Dangerous if Comet ISON?

Now in RuNet artificially raised a wave of panic about the upcoming flight of a comet ISON and its imaginary danger to mankind. They say that it will inevitably fall to Earth, and that it "is accompanied by" some objects. Here and NASA turned off to the delight of those who spins the myth.

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I've been waiting for what will come up with the paranoid, after the breakup with a fabulous end of the world in 2012. Finally, they give birth. People were afraid of old comets, even when more or less understood the origin of these celestial phenomena. Now a global panic comets do not cause. However, they provided ISON loud PR scientists themselves, "brighter than the Moon," "comet of the century", and this has created a basis for trying to intimidate the uneducated masses. True scale is local: seriously afraid of the comet appears to be only in Russia. Western ufologists simply relish feykovye video, depicting "escort ships" comet.

Let's see, is there a comet C / 2012 S1 (ISON) any danger.

Comet ISON is named after the name of the network remote monitoring International Scientific Optical Network (Pulkovo cooperation of optical observers). Discoverers Vitali Nevski and Artyom Novichonok first took her for an asteroid, so Comet did not get their names.

When ISON only discovered in 2012, preliminary estimates of its size and trajectories suggest that it will be very well seen on the terrestrial sky. Therefore, it is hoped that it will be a great comet.

However, since it is much closer, we study it with the help of interplanetary, orbital and ground-based telescopes. Therefore, assess the extent of the event have changed significantly, and is now only by a very successful set of circumstances, we all can see it with the naked eye.

Look closely, what flies to us.

One of the first interesting observation was conducted in January 2013. interplanetary station NASA Deep Impact, which orbits in the asteroid belt between Mars and Jupiter. It is significantly higher than the expected life of the work, he studied everything they could reach and a long time flying around. In fact, shooting ISON began to plant the last big deal - in August 2013 broke off the relationship with her, and in September, NASA announced the final loss of the device.


The next important shot of the comet had space telescope Hubble.

A series of surveys conducted in April and May, at a distance of 650 million. Km has allowed a much better look at the comet. We even managed to make a small taymlaps:

When a comet crossed the orbit of Jupiter and headed in the direction of Mars it became clear that the landmark spectacle we no longer have to wait. Forecasts astronomers became more modest and more modest: the brightness of the comet behind the optimistic assumptions, and the activity of the formation of the coma (atmosphere and tail) did not live up to expectations.

I'm looking forward to the results of observations of a comet in late September and early October, conducted Martian rovers and orbital stations. But as a result Curiosity could not even see a comet in the sky, and a half-meter telescope satellite MRO has sent absolutely paltry fines:

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You've got to understand that the difference between shooting Hubble and MRO that first took the entire comet - its coma, the diameter of which was about 50 thousand. Km, and the second - only the core with a diameter of about 2 km.

Today, watching the comet is practically available to all owners of more or less serious telescopes. For example, picture a telescope with a diameter of 10, 5 cm:

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Now the comet observed dozens of professionals and amateurs, the regular reports and the latest pictures from all over the world, you can easily find if you ask such a purpose. A little more, and it is already possible to take pictures in the conventional cameras with telephoto lenses. Obviously, this will require a clear sky, the lack of illumination and direct hands of the arms.

While NASA imitated omission Hubble science team conducted a new survey ISON October 9 (photo at the beginning of the article). This study allowed us to refine core diameter - 2 km, and make sure that it has not lost the integrity

Now on to the path.
Although Comet ISON will pass closer to Earth than the recent tailed guest Panstarrs, anyway, we will share a considerable distance. Maximum convergence ISON and the Earth will occur on December 26, and the distance will be about 64, 2 million. Km. For example - is greater than the distance from Earth to Mars during closest approach, and is 167 distance from the Earth to the Moon. Therefore, as is a possibility of falling of Mars to Earth, so there is no danger of falling ISON our planet.

Trace the path ISON can be nasovskom Orbit Diagram or service in a convenient interactive website solarsystemscope.com.

But supporters of the theory of "myvseumrem" come up with an excuse in this respect: the comet and suddenly explode, and it will fall upon us fragments?

Let's start with the fact that until ISON not put a Bruce Willis with the drilling rig and the atomic bomb, there are no threats to the explosion of a comet. But the comet can shatter into several pieces. This is a very likely outcome of a close encounter of a comet with the sun, and these events have been observed many times previously.

ISON is expected to pass a distance of 1, 1 million. Km from the surface of the star. From gravitational effects, and tidal forces, it can be divided into several fragments. This was observed during the fall of comet D / 1993 F2 (Shoemaker-Levy) to Jupiter. What is significant: all the pieces of shattered comet continued in good traffic on the same orbit. Maybe the comet to fall apart, and under the influence of internal processes. For example previous hope paranoid - Comet Elenin, collapsed on the approach to the Sun and the Earth pull together only barely noticeable cloud of dust and gas.

Short-period comets Schwassmann-Wachmann splits since 1995:
With every turn of this three-year comet debris is growing, but still they continue to follow the same path. By the way, this "tailed star" is a good example of what happens to the broken, but evaporable comet: large fragments continue to break up, and gradually move away from the nucleus. This occurs by gravitational perturbations of the heavenly bodies, next to which fragments can fly. Depending on the mass of the fragment gravitational fields affect them in different ways, so the tail of a comet gradually becomes wider and wider, but retained the old orbit. The rate of expansion of the tail is only 45 km / h

A linearization disintegration of the comet, scientists were able to catch virtually "live»:

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It is not excluded that such repeated and ISON, but unlike Schwassmann-Wachmann comet current - long-period. Next it will return only after 2 million years. So one month of its fragments do not have time to deviate from the previous orbit of 60 million. Km. That is, if a comet will fall apart right now, at the time of its closest approach to the Earth, its fragments will be closer to us about 75 thousand kilometers, on a cosmic scale is small minuscule.

Yes, the Earth is in January, comes closer to the tail of Comet ISON, but it will be the tail of a comet that was left to its rapprochement with the Sun, ie, large fragments will not be there. Passage through the tail of the comet itself to the earth and earthlings are not scary. Actually, our planet regularly crosses the orbits of comets, which stretched through those "tails." During the meeting of the Earth and the "tail" watch the meteor shower. Probably all admire falling stars in the August sky, but not all thought that the observed result of crossing the Earth's orbit of the comet Swift-Tuttle. Let us hope that we are lucky with the weather and ISON give us a colorful spectacle, even if she does not appear in the sky.

Now let's talk about the fake, which increased by medieval fears.
Let us photos and videos, which is not the first day of the forums to discuss UFO.

The basis for a new myth: «ISON escorted two ships" has become a phenomenon, which aptly reflects the essence of the saying: "fools polraboty do not seem».

April 30, 2013 NASA released a remarkable color image area of ​​the sky where there was a comet ISON.

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At the same time all the objects turned out in color and black-and-white comet. As is well known, a digital picture of any color - the result of triple shooting in three color channels. But due to the fact that the comet and the telescope move in their orbits, and the exposition will take some time (up to 490 seconds), the channel can not be reduced so that all your subjects remained in their places. The picture brought by the stars and the comet left without color. But this was only the beginning. In addition to ready to publish the picture in the archive of raw images Hubble Space Telescope have been placed and those three shots in different color channels of the color which has been collected. At each of these frames comet was in a different position, the shutter speed during shooting, led to the fact that the image of the comet's nucleus turned elongated. Changed position relative to the comet's orbital telescope, so different exposure captured a different position with respect to the core is much more distant background.

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Someone found these images are combined into one and got a "comet with accompaniment."

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The virus was launched and soon there were those who decided to play on it. In the autumn on YouTube there are two (and maybe more) clips that demonstrate the alleged radar imaging the comet's nucleus. Video is positioned as a result of the work of a Chinese satellite:


The second video also shows "support", just specify the name of "Chinese radar»:


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To begin with let's deal with "radar". Tianlian I (Heavenly chain) - a series of geostationary satellites, transponders, which provide stable communication spacecraft "Shenzhou" and the station "Tiangong" with the Earth. This function is similar to its American TDRS devices or our "Ray."

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Apparently falsifiers decided to attribute them to the radar dish features saw deployed.

But even if these devices were radars, and worked in the mode of Very Long Baseline Interferometry, they still could not give a picture that collects views on YouTube. The mistake of counterfeiters began shooting date. Knowing it can be easy to determine the distance to the comet, calculate the angular size of the core and evaluate the possibility to get the image shown. On September 3, 2013 Comet ISON was located at a distance of about 450 million. Km. The size of the comet's nucleus is 2 km away. Based on this view by the formula a = arctg (d / L) its angular size and angular obtain about 10 microseconds, or microseconds of arc. That is, having a radio telescope with a resolution, we would have seen the core of a point, and a video detailing higher orders. But stop at 10 microseconds. A lot or a little?

Today, astronomy is the highest resolution in the radio (and any other) is obtained in the international project "Radioastron" with the Russian Space Telescope "Spektr-R" and a network of ground-based radio telescopes in Russia, Europe and the United States. The maximum resolution is achieved by 27 microseconds of arc, ie 3 times greater than that required to observe the comet's nucleus. "Radioastron" - a unique project, the experience of which only China hopes to repeat in the future. The spacecraft "Spektr-R" is moving away from Earth at thousands of kilometers and it allows you to receive data in Very Long Baseline Interferometry, as if the Earth was a radar with a diameter of Saturn (without a ring). In addition to "Radioastron" this radar no China, no other world. You can, of course, refer to the closeness of China, and his gloomy scientific genius, but if they had a telescope they would actively use it in their advocacy work, as do with manned flights or probes to study the moon.

In addition, such as a high-resolution 27 microarcseconds happened achieved by examining the radio source, and the comet is not. Asteroids flying near the Earth, exploring radar irradiating them, but the orbiter will not find so much energy to irradiate an object 450 million kilometers.

Next item, which does not take into account the creators of fakes about a comet - it is the principle of obtaining the radar image. In the first video we show a comet, if we look at its "head" (even this is not true, because now it is flying at an angle of approximately 45 degrees to the axis of observation), but the radar - this is not a video camera, we get the data reflection signal so the image seen in profile:


Here in the shooting of the asteroid 1998 QE2 (the way to "escort") as the light source performs the radar, not the sun, as it might seem. And we are seeing the object as just "in the profile." By the same principle, an image when doing an ultrasound. (Insert the bottom of the image)

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The second video, "a Chinese radar" has another blunder: it shows the direction of the comet's tail, and in the video is the direction changed by 180 degrees. The comet's tail always pointing in the opposite direction from the Sun, so this change in the direction of the tail is possible in two cases: either the comet during the shooting spread through the sun, or the survey was conducted with the spacecraft, which orbited comet. Of course neither one nor the other did not happen, so, even if he found a radar, able to give the image of a quality that he showed us something quite different.

Here, for example, real shot flyby of Comet Tempel 1 unit NASA Stardust


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Contrary to pessimistic expectations of many astronomers, I still hope that the comet will not collapse from the Sun evaporates to rendezvous with the Earth, and all enjoy a good night's show. I also hope that this show will make reflect those who now believe silly threats of the danger posed by ISON.

The article is not mine, via habrahabr.
I think it will be interesting PL.
Thank you!

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