published in the International Journal of Radiation Oncology, shows the hyperbaric oxygen hype may have been a bit premature.

The trial of hyperbaric oxygen

Back in the 1980s, a small trial in the US showed that giving hyperbaric oxygen before dental surgery could reduce the risk of osteoradionecrosis developing.

What is hyperbaric oxygen therapy?

Hyperbaric oxygen treatment involves sitting in a chamber where the oxygen is at a higher pressure than the air we normally breathe. It’s thought the increase in oxygen can help to promote healing. Sessions typically last 60-90 minutes.

“Prevention is obviously a very good idea, but I think there was concern around whether hyperbaric oxygen was the answer,” says Shaw.

A big question that lingered around the treatment was how applicable the 34-year-old trial results were to patient’s today. Radiotherapy has become a lot more targeted than it was a few decades ago, which may affect the risk of someone developing osteoradionecrosis.

“There really was no recent, good evidence for hyperbaric oxygen,” says Shaw.

No one wants to take the risk with our patients who, after all, had been cured of head and neck cancer and saw themselves as long-term survivors.

– Professor Richard Shaw

Adding to that, hyperbaric oxygen treatment takes time. Patients have to travel to a centre with a specialised chamber every day for 30 days.

And finally, the cost. According to Shaw, the NHS is spending somewhere between £5K and £10K per patient on hyperbaric oxygen treatment.

Expensive, intensive and based on potentially shaky evidence. The feeling was that it was time for hyperbaric oxygen to be put back to the test.

The verdict’s in

Shaw and his team ran a trial testing hyperbaric oxygen treatment in 144 patients who’d had head and neck cancer and now needed dental surgery. Half the patients had a course of hyperbaric oxygen before surgery, the other half didn’t.
Patients were then monitored after dental treatment to see who developed osteoradionecrosis, as well as monitoring pain levels and quality of life.

Professor Richard Shaw (left) and one of the trial team in a hyperbaric chamber

The first thing the team learnt was that osteoradionecrosis is a lot less common now than it was in the 80s.

“We can now say that with modern radiotherapy, someone’s risk of having this jaw problem is about 1 in 20. Which is a lot lower than the previous trial, which had shown it was around 1 in 3,” says Shaw.

The other big finding was that hyperbaric oxygen had no impact on the number of people developing osteoradionecrosis – the numbers were pretty much the same in each side of the trial.

And although people who had hyperbaric oxygen reported fewer short-term side effects and less pain immediately after surgery, there was no difference in long-term pain or quality of life between the two groups.

“It’s very clear that in our health system, hyperbaric oxygen is no longer justified,” says Shaw. “In some ways it could be reported as a negative finding, because hyperbaric oxygen didn’t work. But I think it has given us a definitive change of practice.”

What’s next?

As well as changing practice, the trial leaves another legacy: patient samples. Shaw is planning to use these to understand more about who develops osteoradionecrosis.

“What you’ll deduce with 6% of patients developing osteoradionecrosis in this trial is that 94% of people didn’t, even though they were considered high risk,” he says.

Right now, risk is assessed based on where the radiotherapy was aimed, as well as the type of follow-up dental work that’s being done. But Shaw believes risk could be predicted more precisely. The team will now study the patient samples to look if there are any differences in the DNA of patients who went on to develop osteoradionecrosis.

“We’re looking for a genetic signal or a ‘fingerprint’ that identifies people at high risk of osteoradionecrosis that we could validate in future trials,” says Shaw.

For now, Shaw says doctors can help to reduce the risk of osteoradionecrosis by making sure patients’ teeth are in the best possible condition before and after radiotherapy.

This, Shaw says, could help make sure “these conditions that require surgery don’t arise in the first place.”

Katie

Reference

Shaw RJ, et al. (2019) HOPON (Hyperbaric Oxygen for the Prevention of Osteoradionecrosis): A Randomized Controlled Trial of Hyperbaric Oxygen to Prevent Osteoradionecrosis of the Irradiated Mandible After Dentoalveolar Surgery. Int J Radiat Oncol Biol Phys. DOI: 10.1016/j.ijrobp.2019.02.044.

from Cancer Research UK – Science blog http://bit.ly/2PFNLrT

Star-hop to the Hunting Dogs

Tonight, find the Hunting Dogs. The chart above looks directly overhead at nightfall or early evening in May, as seen from a mid-latitude in the Northern Hemisphere. It’s as if we’re viewing the sky from the comfort of a reclining lawn chair, with our feet pointing southward. The constellation Leo the Lion stands high in the southern sky, while the upside-down Big Dipper is high in the north. Notice the Big Dipper and Leo. You can use them to star-hop to to the constellation Canes Venatici, the Hunting Dogs.

Many people know how to find Polaris, the North Star, by drawing a line through the Big Dipper pointer stars, Dubhe and Merak. You can also find Leo by drawing a line through these same pointer stars, but in the opposite direction.

Extend a line from the star Alkaid in the Big Dipper to the star Denebola in Leo. One-third the way along this line, you’ll see Cor Caroli, Canes Venatici’s brightest star. A telescope reveals that Cor Caroli is a binary star – two stars orbiting a common center of mass.

Cor Caroli (Latin for “Heart of Charles”) is named in honor of England’s King Charles I, who had his head cut off in 1649. The name first appeared on English star maps in the late 1600s as Cor Caroli Regis Martyris (“Heart of Charles the Martyr King”). King Charles II, the son of King Charles I, founded the Royal Greenwich Observatory in 1675.

Bottom line: Star-hop to Canes Venatici, the Hunting Dogs, tonight! You can do it, if you can find the constellation Leo and the famous Big Dipper asterism.

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

from EarthSky http://bit.ly/2WgfhyB

Tonight, find the Hunting Dogs. The chart above looks directly overhead at nightfall or early evening in May, as seen from a mid-latitude in the Northern Hemisphere. It’s as if we’re viewing the sky from the comfort of a reclining lawn chair, with our feet pointing southward. The constellation Leo the Lion stands high in the southern sky, while the upside-down Big Dipper is high in the north. Notice the Big Dipper and Leo. You can use them to star-hop to to the constellation Canes Venatici, the Hunting Dogs.

Many people know how to find Polaris, the North Star, by drawing a line through the Big Dipper pointer stars, Dubhe and Merak. You can also find Leo by drawing a line through these same pointer stars, but in the opposite direction.

Extend a line from the star Alkaid in the Big Dipper to the star Denebola in Leo. One-third the way along this line, you’ll see Cor Caroli, Canes Venatici’s brightest star. A telescope reveals that Cor Caroli is a binary star – two stars orbiting a common center of mass.

Cor Caroli (Latin for “Heart of Charles”) is named in honor of England’s King Charles I, who had his head cut off in 1649. The name first appeared on English star maps in the late 1600s as Cor Caroli Regis Martyris (“Heart of Charles the Martyr King”). King Charles II, the son of King Charles I, founded the Royal Greenwich Observatory in 1675.

Bottom line: Star-hop to Canes Venatici, the Hunting Dogs, tonight! You can do it, if you can find the constellation Leo and the famous Big Dipper asterism.

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

from EarthSky http://bit.ly/2WgfhyB

Why do we celebrate May Day?

Image via Goodnews.

You might not realize it, but May Day – an ancient spring festival in the Northern Hemisphere – is an astronomical holiday. It’s one of the year’s four cross-quarter days, or a day that falls more or less midway between an equinox and solstice, in this case the March equinox and June solstice. The other cross-quarter days are Groundhog Day on February 2, Lammas on August 1 and Halloween on October 31. May Day also stems from the Celtic festival of Beltane, which was related to the waxing power of the sun as we in the Northern Hemisphere move closer to summer. At Beltane, people lit fires through which livestock were driven and around which people danced, moving in the same direction that the sun crosses the sky.

May Day is Lei Day in Hawaii, a statewide celebration of the aloha spirit and the giving of the flower lei. Image via Joel/Poipu Beach.

School children rehearsing Maypole festivity, in Gee's Bend, Alabama, 1939. Image via Wikimedia Commons

The top of a Maypole set up for a May 1 celebration. Image via WrldVoyagr/Flickr.

Wrapping a Maypole with colorful ribbons is perhaps the best known of all May Day traditions. In the Middle Ages, English villages all had Maypoles, which were actual trees brought in from the woods in the midst of rejoicing and raucous merrymaking. Maypoles came in many sizes, and villages were said to compete with each other to show whose Maypole was tallest. Maypoles were usually set up for the day in small towns, but in London and the larger towns they were erected permanently.

We’re not too far away from a time in the late 20th century when people left homemade May baskets filled with spring flowers and sweets on each others’ doorsteps, usually anonymously. I can remember doing this as a child. Maybe it’s a tradition that can be revived.

Image via Contours.

Bottom line: May 1 is one of four cross-quarter days, midway between an equinox and a solstice. Happy May Day 2019!

from EarthSky http://bit.ly/2J4oI0k

Image via Goodnews.

You might not realize it, but May Day – an ancient spring festival in the Northern Hemisphere – is an astronomical holiday. It’s one of the year’s four cross-quarter days, or a day that falls more or less midway between an equinox and solstice, in this case the March equinox and June solstice. The other cross-quarter days are Groundhog Day on February 2, Lammas on August 1 and Halloween on October 31. May Day also stems from the Celtic festival of Beltane, which was related to the waxing power of the sun as we in the Northern Hemisphere move closer to summer. At Beltane, people lit fires through which livestock were driven and around which people danced, moving in the same direction that the sun crosses the sky.

May Day is Lei Day in Hawaii, a statewide celebration of the aloha spirit and the giving of the flower lei. Image via Joel/Poipu Beach.

School children rehearsing Maypole festivity, in Gee's Bend, Alabama, 1939. Image via Wikimedia Commons

The top of a Maypole set up for a May 1 celebration. Image via WrldVoyagr/Flickr.

Wrapping a Maypole with colorful ribbons is perhaps the best known of all May Day traditions. In the Middle Ages, English villages all had Maypoles, which were actual trees brought in from the woods in the midst of rejoicing and raucous merrymaking. Maypoles came in many sizes, and villages were said to compete with each other to show whose Maypole was tallest. Maypoles were usually set up for the day in small towns, but in London and the larger towns they were erected permanently.

We’re not too far away from a time in the late 20th century when people left homemade May baskets filled with spring flowers and sweets on each others’ doorsteps, usually anonymously. I can remember doing this as a child. Maybe it’s a tradition that can be revived.

Image via Contours.

Bottom line: May 1 is one of four cross-quarter days, midway between an equinox and a solstice. Happy May Day 2019!

from EarthSky http://bit.ly/2J4oI0k

What’s the birthstone for May?

Image via shutterstock.

The emerald belongs to the beryl family of minerals that include aquamarine (one of March’s birthstones), heliodor, and morganite. Beryl, or beryllium aluminum silicate in chemical jargon, is a six-sided symmetrical crystal. Beryl contains beryllium, aluminum, silicon, and oxygen.

Emeralds vary in color from light to deep green. It’s commonly thought that an emerald’s color derives from the presence of chromium and/or vanadium replacing some of the aluminum in the mineral’s structure. The stone can, however, lose its color when heated strongly.

Several famous historical artifacts were made of emeralds. Among them is the Crown of the Andes, said to be made from emeralds worn by Atahualpa, the last Inca (king) of Peru. The crown is set with about 450 emeralds, collectively weighing 10 ounces (1523 carats).

Emeralds are most frequently found inside a form of shale – a fine-grained sedimentary rock. Emerald-bearing shale has undergone recrystallization caused by changes in the physical environment such as pressure and temperature. Colombia produces the largest and highest quality emeralds. They were also discovered, and subsequently mined, in the Ural Mountains of Russia around 1830. In the United States, emeralds can be found in North Carolina. Around the world, they also occur in Zambia, Brazil, Pakistan, Norway, Austria, India, Madagascar, and Australia.

Emerald slices at a gem show. Image via cobalt123

Synthetic manufacture of emeralds was achieved by German chemists shortly before World War II. But growing synthetic stones of fine quality began in the United States in 1946. There are also excellent imitation emeralds on the market made of colored cut glass.

The emerald’s name is indirectly derived from the Greek word “smaragdos,” a term applied to several kinds of green stones. The history of emeralds can be traced back to antiquity. They were worn by royalty in Babylon and Egypt. Tools dating back to 1300 B.C., during the reign of Rameses II, have been found in emerald mines in Egypt. Queen Cleopatra’s emeralds were believed to originate from mines in Southern Egypt, near the Red Sea.

When the conquistadors first arrived in South America from Spain, they saw indigenous rulers wearing emeralds. They took large quantities of emeralds from the Peruvians during the invasion, but the source of the emeralds was not discovered. Then in 1537, the Spaniards found Chivor in Colombia, now the location of an important emerald mine. They also took over the Muzo mine following the defeat of the Muzo Indians. Mining operations at Muzo have continued almost uninterrupted since the Spanish invasion. It is perhaps the most famous emerald mine in Colombia and is said to produce the world’s best emeralds.

There are many myths associated with the emerald. The stone was once believed to prevent epilepsy, stop bleeding, cure dysentery and fever, and protect the wearer from panic. Its magnificent green color was said to rest and relieve the eye. To the ancient Romans, emeralds were dedicated to the goddess Venus because the green emerald symbolized the reproductive forces of nature. Early Christians saw it as a symbol of the resurrection of Christ. In the Middle Ages, emeralds were believed to hold the power to foretell the future.

Find out about the birthstones for the other months of the year.
January birthstone
February birthstone
March birthstone
April birthstone
May birthstone
June birthstone
July birthstone
August birthstone
September birthstone
October birthstone
November birthstone
December birthstone

Bottom line: The birthstone for May is the emerald.

from EarthSky http://bit.ly/2VKifi5

Image via shutterstock.

The emerald belongs to the beryl family of minerals that include aquamarine (one of March’s birthstones), heliodor, and morganite. Beryl, or beryllium aluminum silicate in chemical jargon, is a six-sided symmetrical crystal. Beryl contains beryllium, aluminum, silicon, and oxygen.

Emeralds vary in color from light to deep green. It’s commonly thought that an emerald’s color derives from the presence of chromium and/or vanadium replacing some of the aluminum in the mineral’s structure. The stone can, however, lose its color when heated strongly.

Several famous historical artifacts were made of emeralds. Among them is the Crown of the Andes, said to be made from emeralds worn by Atahualpa, the last Inca (king) of Peru. The crown is set with about 450 emeralds, collectively weighing 10 ounces (1523 carats).

Emeralds are most frequently found inside a form of shale – a fine-grained sedimentary rock. Emerald-bearing shale has undergone recrystallization caused by changes in the physical environment such as pressure and temperature. Colombia produces the largest and highest quality emeralds. They were also discovered, and subsequently mined, in the Ural Mountains of Russia around 1830. In the United States, emeralds can be found in North Carolina. Around the world, they also occur in Zambia, Brazil, Pakistan, Norway, Austria, India, Madagascar, and Australia.

Emerald slices at a gem show. Image via cobalt123

Synthetic manufacture of emeralds was achieved by German chemists shortly before World War II. But growing synthetic stones of fine quality began in the United States in 1946. There are also excellent imitation emeralds on the market made of colored cut glass.

The emerald’s name is indirectly derived from the Greek word “smaragdos,” a term applied to several kinds of green stones. The history of emeralds can be traced back to antiquity. They were worn by royalty in Babylon and Egypt. Tools dating back to 1300 B.C., during the reign of Rameses II, have been found in emerald mines in Egypt. Queen Cleopatra’s emeralds were believed to originate from mines in Southern Egypt, near the Red Sea.

When the conquistadors first arrived in South America from Spain, they saw indigenous rulers wearing emeralds. They took large quantities of emeralds from the Peruvians during the invasion, but the source of the emeralds was not discovered. Then in 1537, the Spaniards found Chivor in Colombia, now the location of an important emerald mine. They also took over the Muzo mine following the defeat of the Muzo Indians. Mining operations at Muzo have continued almost uninterrupted since the Spanish invasion. It is perhaps the most famous emerald mine in Colombia and is said to produce the world’s best emeralds.

There are many myths associated with the emerald. The stone was once believed to prevent epilepsy, stop bleeding, cure dysentery and fever, and protect the wearer from panic. Its magnificent green color was said to rest and relieve the eye. To the ancient Romans, emeralds were dedicated to the goddess Venus because the green emerald symbolized the reproductive forces of nature. Early Christians saw it as a symbol of the resurrection of Christ. In the Middle Ages, emeralds were believed to hold the power to foretell the future.

Find out about the birthstones for the other months of the year.
January birthstone
February birthstone
March birthstone
April birthstone
May birthstone
June birthstone
July birthstone
August birthstone
September birthstone
October birthstone
November birthstone
December birthstone

Bottom line: The birthstone for May is the emerald.

from EarthSky http://bit.ly/2VKifi5

Milky Way and Jupiter

Image via Maureen Allen.

from EarthSky http://bit.ly/2IS1lI7

Image via Maureen Allen.

from EarthSky http://bit.ly/2IS1lI7