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Thu, 23 May 2019
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Strange Skies


Moon

Moon's nearside-farside asymmetries the result of a giant impact says new study

Collision between two planetary bodies
© NASA/JPL-Caltech
Artist’s depiction of a collision between two planetary bodies. New research suggests the stark difference between the Moon’s heavily-cratered farside and the lower-lying open basins of the nearside were caused by a wayward dwarf planet colliding with the Moon in the early history of the solar system.
WASHINGTON-The stark difference between the Moon's heavily-cratered farside and the lower-lying open basins of the Earth-facing nearside has puzzled scientists for decades.

Now, new evidence about the Moon's crust suggests the differences were caused by a wayward dwarf planet colliding with the Moon in the early history of the solar system. A report on the new research has been published in AGU's Journal of Geophysical Research: Planets.

The mystery of the Moon's two faces began in the Apollo era when the first views of its farside revealed the surprising differences. Measurements made by the Gravity Recovery and Interior Laboratory (GRAIL) mission in 2012 filled in more details about the structure of the Moon - including how its crust is thicker and includes an extra layer of material on its farside.

There are a number of ideas that have been used to try and explain the Moon's asymmetry. One is that there were once two moons orbiting Earth and they merged in the very early days of the Moon's formation. Another idea is that a large body, perhaps a young dwarf planet, found itself in an orbit around the Sun that put it on a collision course with the Moon. This latter giant impact idea would have happened somewhat later than a merging-moons scenario and after the Moon had formed a solid crust, said Meng Hua Zhu of the Space Science Institute at Macau University of Science and Technology and lead author of the new study. Signs of such an impact should be visible in the structure of the lunar crust today.

"The detailed gravity data obtained by GRAIL has given new insight into the structure of the lunar crust underneath the surface," Zhu said.

Rainbow

Circumzenithal arc seen in skies of Myrtle Beach, South Carolina

Today's Ask Storm Team 11 question: What makes a cloud rainbow?
Circumzenithal arc over Myrtle Beach, SC
© Eva Higginson

This question was submitted by Eva Higginson. A cloud rainbow could be either a circumzenithal arc or what we call iridescence. The photo that Eva submitted, pictured is likely a circumzenithal arc.


Cassiopaea

Rare blue aurora and STEVE photographed over Calgary, Canada

blue aurora steve
© Taken by Harlan Thomas on May 11, 2019 @ NorthWest of Calgary, Alberta
Storm conditions developed later as Earth moved into the CMEs turbulent wake couldnt have been more true as these images protest, but to see these incredible blue pillars was out of this world. And top it off STEVE showed for several minutes
Northern Lights are usually green, sometimes red. Those are the colors we see when oxygen is hit by electrons raining down from space during a geomagnetic storm. On Friday night, May 11, 2019, however, Harlan Thomas of Calgary, Alberta, witnessed a different color: DEEP BLUE

Harlan Thomas: "To see these incredible blue pillars was out of this world," says Thomas.

In auroras, blue is a sign of nitrogen. Energetic particles striking ionized molecular nitrogen (N2+) at very high altitudes can produce a blue glow rarely seen during auroral displays. In this case, it was the afterglow of a CME impact.

The CME left the sun on May 6th, propelled in our direction by an explosion in the magnetic canopy of sunspot AR2740. When it finally arrived on May 10th, the slow-moving storm cloud rattled Earth's magnetic field, triggering a minor G1-class geomagnetic storm. Auroras were sighted in parts of Canada as well as US States such as Michigan and Minnesota.

Comment: For more on our changing skies, see: For an idea of what's driving these changes, check out SOTT radio's Behind the Headlines: Earth changes in an electric universe: Is climate change really man-made? as well as our monthly documentary SOTT Earth Changes Summary - April 2019: Extreme Weather, Planetary Upheaval, Meteor Fireballs:




Sun

'Ring around the sun' seen in Santa Ana, Costa Rica

I have never seen this before. Googling it, I learned a halo or ring around the sun is a fairly common phenomenon, typically caused when there are very high, very thin clouds, clouds, being so high in the sky, made from ice crystals, refracting and reflecting the light.
Sun halo over Costa Rica
© QCostaRica/Rico
This is the view in the sky over Santa Ana (and suspect most of Costa Rica) this morning.

Rainbow

Circumhorizontal arc spotted in western New York

Circumhorizontal arc over Lake View, NY
© WIVB/Ray
Circumhorizontal arc over Lake View, NY.
The WIVB newsroom email was filled Saturday with pictures of what looked like a horizontal rainbow.

News 4 meteorologist Stevie Daniels explained that the phenomenon is called a circumhorizontal arc.

"They form when the sun is at least 58 degrees above the horizon. The light from the sun refracts when it hits the ice crystals in the cirrus clouds!" she wrote.


Camera

Rare blue auroras seen over Calgary, Alberta

Northern Lights are usually green, sometimes red. Those are the colors we see when oxygen is hit by electrons raining down from space during a geomagnetic storm. On Friday night, however, Harlan Thomas of Calgary, Alberta, witnessed a different color: deep-blue.
Rare blue auroras over Calgary, AB
© Harlan Thomas
"To see these incredible blue pillars was out of this world," says Thomas.

In auroras, blue is a sign of nitrogen. Energetic particles striking ionized molecular nitrogen (N2+) at very high altitudes can produce a blue glow rarely seen during auroral displays. In this case, it was the afterglow of a CME impact.

Info

Scientists confirm ancient Chinese astronomical observations of a supernova

Chinese Astro Calender
© ÖTTGENS, ET AL
The text, dating from 48BCE, recording the glow in a particular spot in the night sky.
Scientists have repeated observations made almost 2070 years ago by Chinese astronomers, confirming one of the earliest ever discoveries of an event occurring beyond the solar system.

In 48BCE, the Chinese sky-watchers recorded a bright glow in a particular part of the night sky.

Now a team of researchers led by astrophysicist Fabian Göttgens from the University of Göttingen in Germany have shown that the observations related to a nova - an explosion of hydrogen on the surface of a star, located in a global cluster known as Messier 22.

The cluster, one of at least 150 thus far identified in the Milky Way, is a tightly packed group of stars located close to the galaxy's centre, some 10,600 light-years from Earth. It is sometimes called the Sagittarius Cluster.

Sun

Rare green flash snapped above clouds in California

greenflash sun
© Thom Peck
The Sun setting, but above true horizon due to the hills between us and the Pacific 20 mile away. The incoming marine layer doing some optical aid, I suspect. The green flash was not naked eye, or at least we didnt see it.
Canon t6i at f/13, 1/2000 second 250mm, ISO 200
For seaside photographers, nothing beats a green flash--that sudden pulse of verdant light at sunset as the sun vanishes beneath the ocean waves. Thom Peck of Poway CA was near the Pacific Ocean on May 4th when he captured a green flash. But it didn't come from the ocean waves. It came from the top of a cloud:

This is a rare 'cloud-top' green flash, sometimes seen as the sun's rays graze a distant cloud bank. They are not well understood. Ordinary green flashes require a temperature inversion layer near the sea surface. Similar inversions may sometimes occur at the top of marine stratus clouds.

"The green flash was not naked eye--or at least we didn't see it," says Peck. "But we photographed it easily enough using my Canon T6i digital camera." Photo settings may be found here.

Comment: Rare and yet, apparently, like many unusual phenomena, increasingly common: Also check out SOTT radio's: Behind the Headlines: Earth changes in an electric universe: Is climate change really man-made?


Info

Star in Ursa Major hints at Milky Way's cataclysmic past

Ursa Major
© Universal History Archive/UIG via Getty Images
An eighteenth century engraving of Ursa Major. Somewhere within the bear lurks a star from outside the galaxy.
Researchers have identified a star in the Milky Way they believe originated from outside the galaxy.

In a paper published in the journal Nature Astronomy, a team led by Qian-Fan Xing from the National Astronomical Observatories at the Chinese Academy of Sciences in Beijing, China, describes a star dubbed J1124+4535, located in the Milky Way constellation known as Ursa Major, or the Big Dipper.

Interest in the star began following observations made through China's Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), which indicated that the star had an unusually low abundance of magnesium.

Seeking more detail, the researchers switched to the High Dispersion Spectrograph (HDS) on the Subaru Telescope in Hawaii.

Rainbow

Circumhorizontal arc seen over Sylvania, Alabama

Circumhorizontal arc over AL
© Carly S Windsor via Twitter
This is the time of year that some neat things happen in the sky as clouds interact with sunlight! High thin cirrus, altocumulus and daytime heating-driven, puffy, white cumulus clouds made for a cool scene over DeKalb County Wednesday afternoon.

This is a 'fire rainbow' (or the scientific name: circumhorizontal arc - here's one from a year ago on WHNT.com.)