Spacecraft are moving in orbits of the Sun, Venus, Saturn, and several are preparing to leave the solar system. There are two rovers on Mars, and astronauts on board the ISS are doing experiments and taking amazing photos, writes The Atlantic.

The family photo album of the solar system has been replenished with new pictures: the sunset on Mars, the Churyumov-Gerasimenko comet, the dwarf Ceres, Pluto and, of course, photos of our home, planet Earth.

The dwarf planet Pluto and Charon, one of its five moons, photographed on June 23, 2015 by NASA's New Horizons interplanetary station from a distance of 24.4 million kilometers. New Horizons will make its closest approach to Pluto on July 14, 2015, on which day it will be 12,500 kilometers from the planet.

Saturn's moon Dione, photographed by the Cassini spacecraft on June 16, 2015. The spacecraft was located 516 kilometers from the surface of the satellite. The bright rings of Saturn are visible on the left.

Satuna's satellite Hyperion, photographed by Cassini on May 31, 2015 from a distance of about 60,000 kilometers, is Cassini's closest contact with a satellite for this mission. Hyperion is the largest of Saturn's irregularly shaped moons. In the photo, the north of Hyperion is at the top and rotated 37 degrees to the right

At the bottom of the image you can see the ring A, at the top - the limb of Saturn. The rings cast shadows on the part of the planet depicted here, creating a checkerboard pattern of dark and light areas. This pattern can even be seen through ring A, which, unlike the neighboring ring B, is not completely opaque. Ring shadows often intersect on Saturn's surface at bizarre angles. This image was taken by the narrow-angle camera of the Cassini spacecraft on December 5, 2014.

Bright spots on the dwarf planet Ceres, photographed by the Dawn spacecraft on May 6, 2015. This is one of the first images taken by the Dawn spacecraft from a circular orbit at a distance of 4,400 kilometers. The resolution is 410 meters per pixel. Scientists have not yet been able to find an explanation for these spots - they suggest that these are deposits of salt and ice.

The dwarf planet Ceres, photographed by the Dawn spacecraft on May 5-6, 2015 from a distance of 13,600 kilometers

The Opportunity rover has been on Mars for more than a decade - and continues to do so. The center of this false-color image taken by the Pancam rover's camera is an oblong crater called the Spirit of St. Louis and a mountain peak in it. April 26, 2015 was the 4,000th Martian day (sol) of the rover's operation. The rover has been studying Mars since early 2004. The small crater of the Spirit of St. Louis is 34 meters long and about 24 meters wide, its bottom is slightly darker than the surrounding plain. Rock formations in the far part of the crater rise about 2-3 meters above the edges of the crater

In this self-portrait, the Curiosity rover captured itself in Mojave Crater, where it took a second soil sample on Mount Sharp. Collected here are dozens of images taken in January 2015 by the MAHLI camera on the rover's mechanical arm. The rover is surrounded by the pale Pahrump Hills, with the peak of Mount Sharp on the horizon.

In this image of the Martian surface, taken on April 8, 2015 by the Mars Reconnaissance Orbiter, the Curiosity rover passes through Artists Drive Valley on the lower slope of Mount Sharp. The photo was taken with a HiRISE camera. It shows the position of the rover after it traveled about 23 meters on the 949th Martian day, or sol, of its operation on Mars. The image shows an area approximately 500 meters long.

The surface of comet 67P/Churyumov-Gerasimenko, photographed by the camera of the Rosetta spacecraft from a distance of 15.3 kilometers, February 14, 2015

Comet 67P/Churyumov-Gerasimenko photographed by the Rosetta spacecraft from a distance of 77.8 kilometers on March 22, 2015

South of the Scandinavian Peninsula on the eve of midnight April 3, 2015. Green aurora in the north, Baltic Sea black patch (bottom right), clouds (top right) and snow (in Norway) illuminated by a full moon

Terra's MODIS probe captured this image of cloud swirls over the Canary Islands and Madeira on May 20, 2015

Off the coast of South Korea, algae are grown in nets that are held to the surface with special floats. This technique allows the algae to stay close enough to the surface to receive the required amount of light at high tide, and keep them from sinking to the bottom at low tide. This image of a shallow water seaweed farm off Sisan Island was taken by the Landsat 8 Earth Remote Sensing Satellite on January 31, 2014.

Sunset on Mars. The Curiosity rover took this picture of the setting sun at the end of the 956th Martian day, or sol (April 15, 2015 Earth time), while in Gale Crater. There are small particles in the dust of the Martian atmosphere, due to which blue-colored light propagates through it more strongly than longer-wavelength colored light. For this reason, blues appear in the brighter part of the sky, and yellows and reds are farther from the Sun.

The European Space Agency has announced the successful landing of the Philae probe on comet 67P/Churyumov-Gerasimenko. The probe separated from the Rosetta apparatus on the afternoon of November 12 (Moscow time). Rosetta left the Earth on March 2, 2004 and flew to the comet for more than ten years. The main goal of the mission is to study the evolution of the early solar system. If successful, ESA's most ambitious project could become a kind of Rosetta stone not only for astronomy but also for technology.

long-awaited guest

Comet 67P/Churyumov-Gerasimenko was discovered in 1969 by Soviet astronomer Klim Churyumov while studying photographs taken by Svetlana Gerasimenko. The comet belongs to the group of short-period comets: the period of revolution around the Sun is 6.6 years. The semi-major axis of the orbit is a little over 3.5 astronomical units, the mass is about 10 13 kilograms, the linear dimensions of the nucleus are several kilometers.

The study of such cosmic bodies is necessary, firstly, to study the evolution of cometary matter, and, secondly, to understand the possible influence of gases evaporating in a comet on the motion of surrounding celestial bodies. The data obtained by the Rosetta mission will help explain the evolution of the solar system and the emergence of water on Earth. In addition, scientists hope to find organic traces of the L-forms ("left-handed" forms) of amino acids, which are the basis of life on Earth. If these substances are found, the hypothesis of extraterrestrial sources of terrestrial organic matter will receive new confirmation. However, by now, thanks to the Rosetta project, astronomers have learned a lot of interesting things about the comet itself.

The average surface temperature of the comet's nucleus is minus 70 degrees Celsius. Measurements made as part of the Rosetta mission showed that the temperature of the comet is too high for its core to be completely covered with a layer of ice. According to the researchers, the surface of the core is a dark dusty crust. Nevertheless, scientists do not exclude that there may be ice patches there.

It has also been found that the stream of gases emanating from the coma (clouds around the comet's nucleus) includes hydrogen sulfide, ammonia, formaldehyde, hydrocyanic acid, methanol, sulfur dioxide and carbon disulfide. Previously, it was believed that as the icy surface of a comet approaching the Sun heats up, only the most volatile compounds, carbon dioxide and carbon monoxide, are released.

Also thanks to the Rosetta mission, astronomers drew attention to the dumbbell shape of the nucleus. It is possible that this comet could have formed as a result of a collision of a pair of protocomets. It is likely that the two parts of the 67P/Churyumov-Gerasimenko body will separate over time.

There is another hypothesis that explains the formation of a double structure by intense evaporation of water vapor in the central part of the comet's once spherical nucleus.

With the help of Rosetta, scientists have found that every second comet 67P / Churyumov-Gerasimenko releases water vapor into the surrounding space in the amount of about two glasses (150 milliliters each). At this rate, the comet would fill an Olympic-sized pool in 100 days. As we get closer to the Sun, the steam emission only increases.

The closest approach to the Sun will occur on August 13, 2015, when comet 67P/Churyumov-Gerasimenko will be at the perihelion point. Then the most intense evaporation of its matter will be observed.

Rosetta spacecraft

The Rosetta spacecraft, together with the Philae descent probe, was launched on March 2, 2004 on an Ariane 5 launch vehicle from the Kourou launch site in French Guiana.

The name of the spacecraft was in honor of the Rosetta stone. The deciphering of the inscriptions on this ancient stone slab, completed by 1822 by the Frenchman Jean-Francois Champollion, allowed linguists to make a giant breakthrough in the study of Egyptian hieroglyphic writing. Scientists expect a similar qualitative leap in the study of the evolution of the solar system from the Rosetta mission.

Rosetta itself is an aluminum box measuring 2.8x2.1x2.0 meters with two solar panels of 14 meters each. The cost of the project is 1.3 billion dollars, and its main organizer is the European Space Agency (ESA). NASA, as well as the national space agencies of other countries, take a smaller part in it. In total, 50 companies from 14 European countries and the USA are involved in the project. Rosetta hosts eleven scientific instruments - special systems of sensors and analyzers.

During its journey, Rosetta made three maneuvers around the orbit of the Earth and one around Mars. The device approached the orbit of the comet on August 6, 2014. During its long journey, the device managed to perform a number of studies. So, in 2007, flying past Mars at a distance of a thousand kilometers, he transmitted to Earth data on the planet's magnetic field.

In 2008, in order to avoid a collision with the Steins asteroid, ground specialists corrected the ship's orbit, which did not prevent it from photographing the surface of a celestial body. In the pictures, scientists found more than 20 craters with diameters of 200 meters or more. In 2010, Rosetta transmitted photographs of another asteroid, Lutetia, to Earth. This celestial body turned out to be a planetesimal - a formation from which planets were formed in the past. In June 2011, the device was put into sleep mode to save energy, and on January 20, 2014, Rosetta “woke up”.

Philae probe

The probe is named after the island of Philae on the Nile River in Egypt. There were ancient religious buildings, and a plate with hieroglyphic records of the queens Cleopatra II and Cleopatra III was also found. As a place to land on the comet, scientists chose a site called Agilika. On Earth, this is also an island on the Nile River, where some of the ancient monuments were transferred, which were threatened by flooding as a result of the construction of the Aswan Dam.

The mass of the Philae descent probe is one hundred kilograms. Linear dimensions do not exceed a meter. The probe carries ten instruments needed to study the comet's nucleus. With the help of radio waves, scientists plan to study the internal structure of the nucleus, and microcameras will make it possible to take panoramic pictures from the surface of the comet. The drill installed on Philae will help to take soil samples from a depth of up to 20 centimeters.

Philae batteries will last for 60 hours of battery life, then the power will be switched to solar panels. All measurement data will be sent online to the Rosetta spacecraft, and from it to the Earth. After the descent of Philae, the Rosetta apparatus will begin to move away from the comet, turning into its satellite.

1. Are there any satellites of the planets that are larger than Mars in size? Mercury? moon?
   Answer

   There are no moons larger than Mars. Satellites superior to Mercury are Ganymede (sp. Jupiter) and Titan (sp. Saturn). Satellites larger than the Moon: Ganymede, Titan, Callisto (sp. Jupiter) and Triton (sp. Neptune).

2. Which moons of the planets have an atmosphere?
   Answer

   Saturn's moon Titan has an atmosphere composed of methane and ammonia. Neptune's moon Triton has a nitrogen atmosphere.

3. Why is it more correct to consider the Earth and the Moon not as a planet with a satellite, but as a double planet?
   Answer

   Because the Moon, in comparison with the Earth, has a fairly significant mass, and the satellites of other planets, in comparison with these planets, are incomparably less massive.

4. “For the first time, this (measuring the speed of light) was possible by observing the eclipses of the satellites of Jupiter. According to accurate calculations, these tiny planets were already disappearing behind the disk of Jupiter, but astronomers still saw their light. Is everything correct in this passage?
   Answer
5. Calculate the angular dimensions of Phobos when observed from the surface of Mars and compare them with the angular dimensions of the Moon when observed from the Earth's surface at its average distance.
   Answer

   The distance of Phobos from the center of Mars is 9400 km, and from its surface - 6030 km. At this distance, Phobos is visible from Mars at an angle of about 9", i.e., much smaller than the Moon is visible from Earth.

6. Are there among the satellites of the major planets those that in turn have satellites, in other words, are there satellites of the second order in the solar system?
   Answer

   Second-order satellites in the solar system have not yet been discovered.

7. What is the peculiarity of the asteroids that make up the group of "Trojans"?
   Answer

   Any of the asteroids that are part of the Trojan group, together with Jupiter and the Sun, forms an equilateral triangle and, therefore, moves around the Sun in the same way as Jupiter, but either ahead or behind it.

8. Which of the asteroids can be seen with the naked eye?
   Answer

   Under favorable conditions, you can see Vesta.

9. How did you determine that some asteroids have an irregular, angular shape?
   Answer

   By changing their brightness over a short time, and the angular shape of the asteroid Eros was revealed by direct measurements.

10. Let's say that the Sun has just set somewhere on a plain at the equator. To what height would it be necessary to rise there in order to see the Sun again with its lower edge on the horizon line? Sun diameter 32".
    Answer

    Taking the range of the horizon at the equator for a height of 1.6 m equal to approximately 4.9 km, and the length of the arc in G equal to 1855 m (along the parallel), we find that in angular measures the range of the visible horizon is 2 "6. By a simple construction, we are convinced that that, in order for the Sun to become visible again, the range of the horizon must increase by 32", i.e., become equal to 34", 6 or 64 km. From here we find the desired height of the new observation site: 275 m.

11. Does the range of the visible horizon increase when looking at the area through binoculars?
    Answer
12. “Experienced people said that with especially clear weather halfway between the capes, it is possible to see the Earth from both sides from the top of the mast.” Here we are talking about the narrowest point of the Black Sea, where its width is 263 km. Calculate the height of the mast, from which one could see both shores of the Black Sea there. Use a formula that takes into account refraction.
    Answer

    The height of the mast should be ≈1160 m.

13. Imagine the Earth as a relief globe with a diameter of 1 m and calculate how much the smoothness of its surface is disturbed by the deepest depression in the Pacific Ocean at 11,613 m and the highest mountain Chomolungma at 8882 m. diameter?
    Answer

    Assuming the diameter of the globe to be 12,800 km, we get that one kilometer on this globe would correspond to ~0.08 mm. Therefore, the deepest depression on this globe would be only 0.9 mm, and Chomolungma 0.7 mm, which would be invisible to the eye. The globe along the polar diameter would be compressed by 3.3 mm, which also could not be detected with the eyes.

14. August 11-12. During the day we were carried (on an ice floe) to the east by as much as eight degrees. And we are already so close to the pole that one degree of longitude is equal to only two or three kilometers. At the indicated time, the drifting ice floe was approximately 89°N. sh. What is the length of 1° of longitude at this latitude?
    Answer

    As is known, r\u003d cosφ, and the length of 1 ° in longitude is .

15. How has it been proven that comets have such a low mass that one astronomer even called them "visible nothingness"?
    Answer

    Comets do not cause any disturbances in the movements of the planets near which they pass, but, on the contrary, they themselves are subjected to strong disturbances from their side.

16. How has it been proven that comets do not have any significant solid core?
    Answer

    During the passage of comets in the immediate vicinity of the Sun (as if along the solar disk), the comets merge completely with the general solar background, and no dark spots have ever been noticed against this background. This means that the nuclei of comets are so small that they cannot be seen even with the help of optical instruments.

17. Sometimes comets have two tails, one of which is directed towards the Sun, and the other - away from the Sun. How can this be explained?
    Answer

    The tail, directed towards the Sun, consists of larger particles, for which the force of solar attraction is greater than the repulsive force of its rays.

18. “If you want to see a comet worth seeing, you have to get out of our solar system, where they can turn around, you know? I, my friend, saw there such specimens that could not even fit into the orbits of our most famous comets - their tails would definitely hang outward. Understand the reality of this statement.
    Answer

    Outside the solar system and far from other similar systems, comets have no tails and are of negligible size.

19. After listening to a lecture on comets, one listener asked the lecturer the following question: “You said that comets always turn their tail away from the Sun. But when I saw a comet, its tail always turned in the same direction, and the Sun behind this time was many times in the south, and in the east, and in the west. Why didn't the comet turn its tail in different directions? How would you respond to this listener?
    Answer

    That movement of the Sun, which the listener pointed out, is apparent. The direction of the tails of comets is constantly changing, and this is detected, although not immediately.

Scientists have provided new updated information regarding debris, large pieces, dust particles near Comet 67P/Churyumov-Gerasimenko. The studies concerned the material surrounding this small celestial body and were aimed at searching for satellites near it.

Since its arrival at comet 67P/Churyumov-Gerasimenko, the Rosetta probe has been studying its nucleus and environment using various instruments and equipment. One of the key areas is the study of dust particles and other objects around it.

An analysis of measurements from the GIADA instrument, which analyzes and studies dust particles, as well as images taken by the OSIRIS camera, revealed hundreds of individual dust objects, either associated with the comet by its attraction, or receding from it.

Small objects were found in the images, as well as much larger blocks, ranging in size from a few centimeters to two meters. It is worth saying that blocks up to four meters were found only once during the NASA mission to comet 103P / Hartley 2 in 2010.

The new imaging study builds on previous studies of cometary dust. Scientists, using special methods to perform dynamic studies, for the first time determined the orbits of four categories of debris, the largest of which was up to one and a half meters in diameter.

The studies were based on several images of this area, and this was enough to confirm that the pieces of material are moving along a certain trajectory. However, to understand how they are related to the comet, it took hundreds of pictures over a long period of time.

To track the movement of debris in fine detail, the scientists observed a piece of the sky with the OSIRIS camera, which allows you to explore objects over large areas. Taking pictures at 30 minute intervals with exposures of 10.2 seconds each, they obtained 30 images. Images were taken prior to September 10, 2014.

By the way, the photograph was taken just a few hours before the start of the maneuver, which was associated with the launch of the probe into orbit around the comet. The distance at that moment to the core was 30 km.

When scientists later analyzed the images, they identified four categories of debris, ranging in size from 15 to 50 centimeters, visible in the starry sky. It was found that they move very slowly, at a speed of several tens of centimeters per second, and are within four to 17 kilometers from the nucleus.

It can be said that for the first time scientists were able to determine the individual orbits of such fragments located next to the comet. This information is very important for studying their origin and helps us understand the processes associated with the loss of mass by such celestial bodies.

In fact, three of these categories were found to be gravitationally bound to the comet and move in elliptical orbits. However, the distance that small particles traveled in a 30-minute interval was too small to determine their orbits, so scientists do not exclude that these three categories of debris and small dust particles may be in unrelated, hyperbolic orbits.

As for the origin of the debris, it probably refers to the time when the comet last reached its closest point to the Sun, passing perihelion in 2009, after which it broke away from the nucleus due to strong evaporative processes. But because the force of the gas jets was not enough to free them from the gravity of the core, they lingered in her sphere of gravity instead of dissolving into space. It is possible that some of them have been constantly near the core for a long time.

This study proves that such large chunks of material can be ejected from comets and that they also remain attached to them for a long time as they orbit the Sun.

On the other hand, one of the categories of debris, for sure, is moving along a hyperbolic trajectory, which will allow them to leave the comet's sphere of gravity and go into outer space in the near future.

During the research, a large fragment was found in the photographs, which had a very interesting trajectory that intersects with the core. Scientists have suggested that shortly before the observations, he could break away from him. This assumption, as intriguing as it is, is perplexing, since at that time the comet was still at a fairly large distance from the Sun.

A few more image sets were taken after Rosetta orbited the comet last September. Now they are being analyzed to determine and study the trajectories of other fragments. However, new images will make it almost impossible to reconstruct and identify the same debris from later images.

But what about the relatively large pieces of cometary dust that are several tens of meters across? Are they satellites of a comet? After all, such satellites have been found around many asteroids and other small bodies in the solar system. Is there any evidence of such ‘comrades’ in 67R/Ch-G?

Italian scientists conducted a study to find satellites around the comet. They used images taken by OSIRIS in July 2014, prior to Rosetta's arrival, to view the comet's large-scale environment in high resolution.

After carefully examining these images, the scientists found no evidence of satellites around 67P/Ch-G. These studies suggest that no debris larger than six meters was found at a distance of 20 kilometers, and none larger than one meter at distances between 20 and 110 kilometers from the core.

The discovery of such a large satellite around the comet would perhaps provide additional information regarding the origin of this small celestial body. However, scientists do not exclude that 67Р/Ч-Г could have had such a companion in the past, and it was lost, given the unfavorable conditions in which this comet lives.

The “family” of satellites, asteroids and comet nuclei is very diverse in composition. On the one hand, it includes the huge satellite of Saturn Titan with a dense nitrogen atmosphere, and on the other hand, small ice blocks of comet nuclei, spending most of the time on the far periphery There has never been a serious hope of discovering life on these bodies, although the study of organic compounds as precursors of life on them is of particular interest.

Recently, the attention of exobiologists (specialists in extraterrestrial life) has been attracted by Jupiter's moon Europa. (See appendix fig. 3) There must be an ocean of liquid water under the ice crust of this satellite. And where there is water, there is life: Lake Vostok, located in Antarctica, enjoys increased attention from researchers, since it is considered the terrestrial analogue of the surface of Europa, the satellite of Jupiter. The conditions of this lake, covered by almost four kilometers of ice, are close to those expected for an ocean found under the icy crust of Jupiter's moon, scientists say. Until recently, geothermal heating was thought to be a possible cause of both formations. These reservoirs are covered with such a thick layer of ice that for millions of years neither atmospheric air nor sunlight has entered there. Therefore, if in the future scientists can detect life in Lake Vostok (at present, drilling wells have not yet reached the liquid layer), then this will serve as a real argument in favor of the existence of life in the Europa ocean. "Most of life on the surface of the Earth - on land or in the sea - depends on photosynthesis. The first link in the food chain is the conversion of sunlight by chlorophyll into chemically stored energy. But imagine the ocean on Europa - a huge reservoir of water covered with kilometers of ice. Photosynthesis doesn't work there, but despite everything, there are other ways for life to exist there,” Chaiba said.

The data coming from the Galileo spacecraft suggest the existence of an ocean under the surface layers of not only Europa, but also other satellites - Ganymede and Callisto. The presence of liquid water is the most important prerequisite for the development of life, but to maintain it, an energy source is also needed "Oxygen, a product of photosynthesis, is an important oxidizing agent in Earth's oceans, but it is unlikely to play any role in the oceans of Jupiter's moons. It is possible that oxidizing agents, like hydrogen peroxide, can be formed in the ice sheet by high-energy particles from Jupiter's magnetosphere and seeping into the ocean through the ice sheet, such substances can serve as the basis for the necessary reactions.

Scientists are not sure that such a mechanism plays a leading role, and therefore they have been looking for other possibilities for the formation of molecular oxygen in the oceans. One of them turned out to be the potassium-40 isotope, the presence of which is possible both in ice and in water. The decay of potassium-40 atoms leads to the splitting of water molecules and the formation of molecular oxygen. The amount of oxygen thus produced is sufficient to sustain the biosphere in the oceans of the satellites.

In meteorites that have fallen to the ground, complex organic molecules are sometimes found. At first there was a suspicion that they fall into meteorites from the earth's soil, but now their extraterrestrial origin is quite reliably proven. For example, the Murchison meteorite that fell in Australia in 1972 was picked up the very next morning. 16 amino acids were found in its substance - the main building blocks of animal and vegetable proteins, and only 5 of them are present in terrestrial organisms, and the remaining 11 are rare on Earth. In addition, among the amino acids of the Murchison meteorite, left and right molecules (mirror symmetrical to each other) are present in equal proportions, while in terrestrial organisms they are mostly left. In addition, in meteorite molecules, carbon isotopes 12C and 13C are presented in a different proportion than on Earth. This undoubtedly proves that amino acids, as well as guanine and adenine, the constituents of DNA and RNA molecules, can independently form in space.

So, while in the solar system nowhere except the Earth, life has not been discovered. Scientists do not have high hopes on this score; Most likely the Earth will be the only living planet. For example, the climate of Mars in the past was milder than it is now. Life could originate there and advance to a certain stage. There is a suspicion that among the meteorites that hit the Earth, some are ancient fragments of Mars; in one of them strange traces were found, possibly belonging to bacteria. These are still preliminary results, but even they attract interest to Mars.