Heavy atom tunneling in semibullvalene

Another prediction made by quantum chemistry has now been confirmed. In 2010, Zhang, Hrovat, and Borden predicted that the degenerate rearrangement of semibullvalene 1 occurs with heavy atom tunneling.¹ For example, the computed rate of the rearrangement including tunneling correction is 1.43 x 10^-3 s^-1 at 40 K, and this rate does not change with decreasing temperature. The predicted half-life of 485 s is 10¹⁰ shorter than that predicted by transition state theory.

Now a group led by Sander has examined the rearrangement of deuterated 2.² The room temperature equilibrium mixture of d⁴–2 and d²–2 was deposited at 3 K. IR observation showed a decrease in signal intensities associated with d⁴–2 and concomitant growth of signals associated with d²–2. The barrier for this interconversion is about 5 kcal mol^-1, too large to be crossed at this temperature. Instead, the interconversion is happening by tunneling through the barrier (with a rate about 10^-4 s^-1), forming the more stable isomer d²–2 preferentially. This is exactly as predicted by theory!

References

1. Zhang, X.; Hrovat, D. A.; Borden, W. T., "Calculations Predict That Carbon Tunneling Allows the Degenerate Cope Rearrangement of Semibullvalene to Occur Rapidly at Cryogenic Temperatures." Org. Letters 2010, 12, 2798-2801, DOI: 10.1021/ol100879t.

2. Schleif, T.; Mieres-Perez, J.; Henkel, S.; Ertelt, M.; Borden, W. T.; Sander, W., "The Cope Rearrangement of 1,5-Dimethylsemibullvalene-2(4)-d1: Experimental Evidence for Heavy-Atom Tunneling." Angew. Chem. Int. Ed. 2017, 56, 10746-10749, DOI: 10.1002/anie.201704787.

InChIs

1: InChI=1S/C8H8/c1-3-6-7-4-2-5(1)8(6)7/h1-8H
InChIKey=VEAPRCKNPMGWCP-UHFFFAOYSA-N

d⁴–2: InChI=1S/C10H12/c1-9-5-3-7-8(4-6-9)10(7,9)2/h3-8H,1-2H3/i5D
InChIKey=WUJOLJNLXLACNA-UICOGKGYSA-N

d²–2: InChI=1S/C10H12/c1-9-5-3-7-8(4-6-9)10(7,9)2/h3-8H,1-2H3/i7D
InChIKey=WUJOLJNLXLACNA-WHRKIXHSSA-N

from Computational Organic Chemistry http://ift.tt/2A9m2I5

Another prediction made by quantum chemistry has now been confirmed. In 2010, Zhang, Hrovat, and Borden predicted that the degenerate rearrangement of semibullvalene 1 occurs with heavy atom tunneling.¹ For example, the computed rate of the rearrangement including tunneling correction is 1.43 x 10^-3 s^-1 at 40 K, and this rate does not change with decreasing temperature. The predicted half-life of 485 s is 10¹⁰ shorter than that predicted by transition state theory.

Now a group led by Sander has examined the rearrangement of deuterated 2.² The room temperature equilibrium mixture of d⁴–2 and d²–2 was deposited at 3 K. IR observation showed a decrease in signal intensities associated with d⁴–2 and concomitant growth of signals associated with d²–2. The barrier for this interconversion is about 5 kcal mol^-1, too large to be crossed at this temperature. Instead, the interconversion is happening by tunneling through the barrier (with a rate about 10^-4 s^-1), forming the more stable isomer d²–2 preferentially. This is exactly as predicted by theory!

References

1. Zhang, X.; Hrovat, D. A.; Borden, W. T., "Calculations Predict That Carbon Tunneling Allows the Degenerate Cope Rearrangement of Semibullvalene to Occur Rapidly at Cryogenic Temperatures." Org. Letters 2010, 12, 2798-2801, DOI: 10.1021/ol100879t.

2. Schleif, T.; Mieres-Perez, J.; Henkel, S.; Ertelt, M.; Borden, W. T.; Sander, W., "The Cope Rearrangement of 1,5-Dimethylsemibullvalene-2(4)-d1: Experimental Evidence for Heavy-Atom Tunneling." Angew. Chem. Int. Ed. 2017, 56, 10746-10749, DOI: 10.1002/anie.201704787.

InChIs

1: InChI=1S/C8H8/c1-3-6-7-4-2-5(1)8(6)7/h1-8H
InChIKey=VEAPRCKNPMGWCP-UHFFFAOYSA-N

d⁴–2: InChI=1S/C10H12/c1-9-5-3-7-8(4-6-9)10(7,9)2/h3-8H,1-2H3/i5D
InChIKey=WUJOLJNLXLACNA-UICOGKGYSA-N

d²–2: InChI=1S/C10H12/c1-9-5-3-7-8(4-6-9)10(7,9)2/h3-8H,1-2H3/i7D
InChIKey=WUJOLJNLXLACNA-WHRKIXHSSA-N

from Computational Organic Chemistry http://ift.tt/2A9m2I5

Busting ghosts

Editor’s note: Just in time for the spooky season, we are pleased to share this post reporting on some alarming, apparently paranormal activity. The reader is advised that the editors cannot confirm the veracity of this report, and although an apparently perfectly rational cause may have been found, one can’t ever be too cautious in these matters.

This image was taken by Byron Bay-based astrophotographer Dylan O’Donnell in October during a photo shoot at the New Norcia station, some 120 km north of Perth, Western Australia.

According to some, the ghost of Ted Leighton is said to be most often active in winter, causing trouble if ever any part of Western Australia’s famous Cuballing Hotel and Tavern, built in 1912, were to be changed or modified. Evidently, he likes his home just the way it was a hundred years ago.

Ted was the yardman at the Cuballing hotel before he died (history – or at least Google – has not recorded a specific date of death). Since the, strange occurrences like gas bottles being turned on, kegs rolling around, doors slamming and the ice machine being turned off have been attributed to Ted’s ghost. He seems not to like change of any sort…

Note that Cuballing is situated about 260 km south of ESA’s deep space ground station at New Norcia, the monastery town, a trivial distance for paranormal shenanigans. The station has recently been updated with an array of solar power panels, which now provide a significant portion of the station’s electrical power

One recent morning, upon arrival for another day of tracking missions across the solar system, the New Norcia station maintenance team discovered that a portion of the perimeter fence was broken, as though some large, heavy mass had charged right through.

Solar panel construction – showing unmistakable evidence of tampering? Credit: ESA/D. O’Donnell

Inside the fence, a portion of the station’s gentle rolling property had recently been allocated for the solar panel construction.

This morning, there were unidentifiable foot prints – Or were they cloven hoof prints? – on the ground around the broken fence and over by the first row of panels, and some of the panel support arms were broken and bore marks as though someone – or something – had tried to chew through them. Tufts of unidentifiable hair were stuck to some of the undamaged support arms.

Apparently, whoever it was didn’t like the rows of neat, high-tech panels disturbing ‘their’ landscape.

Could it have anything to do with our long-departed friend, Ted? The ghost who doesn’t like to be disturbed? Ted was far away but everyone knows how much he dislikes change. First the broken fence, then the chewed-up panel supports… what could be next?! The station itself might be under threat…

The team scrupulously examined all evidence.

One of them, Old Digger Jack, a local who had served in the army signal corps years ago, recalled the history of the hillsides.

ABC audio report: Paranormal investigator claims to have recorded the voice of a ghost who haunts the Cuballing Tavern Credit: Australian Broadcasting Corp.

Prior to ESA’s station being built in the early 2000s, the area had been unused, and Digger Jack remembered acres of emerald grass with gentle breezes in summer, while the cold winter days brought bright austral sunlight to a peaceful, bucolic scene.

Suddenly it appeared.

None of the station team could recall later how it arrived, not when they first noticed it approaching across the grassy hill.

It moved slowly but steadily, making little sound despite its clumsy size. It had a large, hairy head and was making a beeline for the break in the station fence, drawing ever nearer.

In an instant, the team realised precisely what they were facing.

Scroll down…

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

It was Lucy the cow, grazing her way up the hill, heading to the break in the fence that allowed access to the scrumptious October grass growing around and between the rows of solar panels! Happy Halloween!

 

from Rocket Science http://ift.tt/2zq5uhT
v

Editor’s note: Just in time for the spooky season, we are pleased to share this post reporting on some alarming, apparently paranormal activity. The reader is advised that the editors cannot confirm the veracity of this report, and although an apparently perfectly rational cause may have been found, one can’t ever be too cautious in these matters.

This image was taken by Byron Bay-based astrophotographer Dylan O’Donnell in October during a photo shoot at the New Norcia station, some 120 km north of Perth, Western Australia.

According to some, the ghost of Ted Leighton is said to be most often active in winter, causing trouble if ever any part of Western Australia’s famous Cuballing Hotel and Tavern, built in 1912, were to be changed or modified. Evidently, he likes his home just the way it was a hundred years ago.

Ted was the yardman at the Cuballing hotel before he died (history – or at least Google – has not recorded a specific date of death). Since the, strange occurrences like gas bottles being turned on, kegs rolling around, doors slamming and the ice machine being turned off have been attributed to Ted’s ghost. He seems not to like change of any sort…

Note that Cuballing is situated about 260 km south of ESA’s deep space ground station at New Norcia, the monastery town, a trivial distance for paranormal shenanigans. The station has recently been updated with an array of solar power panels, which now provide a significant portion of the station’s electrical power

One recent morning, upon arrival for another day of tracking missions across the solar system, the New Norcia station maintenance team discovered that a portion of the perimeter fence was broken, as though some large, heavy mass had charged right through.

Solar panel construction – showing unmistakable evidence of tampering? Credit: ESA/D. O’Donnell

Inside the fence, a portion of the station’s gentle rolling property had recently been allocated for the solar panel construction.

This morning, there were unidentifiable foot prints – Or were they cloven hoof prints? – on the ground around the broken fence and over by the first row of panels, and some of the panel support arms were broken and bore marks as though someone – or something – had tried to chew through them. Tufts of unidentifiable hair were stuck to some of the undamaged support arms.

Apparently, whoever it was didn’t like the rows of neat, high-tech panels disturbing ‘their’ landscape.

Could it have anything to do with our long-departed friend, Ted? The ghost who doesn’t like to be disturbed? Ted was far away but everyone knows how much he dislikes change. First the broken fence, then the chewed-up panel supports… what could be next?! The station itself might be under threat…

The team scrupulously examined all evidence.

One of them, Old Digger Jack, a local who had served in the army signal corps years ago, recalled the history of the hillsides.

ABC audio report: Paranormal investigator claims to have recorded the voice of a ghost who haunts the Cuballing Tavern Credit: Australian Broadcasting Corp.

Prior to ESA’s station being built in the early 2000s, the area had been unused, and Digger Jack remembered acres of emerald grass with gentle breezes in summer, while the cold winter days brought bright austral sunlight to a peaceful, bucolic scene.

Suddenly it appeared.

None of the station team could recall later how it arrived, not when they first noticed it approaching across the grassy hill.

It moved slowly but steadily, making little sound despite its clumsy size. It had a large, hairy head and was making a beeline for the break in the station fence, drawing ever nearer.

In an instant, the team realised precisely what they were facing.

Scroll down…

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

It was Lucy the cow, grazing her way up the hill, heading to the break in the fence that allowed access to the scrumptious October grass growing around and between the rows of solar panels! Happy Halloween!

 

from Rocket Science http://ift.tt/2zq5uhT
v

Twin Yellowstone super-eruptions altered global climate

The gorgeous colors of Yellowstone National Park’s Grand Prismatic hot spring are among the park’s myriad hydrothermal features created by the fact that Yellowstone is a supervolcano – the largest type of volcano on Earth. Photo via Windows into the Earth by Robert B. Smith and Lee J. Siegel

The Yellowstone supervolcano’s last catastrophic eruption, about 630,000 years ago, was not a single event, but two powerful and closely-spaced eruptions, according to a new study. The super-eruptions were powerful enough, the researchers say, to slow a natural global warming trend that eventually led the planet out of a major ice age.

For the study, presented at the Geological Society of American’s annual meeting in Seattle on October 25, 2017, a team of geologists from the University of California Santa Barbara (UCSB) analyzed two layers of volcanic ash discovered in seafloor sediments off the coast of Southern California. These layers of ash, sandwiched among sediments, bear the unique chemical fingerprint of Yellowstone’s most recent super eruption. and contain a remarkably detailed climate record of the violent events that formed the vast Yellowstone caldera – or cauldron-like crater – that we see today.
UCSB geologist Jim Kennett said in a statement:

We discovered here that there are two ash-forming super eruptions 170 years apart, and each cooled the ocean by about three degrees Celsius.

Read more about the research here.

By comparing the volcanic ash record with the climate record of single-celled marine animal fossils, it’s quite clear, Kennet said, that both of these eruptions caused separate volcanic winters, when ash and volcanic sulfur dioxide emissions reduce the amount of sunlight reaching Earth’s surface and cause temporary cooling. According to the study, the onset of the global cooling events was abrupt and coincided precisely with the timing of the supervolcanic eruptions.

These cooling events occurred at an especially sensitive time, Kennet said, when the global climate was warming out of an ice age and easily disrupted by such events. But, Kennet added, each time, the cooling lasted longer than it should have, according to simple climate models. He said:

We see planetary cooling of sufficient magnitude and duration that there had to be other feedbacks involved.

These feedbacks might include increased sunlight-reflecting sea ice and snow cover or a change in ocean circulation that would cool the planet for a longer time.

Bottom line: New research suggest that the Yellowstone supervolcano’s last eruption wasn’t a single event, but 2 closely-spaced eruptions that slowed a natural global-warming trend.

Read more from the Geological Society of America

from EarthSky http://ift.tt/2h5irpM

The gorgeous colors of Yellowstone National Park’s Grand Prismatic hot spring are among the park’s myriad hydrothermal features created by the fact that Yellowstone is a supervolcano – the largest type of volcano on Earth. Photo via Windows into the Earth by Robert B. Smith and Lee J. Siegel

The Yellowstone supervolcano’s last catastrophic eruption, about 630,000 years ago, was not a single event, but two powerful and closely-spaced eruptions, according to a new study. The super-eruptions were powerful enough, the researchers say, to slow a natural global warming trend that eventually led the planet out of a major ice age.

For the study, presented at the Geological Society of American’s annual meeting in Seattle on October 25, 2017, a team of geologists from the University of California Santa Barbara (UCSB) analyzed two layers of volcanic ash discovered in seafloor sediments off the coast of Southern California. These layers of ash, sandwiched among sediments, bear the unique chemical fingerprint of Yellowstone’s most recent super eruption. and contain a remarkably detailed climate record of the violent events that formed the vast Yellowstone caldera – or cauldron-like crater – that we see today.
UCSB geologist Jim Kennett said in a statement:

We discovered here that there are two ash-forming super eruptions 170 years apart, and each cooled the ocean by about three degrees Celsius.

Read more about the research here.

By comparing the volcanic ash record with the climate record of single-celled marine animal fossils, it’s quite clear, Kennet said, that both of these eruptions caused separate volcanic winters, when ash and volcanic sulfur dioxide emissions reduce the amount of sunlight reaching Earth’s surface and cause temporary cooling. According to the study, the onset of the global cooling events was abrupt and coincided precisely with the timing of the supervolcanic eruptions.

These cooling events occurred at an especially sensitive time, Kennet said, when the global climate was warming out of an ice age and easily disrupted by such events. But, Kennet added, each time, the cooling lasted longer than it should have, according to simple climate models. He said:

We see planetary cooling of sufficient magnitude and duration that there had to be other feedbacks involved.

These feedbacks might include increased sunlight-reflecting sea ice and snow cover or a change in ocean circulation that would cool the planet for a longer time.

Bottom line: New research suggest that the Yellowstone supervolcano’s last eruption wasn’t a single event, but 2 closely-spaced eruptions that slowed a natural global-warming trend.

Read more from the Geological Society of America

from EarthSky http://ift.tt/2h5irpM

November 2017 full moon a supermoon?

Apparent size of a full supermoon, or close moon, contrasted with a full micro-moon, or far moon. Image by Peter Lowenstein.

The 11th of 2017’s 12 full moons falls on November 3-4; click here to learn the exact time of full moon. This full moon ranks as the second-closest one of 2017, but it’s less than clear whether it should be dubbed a supermoon, mainly because people disagree on what constitutes a supermoon. Follow the links below to learn more.

Who are the commentators, and what do they say?

Original definition of supermoon

Nolle’s 90% based on 2017’s closest perigee and farthest apogee

Espenak’s 90% based on perigee and apogee of each month’s orbit

November full moon’s distance relative to 2017’s closest perigee and farthest apogee

Astrophysicist Fred Espenak, aka Mr. Eclipse – a 30-year NASA veteran and world-renowned expert on eclipses – says the January 12, 2017 full moon is a supermoon in his post Moon in 2017.

Who are the commentators, and what do they say? The International Astronomical Union (IAU) is the group generally recognized for naming and defining things in astronomy. But the IAU has been, so far, silent on the subject of supermoons, which, professional astronomers tend to call perigean full moons.

Meanwhile, Fred Espenak, the go-to astronomer on all things related to lunar and solar eclipses (Mr. Eclipse!), lists the full moons of January, November and December 2017 as full moon supermoons in his great post, Moon in 2017.

We also need to consider the astrologer Richard Nolle. Whatever your thoughts or feelings are on astrology, Nolle is, after all, the person who coined the term supermoon. Of the 12 full moons that take place in 2017, he lists only the December full moon as a supermoon. The supermoon definition, as originally defined by Nolle, comes with ambiguity. That’s why there are different answers to the question of the number of supermoons in 2017.

Click here to learn more about Richard Nolle

Click here to learn more about Fred Espenak

We refer you to two different supermoon tables for the 21st century (2001 to 2100). Here is Richard Nolle’s table, and here is Fred Espenak’s table.

Richard Nolle lists only one full moon supermoon for 2017:

2017 December 3

Meanwhile, Fred Espenak lists three full moon supermoons in 2017:

2017 January 12

2017 November 4

2017 December 3

Why are their lists different?

Image via NASA

Original definition of supermoon. Supermoons are based on lunar perigee and apogee. Each month, the moon comes closest to Earth at perigee and swings farthest away at apogee.

In his original definition, Richard Nolle defined a supermoon as:

… a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.

If a new or full moon aligns with apogee, then it’s at 0% of its closest approach to Earth. On the other hand, if a new or full moon aligns with perigee, then it’s at 100% of its closest approach to Earth. That’s something we can all agree on.

But the phrase 90% of perigee is ambiguous. Read on.

A 2013 supermoon, as captured by EarthSky Facebook Anthony Lynch in Dublin, Ireland.

Nolle’s 90% is based on 2017’s closest perigee and farthest apogee. Looking at Richard Nolle’s list for all the supermoons in the 21st century, it appears that Richard Nolle bases his 90% figure on the year’s closest perigee and farthest apogee. Take the year 2017, for instance, whereby any new or full moon coming closer than 362,146.6 km qualifies as a supermoon.

This year, in 2017, the moon comes closest to Earth on May 26 (357,207 kilometers) and swings farthest away toward the end of the year, on December 19 (406,603 kilometers). That’s a difference of 49,396 km (406,603 – 357,207 = 49,396 km). Ninety percent of this 49,396-figure equals 44,456.4 kilometers (0.9 x 49,396 = 44,456.4). Presumably, any new or full moon coming closer than 362,146.6 kilometers (406,603 – 44,456.4 = 362,146.6) would be “at or near (within 90% of) its closest approach to Earth.”

Farthest apogee (2017): 406,603 km
Closest perigee (2017): 357,207 km
Difference: 49,396 km

90% x 49,396 = 44,456.4 km

406,603 – 44,456.4 = 362,146.6 km = 90% of moon’s closest distance to Earth

Thus, figuring out “90% of the moon’s closest approach to Earth” by the year’s closest perigee and farthest apogee, any new or full moon swinging closer than 362,146.6 km to Earth in 2017 counts as a supermoon.

Since the full moon on November 4, 2017, only comes within 364,004 km of Earth, it doesn’t count as a supermoon on Richard Nolle’s list.

July 2014 supermoon via Evgeny Yorobe Photography

Espenak’s 90% based on perigee and apogee of each month’s orbit. Ironically, Fred Espenak’s full supermoon list might more strictly adhere to Richard Nolle’s definition (at least as it is written) than Richard Nolle himself does.

Once again, Richard Nolle describes a supermoon as:

… a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit.

If given orbit can be taken to mean current monthly orbit, then the November 2017 full moon comes to within 94.1% of its closest approach to Earth relative to the most recent perigee and the upcoming apogee.

October 25, 2017 apogee: 405,151 km
November 6, 2017 perigee: 361,438 km
Difference: 43,713 km

October 25, 2017 apogee: 405,151 km
November 4, 2017 full moon: 364,004 km
Difference: 41,147 km

41,147/43,713 = 0.941 (94.1%) = distance of the November 2017 full moon relative to the most recent perigee and upcoming apogee

Depending on what meaning we give to the words in a given orbit, we could say the October 25 apogee = 0% of the moon’s closest approach to Earth for this orbit, and the November 6 perigee = 100% of the moon’s closest approach to Earth.

That being the case, then the November full moon comes to within 94.1% of its closest approach to Earth for the month: 41,147/43,713 = 0.941 = 94.1%

Super cool super-moonrise composite from Fiona M. Donnelly in Ontario. This photo is from the August 2014 supermoon.

November full moon’s distance relative to 2017’s closest perigee/farthest apogee. However, if we compute the percentage distance of the November full moon relative to the year’s farthest apogee and closest perigee, then the November full moon only comes to within 86.2% of its closest approach to Earth:

Farthest apogee (2017): 406,603 km
Closest perigee (2017): 357,207 km
Difference: 49,396 km

Farthest apogee (2017): 406,603 km
November full moon (2017): 364,004 km
Difference: 42,599 km

42,599/49,396 = 0.862 (86.2%) = distance of the November full moon relative to the year’s farthest apogee and closest perigee

Another contrast of a full supermoon (full moon at perigee) with a micro-moon (full moon at apogee). Image credit: Stefano Sciarpetti

Is the November full moon a supermoon? Depends on which perigee/apogee distances you choose. The moon’s perigee and apogee distances vary throughout the year, so it appears that the limiting distance for the supermoon depends on which perigee and apogee distances are being used to compute 90% of the moon’s closest approach to Earth.

If we choose the year’s closest perigee and farthest apogee, as Nolle did, we narrow the definition of supermoon.

If we choose the perigee and apogee for a given monthly orbit, as Espenak did, then we broaden the definition of supermoon.

Given the narrower definition, the full moon on November 4, 2017, is not a supermoon, but given the broader one, it is.

Take your choice!

The moon’s apparent size in our sky depends on its distance from Earth. The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Image by Marco Langbroek of the Netherlands via Wikimedia Commons.

Bottom line: At least two commentators – Richard Nolle and Fred Espenak – disagree on whether the November 4, 2017, full moon should be called a supermoon. Is it? If you define a supermoon based on the year’s closest perigee and farthest apogee, then the November 2017 full moon is not a supermoon. If you define a supermoon based on the perigee and apogee for a given monthly orbit, then it is a supermoon. Take your choice!

from EarthSky http://ift.tt/2iK8qd3

Apparent size of a full supermoon, or close moon, contrasted with a full micro-moon, or far moon. Image by Peter Lowenstein.

The 11th of 2017’s 12 full moons falls on November 3-4; click here to learn the exact time of full moon. This full moon ranks as the second-closest one of 2017, but it’s less than clear whether it should be dubbed a supermoon, mainly because people disagree on what constitutes a supermoon. Follow the links below to learn more.

Who are the commentators, and what do they say?

Original definition of supermoon

Nolle’s 90% based on 2017’s closest perigee and farthest apogee

Espenak’s 90% based on perigee and apogee of each month’s orbit

November full moon’s distance relative to 2017’s closest perigee and farthest apogee

Astrophysicist Fred Espenak, aka Mr. Eclipse – a 30-year NASA veteran and world-renowned expert on eclipses – says the January 12, 2017 full moon is a supermoon in his post Moon in 2017.

Who are the commentators, and what do they say? The International Astronomical Union (IAU) is the group generally recognized for naming and defining things in astronomy. But the IAU has been, so far, silent on the subject of supermoons, which, professional astronomers tend to call perigean full moons.

Meanwhile, Fred Espenak, the go-to astronomer on all things related to lunar and solar eclipses (Mr. Eclipse!), lists the full moons of January, November and December 2017 as full moon supermoons in his great post, Moon in 2017.

We also need to consider the astrologer Richard Nolle. Whatever your thoughts or feelings are on astrology, Nolle is, after all, the person who coined the term supermoon. Of the 12 full moons that take place in 2017, he lists only the December full moon as a supermoon. The supermoon definition, as originally defined by Nolle, comes with ambiguity. That’s why there are different answers to the question of the number of supermoons in 2017.

Click here to learn more about Richard Nolle

Click here to learn more about Fred Espenak

We refer you to two different supermoon tables for the 21st century (2001 to 2100). Here is Richard Nolle’s table, and here is Fred Espenak’s table.

Richard Nolle lists only one full moon supermoon for 2017:

2017 December 3

Meanwhile, Fred Espenak lists three full moon supermoons in 2017:

2017 January 12

2017 November 4

2017 December 3

Why are their lists different?

Image via NASA

Original definition of supermoon. Supermoons are based on lunar perigee and apogee. Each month, the moon comes closest to Earth at perigee and swings farthest away at apogee.

In his original definition, Richard Nolle defined a supermoon as:

… a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.

If a new or full moon aligns with apogee, then it’s at 0% of its closest approach to Earth. On the other hand, if a new or full moon aligns with perigee, then it’s at 100% of its closest approach to Earth. That’s something we can all agree on.

But the phrase 90% of perigee is ambiguous. Read on.

A 2013 supermoon, as captured by EarthSky Facebook Anthony Lynch in Dublin, Ireland.

Nolle’s 90% is based on 2017’s closest perigee and farthest apogee. Looking at Richard Nolle’s list for all the supermoons in the 21st century, it appears that Richard Nolle bases his 90% figure on the year’s closest perigee and farthest apogee. Take the year 2017, for instance, whereby any new or full moon coming closer than 362,146.6 km qualifies as a supermoon.

This year, in 2017, the moon comes closest to Earth on May 26 (357,207 kilometers) and swings farthest away toward the end of the year, on December 19 (406,603 kilometers). That’s a difference of 49,396 km (406,603 – 357,207 = 49,396 km). Ninety percent of this 49,396-figure equals 44,456.4 kilometers (0.9 x 49,396 = 44,456.4). Presumably, any new or full moon coming closer than 362,146.6 kilometers (406,603 – 44,456.4 = 362,146.6) would be “at or near (within 90% of) its closest approach to Earth.”

Farthest apogee (2017): 406,603 km
Closest perigee (2017): 357,207 km
Difference: 49,396 km

90% x 49,396 = 44,456.4 km

406,603 – 44,456.4 = 362,146.6 km = 90% of moon’s closest distance to Earth

Thus, figuring out “90% of the moon’s closest approach to Earth” by the year’s closest perigee and farthest apogee, any new or full moon swinging closer than 362,146.6 km to Earth in 2017 counts as a supermoon.

Since the full moon on November 4, 2017, only comes within 364,004 km of Earth, it doesn’t count as a supermoon on Richard Nolle’s list.

July 2014 supermoon via Evgeny Yorobe Photography

Espenak’s 90% based on perigee and apogee of each month’s orbit. Ironically, Fred Espenak’s full supermoon list might more strictly adhere to Richard Nolle’s definition (at least as it is written) than Richard Nolle himself does.

Once again, Richard Nolle describes a supermoon as:

… a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit.

If given orbit can be taken to mean current monthly orbit, then the November 2017 full moon comes to within 94.1% of its closest approach to Earth relative to the most recent perigee and the upcoming apogee.

October 25, 2017 apogee: 405,151 km
November 6, 2017 perigee: 361,438 km
Difference: 43,713 km

October 25, 2017 apogee: 405,151 km
November 4, 2017 full moon: 364,004 km
Difference: 41,147 km

41,147/43,713 = 0.941 (94.1%) = distance of the November 2017 full moon relative to the most recent perigee and upcoming apogee

Depending on what meaning we give to the words in a given orbit, we could say the October 25 apogee = 0% of the moon’s closest approach to Earth for this orbit, and the November 6 perigee = 100% of the moon’s closest approach to Earth.

That being the case, then the November full moon comes to within 94.1% of its closest approach to Earth for the month: 41,147/43,713 = 0.941 = 94.1%

Super cool super-moonrise composite from Fiona M. Donnelly in Ontario. This photo is from the August 2014 supermoon.

November full moon’s distance relative to 2017’s closest perigee/farthest apogee. However, if we compute the percentage distance of the November full moon relative to the year’s farthest apogee and closest perigee, then the November full moon only comes to within 86.2% of its closest approach to Earth:

Farthest apogee (2017): 406,603 km
Closest perigee (2017): 357,207 km
Difference: 49,396 km

Farthest apogee (2017): 406,603 km
November full moon (2017): 364,004 km
Difference: 42,599 km

42,599/49,396 = 0.862 (86.2%) = distance of the November full moon relative to the year’s farthest apogee and closest perigee

Another contrast of a full supermoon (full moon at perigee) with a micro-moon (full moon at apogee). Image credit: Stefano Sciarpetti

Is the November full moon a supermoon? Depends on which perigee/apogee distances you choose. The moon’s perigee and apogee distances vary throughout the year, so it appears that the limiting distance for the supermoon depends on which perigee and apogee distances are being used to compute 90% of the moon’s closest approach to Earth.

If we choose the year’s closest perigee and farthest apogee, as Nolle did, we narrow the definition of supermoon.

If we choose the perigee and apogee for a given monthly orbit, as Espenak did, then we broaden the definition of supermoon.

Given the narrower definition, the full moon on November 4, 2017, is not a supermoon, but given the broader one, it is.

Take your choice!

The moon’s apparent size in our sky depends on its distance from Earth. The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Image by Marco Langbroek of the Netherlands via Wikimedia Commons.

Bottom line: At least two commentators – Richard Nolle and Fred Espenak – disagree on whether the November 4, 2017, full moon should be called a supermoon. Is it? If you define a supermoon based on the year’s closest perigee and farthest apogee, then the November 2017 full moon is not a supermoon. If you define a supermoon based on the perigee and apogee for a given monthly orbit, then it is a supermoon. Take your choice!

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Taurid fireballs this weekend?

Taurid fireball on the evening of October 21, 2017 – 10:27 p.m. – from Joanne West at Gold Canyon, Arizona.

The South and North Taurid meteor showers aren’t known for their large numbers of meteors, but they do offer many fireballs, or exceptionally bright meteors. This shower made a huge splash two years ago, in 2015, when there were many, many reports and photos featuring Taurid fireball sightings. Higher rates of Taurid fireballs appears to happen in seven-year cycles. Grand fireball displays did indeed take place in 2008 and 2015. No elevated levels of fireballs are expected in 2017, and the presence of moonlight will make this a difficult year for watching the South Taurid shower, which peaks on November 5. However, if you watch from a country location, you might find Taurid fireballs overcome the moon’s glare.

So watch out for Taurid meteors – and possible fireballs – starting now and throughout the weekend.

Taurid fireball caught on the evening of October 21 – 10:27 p.m. – by Eliot Herman in Tucson, Arizona. This is the same meteor as that caught by Joanne West, in the image above. Read more about these 2 photos.

How can you watch for Taurid fireballs? Moonlight will interfere on the prime time viewing hours from late night until dawn, with the peak viewing coming just after the midnight hour. Still, if you’re in a country location, be watchful. Maybe grab a lawn chair and bask under the moonlight for an hour or two, keeping an eye out for meteors.

In general, the South Taurids offer about 5 meteors per hour at their peak, but the North Taurid shower may a few more meteors to the mix. How many you’ll see will depend on how far from city lights you are … and how bright the meteors are. If they’re bright enough, they’ll overcome the bright moonlight.

Taurid meteors radiate from the constellation Taurus, but they’ll appear in all parts of the sky.

The Taurid meteor stream consists of an extremely wide roadway of far-flung debris left behind by Comet 2P Encke. When Earth travels through this belt of comet debris, bits and pieces of Comet 2P Encke smash into the Earth’s upper atmosphere to vaporize as rather slow-moving Taurid meteors (28 km/17 miles per second).

Apparently, the original Taurid stream has been perturbed by Jupiter into two branches: South and North Taurids.

Comet Encke, parent of the Taurid meteor shower. Image via Messenger

Bottom line: Despite the bright moon, we’re hoping for at least a smattering of Taurid fireballs in 2017! It’s time to start watching for them. What to expect from the South Taurid shower, and when to watch.

from EarthSky http://ift.tt/2z7r7Tp

Taurid fireball on the evening of October 21, 2017 – 10:27 p.m. – from Joanne West at Gold Canyon, Arizona.

The South and North Taurid meteor showers aren’t known for their large numbers of meteors, but they do offer many fireballs, or exceptionally bright meteors. This shower made a huge splash two years ago, in 2015, when there were many, many reports and photos featuring Taurid fireball sightings. Higher rates of Taurid fireballs appears to happen in seven-year cycles. Grand fireball displays did indeed take place in 2008 and 2015. No elevated levels of fireballs are expected in 2017, and the presence of moonlight will make this a difficult year for watching the South Taurid shower, which peaks on November 5. However, if you watch from a country location, you might find Taurid fireballs overcome the moon’s glare.

So watch out for Taurid meteors – and possible fireballs – starting now and throughout the weekend.

Taurid fireball caught on the evening of October 21 – 10:27 p.m. – by Eliot Herman in Tucson, Arizona. This is the same meteor as that caught by Joanne West, in the image above. Read more about these 2 photos.

How can you watch for Taurid fireballs? Moonlight will interfere on the prime time viewing hours from late night until dawn, with the peak viewing coming just after the midnight hour. Still, if you’re in a country location, be watchful. Maybe grab a lawn chair and bask under the moonlight for an hour or two, keeping an eye out for meteors.

In general, the South Taurids offer about 5 meteors per hour at their peak, but the North Taurid shower may a few more meteors to the mix. How many you’ll see will depend on how far from city lights you are … and how bright the meteors are. If they’re bright enough, they’ll overcome the bright moonlight.

Taurid meteors radiate from the constellation Taurus, but they’ll appear in all parts of the sky.

The Taurid meteor stream consists of an extremely wide roadway of far-flung debris left behind by Comet 2P Encke. When Earth travels through this belt of comet debris, bits and pieces of Comet 2P Encke smash into the Earth’s upper atmosphere to vaporize as rather slow-moving Taurid meteors (28 km/17 miles per second).

Apparently, the original Taurid stream has been perturbed by Jupiter into two branches: South and North Taurids.

Comet Encke, parent of the Taurid meteor shower. Image via Messenger

Bottom line: Despite the bright moon, we’re hoping for at least a smattering of Taurid fireballs in 2017! It’s time to start watching for them. What to expect from the South Taurid shower, and when to watch.

from EarthSky http://ift.tt/2z7r7Tp

Manasquan Reservoir reflections

Image via John Entwistle.

John Entwistle captured this image of fall colors reflected in New Jersey’s Manasquan Reservoir in late October 2017. Notice all the layers – the blue sky, white clouds, autumn leaves, the water in shadow and light, the grassy ground.

Thank you John!

from EarthSky http://ift.tt/2gV6Jdp

Image via John Entwistle.

John Entwistle captured this image of fall colors reflected in New Jersey’s Manasquan Reservoir in late October 2017. Notice all the layers – the blue sky, white clouds, autumn leaves, the water in shadow and light, the grassy ground.

Thank you John!

from EarthSky http://ift.tt/2gV6Jdp

Waxing toward full Hunter’s Moon

Image above: Jacob Baker of Fall River, Massachusetts calls this image the “Path of the Hunter Moon.” It’s a 16-shot composite of 2016’s Hunter’s Moon, made of photos taken in 10-minute intervals over 2 1/2 hours.

Tonight – November 2, 2017 – the moon is waxing for all of us, around the globe. If you’re in the Northern Hemisphere, it’s waxing toward a full Hunter’s Moon and second full moon of autumn. If you’re in the Southern Hemisphere, the moon is waxing toward your second full moon of springtime.

For all of us, full moon will come on November 4 at 5:23 UTC; translate to your time zone. At United States time zones, that places the time of full moon on November 4, 2017 at 1:23 a.m. EDT, 12:23 a.m. CDT- and on November 3 at 11:23 p.m. MDT and 10:23 p.m. PDT.

The times don’t really matter. No matter where you live worldwide, look for a full-looking moon in the east as the sun goes down over the next several days. This full or full-looking moon will cross our skies throughout the night, as seen from around the globe.

For us in the Northern Hemisphere, this Hunter’s Moon will be displaying its unique features, characteristic of this time of year. That is, the inclination of our moon’s orbital plane to the celestial equator will cause the moon to rise further north along the eastern horizon for nearly all of the upcoming week. For northerly latitudes in the Northern Hemisphere, these more northerly moonrises reduce the lag time between successive moonrises, which is the legacy of the Hunter’s Moon.

Meanwhile, in the Southern Hemisphere, the opposite is taking place. The more northerly moonrises along the horizon mean a longer-than-average time between successive moonrises, from night to night, over the coming nights.

Tonight’s moon shines fairly close to the planet Uranus on the sky’s dome. That means this faint world will be lost in the glare of the almost-full moon.

November 2-3, 2017 moon is near the planet Uranus on the sky’s dome.

Even on a dark moonless night, Uranus appears – at best – as a faint speck of light to the eye alone. You need exceptional vision to see this distant world without an optical aid, even under the best conditions. Here’s a good sky chart, if you want to see Uranus.

Just be aware Uranus is up there, near this nearly full moon. And think about the fact that Uranus is a real oddity in that it goes around the sun “sideways,” with its rotational axis almost lining up with its orbital plane. In contrast, the rotational axis of our planet Earth is inclined about 23.5^o out of perpendicular to our orbital plane.

The orbital planes of Uranus’ major moons pretty much coincide with the planet’s equatorial plane. That’s in spite of the fact that Uranus’ equatorial plane is nearly perpendicular to the plane of its orbit around the sun.

As a general rule, the major moons in our solar system orbit their parent planets above their respective planets’ equators. There are a few exceptions: Saturn’s moon Iapetus, Neptune’s moon Triton – and, perhaps most significantly to us earthlings: Earth’s moon.

Our moon doesn’t orbit the Earth above our planet’s equator (0^o latitude). Rather the moon’s orbital plane is inclined to the Earth’s equatorial plane. The moon’s orbital path took the moon from its maximum declination of 19.7^o south of the celestial equator on October 26, and then the moon will swing to its maximum declination of 19.5^o north of the celestial equator on November 8.

If the moon’s orbital plane – like that of Uranus’ moons – coincided with our planet’s equatorial plane, our moon would always rise due east and set due west – meaning no Hunter’s Moon in autumn. The Hunter’s Moon will come on the night of November 3-4, as the moon is going eastward as well as northward in its orbit.

Near-infrared image of the ice giant Uranus , its rings and some of its moons. Image credit: European Southern Observatory

Bottom line: To the eye, the moon will appear nearly full as the sun sets on November 2. Watch for it in the east as soon as the sun goes down. In fact, it has a bit more to go, and full moon is November 3-4.

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Image above: Jacob Baker of Fall River, Massachusetts calls this image the “Path of the Hunter Moon.” It’s a 16-shot composite of 2016’s Hunter’s Moon, made of photos taken in 10-minute intervals over 2 1/2 hours.

Tonight – November 2, 2017 – the moon is waxing for all of us, around the globe. If you’re in the Northern Hemisphere, it’s waxing toward a full Hunter’s Moon and second full moon of autumn. If you’re in the Southern Hemisphere, the moon is waxing toward your second full moon of springtime.

For all of us, full moon will come on November 4 at 5:23 UTC; translate to your time zone. At United States time zones, that places the time of full moon on November 4, 2017 at 1:23 a.m. EDT, 12:23 a.m. CDT- and on November 3 at 11:23 p.m. MDT and 10:23 p.m. PDT.

The times don’t really matter. No matter where you live worldwide, look for a full-looking moon in the east as the sun goes down over the next several days. This full or full-looking moon will cross our skies throughout the night, as seen from around the globe.

For us in the Northern Hemisphere, this Hunter’s Moon will be displaying its unique features, characteristic of this time of year. That is, the inclination of our moon’s orbital plane to the celestial equator will cause the moon to rise further north along the eastern horizon for nearly all of the upcoming week. For northerly latitudes in the Northern Hemisphere, these more northerly moonrises reduce the lag time between successive moonrises, which is the legacy of the Hunter’s Moon.

Meanwhile, in the Southern Hemisphere, the opposite is taking place. The more northerly moonrises along the horizon mean a longer-than-average time between successive moonrises, from night to night, over the coming nights.

Tonight’s moon shines fairly close to the planet Uranus on the sky’s dome. That means this faint world will be lost in the glare of the almost-full moon.

November 2-3, 2017 moon is near the planet Uranus on the sky’s dome.

Even on a dark moonless night, Uranus appears – at best – as a faint speck of light to the eye alone. You need exceptional vision to see this distant world without an optical aid, even under the best conditions. Here’s a good sky chart, if you want to see Uranus.

Just be aware Uranus is up there, near this nearly full moon. And think about the fact that Uranus is a real oddity in that it goes around the sun “sideways,” with its rotational axis almost lining up with its orbital plane. In contrast, the rotational axis of our planet Earth is inclined about 23.5^o out of perpendicular to our orbital plane.

The orbital planes of Uranus’ major moons pretty much coincide with the planet’s equatorial plane. That’s in spite of the fact that Uranus’ equatorial plane is nearly perpendicular to the plane of its orbit around the sun.

As a general rule, the major moons in our solar system orbit their parent planets above their respective planets’ equators. There are a few exceptions: Saturn’s moon Iapetus, Neptune’s moon Triton – and, perhaps most significantly to us earthlings: Earth’s moon.

Our moon doesn’t orbit the Earth above our planet’s equator (0^o latitude). Rather the moon’s orbital plane is inclined to the Earth’s equatorial plane. The moon’s orbital path took the moon from its maximum declination of 19.7^o south of the celestial equator on October 26, and then the moon will swing to its maximum declination of 19.5^o north of the celestial equator on November 8.

If the moon’s orbital plane – like that of Uranus’ moons – coincided with our planet’s equatorial plane, our moon would always rise due east and set due west – meaning no Hunter’s Moon in autumn. The Hunter’s Moon will come on the night of November 3-4, as the moon is going eastward as well as northward in its orbit.

Near-infrared image of the ice giant Uranus , its rings and some of its moons. Image credit: European Southern Observatory

Bottom line: To the eye, the moon will appear nearly full as the sun sets on November 2. Watch for it in the east as soon as the sun goes down. In fact, it has a bit more to go, and full moon is November 3-4.

from EarthSky http://ift.tt/2enYxEd