Comet - space object, which moves at high speed around the Sun. Translated from Greek language the name means "long-tailed". Sometimes these space objects come close to the Earth, then they can be seen in the starry sky with the naked eye. The brightest comet is Halley, which passes the Earth every 75 years. Introducing Interesting Facts about comets.
Astronomy
Astronomers have counted four thousand comets that originate from the Kuiper belt (the planet Pluto is located in this belt). In the Oort belt, which is further from the Sun than the Kuiper belt, there may be millions of comets (sometimes even a trillion of these). space objects). Scientists discover an average of five comets each year.
The diameter of the nucleus of the smallest comet is 16 kilometers, the record diameter of the nucleus is 40 kilometers.
Photo by Kohoutek
Jupiter has such large mass, which affects the direction of movement of comets. In July 1994, astronomers witnessed Comet Shoemaker Levy 9 disintegrate as it fell toward Jupiter.
For the first time, Halley's comet (it was not called that at that time) was mentioned in Chinese chronicles in 240 BC.
In 2014, the Rosetta probe landed on comet Churyumov-Gerasimenko. The spacecraft approached this space object for about ten years.
Properties
This space object is actually a dirty snowball consisting of water, frozen ammonia, dust and rocks. The core is dark in color, its composition is unknown, perhaps the composition of the core is the same as that of meteorites that fall to Earth - they are iron, stone and iron-stone.
In fact, it is an asteroid that becomes noticeable due to its long tail. This tail appears when this block of ice approaches the Sun as close as possible, then the ice melts and a dust cloud forms behind the comet. When an ice block is even closer to the Sun, the process of sublimation occurs (this phenomenon of physics is also called sublimation - a transition from a solid to a gaseous state without staying in liquid state). When ice is close to the surface, it heats up and creates a stream of gas, a phenomenon similar in appearance to a geyser eruption.
The tail can be very long; Comet Hyakutake's tail is 580 million kilometers long, three times the distance from Earth to the Sun.
A comet has two tails. The first tail consists of dust, which we see with naked gas. The second is invisible because it consists of gases that are blown by the solar wind.
As it moves away from the Sun, the comet becomes like an asteroid, its tail disappears, leaving only a rocky core surrounded by ice.
Hyakutake Photography
Craters
Perhaps dinosaurs became extinct due to a collision between the Earth and a comet. On our earth there are many meteorite craters that could have been left by comets. According to some sources Gulf of Mexico is the largest meteorite crater on Earth with a diameter of more than 1 thousand kilometers.
120 kilometers from Johannesburg, South Africa, there is a large meteorite crater called Vredefort (diameter about 300 kilometers). The crater is still large sizes is located in Antarctica - the Wilkes Land crater has a diameter of 500 kilometers, but it has not been studied well enough, since it is located under a layer of ice.
Large craters were discovered in the Canadian province of Ontario (Sudbury, diameter 200 kilometers) and on the Yucatan Peninsula, North America(Chicxulub, diameter - 170 kilometers). Such large craters could be formed by the impact of asteroids or comets.
Every fall cosmic body, which formed such large craters on the surface of the earth, led to disasters on Earth. For example, the Chicxulub crater was formed from the fall of a block with a diameter of about 10 kilometers, the energy from the fall is estimated at 100 teratons in TNT equivalent, for comparison - the most powerful thermonuclear bomb had a power two million times less. The impact of the meteorite or comet that formed the Chicxulub crater should have caused a tsunami up to 100 meters high, rocks had to be lifted into the air 100 kilometers (that is, into space), when they fell back they would become hot and could cause Forest fires thousands of kilometers from the crash site. It is believed that the ash that entered the atmosphere led to a cooling of the air by 28 degrees, the water became colder by 11 degrees, which led to the extinction of many species of animals and plants.
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 interplanetary station Rosetta and will 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.
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 Hungarian army and inspired her. The Turks near Belgrade were defeated.
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 deadly poison. The enlightened world was seized with panic, but nothing terrible happened.
For a long time it was believed that comets are the remains of planets and satellites that have not been sorted out ancient substance, from which our solar system was formed. It was believed that the basis of the comet was made up of frozen solid state gases and water 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.
Thus, a kind of halo or coma is formed around the comet’s nucleus, clearly visible in the light of the Sun. Coma much more core and can reach millions of kilometers in diameter. Pressure 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. Because the chemical composition of comets is quite varied, different molecules and dust particles are deflected differently solar radiation Therefore, comets have a separate dust tail and a separate gas tail, and the gas tail itself can have a completely different appearance.
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 of the hypotheses, earth's oceans- this is 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 the composition stony meteorites. However, when the comet Ikeya-Seki, discovered on September 18, 1965, began to approach the Sun, scientific world I was slightly shocked - 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.
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 objects during their journey. celestial bodies. For example, the 1996 Comet Hyakutake had an estimated orbital period of 17 thousand years, but gravity outer planets changed its orbit, and now it will return to us no earlier than in 70 thousand years.
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.
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.
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. On Soviet stations There was also equipment from the European Space Agency. At the same time, ESA launched its station, Giotto, and the Japanese launched the Sakigake and Suisei probes.
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.
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 relative speed is 70 km/sec, are simply meaningless. You need to chase the comet. And in this pursuit there is a chance of capturing particles of cometary material.
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
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 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.
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 extreme high temperatures, most likely, not far from the surface of the Sun 4.5 billion years ago, that is, a lot later started formation of the solar system. Scientists wondered: how did the comet then collect ice, frozen gases and particulate matter 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 is unusually dark in this range, and there is no evidence of areas open ice didn't watch. 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 become so strange over time? general shape? 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? They can be split, for example, 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? On at this stage Every joke has a grain of 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.
The largest collection of amazing information about celestial bodies. Interesting facts about comets and asteroids will be revealed to you completely new world, which you never knew existed.
Translated from Greek, “comet” means “long-haired,” since ancient people associated a star with a long tail with hair blowing in the wind.
Comets are dirty ice
A comet's tail is formed only when close proximity with the Sun. Far from it heavenly body Comets are icy, dark objects.
90% of a comet is ice, dirt and dust. In the center is a stone core. As it approaches the Sun, the ice melts, forming a dust cloud behind it. This is the tail we see.
Incredible amount
The smallest comets reach a core diameter of 16 km. The largest recorded is 40 km. The length of the tails can be very long. For example, comet Hyakutake's tail length was 580 million km.
A cluster of comets can number in the trillions. That's exactly how much is in the Oort Cloud, the cluster surrounding solar system. Within the solar system, astrologers count at least 4,000 comets.
Jupiter, as the most big planet Solar system, is capable of changing the direction of comets by the force of its gravity. So, one day comet Shoemaker-Levy 9 crashed into the atmosphere of Jupiter.
Shapeless asteroids
Cosmic bodies form a spherical shape under the influence of their gravity. Asteroids are too small to form a sphere, so they look like ellipsoids or dumbbells.
Integrity of form is rare for an asteroid. More often it is a pile of compounds, which is held by its own gravity. The accumulations contain coal, stone, iron, and volcanic materials.
The diameter of the largest asteroid, Caecesere, is 950 km.
If an asteroid enters a planet's atmosphere, it is a meteor. If it falls to the ground, then it is a meteorite.
Is there a threat to us?
Asteroids pose a potential threat to the planet, but modern technologies easily prevent this from happening.
To imagine how an asteroid falls onto the surface of the planet, you can look. Interesting fact - the Earth can be destroyed with just one meteor with a diameter of 1 km.
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.
Core - hard part, which contains most mass of the celestial body. The size of the core usually varies within a few kilometers. By earthly standards - big mountain, in cosmic terms - 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.
Cloud of gases melted due to solar temperature, begins to dissipate around the comet, and as it moves, this cloud takes the shape of a tail and reaches behind it. In the sky we see the tail of a comet, the size of which reaches several solar diameters. Different shapes comet tails explained various compositions gases Different gases react differently to temperature and have different properties, chemical structure and expand in different ways.
Interesting facts about comets, collected in one place:
- The word "comet" originates in ancient Greece, which means "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.
- On this moment 4 thousand phones 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.
Since ancient times, people began to distinguish comets from other celestial bodies, attributing to them completely extraordinary properties. Although Halley's comet was the first of those that natural scientists began to study seriously, great fears were associated with it for a very long time. They persisted even into the twentieth century.
History of Halley's Comet
Although today we already know everything about Halley’s comet (or almost everything), it is very useful to understand why it provoked such fear in the past (like other “shaggy stars”). Extremely poor knowledge about space processes in the past has led to their mystification.
From time to time, suddenly appearing comets, which soon just as suddenly disappeared from sight, were perfectly suited to the role of a scarecrow. At every such occasion they expected wars, upheavals, famines and natural Disasters. It must be said that at that time such incidents were not uncommon, and often coincided with the arrival of comets.
What can we say about ancient and medieval people! When Halley's comet approached the Earth in 1910 and our planet passed through its tail, such a famous astronomer as Flammarion, wittingly or unwittingly, caused panic. Poisonous gases, he said, are capable of destroying all living things. Some merchants took advantage of the general shock and sold a lot of gas masks, pills and even...umbrellas!
When was Halley's Comet last seen?
Halley's comet is classified as short-period - it makes a revolution around the Sun in strictly 74-79 years, on average 76 years. The last such appearance occurred in the spring of 1986. The distance between it and our planet was about sixty three million kilometers even at the moment of closest approach.
Of course, the researchers could not help but take advantage of this opportunity. Were launched in advance spacecraft who photographed the nucleus of Comet Halley. By the way, it turned out to be very dark - blacker than any coal. The density of the core is very low, and it appears to be porous.
Comet meaning
Halley's Comet is interesting to scientists primarily because it was the first to be studied in detail. However, it is hardly possible to extend the conclusions drawn to comets in general. After all, Halley's comet is atypical in size, in the definiteness of its orbit, and in other parameters.
The next appearance of Halley's Comet will occur in the second half of this century, or more precisely, in 2061. Well, forty-six years just seems like a long time. Surely many of those who are now reading this article will still be able to enjoy the spectacle of the “shaggy star”.