Re: Planets, Comets, Asteroids, etc.
Posted: Tue Mar 22, 2022 8:18 pm
Off Topic
I speak from experience when I tell you not to listen to singing wine glasses or a glass harmonica while driving long-distance.
Falsehoods Unchallenged Only Fester and Grow
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W. Kevin Vicklund wrote: ↑Tue Mar 22, 2022 8:18 pmOff TopicI speak from experience when I tell you not to listen to singing wine glasses or a glass harmonica while driving long-distance.
Strange 'reverse shock wave' supernova is exploding in the wrong direction
Part of the shock wave is shrinking rather than expanding.
A powerful shock wave traveling through a cloud of gas left behind by the explosive death of a star has a bizarre quirk: Part of it is traveling in the wrong direction, a new study reveals.
In the study, researchers found that the shock wave is accelerating at different rates, with one section collapsing back toward the origin of the stellar explosion, or supernova, in what the study authors call a "reverse shock."
Cassiopeia A is a nebula, or gas cloud, left behind by a supernova in the constellation Cassiopeia, around 11,000 light-years from Earth, making it one of the closest supernova remnants. The nebula, which is around 16 light-years wide, is made of gas (mainly hydrogen) that was expelled both before and during the explosion that ripped apart the original star. A shock wave from that explosion is still rippling through the gas, and theoretical models show that this shock wave should be expanding evenly, like a perfectly rounded balloon that's constantly being inflated.
In the new study, the researchers analyzed the movement of the shock wave, using X-ray images collected by NASA's Chandra X-ray Observatory, a telescope that orbits Earth. The data, collected over 19 years, confirmed that part of the western region of the shock wave was, in fact, retreating in the opposite direction in a reverse shock.
But they also discovered something even more surprising: Parts of the same region were still accelerating away from the supernova's epicenter, like the rest of the shock wave.
Scientists simulated a supernova blast with a foam ball and a laser
Simulating clouds of gas in space with foam balls and laser beams is helping us figure out how supernovae can stimulate star formation. These small-scale experiments could deepen our understanding of the formation of our own solar system, which may have been born in such a cloud.
Astrophysicists think that molecular clouds, which are billowing clumps of gas, dust and space, can become stellar nurseries when they interact with shock waves from supernovae. In theory, the shock waves stretch and squeeze the gas and create dense areas that can then collapse into stars. This process is difficult to study in detail from afar, though, and it includes complex dynamical effects such as turbulence that are difficult to simulate in computers.
One solution is to build models of these systems in a laboratory that behave similarly and can be observed in detail. Bruno Albertazzi at the École Polytechnique in Paris and his colleagues used a sphere of carbon-hydrogen foam about 1 millimetre across to represent the molecular cloud.
They placed the sphere in a chamber with a small carbon pin, then fired a high-energy laser at the pin, rapidly heating it until it exploded. “It’s similar to the explosion of a star, but much smaller,” says Albertazzi. This explosion sent a shock wave through the foam similar to the shock wave that a supernova could send through a molecular cloud.
The researchers then analysed the foam ball to see if it ended up with any anomalously dense spots after the shock wave passed. These spots would represent the dense areas in a molecular cloud that could then collapse in on themselves to form stars.
https://www.nytimes.com/2022/04/21/scie ... hower.html. Thursday night into Friday morning will be one of the special dates scattered throughout each year when skywatchers can catch a meteor shower as a multitude of flares potentially burst in the darkness.
Meteor showers occur when our planet runs into the debris field left behind by icy comets or rocky asteroids going around the sun. These small particles burn up in the atmosphere, leading to blazing trails of light. The regularity of orbital mechanics means that any given meteor shower happens at roughly the same time each year.
One of the first major meteor showers of spring is the Lyrids. They have been active since April 15 and go to the 29th, but they will peak April 21 to 22, or Thursday night and early Friday morning.
The meteors originate from a comet called C/1861 G1, also known as Thatcher. It is a morning shower, best viewed in the early hours before dawn in the Northern Hemisphere, though some activity will be visible in the Southern Hemisphere.
How to See Jupiter and Venus Appear to 'Nearly Collide' This Week
The planets join the waning moon this month to provide a celestial wake-up call worth answering before sunrise.
The pre-dawn hours are bringing a planet-spotting party for skywatchers this week. Jupiter, Venus, Mars and Saturn will be visible in a diagonal line, joined by a waning crescent moon.
Look for this cosmic gang in the east-southeast sky before dawn. You can typically distinguish planets from stars as they are brighter and twinkle less. Jupiter will be the lowest and furthest to the left, followed by Venus, Mars and Saturn tracing an invisible line moving up and to the right.
For help spotting planets, an app like Stellarium can be quite helpful.
A fifth planet is also visible in the night sky but not at the same time. Mercury can be seen in the evening but will set before the others arise in the morning.
The quartet of worlds will reappear each morning for the rest of the month as the moon shrinks in the sky. In the coming nights, we'll see this grinning moon slide beneath the lineup of planets on successive nights. It underlined Saturn on April 25, Mars the following night, and emphasizes both Jupiter and Venus on April 27.
A loud boom prefaced a streaking fireball spotted in three Southern states, scientists confirmed Thursday.
More than 30 people in Arkansas, Louisiana and Mississippi reported seeing the exceptionally bright meteor in the sky around 8am Wednesday after hearing loud booms in Claiborne county, Mississippi, and surrounding areas, Nasa reported. It was first spotted 54 miles (87 km) above the Mississippi River, near Alcorn, Mississippi, officials said.
“This is one of the nicer events I have seen in the GLM (Geostationary Lightning Mappers) data,” said Bill Cooke, lead of Nasa’s Meteoroid Environments Office at Marshall Space Flight Center in Huntsville, Alabama.
The object, which scientists called a bolide, moved south-west at a speed of 55,000 miles per hour, breaking into pieces as it descended deeper into Earth’s atmosphere. It disintegrated about 34 miles (55 km) above a swampy area north of the unincorporated Concordia Parish community of Minorca in Louisiana.
NASA Mars Rover Makes a Charming Zen Rock Garden by Accident
Breathe deep and enjoy the meditative Martian view.
Sky here is pretty clear ... went outside to look -- the moon is about 1/2 covered -- supposed to completely eclipse at ~12am. (SWFL)
Saw it at max. Looked good. Odd that nobody else was outside watching (which was okay with me -- peaceful) -- guess they went to bed for school and work in the morning.