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Thu, 06 May 2021
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Strange Skies


Kentucky viewer video captures multiple optical phenomenon in the sky at once

Multiple sky phenomena in Kentucky
© Maria Escobar
Our weather has been quiet, but that doesn't mean unique and interesting things can't still happen. A WHAS11 viewer sent the First Alert Storm Team video of multiple halos in the Kentucky sky early Thursday afternoon. We all have seen halos around the sun, but how about four? Seeing more than one optical phenomena in the sky isn't uncommon but becomes increasingly rare as you count up.

In the video we count at least four different optics: a 22° circular halo, sun dog, upper tangent, and circumzenithal. How do these come to be? In the sky, under the right conditions, water drops or ice crystals act as a prism. As light passes through the water or ice in high cirrus clouds, it is refracted or reflected and creates halos, sun dogs and other features.
Sun halos over Kentucky


Follow-up on recent NEO objects

Below you can find a selection of some objects for which we recently made follow-up observations at the "Osservatorio Salvatore di Giacomo, Agerola, ITALY" (MPC code L07; Observers E. Guido, A. Catapano, F. Coccia) while they still were on the NEOCP list. More details about the telescope, the magnitude, number of images & exposition, asteroid speed & PA etc. are on the images. Click on each image for a bigger version. All the processing has been made with TYCHO software by D. Parrott.

2020 VX5 (neocp designation C3WZUQ2) is an Apollo-type asteroid discovered by G96 Mt. Lemmon Survey on November 15, 2020. This asteroid has an estimated size of 55 m - 120 m (H=23.4) and it had a close approach with Earth at about 29 LD (Lunar Distances = ~384,000 kilometers) or 0.074 AU (1 AU = ~150 million kilometers) at 1950 UT on 11 Nov. 2020.
2020 VX5
© Remanzacco Blogspot


Sun halo, tangental arcs spotted in the skies of central Alabama

Sun halo Alabama
© Michelle Miklik
Sun dog with upper and lower tangental arcs above and below the sun.
Michelle Miklik spotted this in the sky over Weaver, Alabama Wednesday afternoon. Did you see something similar?

Sun dog with upper and lower tangental arcs above and below the sun. Photo: Michelle Miklik

If you did, you spotted an atmospheric optical phenomenon known as a 22-degree halo.

What are sun halos?

Earthsky.org explains it very simply: "Halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads."


New feature of STEVE discovered by scientist

STEVE over Kenosee Lake
© Copyright Neil Zeller, used with permission
Taken July 17, 2018, at Little Kenosee Lake, Saskatchewan, Canada, this photo shows the tiny green streaks below STEVE. Neil Zeller, photographer and co-author on the paper, commented “STEVE was bright and powerful for a full hour that night.”
In 2018, a new aurora-like discovery struck the world. From 2015 to 2016, citizen scientists reported 30 instances of a purple ribbon in the sky, with a green picket fence structure underneath. Now named STEVE, or Strong Thermal Emission Velocity Enhancement, this phenomenon is still new to scientists, who are working to understand all its details. What they do know is that STEVE is not a normal aurora - some think maybe it's not an aurora at all - and a new finding about the formation of streaks within the structure brings scientists one step closer to solving the mystery.

"Often in physics, we build our understanding then test the extreme cases or test the cases in a different environment," Elizabeth MacDonald, a space scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, explains. "STEVE is different than the usual aurora, but it is made of light and it is driven by the auroral system. In finding these tiny little streaks, we may be learning something fundamentally new in how green auroral light can be produced."

These "tiny little streaks" are extraordinarily small point-like features within the green picket fence of STEVE. In a new paper for AGU Advances, researchers share their latest findings on these points. They suggest the streaks could be moving points of light - elongated in the images due to blur from the cameras. The tip of the streak in one image will line up with the end of the tail in the next image, contributing to this speculation from the scientists. However, there are still a lot of questions to be answered - determining whether the green light is a point or indeed a line, is one extra clue to help scientists figure out what causes green light.

"I'm not entirely sure about anything with respect to this phenomenon just yet," Joshua Semeter, a professor at Boston University and first author on the paper, said. "You have other sequences where it looks like there is a tube-shaped structure that persists from image to image and doesn't seem to conform to a moving point source, so we're not really sure about that yet."


Unexplained brightness from colossal explosion that outshone a kilonova

Merger of Two Neutron Stars
© NASA, ESA, W. Fong (Northwestern University), and T. Laskar (University of Bath, UK)
Maunakea, Hawaii - Astronomers have discovered the brightest infrared light from a short gamma-ray burst ever seen, with a bizarre glow that is more luminous than previously thought was possible.

Its half-second flash of light, detected in May of this year, came from a violent explosion of gamma rays billons of light-years away that unleashed more energy in a blink of an eye than the Sun will produce over its entire 10-billion-year lifetime.

The study has been accepted in The Astrophysical Journal and will be published online later this year. A pre-print is available on arXiv.org.

"It's amazing to me that after 10 years of studying the same type of phenomenon, we can discover unprecedented behavior like this," said Wen-fai Fong, assistant professor of physics and astronomy at Northwestern University and lead author of the study. "It just reveals the diversity of explosions that the universe is capable of producing, which is very exciting."

NASA's Hubble Space Telescope quickly captured the glow within just three days after the burst and determined its near-infrared emission was 10 times brighter than predicted, defying conventional models.

"These observations do not fit traditional explanations for short gamma-ray bursts," said Fong. "Given what we know about the radio and X-rays from this blast, it just doesn't match up. The near-infrared emission that we're finding with Hubble is way too bright."


Another possible Nova in M31

Just few days after the discovery of the nova in M31 designated as AT2020xyv, we report our discovery of another possible nova in M31 on a 240-s R-band CCD frame taken on 2020 Oct. 30.91 UT with the 0.5 m f/8 Ritchey Chretien + CCD FLI PL4240 at MPC Code L07 (Osservatorio Salvatore di Giacomo, Agerola, ITALY), with magnitude R = 18.48 +- 0.10 at coordinates:

R.A. = 00 45 28.80, Decl.= +41 54 10.0 (equinox 2000.0; Gaia DR2).

This transient PNV J00452880+4154100 has been independently discovered by Darnley et al. as reported on ATel #14130 of 31 Oct 2020; 07:32 UT and identified by them as the eruption of recurrent Nova M31N 2008-12a.

Our discovery image of this transient (click on it for a bigger version):
Nova M31
© Remanzacco Blogspot


Discovery of a new nova in M31

A new M31 nova candidate was independently discovered on 2020 Oct. 21.741 (by K. Hornoch and H. Kucakova), on 2020 Oct. 21.92 UT (by A. Catapano, L. Izzo, E. Guido, A. Noschese, F. Coccia, L. D'Avino) and 2020 Oct. 22.550 UT (by M. Zhang and X. Gao) and designated as PNV J00423733+4120519 = AT2020xyv = M31N 2020-10e (ATel #14114). This possible nova was first reported on 2020 Oct. 22.56 by Zhang and Gao as a new source of G ~ 16.9 mag on CBAT "Transient Object Followup Reports" (TOCP PNV J00423733+4120519).

Spectroscopic observations of AT2020xyv (PNVJ00423733+4120519) were obtained with the 3.58m TNG telescope equipped with LRS at Observatorio del Roque de los Muchachos in La Palma (Spain) by L. Izzo et al. (ATel #14116). Observations started on October 24 at 01:12:54 UT and they consisted of three exposures of 600s each: "The combined spectrum (covering the range 3,500-8,000 AA, resolving power R = 585) shows bright emission lines of H-alpha and H-beta, the presence of O I 7773 and Fe II lines (multiplet 42 and blended multiplets 37 and 38). From the H-alpha profile, we measure an FWHM of ~4,000 km/s. H-alpha and H-beta lines show P-Cygni profiles (although not prominent) with a minimum at ~ -2,800 km/s. The spectrum is then consistent with a broad-line Fe IIb Classical Nova in M31".

On 2020 Oct. 22.6, we reported on the TOCP our independent discovery of this nova in M31 on a 180-s R-band CCD frame taken on 2020 Oct. 21.92 UT with the 0.5 m f/8 Ritchey Chretien + CCD FLI PL4240 at MPC Code L07 (Osservatorio Salvatore di Giacomo, Agerola, ITALY) at the following coordinates:

R.A. = 00 42 37.33, Decl.= +41 20 52.1 (equinox 2000.0; Gaia DR2).

Our discovery image (click on it for a bigger version):
New Nova in M31
© Remanzacco Blogspot

Bizarro Earth

Largest and deepest ozone hole in years over Antarctica

Antarctica, White Island
© CC BY-SA 2.0 / Eli Duke / Antarctica, White Island
Both small and short-lived ozone holes, as well as bigger ones are known to be driven by very special meteorological conditions: cold stratosphere temperatures have been found to be behind astonishing increases in their size, whereas warming typically causes them to shrink.

A hole in the ozone layer over Antarctica occurs regularly, but now it has expanded to one of its biggest recorded sizes over the past few years, scientists report, as cited by Science Alert.

Fresh estimates from the European Space Agency's Copernicus Sentinel-5P satellite show that the ozone hole reached a maximum size of roughly 25 million square kilometres on 2 October, thereby outpacing the measurements of 2018 and 2015's ozone holes - 22.9 and 25.6 million square kilometres respectively.

Yet, 2020's maximum peak isn't the largest on record. That title belongs to the 29.9-million square kilometre hole registered back in 2000, however, this year's hole is still one of the deepest in recent years.

Atmospheric scientist Vincent-Henri Peuch from the European Centre for Medium-Range Weather Forecasts admits there is a certain variability in the development of such holes from year to year, noting that while it resembles the one from 2018, it "is definitely in the upper part of the pack of the last 15 years or so".


More mysterious red auroras captured around the Arctic Circle

Auroras are still glowing red @ Utsjoki, Finnish Lapland
© Rayann Elzein
Taken on October 17, 2020 @ Utsjoki, Finnish Lapland
Spoiler alert: We do not know the answer to this question. Where did all the red auroras come from? For much of mid-October, Earth's magnetic field has been very quiet. Extremely quiet. There should have been no auroras at all, yet around the Arctic Circle, photographers recorded scenes like this.

Photographer Rayann Elzein of Utsjoki, Finland, took the picture on Oct. 17th. "I photographed similar displays on Oct. 12th, 13th, 14th, and 15th," says Elzein. "On each occasion, geomagnetic activity was very low (with K-indices no greater than 0 or 1)."

Red auroras appear when particles from space strike oxygen atoms near the top of Earth's atmosphere. However, as Les Cowley explains, the very slow atomic transitions which produce red photons in the aurora zone are easily interrupted. Even experienced observers rarely see them.

Elzein has been chasing auroras in Finland for 10 years. He prides himself on going out in all conditions--even when geomagnetic activity is nominally low. "I can't recall ever seeing so much red on top of the green layer before," he says.

In Tromsø, Norway, aurora tour guide Markus Varik had a similar experience. "Activity was extremely low on Oct. 17th when pink and red colors appeared. After years of guiding, I have never seen anything similar to this."

Comment: Rare red auroras captured over Utsjoki, Finland


'Three suns' appear in the sky of China's northernmost city

Three suns over China
Residents of a Chinese city have been amazed to see what appeared to be three suns hanging in the sky at the same time.

The optical illusion lasted three hours this morning in Mohe, the country's northernmost city near the Russian border.

The spectacle is caused by a natural phenomenon known as 'sun dogs' and rarely happens in China, according to experts.

The stunning scene occurred from 6.30am to 9.30am in the Mohe town of Tuqiang. Mohe is part of the Daxing'anling region of north-eastern Heilongjiang Province.