The strange glowing rings around a distant ice giant

Strange things happened a long time ago in the cold and distant realm of the two giant ice planets of our Solar System, Uranus and Neptune, the duo of beautiful blue-banded inhabitants of the outer region of the planetary system that surrounds our Sun. , the blue-green Uranus stands out from the crowd of the eight known major planets in our Solar System. This is because Uranus is believed to have been violently toppled on its side when a doomed primordial world that was twice the size of Earth plunged into it billions of years ago. Uranus is also surrounded by a system of mysterious dark, thin rings that are invisible to all but the largest telescopes. For this reason, the moons of Uranus were not discovered until 1977. Nevertheless, In June 2019, a team of astronomers announced that Uranus’s rings are surprisingly bright in heat images of the ice giant taken by a pair of large telescopes in the high deserts of Chile.

This thermal glow provides astronomers with a new understanding of the nature of these exotic rings, which have been successfully observed simply because they reflect a small amount of light in the visible or optical range and in the near infrared. The new images were obtained from the Atacama Large Millimeter / submillimeter Array (ALMA) and the Very Large Telescope (VLT), and allowed the team of astronomers to measure the temperature of the rings for the first time. The rings of Uranus are icy structures: a cold 77 Kelvin, or 77 degrees above absolute zero: the boiling temperature of liquid nitrogen and equivalent to 320 degrees below zero Fahrenheit.

The new observations also verify that Uranus’ brightest and densest ring, called the epsillon ring, is different from the other known ring systems that surround other planets in our Solar System. This difference is especially pronounced for Saturn’s beautiful and spectacular ring system.

“Saturn’s mostly icy rings are wide, bright, and have a variety of particle sizes, from micron-sized dust in the innermost part. Ring D to tens of meters in size in the main rings. The small end is missing on the main rings of Uranus, the brightest ring epsilon it is made up of rocks the size of a golf ball and larger, “commented Dr. Imke de Pater on June 20, 2019. University of California Berkeley (UCB) press release. Dr. de Pater is a professor of astronomy at UCB.

In dramatic contrast, Jupiter’s rings are made up mostly of tiny, micrometer-sized particles. Neptune’s rings are also mostly made up of dust, and even Uranus has extensive layers of dust sandwiched between its thin main rings. One micron it is one thousandth of a millimeter.

Wandering primordial worlds

In the cold and dim outer solar system, in the distant realm of the giant planets, Uranus casts a mysterious emerald-green glow on its icy family of moons. The moon of Uranus Miranda is especially interesting. It is a tiny lunar world that shows a chaotic icy surface that is unlike any other known world in our Solar System. Many astronomers think that the original Miranda was smashed into fragments billions of years ago, and after the shipwreck, the remaining, frozen, mismatched fragments of the original moon collided and merged. The messy chunks of ice, brought together again by the force of gravity, created a strange new moon with a chaotic and messy terrain.

Uranus was discovered on March 13, 1781 by the German-born English astronomer William Herschel (1738-1822), and its discovery was a complete accident. While observing the stars in the night sky, using a telescope that he had built, Herschel noticed that one of these “stars” seemed to travel to the beat of a different drum. After observing this strange “star” many more times, he realized that it was not a star at all, and that it was orbiting our Sun. The strange “star” was the planet we now call Uranus.

At last count, Uranus is orbiting 27 moons that are made up of rock, ice, or both. All the moons of Uranus are named after characters from the works of William Shakespeare. The character Miranda is the heroine of FOR Summer night Dream.

Uranus is the seventh major planet from our star, and Uranus, and its ice giant brother Neptune, almost certainly did not form where they are now, 19 and 30. astronomical units (AU) of the sun. One FOR it is equivalent to the average separation between the Sun and the Earth, which is approximately 93,000,000 miles. The accretion process, which was responsible for the formation of the planets that inhabit our Solar System, was much slower farther from the Sun, where Uranus and Neptune are currently located. This primordial protoplanetary accretion disk, which was composed of gas, dust and ice, was too thin in this outer domain to allow planets of this large size to form as quickly as they would in the warmer and denser region of the disk that rotates closest to our star .

Astronomers have had a hard time creating a model that can explain how the duo of ice giants reached their present enormous sizes if they were born where they are today. Tea protoplanetary accretion disk It would have dissipated long before the giant worlds had a chance to be born in this region of our Solar System. For this reason, many astronomers think that the cores of Uranus and Neptune formed closer to the ancient Sun and then traveled to their present remote locations long ago.

While it may seem peaceful now, we really do live in a “cosmic shooting gallery.” Our first Solar System was a turbulent place where ancient objects, large and small, relentlessly smashed into each other, smashing each other into fragments after colliding. These ever-growing primordial objects grew from the size of a pebble, to the size of a mountain, to the size of the moon, to the size of a planet in the crowded and violent disk environment. Sometimes ancient planet-sized bodies smashed into other planet-sized worlds, wreaking havoc. Gravitational influences, which resulted from the wanderings of these migrating worlds, shot some planets howling into other regions of our Solar System, or even outside of our Solar System altogether.

Uranus orbits our star sideways. Uranus’ axis of rotation is roughly parallel to the plane of our Solar System, with an axial tilt of 97.77 (defined by prograde rotation). For this reason, Uranus undergoes seasonal changes that are different from all other planets in our Sun’s family. Near the solstice, one pole faces our star continuously, while the other pole continually moves away. Only a very narrow region around the equator of Uranus experiences a rapid day-night cycle.but with the sun hovering low over the horizon. On the contrary, on the other side of the orbit of Uranus, the orientation of the poles towards our Sun is the opposite. Each pole receives approximately 42 years of incessant sunlight, followed by approximately 42 years of endless darkness. Approaching the time of the equinoxes, our Star faces the equator of Uranus giving a period of day-night cycles similar to those experienced in most of the other planets that inhabit our Solar System.

Uranus experienced its most recent equinox on December 7, 2007. One consequence of this axis orientation is that, averaged over the span of one Uranian year, the polar regions of Uranus receive a greater input of energy from our Sun than its equatorial regions. . Despite this, Uranus is hotter at its equator than at its poles, and the cause of this is unknown. The reason given for Uranus’ strange axial tilt is equally unknown. However, the usual explanation given is that, about 4.5 billion years ago, an Earth-sized protoplanet collided with Uranus, thus skewing its orientation.

The strange rings of a distant ice giant

Various theories have been proposed to explain the origin of Uranus’s rings: they could be ancient asteroids trapped by the gravity of the giant green planet, the shattered remains of shattered moons that blew up against each other, the relic fragments of shattered moons when they roamed as well. near its parent planet, or remnants of the ancient formation of our Solar System.

The new data was published in the July 2019 issue of The astronomical diary. De Pater and Molter led the SOUL observations, while Dr Michael Roman and Dr Leigh Fletcher from the University of Leicester in the UK led the VLT observations.

“The rings of Uranus are compositionally different from the main ring of Saturn in that in optics and infrared the albedo is much lower; they are really dark, like carbon. They are extremely narrow compared to the rings of Saturn. The most wide, the epsilon ring, varies from 20 to 100 kilometers wide, while those of Saturn are 100 or tens of thousands of kilometers wide, “explained Molter on June 20, 2019. UCB press release.

The absence of dust-sized particles in the main rings of Uranus was first detected in 1986, when Travel 2 He flew across the giant green ice planet, and obtained revealing images of them. Unfortunately, the spacecraft was unable to measure the temperature of the rings. Currently, astronomers have counted a total of 13 rings around the planet, with some bands of dust swirling between the rings. The rings of Uranus differ in other respects from those of the gas giant Saturn.

“It’s great that we can even do this with the instruments that we have. I was just trying to get a picture of the planet as best I could and I saw the rings. It was amazing,” added Molter.

Both of them VLT and SOUL The observations were designed to study the temperature structure of Uranus’s atmosphere, with VLT probing wavelengths shorter than SOUL.

The new research presents an intriguing opportunity for the next James Webb Space Telescope, which will have the ability to provide much improved spectroscopic constraints on the rings of Uranus over the next decade.

Dr. Fletcher commented on June 20, 2019. UCB press release that “We were surprised to see that the rings clearly jumped when we first reduced the data.”

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