Space objects: Pluto

The farthest planet of Solar system, Pluto, - the least investigated from all planets. It was open in March, 1930 by the American astronomer K.Tombo. Later it has been found and in earlier photos of the sky, since 1914.

The remarkable history of opening of the Neptune and Pluto actually begins with opening Uranus because, there will be no supervision of Uranus, later two opening could be late for many years. At the same time opening of Uranus marks the beginning of a new epoch in a history of astronomy as Uranus was the first planet which "was open". In fact Mercury, Venus, Mars, the Jove and Saturn have been always visible with the naked eye to any person who has looked at the sky (if only eyes of our prehistoric ancestors were not much more imperfect than our eyes).

Pluto looks as a star about 15-th star sizes. It is uneasy to count up, that almost same shine would have Mars if it to relate on distance of Pluto. It means, that Pluto about the same sizes, as well as Mars. More exact estimation of diameter of a planet has been made in 1950 by the Koyper measured with the help of a 5-meter telescope its angular diameter and found it equal 0,23. To this value there corresponds diameter of a planet of 5900 km.

At night with 28 for April, 29, 1965 Pluto should pass near to a star of 15-th star size and so it is close that could close it if its diameter was equal determined by the Koyper. Twelve observatories watched shine of a star, but it has not weakened for a second. It meant, that diameter of Pluto does not surpass 5500 km.

It was even more difficult to define weight of Pluto. Till 1978 of satellites at it it was known not, comets near to it did not pass. It was necessary to study the weak indignations created by Pluto in movement of the planets nearest to it of the Neptune and Uranus.

At a sight at the plan of Solar system the impression can be created, that orbits of the Neptune and Pluto are crossed. This impression is erroneous, as the orbit of Pluto is inclined on a corner 17 ° to a plane of an ecliptic and an orbit of the Neptune, and the line of units (crossing of planes of orbits) is located so, that just in area seeming "points of crossing" Pluto is on 10 a.u. to the north of an ecliptic. Moreover, because of a commensurability of cycle times of the Neptune and Pluto (three periods of the Neptune are almost equal to two periods of Pluto) the distance between both planets never can be less than 18 a.u. Now Pluto comes nearer to the perigelius and it(he) is already closer to the Sun, than the Neptune.

Closer to Pluto as it is not strange, Uranus can approach - the distance between them can sometimes be reduced up to 14 a.u. But nevertheless this distance is too great. The American astronomers R.Dankomb, P.Sejdelman, E.Jackson and Polish astronomer V.Klepchinsky have done enormous work on processing 5426 supervision of positions of the Neptune for 1846 - 1868 in view of indignations from all other planets and have received the best consent of the theory with supervision in case the weight of Pluto is equal 0,11 terrestrial. It is those, as we remember, the weight of Mars, but Pluto is less than Mars and if we shall accept for it such weight and diameter of 5500 km the average density of Pluto appears equal 8 g/sm3 that is too much. And suddenly unexpectedly American astronomer of Joules. Christie on the plates which have been taken off in April - May, 1978 on a 155-centimetric reflector of the Sea observatory in Flagstaff, has found out in Pluto the satellite in diameter about 500 km. Opening has been confirmed with the help of 4 meter reflectors of an observatory of Serro-Tololo. Under the reference of the satellite around of a planet it was possible to define weight of Pluto - 1,110^25 G or about 1/500 weights of the Earth! Diameter of Pluto by Christie's definitions is equal 2600 km in other words, Pluto, instead of Mercury, - the smallest among major planets of Solar system. The density of Pluto turns out equal 1,4 g/sm3 - almost as at the satellite of the Jove Callisto. On diameter of a planet and its shine it is easy to define an albedo; it is equal 0,5. Usual rocky breeds as sets an example the Moon and Mercury, do not possess so high an albedo, means, it is possible to assume, that the significant part of a surface of Pluto is covered with ice or hoarfrost.

The temperature on Pluto should be about 40°K. This value is lower than temperature of condensation of metane at very low pressure (50°K). Therefore on a surface of Pluto there can be a metane ice. And here more recently, in 1977, the American astronomers D.Krukshenk, D.Morrison and K.Pilcher with the help of 4 meter reflectors of an observatory the Kitt have found out Peak in an infra-red spectrum of Pluto two strips, characteristic for metane ice.

On the other hand, Canadian astronomer L.Manning, having studied a spectrum of Pluto in the seen area, received in 1970 the Fics, the Neff and L.Kelsi on a 60-centimetric reflector with a spectrophotometer has found in it attributes of strips of absorption of ions of iron and has come to a conclusion, that breeds of a planet are enriched with iron.

In 1955 the American astronomers M.Walker and R.Hardi from photo-electric supervision have found the period of rotation of Pluto around of an axis - 6 day of 9 hours of 16,9 minutes. Later 12 years the Soviet astronomer R.I.Kiladze has confirmed this period on own supervision. Now it is clear, that this period is at the same time a cycle time of the satellite of Pluto around of a planet.

Penetration into secrets of solar system on the basis of use of the newton law of universal gravitation and the most careful supervision proceeded and in our century. The culmination of these efforts was opening Pluto, and circumstances of this opening were surprisingly similar to circumstances of opening of the Neptune. As well as then, the planet has practically been found out during one of early searches, but by virtue of vicissitudes of life its identification has taken place much later.

In the beginning of our century the Persival the Lowell (1855-1916) which have based in Flagstaff (Arizona) an observatory by the purpose of supervision of planets, and in particular Mars, has actively become interested in an opportunity of existence of a planet farther, what the Neptune. He anew investigated an orbit of Uranus and has come to a conclusion, that seeming mistakes of supervision could reduce essentially if to take into account indignations of Uranus of a unknown planet. Calculated an orbit and positions of a planet have not been published by Lowell about 1914 though he began searches of a planet from 1905. In 24 years in 1929 the construction of a new 13-inch refractor which has been established on observatories of Lowell for acceleration of search of a new planet has been completed.

It was entrusted to photograph regularly areas of the sky along an ecliptic to the young assistant Clyde Tombo. For each area he made two photos with the long expositions, shared on time on 2 - 3 days. Then in searches of an expected planet he very carefully compared the received photographic plates. Comparison was done by means of the blink-comparator - the device supplied with a double microscope that allows the observer to see alternately the same area of the sky on two plates. Any object which during an interval between two expositions moved on the sky, seems jumping "there - here" while stars look motionless.

On March, 12, 1930, i.e. less than one year later after the beginning of realization of the new program, the observatory of Lowell through the Harward bureau has telegraphed to astronomical observatories the following message: "regularly started it is a lot of years back searches in connection with researches of a planet by Lowell behind an orbit of the Neptune have led to to opening of object, speed of movement and which trajectory within seven weeks consistently corresponded to a body which is taking place behind an orbit of the Neptune approximately on that distance which to it was attributed by Lowell. The fifteenth star size. Position at 3 o'clock world time on March, 12 was 7 to the West from d Twins that will be coordinated to the longitude predicted by Lowell". The astronomical world soon has unanimously accepted for this planet the name Pluto which approaches it as it goes in the external areas of solar system not covered by the Sun.

Besides first two letters of the name correspond to the initials of the Persival Lowell died in 1916, i.e. all in two years after he had been published a detailed prediction of movement of a new planet.

The subsequent calculations of an orbit executed on the basis of photos of a new planet, made even before its opening, have shown, that it goes around of the Sun with the period 246,5 years on an orbit inclined on 17 " to an average plane of other planets.

In a perigelius the orbit of Pluto passes inside an orbit of the Neptune, but owing to the big inclination of an orbit these two bodies cannot collide.

Only unhappy accident has prevented to open Pluto in 1919 to astronomers of an observatory Mount Willson. At this time the Milton Humason on behalf of William Pikering (1858-1938) who has independently carried out calculations of prospective position of a planet, has photographed areas around of the predicted position of a planet and has really received the image of a planet on some plates. However the image of Pluto on one of two best plates has got just on a small spoilage of an emulsion (at first sight it seemed a part of this spoilage) while on other plate the image of a planet appeared in part imposed on any star! Even in 1930 when position of a planet in 1919 was rather well-known from the calculated orbit, hardly it was possible to identify those images of Pluto which have been received 11 years ago.

If only Pluto does not possess extremely big density or is not extremely bad reflector of light, its weight is insufficiently great to cause those deviations in movement of the Neptune on the basis of which existence of Pluto has been predicted. That is why many astronomers nowadays believe, that opening of Pluto was casual. Nevertheless the opening which has followed in result of indefatigable searches of a planet, represents one more step on a way of progress in science. All employees of an observatory of Lowell are worthy the maximum praise for the laborious work and the received results.

The Tombo has distributed started on observatories of Lowell searches to all sky, but has established, that in the limits accessible to supervision with a 13-inch telescope, more planets are not present. If other planets also exist, they should or be much further or be it is much less. Continuation of searches of much weaker planets with one of the big telescopes, for example, with 5-meter, is unjustified from the practical point of view. The more it photographes a telescope, the proportionally smaller area of the sky. Searches on all sky with scope of all objects which shine is limiting for supervision with a 5-meter telescope, would demand its continuous use within all moonless nights during long centuries. Therefore opening of planets, probably, and existing for an orbit of Pluto, is represented by rather difficult business if roles any happy case only will not play or new methods of supervision will not be applied. For radar-tracking telescopes such distances are too great. The big optical telescope started in interplanetary space or established on the Moon and working in a combination to television technics and the automatic equipment, intended for searches of planets, probably, also could promote success, however some astronomers in general doubt that any planets of the significant sizes will be found still.

The farthest from the Sun from all planets open till now is absolutely not similar to other planets which are taking place in external areas of solar system. The stranger - dwarf Pluto among planets - giants looks. Our data on Pluto are rather limited; besides an orbit and consequently, and distances to us are known its shine and color, but the weight of Pluto is unknown. According to definition of the Koyper the seen diameter of Pluto is equal 0 ", 20 ", 3, that corresponds about 5800 km. If to consider, that the weight of Pluto even approximately corresponds to the calculated size (0,8 weights of the Earth) the average density of a planet turns out more density of gold! As metals and other substances, which density are higher, than at iron, apparently, meet in stars as well as on the Earth, in small amounts, it is represented completely improbable that the density of Pluto was much higher than density of iron which in 7,8 times is higher than density of water. Obviously, either its weight or diameter are determined with the big mistake. If to assume, that the density of Pluto is close to density of the Earth this assumption with inevitability entails increase in its diameter twice but as such diameter is quite measurable, we are compelled together with the Brower and the Clemens to draw a conclusion, that the weight of Pluto is determined for the present unreliably.

Completely other explanation to the same data on Pluto was offered by the Olter according to whom diameter of Pluto more than its seen diameter, but due to that the planet has rather smooth surface, the sunlight is reflected only from its small central area. So, for example, the polished spherical or oval surfaces at illumination by their dot light source allow blick with concentration of light to the center of a surface. However the explanation of the Olter nevertheless does not solve a problem of rather weak shine of Pluto. If Pluto had reflective ability so low, as the Moon which albedo is equal 0,07 and then it should look twice brighter, than it is observed actually. In result we are compelled to draw an improbable conclusion that a surface at Pluto rather smooth, but its(her) reflective ability is equal only 3 - 4 %.

As the temperature of Pluto, apparently, is lower 220 C° i.e. only on any 50 - 60 (temperatures of absolute zero the majority of usual gases should pass to its surfaces in a liquid condition are higher or freeze.

It is possible to imagine, certainly, that Pluto is covered with ocean from liquid (or firm) oxygen (if oxygen was not so chemically active) or from nitrogen, and hydrogen and helium which could remain on Pluto gaseous, therefore, probably, no.

Though also it is possible to imagine, that reflective ability of a surface of a planet due to presence of ice from crystals of ammonia and other widespread connections will be rather high, all of us in practice should be ready to that this surface is similar lunar, owing to loss on it of meteoric and cometed substance in particular at early stages of a history of a planet, rather rough. By yellow-white painting, it is possible to assert, that the surface of Pluto is covered with not too pigmentary materials. With the assumption of the Olter of rather smooth surface of Pluto in a combination to record-breaking low value the albedo therefore is very difficult to agree.

Probably, Pluto is a fruitless cold small sphere; diameter of it is little bit less than half of diameter of the Earth, and an albedo about 0,15, i.e. the albedo of the Moon is twice more. Certainly, this planet is inhospitable for stay on it of the person; fatally cold night proceeds there 76,5 hours, and after it there comes the same long day, but also in the afternoon shine of the Sun in 1600 times will be weaker, than on the Earth.

Came out even with the assumption, that Pluto-at all true planet, and only the satellite lost by the Neptune.

However this question cannot be resolved, while we shall not have the big data on the mechanism of occurrence in planets of satellites.