Is comet ISON dangerous?

    Now in RuNet, a panic wave is artificially rising over the upcoming passage of comet ISON and its imaginary danger to humanity. They say that it will inevitably fall to the Earth, and that some objects "accompany" it. Then NASA turned off to the delight of those who are promoting this myth.



    I have long been waiting for what the paranoid will come up with after an enchanting bummer with the end of the world in 2012. And finally, they were born. From ancient times, people were afraid of comets, even when they more or less understood the origin of these celestial phenomena. Now comets no longer cause global panic. However, ISON was provided by loud PR by the scientists themselves: “brighter than the Moon”, “comet of the century”, and this created the basis for attempts to intimidate uneducated masses. True, the scale is local: comets are seriously afraid, it seems, only in Russia. Western ufologists simply relish the fake videos, with the image of the "escort ships" of the comet.

    Let's see if C / 2012 S1 (ISON) is a danger.

    Comet ISON is named for the International Scientific Optical Network (Pulkovo cooperation of optical observers ). The pioneers Vitaly Nevsky and Artem Novichonok first mistook her for an asteroid, so the comet did not receive their names.

    When ISON was first discovered in 2012, preliminary estimates of its size and trajectory suggested that it would be very visible in the sky. Therefore, there was hope that it would be a Big Comet .

    However, since then it has come much closer, it was studied using interplanetary, orbital and ground-based telescopes. Therefore, estimates of the scale of the event have changed significantly, and now only as a result of a very successful set of circumstances can we even see it with the naked eye.

    Let’s take a closer look at what flies to us.

    One of the first interesting observations was made in January 2013 by the NASA Deep Impact interplanetary station, which rotates in an asteroid belt between Mars and Jupiter. She significantly exceeded the expected resource of her work, studied everything that she could reach and for a long time flew idle. In fact, the ISON survey was the last big thing for the station - in August 2013, communication with it was interrupted, and in September, NASA experts announced the final loss of the device.



    The next important shot of the comet was conducted by the Hubble Space Telescope.

    A series of surveys conducted in April and May, from a distance of 650 million km, allowed a much better view of the comet. It was even possible to make a small time-lapse:



    When the comet crossed the orbit of Jupiter and headed towards Mars, it became clear that we no longer had to wait for an epoch-making spectacle. The forecasts of astronomers became more modest and modest: the brightness of the comet lagged behind optimistic assumptions, and the activity of the formation of a coma (atmosphere and tail) did not live up to expectations.

    I was looking forward to the results of observations of the comet in late September and early October, conducted by Martian orbital stations and rovers. But as a result, Curiosity couldn’t even make out the comet in the sky, and the half-meter telescope of the MRO satellite sent a very frivolous trifle:

    image

    Here it must be understood that the difference between the Hubble and MRO shooting is that the first shot the whole comet - with its coma, whose diameter was about 50 thousand km, and the second - only the core, with a diameter of about 2 km.

    Today, comet observation is available to almost all owners of more or less serious telescopes. For example, a shot from a telescope with a diameter of 10.5 cm:



    Now dozens of professionals and amateurs are watching the comet, regular reports and fresh pictures from around the world can be easily found if you set yourself this goal. A little more and it can already be photographed on ordinary cameras with telephoto lenses. True, this will require a clear sky, no flare, and straight arms from the shoulders.

    While NASA simulated inaction, the Hubble science team conducted new ISON surveys on October 9 (photo at the beginning of the article). This study made it possible to clarify the core diameter - 2 km, and to make sure that it did not lose its integrity.

    Now let's talk about the trajectory.
    Although Comet ISON will fly closer to Earth than the recent tailed guest of the Panstarrs, anyway, we will be separated by a considerable distance. The maximum convergence of ISON and the Earth will occur on December 26, and the distance will be about 64.2 million km. For example, this exceeds the distance from Earth to Mars during the maximum approach, and is 167 distances from Earth to the Moon. Therefore, as the probability of the fall of Mars to Earth is excluded, there is no danger of ISON falling onto our planet.

    You can trace the ISON trajectory in the Nasov service Orbit Diagram or in the convenient online site solarsystemscope.com .



    But the proponents of the “we all-wise” theory came up with an excuse in this regard: what if the comet explodes and its fragments fall on us?

    To begin with, until Bruce Willis lands on the ISON with a rig and an atomic bomb, there is no danger of a comet explosion. But a comet may break up into several fragments. This is a very likely outcome of the close proximity of the comet to the Sun, and such events have been observed repeatedly before.

    ISON should pass at a distance of 1.1 million km from the surface of the star. From gravitational impact and tidal forces, it can be divided into several fragments. A similar thing was observed during the fall of comet D / 1993 F2 (Shoemaker-Levy) on Jupiter. What is significant: all the pieces of the fragmented comet continued their normal movement in the former orbit.



    A comet may also fall apart under the influence of internal processes. For example, the paranoid’s previous hope - comet Elenin, broke up on approaching the Sun, and only a barely noticeable cloud of dust and gas approached the Earth.

    The short-period comet Schwassman-Wachmann, has been disintegrating since 1995:



    With each three-year round of this comet, there are more and more debris, but all of them continue to follow the previous trajectory. By the way, this “tailed star” is a good example of what happens to a decayed, but not vaporized comet: large debris continues to fragment, and gradually move away from the nucleus. This happens from the difference in gravitational perturbations of celestial bodies, next to which fragments can fly. Depending on the distance to the fragment, gravitational fields affect them differently, therefore, the comet's tail gradually becomes wider and wider, but the previous orbit is preserved. The tail expansion speed is only 45 km / h.

    And the collapse of the comet Linear, scientists were able to catch almost "live":



    It is possible that this will happen again with ISON, but the current comet is a long-term difference from Schwassman-Wachmann. Her next return is expected only after 2 million years, so in one month her fragments will not have time to deviate from the previous orbit by 60 million km. That is, if the comet collapses right now, at the time of its closest approach to the Earth, its fragments will be closer to us by about 75 thousand km, which on a cosmic scale is an insignificant meager.

    Yes, the Earth in January will come closer to the tail of the comet ISON, but it will be the tail that remained from the comet to its approach to the Sun, i.e. large fragments will not be there. Passing through the tail of a comet in itself is not terrible for the Earth and earthlings. Actually, our planet regularly crosses the orbits of comets, through which the same “tails” are stretched. In the days of the meeting of the Earth and the "tail" meteor showers are observed. Probably everyone admired the shooting stars in the August sky, but not everyone thought that they were observing the result of the Earth crossing the orbit of the Swift-Tuttle comet. Let's hope that we are lucky with the weather and ISON will give us a colorful sight, even if it does not appear in the sky.

    Now let's talk about fakes that grew up on medieval fears.
    We will analyze photos and videos that have been discussed on the forums of ufologists for more than a day.

    The basis for the new myth: “ISON escort two ships” was a phenomenon whose essence is succinctly reflected in the saying: “They don’t seem to work half the job to fools.”

    April 30, 2013 NASA published a wonderful color photograph of the celestial sphere where the comet ISON was observed.



    In this case, all objects turned out in color, and the comet is black and white. As you know, any color digital image is the result of three shots through three color channels. But due to the fact that the comet and telescope move in their orbits, and the exposure takes a certain time (up to 490 seconds), it is impossible to reduce the channels so that all the shooting objects remain in place. The picture was reduced to the stars, and the comet was left without color. But this was only the beginning. In addition to the finished published picture, in the archiveThe raw images of the Hubble telescope were placed and those three pictures in different color channels from which color was collected. On each of these frames, the comet was in a different position, while the long shutter speed during the survey led to the image of the comet's nucleus being elongated. The position of the orbital telescope relative to the comet has also changed, so different exposures captured different positions of the nucleus relative to a much more distant background.



    Someone found these pictures, combined them into one and got a “comet with escort”.

    image

    The virus was launched and soon there were those who decided to play on it. In the fall, two (or maybe more) videos appeared on YouTube that show supposedly radar shots of the comet's nucleus. The video is positioned as a result of the work of a certain Chinese satellite:



    The second video also demonstrates "escort", only the name of the "Chinese radar" is clarified:



    To begin with, we’ll deal with the “radar”. Tianlian I (Sky Chain) is a series of geostationary relay satellites that provide stable communication between the Shenzhou spacecraft and the Tiangong station with the Earth. In this, its function is similar to the American TDRS devices or our “Ray”.



    Apparently, the falsifiers decided to assign them radar functions after seeing the unfolded plates.

    But even if these devices were radars, and worked in the mode of a radio interferometer with extra-long bases, they still couldn’t give a picture that collects views on YouTube. The mistake of the falsifiers was the date of the shooting. Knowing it, you can easily determine the distance to the comet, calculate the angular size of the nucleus and evaluate the ability to get the picture shown. On September 3, 2013, comet ISON was located at a distance of approximately 450 million km. The size of the comet's core is 2 km. Based on this, we calculate by the formula a = arctan (d / L) its angular size and obtain about 10 angular microseconds or microseconds of an arc. That is, having a radio telescope with such a resolution, we would see the core in the form of a dot, and the video detail is orders of magnitude higher. But dwell on 10 microseconds. Is it a lot or a little?

    Today, in astronomy, the highest resolution in the radio range (and in any other) is obtained on the international project "Radio astron"using the Russian space telescope" Spectrum-R "and a network of ground-based radio telescopes in Russia, Europe and the United States. The maximum resolution it achieves is 27 microseconds of arc, ie 3 times more than that required to observe the comet's nucleus. Radioastron - this is a unique project, whose experience China is only hoping to repeat in the future. The Spektr-R spacecraft is tens of thousands of kilometers distant from the Earth and this allows receiving data in the radio interferometry mode with extra-long bases, as if the Earth had Hadar with a diameter of Saturn (without a ring). Apart from Radioastron, neither China nor the rest of the world has such a radar. You can, of course, refer to China’s closeness and its gloomy scientific genius, but if they had such a telescope they would actively use him in his propaganda work,

    In addition, it was possible to achieve such a high resolution as 27 microseconds of arc by examining the radio source, and the comet is not. Asteroids flying near the Earth are being examined by radar irradiating them, but the orbital vehicle will not find so much energy to irradiate an object over 450 million km.

    The next detail that the creators of fakes about the comet do not take into account is the principle of obtaining a radar image. In the first video, they show us a comet as if we were looking at it “in the forehead” (even this is not true, because now it flies at an angle of about 45 degrees to the axis of observation), but the radar is not a video camera, we get data about signal reflection therefore the image is visible in profile:



    Here, when shooting the asteroid 1998 QE2 (by the way with “tracking”), the radar acts as the light source, and not the Sun, as it might seem. And we observe the object just “in profile”. The same principle is obtained when an ultrasound



    scan is performed : The second video from the “Chinese radar” has another mistake: it shows the direction of the comet’s tail, and during the video this direction changes by 180 degrees. The tail of the comet is always directed in the opposite direction from the Sun, therefore, such a change in the direction of the tail is possible in two cases: either the comet circled the Sun during the filming, or the survey was conducted from the spacecraft that circled the comet. Of course, neither one nor the other happened, therefore, even if there were a radar capable of giving an image of such quality, it would show us something completely different.

    Here, for example, a real shot of the flight past NASA Stardust’s comet Tempel 1



    Contrary to the pessimistic expectations of many astronomers, I still hope that the comet will not fall apart at the Sun, will not evaporate before approaching the Earth, and everyone will enjoy a wonderful night-time spectacle. I also hope that this spectacle will make you think those who now believe stupid threats about the dangers posed by ISON.

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