New scientific information about comets and asteroids. Interesting facts about comets. Interesting facts about comets collected in one place
These heavenly guests have been considered omens from above for centuries. Then they were relegated to the status of a dirty snowball. Now they have become one of the most amazing mysteries of nature. In mid-September, a point was set where humanity could get an answer to the question of what comets are. The question is surprisingly practical.
On September 15, at a press conference in Paris, it was announced that a team of scientists had chosen a landing site for the Philae scientific module, which was to land on the surface of comet 67P/Churyumov–Gerasimenko. The Philae module will undock from the Rosetta interplanetary station and land on November 11 this year at the conditional point J. The Philae device will attach to the surface of the comet with a special harpoon anchor, drill and observe how the comet begins to heat up and melt as it approaches the Sun.
Although they are too small to merit the "planet" distinction, asteroids and comets loom large in literature and folklore. The reason is clear: one of the short rocks or icy balls of dirt will eventually and irreversibly change the planet. It is believed that such an impact occurred 65 million years ago.
Asteroids and comets are believed to be the remnants of a giant cloud of gas and dust that condensed to create the sun, planets and moons about 5 billion years ago. Today, most asteroids orbit the Sun in a tightly packed belt located between Mars and Jupiter. Comets are thrown away by either a cloud or a belt at the edge of the solar system. Gravity tugs, orbital collisions and interstellar tremors sometimes disturb an asteroid or comet on a wayward path.
Comet Horrors
Comets are the most mysterious celestial bodies in the solar system. They amazed the imagination of earthlings. They were seen as signs from above, although they were not always successfully interpreted. There has long been a story circulating in manuscripts and books about Pope Calixtus III, the famous Alfonso di Borgia, who, wanting to support the Christ-loving army of the Kingdom of Hungary, which opposed the Turks, declared a comet that appeared in the heavens to be a “sign from above,” supposedly in the shape of a cross. The Turks, however, saw that the comet's tail rather resembled a scimitar, and announced that it was the Almighty who was promising them victory. Nevertheless, the pope's message reached the Hungarian army and inspired it. The Turks near Belgrade were defeated.
The difference between asteroids and comets is that fuzzy comets tend to have more chemical compounds that evaporate when heated, such as water, and more elliptical orbits than asteroids. And when viewed through a telescope, comets seem crazier.
Asteroids are essentially pieces of rock ranging in size from a few feet to several miles in diameter. The largest asteroid, Ceres, is about 590 miles wide. Many astronomers believe the belt is primordial material that never entered the planet due to Jupiter's gravitational pull.
Edmund Halley put an end to mysticism in the 18th century. In 1716, he predicted that the same comet that everyone saw in 1682 would arrive in 1758. The great astronomer did not live to see his triumph, but grateful descendants named the comet after him.
By the 20th century, no one believed in ominous omens, but they began to believe in science and pseudo-scientific speculation. With the advent of spectrography, scientists began to study what glows in comets, and they were simply shocked, as was the general public. In 1910, during the next passage of Comet Halley, molecules of HCN, hydrocyanic acid, the salt of which (potassium cyanide) has long become a symbol of a deadly poison, were discovered in its tail. The enlightened world was seized with panic, but nothing terrible happened.
Their short life
Other astronomers say the belt is a planet that was broken apart during a collision. Comets are balls of rock and ice that grow tails as they approach the sun during their highly elliptical orbits. As comets heat up, gas and dust are pushed out and trail them. The sun illuminates this trail, causing it to glow. Glowing trails are visible in the night sky.
While there may be trillions of comets ringing around the outer edges of the solar system, bright comets appear in Earth's visible night sky about once every decade. Short periods of comets such as Halley's are perturbed from the so-called Kuiper belt beyond Neptune's orbit and through the solar system once or twice in a human lifetime. Long-lived comets originate from the Oort cloud, which oscillates from the outer solar system and passes near the Sun once every hundreds or thousands of years.
For a long time it was believed that comets are the remains of ancient matter, not disassembled into planets and satellites, from which our Solar system was formed. It was believed that the basis of the comet was gases and water frozen to a solid state, mixed with dust and small stones. While the comet flies far from the Sun, it looks like an asteroid, but as it approaches the star, the frozen substance takes on a gaseous form, taking dust with it.
Random impacts and gravitational tugs send asteroids and comets toward the sun in highly elliptical orbits, some close enough to Earth to pose an impact hazard. Astronomers are constantly looking for bodies on such a catastrophic trajectory. Fortunately, most asteroids are too small to cause any damage. Instead, they burn up in the atmosphere and appear to us as a shooting star.
Interesting facts about comets collected in one place
Based on the theme of asteroids, Americans love to make films with a scary storyline. The most famous film is “Armageddon” with Bruce Willis. But most viewers have no idea about these space objects, where they come from, where they come from and how they move. All this will help you understand interesting facts about asteroids.
Thus, a kind of halo or coma is formed around the comet’s nucleus, clearly visible in the light of the Sun. The coma is much larger than the nucleus and can reach millions of kilometers across. Pressure from sunlight blows away molecules of gases and microscopic dust, forming comet tails. The tails of comets are extremely sparse - scientists compare it to one thimble of matter scattered over the whole of Moscow - such is their density. Since the chemical composition of comets is quite varied, different molecules and dust particles are deflected differently by solar radiation, so comets have a separate dust tail, a separate gas tail, and the gas tail itself can have a completely different appearance.
By the concept of asteroids or small planets we can understand celestial bodies with a body diameter of at least 30 meters. Bodies with smaller sizes are called meteoroids. The largest number of them are located in the so-called asteroid belt, between the orbits of the planets Mars and Jupiter.
According to the official hypothesis, asteroids are not fragments of the destroyed Phaeton, but embryos of an unformed planet. This conclusion was made based on the fact that minor planets are not of the same age. The largest asteroid is Ceres with a diameter of 950 km, which is 4 times less than the diameter of the Moon. Such enormous dimensions give reason to call Ceres a dwarf planet.
Comet Ikeya–Zang has a beautiful large coma and a straight tail of gas and dust.
It was assumed that comets could contain huge volumes of water. In particular, according to one hypothesis, the Earth's oceans are the water of comets that fell to Earth at the dawn of its existence. The composition of solid particles was assumed to be close to that of stony meteorites. However, when the comet Ikeya-Seki, discovered on September 18, 1965, began to approach the Sun, the scientific world came into a slight shock - the comet turned out to be not only exceptionally bright, but also unusually warm. When its core began to actively collapse from its proximity to the Sun, spectrometers showed the presence of metals such as iron and nickel in its composition. To clarify the details, you will have to wait - comet Ikeya-Seki will return to the Sun only after 1400 years.
The second largest asteroid is Pallas, the third is Vesta, and the fourth is Hygeia. Another 5 minor planets have dimmers up to 300 km, 30 - up to 200 km, 200 - up to 100 km. There is a reasonable theory that water and life on Earth are brought by asteroids. The small planet Icarus during certain periods of its motion approaches the Sun at a distance less than the planet Mercury.
This small planet's intense brightness is caused by its high albedo. The danger for the entire earthly civilization can be represented by collisions with cosmic bodies with a diameter of 3 km. Bodies measuring 50 meters when colliding with the Earth can cause significant economic damage.
Their short life
All comets can be divided into two groups: short-period and long-period. Short-period ones return to the Sun every 200 years or more often - comet Encke rushes to meet it every 3 years, for example. Comet Churyumov - Gerasimenko - every 6 years, a little more. Halley's Comet - every 76 years.
But long-period comets can have an orbital period of tens of thousands of years. All comets can change it if they fly past massive celestial bodies during their journey. For example, the 1996 Comet Hyakutake had an estimated orbital period of 17 thousand years, but the gravity of the outer planets changed its orbit, and now it will not return to us for at least 70 thousand years.
Currently, the most dangerous asteroid is Apophis with a diameter of 300 meters. Its orbit passes dangerously close to the orbit of our planet. The next “dangerous” passage of Apophis will be a year. The largest asteroid that collided with Earth had a diameter of about 10 km. The trace of the fall can be seen today - this is the Gulf of Mexico off the coast of North America. This collision led to great cataclysms that killed more than half of the living beings on our planet.
Asteroids, in addition to being different sizes, also have different chemical compositions. A large percentage of minor planets have a carbon structure; 17% - sand; more than 6% is metal. In general, the composition of asteroids is determined by how close they are to the Sun. The pressure from our nearest star and its heat tends to melt around the ice that is nearby and blow away those elements that are lighter.
The life of comets that fly to the Sun is often short by astronomical standards - tens, hundreds of thousands of years. The reason is simple - each approach of a comet to the Sun evaporates part of it, the comet is destroyed and in the end either turns into something asteroid-like, or simply into a pile of stones, sand and dust, which gradually disperse in space.
They usually consist of iron with admixtures of its silicates and magnesium. "Bright M" asteroids.
- "Dark C" asteroids, which are mostly found in the outer belt.
- They are located in the middle of the asteroid belt and are mainly composed of iron.
Well, they come from the periphery of our solar system, where they slowly float in the darkness of eternal cold. From there they are pulled out by all sorts of gravitational disturbances and collisions. But this benign picture of the life of comets needed confirmation. And then space stations were sent to comets.
To meet a star
It is very difficult to meet a comet in space when it is heading towards the Sun. It is there, in the black distances, that their speed drops to hundreds and tens of meters per second. The closer to the Sun, the greater the speed, which exceeds 40 km/sec. Otherwise, they will not be able to escape from our luminary, and there is only one road left - to hell.
There are other groups of small cosmic bodies: Vulcanoids, near-Earth ones, crossing the orbit of Mars, Trojan and Damocloids. The most famous object of the Centaur class is the small planet Chiron. Its popularity was not only due to its size, but also because it was often confused with the comet. After all, Chiron has the ability to periodically form a “tail” that resembles a comet.
A giant asteroid as big as the one that killed the dinosaurs is heading towards Earth. The earth and all life on it can be destroyed forever! This is the plot of the movie "Armageddon" starring Bruce Willis. Could an asteroid hit Earth and cause the destruction of humanity?
But in the 1980s, humanity already had some experience and knowledge. And a whole armada of scientific apparatus was waiting for Halley’s comet returning to the Sun. The USSR launched two Vega (Venus-Halley) probes, which were supposed to study Venus and then pass by the comet. The Soviet stations also had equipment from the European Space Agency. At the same time, ESA launched its station, Giotto, and the Japanese launched the Sakigake and Suisei probes.
The space is filled with rocks and other substances left over from the Big Bang. None of this debris, be it asteroids, comets or meteors, is currently on a collision course with Earth - but we know that Earth has crashed into Earth in the past and will again in the future. Let's look at what each of these things are, their characteristics, and any impact they have had on Earth or may have in the future.
A comet is an icy ball of rock that grows a tail as it travels close to the Sun. It grows a tail because when comets heat up, gas and dust are forced out of the body and trail behind it. The sun illuminates this trail, which makes it glow. The glow is visible in the night sky, and what we see on Earth is a streak.
Vega and Giotto came closest, at 8000 km and 660 km respectively. They found themselves under an avalanche of particles that caused significant damage to the stations. But they learned that the bright comet's core is actually almost black, and only the gases that erupt into space on the sunny side glow. A porous, black, fragile and unpredictable world - the creators of the film "Armageddon" were based on precisely this data, trying to show us a killer comet.
The way a comet orbits - and the length of its orbit - varies greatly from one comet to another. Most short-period comets come from the Kuiper Belt, a massive region of small objects beyond Neptune. Longer orbital comets come from the Oort cloud, a massive cloud of ice very far out in the outer region.
To meet a star
Every year the Earth sees several comets. Some of them are comets, which we expect because they regularly orbit the Sun. The rest are new comets that have never been seen. The most famous comet is Halley's Comet. Small objects that orbit the Sun. They range in size from a few feet to several miles. Some of the largest asteroids are so large that they are called planetoids. The largest asteroid known so far is named Ceres and is 950 kilometers wide.
This is how the Giotto probe saw Halley's Comet in 1986
Ten years later, American scientists began preparing for their launches. The pursuit of Halley's comet showed that the dust around the comet can kill any station, and attempts to do something on a collision course, when the relative speed is 70 km/sec, are simply pointless. You need to chase the comet. And in this pursuit there is a chance of capturing particles of cometary material.
There are millions of asteroids in the Universe. Most of them live in the asteroid belt between Mars and Jupiter. Most believe that asteroids are leftover pieces of matter from the formation of our solar system that are held in the belt zone by Jupiter's gravity. Others believe that the asteroid belt is a planet that was broken up during a collision. groups of asteroids in the solar system, one of them is located near the Earth.
Asteroids must be very large and close enough to Earth to be visible with binoculars or a small telescope. Since the Earth was first formed, asteroids have hit it. Luckily for us, dangerous asteroids, such as those likely killed by dinosaurs, are extremely rare.
In 1999, the Stardust expedition was sent to comet Wild 2, which was supposed to collect dust samples and return them to Earth for laboratory analysis. Following the “vacuum cleaner,” the Americans prepared a probe to study the density of the comet, and the Europeans began work on the Rosetta project.
The Mystery of Black Potatoes
When an asteroid or part of it crashes into the Earth, it is called a meteorite. It is a natural object that appears in space and penetrates the Earth's atmosphere. When a meteorite enters Earth's atmosphere, it heats up and becomes brighter, similar to a fireball - or unscientifically, like a shooting or shooting star. Meteorites are named after the places where they were found.
When most meteorites enter the Earth's atmosphere, they burn up or disintegrate, but about 500 per year are estimated to hit the Earth's surface. Research on meteorites can tell us about the early solar system, but only about five or six hundred have been found that make it to Earth.
The nucleus of comet Wild 2 was not chosen by chance as the target of the Stardust expedition. Astronomers are convinced that until 1974, this body quietly flew in orbit behind Jupiter, until it passed too close to the giant planet, and it threw Wild 2 towards the Sun, making it a comet with a return period of just over 6 years. That is, Wild 2 is a completely fresh comet, in contrast to the elderly Halley’s comet.
In Earth's history, there have been several meteorites that have struck it that were large enough to create huge impact craters and cause global changes. This size effect is thought to have killed off the dinosaurs 65 million years ago. Fortunately, this doesn't happen very often.
People are still afraid of asteroids and comets because at some point on Earth the future may slam shut and change our history. Astronomers are constantly looking for bodies that are on a catastrophic trajectory. To cause a catastrophic disaster, the asteroid would have to be larger than one-quarter mile.
They decided to catch dust particles from the comet's nucleus using silicate airgel - a substance that is called glass smoke because of its lightness. The probe itself was dressed in armor made of ceramic plates. And January 2 In 2004, the Stardust station came within 250 km of the comet's nucleus. Along the way, the station photographed the core. What scientists saw was superior to the creations of science fiction writers. The core turned out to be decorated with huge notches and peaks. Such a relief has never been seen anywhere in the solar system.
Comet Wild 2 turned out to be an extremely complex form
Experts were even more surprised by the composition of the captured comet particles. Before this, it was believed that comets were assembled from rocky material left over from the formation of planets and asteroids. However, dust samples showed that they were formed under the influence of extremely high temperatures, most likely near the surface of the Sun 4.5 billion years ago, that is, long after the formation of the solar system. Scientists asked the question: how then did the comet collect into one whole the ice, frozen gases and solid particles born near the Sun?
Another question that interested specialists was: how dense is the body of a comet? What is it - an iceberg with frozen stones or a loose lump of snow? This was to be found out by the Deep Impact station, launched at the very beginning of 2005 to comet Tempel-1. The station caught up with the comet and, approaching a short distance, dropped the Impactor probe, which crashed into the body of the comet on July 4, 2005 at a speed of more than 10 km/sec.
The flash upon impact with the loose Tempel-1 surprised scientists with its brightness
A copper charge weighing about 370 kilograms generated a powerful ejection of matter from the comet and a very bright flash. Scientists were slightly perplexed: the nature of the ejection showed that the comet’s nucleus was extremely loose, but why then was there a bright flash? On the other hand, if the core is crumbly, like a boiled starchy potato, then how can such a body retain clear boundaries of craters from numerous meteorite impacts? It was impossible to find out without landing on a comet. It was then that the leisurely Rosetta appeared on the horizon.
If you drive more quietly, you will become a Rosetta
In space everything is relative. Stardust began its mission in 1999 and ended in 2011, looking at the impact of Impactor on comet Tempel 1 in 2005. And the European Space Agency launched the Rosetta probe before the success of Deep Impact, already in 2004. And only 10 years later the station approached its target.
Such a long period was due to the complexity of the task. The Europeans had no intention of bombing the comet, leaving that job to the Americans. They wanted to become a satellite of the comet, and then send a probe to its surface, which would not only take measurements, but also wait until the time when the comet began to melt and evaporate under the rays of the Sun. That is why the station made clever turns around the solar system in order to eventually enter an orbit almost identical to the orbit of the comet itself.
Already at the stage of approaching the comet, some oddities were discovered. However, comet researchers are starting to get used to them. In particular, the ultraviolet spectrograph found that the comet was unusually dark in this range, and did not observe any evidence of areas of open ice. At the same time, both hydrogen and oxygen are fixed in the developing coma of the comet.
But what surprised astronomers most of all was the shape of the comet, reminiscent of a rubber toy duck. The general public thought that scientists had never seen such a shape, and that is why they were so excited. But the intrigue is that astronomers have ALREADY SEEN such an amazing shape - it looks like Halley’s comet.
On the left is Comet Halley, on the right is Churyumov-Gerasimenko. Both comets have a constriction that divides them into two unequal parts
Why did such different comets acquire such strange overall shapes over time? And what are they, hard or loose? Or is the body of a comet something that we have not yet encountered in nature? If they threaten the Earth, how to fight them? Can they be split, for example, by a nuclear explosion, as Bruce Willis’s hero did in Armageddon, or will they simply evaporate? Or maybe they can detonate like a piece of explosive? At this stage, every joke has some humor in it.
Perhaps this is not a threat to our planet, but just a chance for its development, a new Klondike that can change ideas about the search for minerals? Or is it material for terraforming Mars...
All these questions become more relevant in light of reports that NASA is embarking on a program to select asteroids for the purpose of their controlled movement. This may also apply to comets. The wait for the results is not long - and they can be truly sensational.
A comet in the sky is a rare guest. Many interesting facts are known about comets. From time immemorial, people have collected information about celestial bodies and sought to understand their nature, measure their sizes, and understand their structure. The stars appear as small dots, but millions of kilometers separate the curious observer on Earth from the distant star. Without astronomical knowledge, it is impossible to form even an approximate opinion about the size of the celestial body. You will be wrong by several orders of magnitude.
A comet in the sky seems huge next to other celestial bodies. But what are its real dimensions and what is it like?
Any comet consists of 3 parts: the nucleus, the coma and the tail.
Core.
The core is the solid part that contains most of the mass of the celestial body. The size of the core usually varies within a few kilometers. By earthly standards it is a big mountain, but by cosmic standards it is nothing.
Kernel composition:
1. Cosmic dust.
2. Frozen gases.
3. Other solids.
Coma.
Moving along an elliptical trajectory, the comet periodically approaches the Sun, the gases begin to expand and the comet becomes as we see it now. Coma - a cloud of gases around the comet's nucleus. The size of a coma can reach a million kilometers, this is comparable to the size of the Sun. Violent chemical processes occur inside the coma.
The coma and nucleus are the head of the comet, and there is also a tail.
Comet tail.
A cloud of gases, molten by the sun's temperature, begins to dissipate around the comet, and as it moves, this cloud takes the shape of a tail and trails behind it. In the sky we see the tail of a comet, the size of which reaches several solar diameters. The different shapes of comet tails are explained by different gas compositions. Different gases react differently to temperature and have different properties, chemical structures, and expand differently.
Interesting facts about comets, collected in one place:
- The word "comet" originates from ancient Greece, meaning "long-haired". Since the Greeks considered them stars with flowing hair.
- Jupiter, due to its enormous mass, can influence gravity and therefore change the direction of comets. Very often the trajectory of movement changes in an incomprehensible way, frightening scientists.
- These celestial bodies can collide with both stars (the Sun) and planets. Researchers have recorded the collision of comet Shoemaker-Levy 9 with Jupiter.
- Strange sounds emanate from the comet, reminiscent of singing. The reason for this phenomenon is the expansion of the gas cloud.
- The comet has a specific smell. It can be simulated on Earth by combining together a mixture of various gases (mainly ammonia, methane, hydrogen).
- In ancient times they were harbingers of wars and disasters.
- Quite often, a comet can have two tails - dust and gas (can extend for hundreds of millions of kilometers, for example, the tail of Hyakutaki is 580 million km). This is due to gravity and the difference in the specific gravity of gases and dust.
- 90% of its mass is concentrated in the core, the length of which can reach 40 km (average - 16 km).
- In deep space, a comet looks like an ordinary block of ice. The tail appears only when approaching the Sun.
- Once every 10 years, a celestial body can be seen with the naked eye.
- In 1910, Halley's tail hit the Earth.
- The first to document the passage of Halley's Comet were the Chinese in 240 BC.
- Scientists have determined that there are more than two million comets in the Solar System.
- At the moment, 4 thousand bodies are registered.
- In 2014, the first landing of an artificial apparatus on the nucleus of the comet Churyumov-Gerasimenko was carried out. It took 9 years to get closer.