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Gorgeous NASA Simulations Show What Sunsets Would Look Like on Other Worlds – ScienceAlert

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How would the Sun look as it dipped below the horizon on a long (17 hour) day on Uranus? Or what would a late-night sunset on Mars look like, when we finally get there? Thanks to some NASA computer modelling, these scenarios are now a little easier to imagine.

What makes a sunset is the interplay of light from the Sun – which includes all the colours of the rainbow – together with the gases and dust in the atmosphere. The less atmosphere, the less impressive the sunset.

Planetary scientist Geronimo Villanueva, from NASA’s Goddard Space Flight Center in Greenbelt, has created simulations of how sunsets might look on Venus, Mars, Uranus, the Saturn moon Titan, and Trappist-1e.

The shows are quite spectacular, as you can see below, with scenes shown as if you were pointing a camera with a super-wide lens up at the sky.

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On Venus, for example, a bright yellow fades down into orange, brown, and then black as the Sun disappears. Since the planet rotates on its axis so slowly, you’d need to wait around 116 times as long as you would on Earth, which is a little more than half of a Venusian year.

Not that you’d necessarily be settling down to watch the sunset on Venus, what with its thick, CO2-heavy atmosphere, intense surface pressure, and average temperatures of 471 degrees Celsius (880 degrees Fahrenheit).

These simulations aren’t just fun to watch. They have a serious scientific point to them, too – preparations ahead of a potential probe mission to Uranus. There’s still a lot we don’t know about the gas planet, and any readings of its atmosphere would need to interpret the levels of light reaching the spacecraft’s sensors.

With data from this simulation on board, the probe would have a better idea of what it was looking for, and could better assess the composition of the atmosphere as it absorbed sunlight – which wavelengths were being scattered, and by what.

Here’s another look at the beautiful sunset models:

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The new models are now a part of the Planetary Spectrum Generator, built by Villanueva and his colleagues, which is used to interpret light reaching our telescopes, and to decode it to try and understand what the atmosphere is like on other worlds.

Mars is the only other planet we have a realistic chance of living on, unless we’re going to spend all our time in an incredibly strong and robust floating spaceship that can resist extremes of pressure and temperature.

Villanueva’s simulation shows how the Martian sunset would look to its inhabitants, with the atmosphere creating a mix of muddy brown and bright yellow colours as the Sun disappeared behind the horizon.

In fact, these simulations are only part of the story – as the Curiosity rover has already shown, days on Mars can end with a distinctly blue-ish tinge, as the dust scatters the red wavelengths of light away from view, leaving the blue wavelengths to hit our eyes. If only we could go and see for ourselves.

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Researchers spotted something strange in space and can't explain it – lintelligencer

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Researchers spotted something strange in space and can’t explain it

Researchers have spotted a new class of radio objects in space that has never been documented before.

Known as ‘Odd Radio Circles’ or ORC, it’s believed they may be coming from a mysterious structure from another galaxy, unseen by human eyes.

The waves take the form of blasts of colourful circular objects, which were pinpointed by cameras during a survey by the Australian Square Kilometre Array Pathfinder telescope (ASKA).

Despite searching for an optical, infrared, or X-ray source to the pulses, none could be traced, leaving experts baffled.

Researchers have concluded it is a never before recorded phenomenon, a review in Nature Astronomy reports.

The results of the extraordinary study are still to be peer-reviewed but offer a tantalising glimpse of a deep space mystery that could one day yield answers about the mysteries of the universe.

Researchers zoomed in on the objects during a survey of the universe using the ASKA.

After three snaps of the mysterious ORCS were captured they were compared to the existing archive and found to match a similar radio wave structure located in March 2013.

The authors of the study note radio images are normally sphere space objects – like remnants of dying stars as well as proto-planetary discs

These new ORCs by contrast “appear to be a new class of astronomical objects” they said.

A team of Astrophysicists write: ” We have found an unexpected class of astronomical objects which have not previously been reported, in the Evolutionary Map of the Universe Pilot survey, using the Australian Square Kilometre Array Pathfinder telescope.

“The objects appear in radio images as circular edge-brightened discs about one arcmin diameter, and do not seem to correspond to any known type of object.

“We speculate that they may represent a spherical shock wave from an extra-galactic transient event, or the outflow, or a remnant, from a radio galaxy viewed end-on.

“Assumed to be not in any way connected with a supernova remnant—the structure left over after a massive star burst, it was deemed as a possible result of a spherical shock wave arising from galactic winds.

“While this is a theoretical possibility, such a shock has not yet been observed elsewhere.”

They added it is possible the strange discs represent a new category of a previously unknown phenomenon, “such as the jets of a radio galaxy”.

It is not the first time weird radio signals are speculated to be coming from another galaxy. In February Fast radio bursts were documented at the Canadian Hydrogen Intensity Mapping Experiment (CHIME) in British Columbia.

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Bright, rare comet lighting up Canadian skies for next few days – CityNews Vancouver

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WINNIPEG (CITYNEWS) – Stargazers across Canada and the world have been catching rare glimpses of the brightest comet of the last two decades – and there’s still time to do so.

Comet Neowise, named after the satellite that first discovered it, is headed toward Earth and will continue to light up the night sky for the next few days. The best times to see it are just after sunset and around 3 a.m.

Scott Young, manager of the Planetarium at the Manitoba Museum says the comet, which is composed of rock and ice, dates back to the origin of the solar system. 

“Most of the time, these are not something you can see without a telescope,” said Young. “But once in a while, one of these comets surprises us and gets brighter than expected, and that is what we are seeing here. It is visible to the unaided eye and from a location away from city lights.

“It’s really cool to see a comet like this. This is probably, almost certainly, the first time that any humans have seen this particular object.”

Young says the comet will get as close as 100 million kilometres from Earth, which is normally too far to be seen with the naked eye.

“For whatever reason, this comet has melted a lot and the tail has grown very big and bright, and that’s what we’re able to see from this distance,” he said.

Photographer Shannon Bileski has captured several snapshots of the comet in the last few days. She says her photos were made even better by the presence of very vibrant clouds in the upper atmosphere.

“They’re very incredible to see and I knew the spot that I wanted to hit, try to hit the comet and that’s where I went,” said Bileski, whose bucket list included photographing a comet. “Get out, see it, shoot it. It’s pretty amazing to see.”

The last time a comet of this calibre was visible from Earth was Comet Hale-Bopp in 1997, according to Young. He says Comet Neowise is not expected to re-enter our solar system for another 6,000 years.

“They could happen at any time,” said Young. “They’re very unpredictable. We don’t know where they all are, and sometimes a new discovery like this one will come out of nowhere and just surprise us.

“Astronomers have basically dropped everything they are doing to take advantage of this limited opportunity.”

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Cosmic Cataclysm Allows Precise Test of Einstein’s Theory of General Relativity – SciTechDaily

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The MAGIC telescope system at the Roque de los Muchachos Observatory, La Palma, Canary Islands, Spain. Credit: Giovanni Ceribella/MAGIC Collaboration

In 2019, the MAGIC telescopes detected the first Gamma Ray Burst at very high energies. This was the most intense gamma-radiation ever obtained from such a cosmic object. But the GRB data have more to offer: with further analyses, the MAGIC scientists could now confirm that the speed of light is constant in vacuum — and not dependent on energy. So, like many other tests, GRB data also corroborate Einstein’s theory of General Relativity. The study has now been published in Physical Review Letters.

Einstein’s general relativity (GR) is a beautiful theory that explains how mass and energy interact with space-time, creating a phenomenon commonly known as gravity. GR has been tested and retested in various physical situations and over many different scales, and, postulating that the speed of light is constant, it always turned out to outstandingly predict the experimental results. Nevertheless, physicists suspect that GR is not the most fundamental theory, and that there might exist an underlying quantum mechanical description of gravity, referred to as quantum gravity (QG).

Some QG theories consider that the speed of light might be energy dependent. This hypothetical phenomenon is called Lorentz invariance violation (LIV). Its effects are thought to be too tiny to be measured, unless they are accumulated over a very long time. So how to achieve that? One solution is using signals from astronomical sources of gamma rays. Gamma-ray bursts (GRBs) are powerful and far away cosmic explosions, which emit highly variable, extremely energetic signals. They are thus excellent laboratories for experimental tests of QG. The higher energy photons are expected to be more influenced by the QG effects, and there should be plenty of those; these travel billions of years before reaching Earth, which enhances the effect.

Gamma-Ray Burst Hits MAGIC

Artist’s impression of a gamma ray burst observed by the MAGIC telescope system and satellite observatories.
Credit: Superbossa.com and Alice Donini

GRBs are detected on a daily basis with satellite-borne detectors, which observe large portions of the sky, but at lower energies than the ground-based telescopes like MAGIC. On January 14, 2019, the MAGIC telescope system detected the first GRB in the domain of teraelectronvolt energies (TeV, 1000 billion times more energetic than the visible light), hence recording by far the most energetic photons ever observed from such an object. Multiple analyses were performed to study the nature of this object and the very high energy radiation.

Tomislav Terzić, a researcher from the University of Rijeka, says: “No LIV study was ever performed on GRB data in the TeV energy range, simply because there was no such data up to now. For over twenty years we were anticipating that such observation could increase the sensitivity to the LIV effects, but we couldn’t tell by how much until seeing the final results of our analysis. It was a very exciting period.”

Naturally, the MAGIC scientists wanted to use this unique observation to hunt for effects of QG. At the very beginning, they however faced an obstacle: the signal that was recorded with the MAGIC telescopes decayed monotonically with time. While this was an interesting finding for astrophysicists studying GRBs, it was not favorable for LIV testing. Daniel Kerszberg, a researcher at IFAE in Barcelona said: “when comparing the arrival times of two gamma-rays of different energies, one assumes they were emitted instantaneously from the source. However, our knowledge of processes in astronomical objects is still not precise enough to pinpoint the emission time of any given photon.”

Traditionally the astrophysicists rely on recognizable variations of the signal for constraining the emission time of photons. A monotonically changing signal lacks those features. So, the researchers used a theoretical model, which describes the expected gamma-ray emission before the MAGIC telescopes started observing. The model includes a fast rise of the flux, the peak emission and a monotonic decay like that observed by MAGIC. This provided the scientists with a handle to actually hunt for LIV.

A careful analysis then revealed no energy-dependent time delay in arrival times of gamma rays. Einstein still seems to hold the line. “This however does not mean that the MAGIC team was left empty-handed,” said Giacomo D’Amico, a researcher at Max Planck Institute for Physics in Munich; “we were able to set strong constraints on the QG energy scale.” The limits set in this study are comparable to the best available limits obtained using GRB observations with satellite detectors or using ground-based observations of active galactic nuclei.

Cedric Perennes, postdoctoral researcher at the university of Padova added: “We were all very happy and feel privileged to be in the position to perform the first study on Lorentz invariance violation ever on GRB data in TeV energy range, and to crack the door open for future studies!”

In contrast to previous works, this was the first such test ever performed on a GRB signal at TeV energies. With this seminal study, the MAGIC team thus set a foothold for future research and even more stringent tests of Einstein’s theory in the 21st century. Oscar Blanch, spokesperson of the MAGIC collaboration, concluded: “This time, we observed a relatively nearby GRB. We hope to soon catch brighter and more distant events, which would enable even more sensitive tests.”

Reference: “Bounds on Lorentz Invariance Violation from MAGIC Observation of GRB 190114C” by V. A. Acciari et al. (MAGIC Collaboration), 9 July 2020, Physical Review Letters.
DOI: 10.1103/PhysRevLett.125.021301

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