Asteroids Completed by: Student

An asteroid is a relatively small celestial body in the Solar System moving in orbit around the Sun.

Asteroids are significantly smaller in mass and size than planets, have an irregular shape, and do not have an atmosphere, although they may also have satellites.

The main parameter by which classification is carried out is body size. Asteroids are considered bodies with a diameter of more than 30 m; smaller bodies are called meteoroids.

Currently, hundreds of thousands of asteroids have been discovered in the Solar System. It is estimated that there may be from 1.1 to 1.9 million objects in the Solar System that are larger than 1 km. Most currently known asteroids are concentrated within the asteroid belt, located between the orbits of Mars and Jupiter.

Ceres, measuring approximately 975×909 km, was considered the largest asteroid in the Solar System, but since August 24, 2006, it received the status of a dwarf planet. The other two largest asteroids, Pallas and Vesta, have a diameter of ~500 km. Vesta is the only object in the asteroid belt that can be observed with the naked eye.

The total mass of all main belt asteroids is only about 4% of the mass of the Moon. The mass of Ceres is about 32% of the total, and together with the three largest asteroids Vesta (9%), Pallas (7%), Hygeia (3%) - 51%, that is, the vast majority of asteroids have an insignificant mass by astronomical standards.

Asteroids are grouped into groups and families based on the characteristics of their orbits. Usually the group is named after the first asteroid that was discovered in a given orbit. Groups are relatively loose formations, while families are denser, formed in the past during the destruction of large asteroids from collisions with other objects.

The general classification of asteroids is based on the characteristics of their orbits and a description of the visible spectrum of sunlight reflected by their surface. Class C - carbon, 75% of known asteroids. Class S - silicate, 17% of known asteroids. Class M - metal, most others.

The number of asteroids decreases noticeably as their size increases. Approximate number of asteroids N with diameter greater than D

The danger of asteroids At the moment there are no asteroids that could significantly threaten the Earth. The larger and heavier the asteroid, the greater the danger it poses, but in this case it is much easier to detect it. The most dangerous asteroid at the moment is considered to be Apophis, with a diameter of about 300 m, a collision with which, in the event of an accurate hit, can destroy a large city, but such a collision does not pose any threat to humanity as a whole. Asteroids larger than 10 km in diameter can pose a global threat. All asteroids of this size are known to astronomers and are in orbits that cannot lead to a collision with the Earth.

Using the Internet, prepare a presentation on “The Largest Asteroids and Their Motion.”

An asteroid is a small planet-like body in the Solar System (minor planet). The name "asteroid" comes from the Greek word for "like a star." These objects were named by William Herschel on the basis that these objects, when observed through a telescope, looked like points of stars - unlike planets, which when observed through a telescope, looked like disks. The exact definition of the term "asteroid" is still not established. The term “minor planet” (or “planetoid”) is not suitable for defining asteroids, since it also indicates the location of the object in the Solar System. However, not all asteroids are minor planets. One way to classify asteroids is by size. The current classification defines asteroids as objects with a diameter greater than 50 m, separating them from meteoroids, which look like large rocks or may be even smaller. The classification is based on the assertion that asteroids can survive entry into the Earth's atmosphere and reach its surface, while meteors, as a rule, burn up completely in the atmosphere.
Several thousand asteroids are known by their own names. It is believed that there are up to half a million asteroids with a diameter of more than one and a half kilometers, and there may be from 1.1 to 1.9 million objects in the Solar System with dimensions of more than 1 km. Most asteroid orbits are concentrated in the asteroid belt between the orbits of Mars and Jupiter at distances from 2.0 to 3.3 AU. from the Sun. The total mass of all main belt asteroids is estimated at 3.0-3.6 1021 kg, which is only about 4% of the mass of the Moon. There are, however, also asteroids whose orbits lie closer to the Sun, such as the Amur group, the Apollo group and the Athena group. In addition, there are also those more distant from the Sun, such as the Centaurs. In the orbit of Jupiter there are Trojans, of which more than 1560 have already been discovered (the first was discovered in 1906). On August 21, 2001, a small asteroid 2001 QR322 was discovered in the orbit of Neptune. A year later, it became clear that this was the first “Trojan” of the gas giant.
As of October 2, 2001, astronomers around the world had observed 146,677 asteroids. The orbits of 30,716 of them have been determined and they have received their own numbers. Names have been assigned to 8,914 asteroids. Recently, due to the improvement of astronomical observation methods, the number of discovered asteroids is growing exponentially, doubling every two years, but the assignment of new names proceeds at a “constant speed” - approximately 1200 names per year. As of January 10, 2010, there were 482,419 objects in the databases, 231,665 had precisely defined orbits and were assigned an official number. 15,615 of them at this time had officially approved names.

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At the end of the 18th century. astronomers counted seven planets in the solar system: Mercury, Venus, Mars, Jupiter and Saturn were known from ancient times; in 1781, the English scientist William Herschel noticed the seventh planet, named Uranus, through a large telescope. By that time, the periods of revolution of the planets and the dimensions of their orbits had already been determined with sufficient accuracy by the methods of celestial mechanics. And now the first day of the new, 19th century brought the long-awaited discovery. On the night of January 1, 1801, at the observatory in Palermo (island of Sicily), astronomer Giuseppe Piazzi, while compiling a catalog of stars in the constellation Gemini, discovered a faint star of approximately 7th magnitude, which was absent from star maps. A few days later, the scientist, to his surprise, noticed that the star was moving, and in the same way that a planet located further than Mars should move across the sky. Unfortunately, first illness, then unfavorable observation conditions interrupted Piazzi’s work. As a result, the faint celestial object was lost among the stars.

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In 1804, the third representative of the family was discovered, named Juno, and in 1807, the fourth Vesta. All of them were so small that even at thousandfold magnification they looked like faint stars without a noticeable disk. Therefore, William Herschel proposed calling new planets asteroids, i.e. "star-like". In subsequent years, improvements in telescopes and the invention of photography led to an ever-increasing stream of asteroid discoveries. By 1880, about 200 of them were known, in 1923 the thousandth was noticed, by 1980 almost 2500 were included in the lists. And every year their number becomes more and more. By the way, about names. At first, minor planets were given the names of ancient Greek and Roman gods and heroes. When this “repertoire” was exhausted, female names of almost all peoples of the world were used. There probably won’t be a single reader who doesn’t have her own planet in the sky! Now, however, they have begun to deviate from this rule - there are not enough names... Planets are named quite arbitrarily, relying more on the number assigned in the data bank, which is monitored by a special commission of the International Astronomical Union. For example, here are a few names of asteroids: 2 Pallas, 224 Oceana, 265 Anna... So far, only the largest asteroids have been discovered. There are many millions more smaller ones. Name of asteroid Diameter, km 1 Ceres 1003 2 Pallas 608 4 Vesta 538 10 Hygia 450 31 Euphrosyne 370 704 Interamnia 350 511 David 323 65 Cybele 309 52 Europa 289 451 Patientia 276 15 Eunomia 272 1 6 Psyche 250 48 Doris 250 92 Ondine 250

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The orbits of the majority of the numbered minor planets (98%) are located between the orbits of the planets Mars and Jupiter. Their average distances from the Sun range from 2.2 to 3.6 AU. They form the so-called main asteroid belt. All small planets, like large ones, move in a forward direction. The periods of their revolution around the Sun range from three to nine years, depending on the distance. It is easy to calculate that the linear speed is approximately 20 km/s. The orbits of many small planets are noticeably elongated. Eccentricities rarely exceed 0.4, but, for example, for asteroid 2212 Hephaestus it is 0.8. Most orbits are located close to the ecliptic plane, i.e. to the plane of the Earth's orbit. Tilts are usually a few degrees, but there are exceptions. Thus, the orbit of Ceres has an inclination of 35°, and large inclinations are also known.

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From the dark depths of boundless space, a huge asteroid is rushing towards the Earth at great speed, threatening the death of all living things. A blow - and... For the time being, this is just a terrible fairy tale told at night to careless humanity. However, any fairy tale is a “lesson for good fellows.” Not so long ago, about a year ago, the sensational news spread around the world that on February 1, 2019, asteroid 2002 NT7 with a diameter of more than 2 km could collide with the Earth. Soon, however, scientists reported that this time nothing threatens our planet and the end of the world is postponed at least until February 1, 2060.

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The impact of an asteroid with a diameter of about 100 m on the surface of the Earth will destroy everything within a radius of up to 1000 km from the impact site, fires will engulf vast areas, and a huge amount of ash and dust will be thrown into the atmosphere, which will then settle over several years. The sun's rays will not be able to penetrate to the surface of the planet, and a sharp cooling will destroy many species of plants and animals, and photosynthesis will stop. And when the dust finally settles and air circulation is restored, the increase in carbon dioxide in the atmosphere will cause a greenhouse effect. The temperature in the near-Earth layer will rise, polar ice will begin to melt, and most of the land will be flooded. To add insult to injury, the Earth's magnetic field will be disrupted, the dynamics of tectonic processes will change, and volcanic activity will increase.

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An asteroid is a small planet-like celestial body in the Solar System moving in orbit around the Sun. Asteroids, also known as minor planets, are significantly smaller in size than planets.

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The term asteroid (from ancient Greek ἀστεροειδής - “like a star”, from ἀστήρ - “star” and εῖ δος - “appearance, appearance, quality”) was introduced by William Herschel on the basis that these objects looked like when observed through a telescope like points of stars - in contrast to planets, which look like disks when observed through a telescope. The exact definition of the term "asteroid" is still not established.

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To date, tens of thousands of asteroids have been discovered in the Solar System. Most currently known asteroids are concentrated within the asteroid belt, located between the orbits of Mars and Jupiter. The largest asteroid in the Solar System is Ceres, measuring approximately 975×909 km.

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The other two largest asteroids, Pallas and Vesta, have a diameter of ~500 km. Pallas Vesta

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At first, asteroids were given the names of heroes of Roman and Greek mythology, later discoverers received the right to call it whatever they wanted, for example, by their own name. At first, asteroids were given predominantly female names; only asteroids with unusual orbits (for example, Icarus, approaching the Sun closer than Mercury) received male names.

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The larger and heavier the asteroid, the greater the danger it poses, but in this case it is much easier to detect it. The most dangerous asteroid at the moment is considered to be the Apophis asteroid, with a diameter of about 300 meters, a collision with which, in the event of an accurate hit, can destroy a large city, but such a collision does not pose any threat to humanity as a whole.

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A meteorite is a solid body of cosmic origin that fell to the surface of the Earth. Most meteorites found weigh from several grams to several kilograms. The largest meteorite found is Goba (weight 60 tons).

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A crater may form at the site where a large meteorite falls. One of the most famous craters in the world is Arizona. It is assumed that the largest meteorite crater on Earth is Wilkes Earth Crater (diameter about 500 km). Arizona Crater

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The process of meteorites falling to Earth. The meteor body enters the Earth's atmosphere at a speed of about 11-25 km/sec. It begins to warm up and glow. Due to ablation (burning and blowing away by the oncoming flow of particles of the meteorite body), the mass of the body that reaches the ground may be less than its mass at the entrance to the atmosphere. Traces of the combustion of a meteorite body in the atmosphere can be found along almost the entire trajectory of its fall. If the meteorite body does not burn up in the atmosphere, then as it slows down it loses the horizontal component of its speed. This leads to a change in the trajectory of the fall. As it slows down, the glow of the meteor body decreases and it cools down. In addition, the meteorite body may break into fragments, which leads to Meteor shower.

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Interesting facts. The only documented case of a meteorite hitting a person occurred on November 30, 1954 in Alabama. The meteorite, weighing about 4 kg, crashed through the roof of the house and ricocheted Anna Elizabeth Hodges on the arm and thigh. The woman received bruises.

The term asteroid ("star-like") was coined by William Herschel on the basis that these objects, when observed through a telescope, looked like points of stars, in contrast to planets, which when observed through a telescope, looked like disks. Asteroids, like meteorites, are composed of metals (mainly iron and nickel) and rocks. Astronomers have two most popular hypotheses regarding the origin of asteroids. According to one of them, they are fragments of once existing planets that were destroyed as a result of a collision or explosion. According to another version, asteroids were formed from the remains of the substance from which the planets of the solar system were formed. In total, about 700 thousand asteroids have been discovered to date, of which approximately have been registered.

The vast majority of asteroids known to astronomers are located in the Main Asteroid Belt, which lies between the orbits of Mars and Jupiter. Some of them may leave this space, moving in an elliptical orbit around the Sun. A less significant asteroid belt in the solar system is located near the orbits of Neptune and Pluto. It is also called Koyer's belt.

Trojans: These asteroids live in the orbit of large planets and do not collide with them, since they gather only at two special places in the orbits, the so-called Lagrange points L4 and L5 (here the gravitational attraction from the Sun and the planet is balanced) Near-Earth asteroids: These objects have orbits that which are close to the Earth. Asteroids that cross the Earth's orbit are called earth-crossing asteroids. Near-Earth asteroids are known, of which asteroids are considered potentially dangerous to our planet. Asteroid 2004 FH, passing at a distance of only 7 Earth radii

The largest asteroid is Vesta (not counting the dwarf planet Ceres), which has a diameter of about 329 miles (530 kilometers). 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.