Inside-out News

    One of the aspects of the life of a popularizer is the explanation and commenting on news. Sometimes the original news looks at least strange. And at the same time it often turns out that behind the garbage of distortions are really interesting stories. Recently, I was asked to comment on a news package, united by a common theme “space objects inside out”. Not all of them turned out to be really turned out, but the initial scientific news, in my opinion, is really curious.

    Hollow Earth Globe

    Mercury inside out

    News : The unusual “spotted” nature of Mercury in terms of its chemical composition found a simple explanation - it turned out that the planet was actually turned inside out, since the rocks from the boundary between the mantle and the core were on its surface, planetologists said at a conference of geophysicists in Yokohama.

    We understand: With a modern search, finding a news source is usually quick and easy. Having typed in English something like “Mercury inside out Yokohama” we find a good publication that recounts the real-life performance of NASA scientists in Yokohama.

    Northern Volcanic Plains of Mercury, photo by NASA / JHUAPL / Carnegie Institution of Washington with enhanced colors

    The MESSENGER interplanetary station discovered the "problem" of Mercury - regions with great geological diversity were difficult to explain without using the hypothesis of melting of the heterogeneous mantle. An example of such a region is the Northern Volcanic Plains (pictured above). And a group of scientists from the Space Center. Johnson's NASA conducted a series of experiments emulating the conditions of young Mercury. They took a mixture similar in composition to enstatite chondrites.and subjected to pressures and temperatures, which are supposed to be on the border of the core and mantle of young Mercury. Temperatures are not called, and the pressure reached 50 thousand atmospheres. And it turned out that the same chemical composition at different temperatures and pressures produced different rocks, as was discovered on Mercury. Older regions formed deeper than the boundaries of the core and crust, while younger regions formed at a shallower depth. And the way they appeared on the surface is explained by the hypothesis of a collision of Mercury with planetesimal (or Venus), as a result of which Mercury lost most of the crust and upper layer of the mantle.

    Earth inside out

    News : An ancient collision turned the Earth inside out. A mountain-sized space rock hit our planet about 1.8 billion years ago. At the same time, part of the earth's crust was simply stripped off, like a scalp. In essence, it was turned upside down, as a new study of Canadian geologists convinces us.

    We understand: Without difficulty, there is a retelling of a press release of the University of Toronto with the same name "Meteorite crash turned Earth inside out: study" , which is easily misunderstood. In fact, scientists studied the Sudbury Crater, the second largest known on Earth.

    A Brief History of Sudbury Crater

    A ten-kilometer rock collided with the Earth at a speed of 40 km / s 1.8 billion years ago. The meteorite most likely evaporated, while also turning into steam 27 thousand cubic kilometers of crust. The depth of the resulting depression was approximately 30-40 km. Most of them settled in the area of ​​impact for several hours, and it turned out that the upper crust was covered with a condensed lower crust. The fact that it was just a meteorite impact was found to be based on the increased content of iridium, which is found in the Earth’s mantle (i.e. very deeply) and in meteorites. So in a sense, a piece of Earth really turned inside out.

    The nebula inside out

    News : Scientists have noticed in the constellation Snake unusual nebula HuBi 1, which is alarming for astronomers. The observed part of the interstellar medium, distinguished by its radiation or absorption against the general background of the sky, arose as a result of the fact that one of its stars “turned inside out” in the last moment of life. The sun will die in a similar way, astrophysicists say.

    Understanding: Original Blog Entryastronomer Martin Guerrero. In 2018, Martin decided to take a photo of the HuBi 1 nebula, discovered in 1990 by astronomers Hu and Bibo (and the name intentionally or accidentally sounds like “Obi Wan”, hello to “Star Wars”). And, looking at the photo, Martin first decided that he had messed up with the technique, because the nebula seemed turned inside out. The “normal” nebula has a low ionization region, red in the photo, outside, and a high ionization region, blue or green, inside. HuBi 1 had the opposite.

    HuBi 1 in the center, photo by Martin Guerrero

    Additional studies next year showed not only an unusual spectrum, but also that the central star became noticeably less bright. According to photometric data from archives, it was possible to establish that the star has faded ten thousand times since 1971. Simulations on a computer along with spectral data clarified the picture - the outer part is recombined due to a lack of ultraviolet radiation, and the central part is not ionized by photons, but experiences shock excitation from matter discharged from the star. The substance blocks the light of the star for the external observer.

    As a result, it turned out that the central star of the nebula experiences an infrequent case of the “second birth” - a late heat flare, moreover, slower than that of known similar stars (for example, the Sakurai object ).

    An unusual HuBi 1 journey along the Hertzsprung-Russell diagram, illustrated by Martin Guerrero

    It is curious that the mass of the central star HuBi 1 was estimated at 1.1 solar masses, so the probability of such a rebirth of our star may be non-zero. But, since this can only happen after the stage of the red giant (after 7-8 billion years), by that time there will be little left of the inner planets of the Solar system.

    Hollow earth

    Well, the last question worth mentioning concerned the concept of a hollow Earth ( example) In general, when a conversation about a hollow Earth begins, the first thing I remember is the “Inhabited Island” of the Strugatsky brothers. One of the brothers was an astronomer, I am sure he was very pleased to come up with the cosmology of a world turned inside out. But in order for the picture to turn out to be believable, a certain agent had to be added to the atmosphere, creating a completely monstrous refraction, when the horizon seems much higher than the observer, and hide the Sun, planets and stars with constant cloudiness. Because Earth history says that without any telescopes, even in antiquity, people not only established the sphericity of the Earth, but also were able to calculate the sizes of the Sun, Earth, Moon and the distances between them. How they did it, a long and good story can be readhere. Well, the simple experiments available to everyone, I recently laid out .

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