Scientific reports about celestial bodies. Asteroids and comets

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Among the remains of celestial objects formed at the moment of formation solar system, occupy a special place comets and asteroids. Thinking about solar system, we usually imagine the planets included in it with their satellites, as well as Sun.

In reality, there are much more celestial bodies here; first of all, these are “trifles”, like asteroids and comets, which are huge blocks of ice mixed with stones. Their formation occurred during the formation of our entire system.

People knew about comets back in ancient times. When passing close to the planet, the comet leaves a clearly visible fiery tail for quite a long time.

Its secret is the heating of the comet's nucleus by the Sun, while Earth the fire formed during the movement of this hot object is clearly visible. Ancient people considered the appearance of such an ominous sign to be a bad omen, warning of future disasters - drought, lean years, wars, epidemics.

The movement of comets occurs in a certain orbit, which makes their appearance in the earth's sky predictable. Among the most famous are Comet Halley, approaching Earth every 76 years.

The approach of asteroids is most often imperceptible; they can only be seen when they are in upper layers atmosphere, heated by friction with air currents. Although some are so large that they are clearly visible to the naked eye.

First noticed asteroid Ceres back in 1801, a monk from Sicily, Giuseppe Piazzi, then managed to discover great amount similar.

Rock in space

An asteroid can be called a huge rock that moves across outer space. The size of such a “pebble” varies from several meters in diameter to kilometers.

Their orbits may change, but their rotation around the Sun remains unchanged. Most of them are between orbits Jupiter And Mars, so this area was called the Asteroid Belt. In total there are approximately 30,000 of these giant stones.

The history of the origin of the belt is associated with the presence of a planet in this area, more than billions of years ago. Then, for an unknown reason, it was destroyed, after which many fragments remained.

According to another theory, the asteroid belt was formed at the time of the formation of our solar system; all the planets existing today appeared from similar fragments, but some were prevented from uniting by the gigantic gravity of the planet Jupiter.

Which asteroid is the darkest?

The darkest is considered to be the one that reflects the least incident sunlight - Arethuz (No. 95), the reflectivity of which is 1.9%. It belongs to type C asteroids (carbonaceous "carbonaceous»).

Asteroids also differ in size. The diameter of the largest, Ceres, is about 700 km. The orbits of some are elliptical, for this reason they can get significantly closer to other celestial bodies, including the Earth and the Sun.

Penetrating through the atmospheric layer of our planet, they are carried away further, or burn up after contact with air. Their other name is meteors. If the gravity of the Earth captured them and they fell to its surface, then these are meteorites. Studying fallen bodies, scientists are getting a lot of information about asteroids.

Comets: lumps of icy mud.

A comet is a large ball of snow mixed with mud. Some astronomers have nicknamed them dirty snowballs, which they resemble. The composition of the ice from which the comet is created includes frozen gases.

According to astronomers, comets were formed from early matter that took part in the formation of the entire solar system. A number of aircraft spacecraft is sent to comets to collect samples of this substance for researchers. They hope they will help unravel the origins of our system.

All are comets with an inevitable fiery tail; in fact, its appearance indicates the approach of the object to the Sun. At this moment, the core is heated, after which the ice partially transforms into a gaseous state. The released gas, mixed with dust, begins to reach behind the core. All this is illuminated by sunlight.

Which comet is the most famous?

Among the most famous is Halley's Comet. The frequency of appearance is 76 years, having flashed past the Earth in its orbit, it is again carried away into the depths of space, flying past the Sun. It was first recorded 2.5 thousand years ago, sketched in 684. AD

It has been suggested that comets emerged from the dense matter that surrounds the solar system, also called Oort cloud.

It is generally accepted that the trajectory of a comet is influenced by the gravity of a variety of celestial bodies, changing it. There is a version that our Sun is a double star, and the second part, remaining invisible, attracts all comets. However, having gathered together, their total mass overcomes the gravitational force of this star, continuing their movement. This theory can explain the reason for the disappearance of all existing comets, which happens once every hundred million years.

Potential threat?

It is believed that asteroids and comets pose a threat to all earthly life. Space is literally “teeming” with thousands of objects flying close to our planet along a variety of trajectories. From the outside it is very reminiscent of the famous pinball game. Some fly too close to the Earth, which led to them being called “Earth-crossing asteroids.”

In addition, scientists believe that the Oort Cloud, which is affected by the gravity of other stars, is capable of pushing out new batches of comets that set off in flight, according to new trajectories to the planets located in the solar system.

In this case, it is possible to collide with some. The closest example is Moon, whose surface is covered with many craters from celestial bodies falling on it in different time. For the Earth, the high density of the atmosphere provides reliable protection; most bodies do not reach the surface, burning up in it.

Although some large meteorites still managed to reach the planet, leaving clear signs of their fall. Among them:

Arizona crater, a bowl-shaped depression about 180 m, and its diameter reaches 1,200 km.

Several dozen other craters, although finding them is quite difficult due to erosion, which quickly destroys all traces.

The fall of a large meteorite, approximately 15 km in diameter, which led to the death of dinosaurs. The raised dust blocked access to the sun's rays in the atmosphere. After which came a long period of cooling, called the “nuclear winter,” which led to the destruction of almost all living things. It all happened several million years ago.

Quite recently, a similar story almost happened again. After the explosion Tunguska meteorite, the blast wave broke trees for several hundred kilometers, and it circled the globe twice.

There is a huge amount of evidence of their capabilities to hit other planets:

1994 – a large meteorite that fell on Jupiter left a giant crater, the size of which is comparable to the Earth.

One can even argue that our planet is also threatened by the fall of similar celestial bodies, although the probability of this event is so small, and you can find out about this in advance, based on calculations carried out by astronomers.

Sometimes called minor planets, they are rocky debris left over from our formation about 4.6 billion years ago.

10 facts you need to know about asteroids

1. If all the asteroids were combined into one ball, it would still be much smaller than the Moon. If it were the size of a front door, then the Earth would be the size of a dime, the Moon the size of a green pea, and (the largest object in the asteroid belt) the size of a sesame seed.
2. Most asteroids orbit between the orbits of Mars and Jupiter. This region is also known as.
3. Days and years last differently on asteroids. For example, one day on the Ida asteroid takes 4.6 hours (the time it takes for the asteroid to make one full revolution around its axis). Ida makes a full revolution around the Sun (an asteroid year) in 4.8 Earth years.
4. Asteroids are hard, rocky, and unstable objects.
5. Asteroids do not have an atmosphere.
6. At least 150 asteroids are known to have their own satellites (some have two at once). The first open system with an asteroid and a satellite in its orbit: the asteroid Ida and its satellite Dactyl.
7. One asteroid, known as Chariklo, has two dense, narrow rings.
8. More than 10 spacecraft have explored asteroids. The Dawn mission is the first mission to orbit an asteroid (Vesta).
9. As far as we know, asteroids cannot support life.
10. - the first and largest asteroid, which was discovered in 1801 by Giuseppe Piazzi and the closest dwarf planet to.

Where to look for asteroids?

Most of this ancient space debris can be found in the orbit of the Sun, between and where . Asteroids come in different sizes. The most large asteroid is (not to be confused with, as it is now a dwarf planet) measuring about 329 miles (530 kilometers) in diameter. The majority of asteroids are less than 10 meters wide. The total mass of all asteroids is less than the mass of the Earth's Moon.

Editor's note: We know of more than half a million asteroids (maybe more), but there are still many asteroids that are far apart from each other, and not as shown in Hollywood films. On average, their distance is about 1-3 million km (depending on the calculation method).

Distribution of asteroids in

Most asteroids are irregularly shaped, although some are spherical, but most often they have dents and craters. Although they rotate around in an elliptical orbit, they can sometimes rotate chaotically and unpredictably. More than 150 asteroids have their own satellite, the Moon, and some asteroids have two moons as satellites. There are also binary or double asteroids, they are created by connecting two rocky fragments, approximately the same size for one orbit, in this way triple asteroid systems are also created.

Asteroid classification

There are three main classes of asteroids: C, S and M.

C-class asteroids(chondritic) are the most common, they are probably composed of clay and silicate rocks and have a dark appearance. They are among the most ancient objects in.

S-class asteroids(stone) consist of silicate materials and nickel.

M-class asteroids metal, consisting of nickel.

Comparison of the masses of the 20 largest asteroids

Asteroids differ in how far from the Sun they were formed. Some were exposed to high temperatures after formation and partially melted as the iron reached the center of the asteroid and caused basaltic (volcanic) lava to splash onto its surface. Only one such asteroid, under the name Vesta, has survived to this day.

Types of asteroids

Near-Earth asteroids: These objects have orbits that are close to . Asteroids that cross the Earth's orbit are called earth-crossing asteroids. As of June 19, 2013, 10,003 near-Earth asteroids are known, 861 of which have a diameter of more than 1 km, and 1,409 asteroids are considered potentially dangerous to our planet.

How asteroids get their names

The International Astronomical Union Committee on Small Body Nomenclature is less strict with the naming of asteroids than other IAU committees. So, in the orbit of the Sun we have giant space rocks called Mr. Rock (or Mr. Stone in English) in honor of the cat from Star Trek, asteroids in honor of the rock musician Frank Zappa, and asteroids in honor of ordinary guys such as Phil Davis and darker names honoring the Colombian team that died in 2003.

Asteroids are also named after places and other things (the IAU forbids naming asteroids after animals, so Mister Rock is left alone). Asteroids are also assigned a number, for example (99942) Apophis. The Harvard Smithsonian Center for Astrophysics has a complete list of current asteroid names.

Are asteroids a potential threat?

The strong orbit of Jupiter and random collisions with or another object can change the orbit of asteroids, knocking them off the main Belt and scattering them in all directions around the orbits of other planets. Asteroids that have gone astray, as well as asteroid debris, have crashed into other planets in the past, this has played an important role in changing the geological history of the planets and the evolution of life on.

Scientists are constantly monitoring asteroids that cross Earth's orbit, as well as near-Earth asteroids that come within about 45 million kilometers (28 million miles) of Earth's orbit and could pose a danger. Radar is a valuable tool for detecting and monitoring potentially dangerous objects. It reflects signals transmitted from objects, and images and other information can be received from the echo. Thanks to radar, scientists can learn a lot about the orbit of asteroids, their rotation, shape, size, as well as metal concentration.

But several large meteorites still reached the Earth and left traces of their fall on it. One of them, the so-called Arizona crater, is a bowl-shaped depression in the surface of the earth about 180 meters deep and 1200 km in diameter. There are dozens of other craters, but they are very difficult to find because erosion quickly destroys them. Scientists suggest that the death of the dinosaurs was caused by the fall of a large meteorite, about 15 km in diameter. The dust raised into the atmosphere by this meteorite obscured the sun's rays, and a sharp long-term cooling occurred, the so-called nuclear winter, which destroyed almost all life. This happened many millions of years ago.

But recently this story could repeat itself. The explosion of the Tunguska meteorite, when the blast wave broke all the trees around for hundreds of kilometers and circled the planet twice. Evidence that asteroids can hit other planets is abundant. In 1994, a large one fell onto the planet Jupiter, leaving a huge crater the size of . It can be argued that our planet will also be subject to the fall of these celestial bodies. But the probability of this is quite small, and we will learn about it in advance as a result of astronomical calculations.

The year in Chelyabinsk led to the emergence of many questions.

According to the data, a meteorite with a diameter of about 15 meters and weighing 7,000 tons entered the atmosphere at an angle of about 20 degrees at a speed of 65,000 km per hour. It passed through the atmosphere for 30 seconds before breaking apart. This resulted in an explosion approximately 20 km above the ground, producing a shock wave of 300 kilotons. As a result, more than 1000 people were injured.

Meteorite fragments were recently found near Lake Chebarkul.

Events such as the fall of a meteorite once again remind us of the potential danger that exists in outer space. What are a meteorite, an asteroid and a comet? How often do such events occur and can they be prevented?

Meteor falling

Meteor, meteorite, meteoroid - what's the difference?

A meteor is the scientific name for a "shooting star" and is the glowing trail of space debris that ends up in the Earth's atmosphere. They can be small as a grain of sand and large meteoroids up to 10-30 meters in size. As a rule, they burn up in the atmosphere, and those that fall to Earth are called meteorites.

How often does a meteorite fall to Earth?

Small drops happen every few months, but we don't see them. The thing is that two-thirds of the Earth is oceans, so we often miss these events. Such large objects as the one that exploded in Chelyabinsk occur much less frequently, approximately every five years. So in 2008, a similar event was observed in Sudan, but no one was hurt.

A meteorite is flying to Earth: can it be prevented?

Typically, such meteor bodies go unnoticed, since most telescopes are aimed at identifying huge, potentially dangerous asteroids. There is no weapon yet that can prevent the fall of a meteorite or asteroid.

Asteroid impact

The Chelyabinsk meteorite was the largest since the 1908 Tunguska meteorite in Siberia, which was caused by an object roughly the size of asteroid 2012 DA14, which safely passed within a minimum distance of 27,000 km from Earth on February 15, 2013.

Asteroid Passage: What is an asteroid?

An asteroid is a celestial body that orbits the Sun, usually between Mars and Jupiter. Asteroids are also called space debris or fragments left behind when the solar system was formed.

Because of the collisions, some asteroids are ejected from the main belt, and they end up on a trajectory that intersects the Earth's orbit.

Large asteroids are called planetoids, and objects smaller than 30 meters are called meteoroids.

Asteroid sizes: how big can they be?

Asteroid 2012 DA14, which flew by on Friday, was about 45 meters in diameter and weighed about 130,000 tons. Scientists believe there are about 500,000 asteroids the size of asteroid 2012 DA14. However, less than one percent of asteroids have been discovered so far.

The supposed asteroid that killed the dinosaurs 65 million years ago is believed to have been around 10-15 km in diameter. If an asteroid of this magnitude were to fall today, it would wipe out all modern civilization.

Statistically, asteroids larger than 50 meters fall to Earth once a century. Asteroids larger than 1 km in diameter can collide every 100 thousand years.

Comet crash

2013 can be called the year of comets, as we will be able to observe two of the brightest comets in history at once.

What is a comet?

Comets are celestial bodies in our solar system, consisting of ice, dust and gas. Most of them are located in the Oort Cloud, a mysterious region of the outer edge of the solar system. Periodically they pass close to the Sun and begin to evaporate. The solar wind turns this steam into a huge tail.

Most comets are too far from the Sun and Earth to be seen with the naked eye. Bright comets appear every few years; even more rarely, two comets appear at once in one year.

Comet 2013

Comet PANSTARRS

Comet PANSTARRS or C/2011 L4 was discovered in June 2011 using the Pan-STARRS 1 telescope located on the summit of Haleakala in Hawaii. In March 2013, the comet will be closest to the Sun (45,000 km) and the Earth (164 million km).

Although comet PANSTARRS was a dim and distant object at the time of its discovery, it has steadily become brighter since then.

Comet ISON, discovered in 2012

When can you watch? Mid November – December 2013

Comet ISON or C/2012 S1 was discovered on September 21, 2012 by two astronomers Vitaly Nevsky and Artem Novichonok using a telescope International Scientific Optical Network(ISON).

Orbital calculations showed that Comet ISON will make its closest approach to the Sun at a distance of 1.2 million km. The comet will be bright enough to be visible in the sky at its closest approach to the Sun in the first weeks of November.

It is believed that this comet will be brighter than the full Moon and will be visible even during the day.

Comet Impact

Could a comet collide with Earth? It is known from history that the comet Shoemaker-Levi 9 collided with Jupiter in July 1994, and it became the first comet collision observed by scientists. Considering that this happened on an uninhabited planet, the event became more likely interesting example destructive forces of the Universe. However, if this had happened on Earth, history would have taken a completely different turn.

Comets and asteroids

Comets differ from asteroids in that they have an unusually elongated elliptical orbit, meaning they move very large distances from the Sun. On the contrary, asteroids remain within the asteroid belt.

Fortunately, it takes many years to pass the comet's orbit. A comet approaches Earth once every 200,000 years. To date, there are no known comets that pose a threat to our planet in the near future.

Comets with an orbital period greater than 200,000 years have a less predictable orbit and, although there is little chance of colliding with Earth, they should not be forgotten.

Asteroids, meteorites and comets are bullets from space. Interesting fact - if an object with a diameter of 1600 meters falls to Earth, a catastrophe will occur that surpasses all cataclysms known to us. If all nuclear weapons explode, there will be no such power. A deep hole in the Arizona desert, one and a half kilometers wide, indicates a sudden catastrophe caused by a heavenly guest. This crater appeared in an instant. Meteorites are fragments separated from large celestial bodies. Once in the earth's atmosphere, they lose speed and power without causing much damage.

Meteorites rain down on the Earth every day. Most are no larger than a pea. In 1992, hundreds of US residents saw the rain of fire. A meteorite the size of a football, about 4 billion years old, made a hole in the car. In 1908, a blindingly bright ball exploded over a remote region of Siberia. The reflection was visible even in the sky over England. Over an area of ​​over 260 square kilometers, the forest was felled in wide concentric circles. The crater was created by the impact of a thirty-meter meteorite. A mineral was discovered - very dense quartz, which is not capable of creating the most powerful volcano. Within the walls of one of the churches, built 500 years ago, there is quartz of extraterrestrial origin.

Most asteroids wander peacefully between Mars and Jupiter in the so-called asteroid belt. In the image, asteroids are invisible among the stars; they must be looked for using a microscope. There are asteroids as large as the island of Manhattan, and twice as large. When it hits Earth, it will leave a crater the size of Texas. The Earth revolves around the Sun, surrounded by a swarm of asteroids. In the waters of Mexico's Yucatan Peninsula lies a 304 km wide crater created by a 100 million megaton explosion. This happened 65 million years ago, when 2/3 of living species, including dinosaurs, disappeared from the face of the planet.

In 1994, scientists observed a comet colliding with Jupiter. At the same time, fiery whirlwinds the size of the globe were formed. If one of the fragments of this comet fell to Earth, the entire planet would be covered by a black cloud, you would feel like you were roasting in the oven. Asteroids capable of destroying a quarter of the planet fall twice every million years. Small objects that can be erased Big city- once every two or three centuries. Now the starry sky will never be associated with peace and harmony. A missile with the most powerful range must come into play. It will explode above the surface of the asteroid, deflecting it from Earth's orbit.

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