www.Grandars.ru "Natural Science" Astronomy "
Solar System Astronomy Solar System
Lectures on Natural Science Content
Planet Mercury
1.
The solar system, its structure
Planet Venus
2.
The composition of the solar system
Planet Mars Planet Jupiter
3.
The Sun 4.
Planets of the Earth group 5.
Giant planets
Planet Saturn Planet Uranus Planet Neptune Earth's motion The Earth's magnetic field The Earth Moon system
The SOLAR SYSTEM, ITS STRUCTURE The universe (cosmos) is the whole world around us, boundless in time and space and infinitely diverse in the forms that the ever moving matter takes.
The boundlessness of the universe can be partially imagined on a clear night with billions of different sizes of luminous twinkling points in the sky representing distant worlds.
Light rays at a speed of 300,000 km/s from the most distant parts of the Universe reach the Earth in about 10 billion years.
According to scientists, the Universe was formed as a result of the "Big Bang" 17 billion years ago.
It consists of clusters of stars, planets, cosmic dust and other cosmic bodies.
These bodies form systems: planets with satellites (for example.
The solar system), galaxies, metagalactics (a cluster of galaxies).
The Galaxy (Late Greek. galaktikos milky, milky, from the Greek gala milk) is a vast star system that consists of many stars, star clusters and associations, gas and dust nebulae, as well as individual atoms and particles scattered in interstellar space.
There are many galaxies of various sizes and shapes in the universe.
All the stars visible from Earth are part of the Milky Way galaxy.
It got its name due to the fact that most of the stars can be seen on a clear night in the form of the Milky Way — a whitish blurred band.
In total, the Milky Way galaxy contains about 100 billion stars.
Our galaxy is in constant rotation.
The speed of its movement in the universe is 1.5 million km / h.
If you look at our galaxy from the side of its north pole, the rotation occurs clockwise.
The sun and the stars closest to it make a complete revolution around the center of the galaxy in 200 million years.
This period is considered to be a galactic year.
The Andromeda galaxy, or Andromeda Nebula, is similar in size and shape to the Milky Way galaxy, which is located at a distance of about 2 million light years from our galaxy.
A light year is the distance traveled by light in a year, approximately equal to 1013 km (the speed of light is 300,000 km / s).
The concept of the celestial sphere is used to study the movement and location of stars, planets and other celestial bodies for clarity.
Fig.
1. The main lines of the celestial sphere The celestial sphere is an imaginary sphere of arbitrarily large radius, in the center of which the observer is located.
Stars, the Sun, the Moon, and planets are projected onto the celestial sphere.
The most important lines on the celestial sphere are: the vertical line, the zenith, the nadir, the celestial equator, the ecliptic, the celestial meridian, etc.
(Fig. 1).
A plumb line is a straight line passing through the center of the celestial sphere and coinciding with the direction of the plumb line thread at the observation point.
For an observer located on the Earth's surface, a vertical line passes through the center of the Earth and the observation point.
The vertical line intersects with the surface of the celestial sphere at two points - the zenith, above the observer's head, and the nadir the diametrically opposite point.
A large circle of the celestial sphere, the plane of which is perpendicular to the vertical line, is called a mathematical horizon.
It divides the surface of the celestial sphere into two halves: visible to the observer, with a peak at the zenith, and invisible, with a peak at the nadir.
The diameter around which the celestial sphere rotates is the axis of the world.
It intersects with the surface of the celestial sphere at two points - the north pole of the world and the south pole of the world.
The north pole is the one from which the rotation of the celestial sphere occurs clockwise, if you look at the sphere from the outside.
A large circle of the celestial sphere, the plane of which is perpendicular to the axis of the world, is called the celestial equator.
It divides the surface of the celestial sphere into two hemispheres: the northern one, with a peak at the north pole of the world, and the southern one, with a peak at the south pole of the world.
The great circle of the celestial sphere, the plane of which passes through the vertical line and the axis of the world, is the celestial meridian.
It divides the surface of the celestial sphere into two hemispheres - the eastern and western.
The line of intersection of the plane of the celestial meridian and the plane of the mathematical horizon is the midday line.
The ecliptic (from the Greek ekieipsis eclipse) is a large circle of the celestial sphere, along which the visible annual movement of the Sun, more precisely, its center, occurs.
The plane of the ecliptic is inclined to the plane of the celestial equator at an angle of 23°26 '21".
To make it easier to remember the location of the stars in the sky, people in ancient times came up with the idea of combining the brightest of them into constellations.
Currently, 88 constellations are known that bear the names of mythical characters (Hercules, Pegasus, etc.), zodiac signs (Taurus, Pisces, Cancer, etc.), objects (Libra, Lyra, etc.)
(Fig. 2).
Fig.
2. Summer and autumn constellations
The origin of galaxies.
The solar system and its individual planets still remain an unsolved mystery of nature.
There are several hypotheses.
Currently, it is believed that our galaxy was formed from a gas cloud consisting of hydrogen.
At the initial stage of the galaxy's evolution, the first stars were formed from the interstellar gas — dust environment, and the Solar System was formed 4.6 billion years ago.
THE COMPOSITION OF THE SOLAR SYSTEM The totality of celestial bodies moving around the Sun as a central body forms the Solar system.
It is located almost on the outskirts of the Milky Way galaxy.
The solar system participates in the rotation around the center of the galaxy.
The speed of the se movement is about 220 km / s.
This movement takes place in the direction of the constellation Cygnus.
The composition of the Solar system can be represented in the form of a simplified scheme, shown in Fig.
3. Over 99.9 % of the mass of the matter of the Solar system falls on the Sun and only 0.1% - on all its other elements.
The hypothesis of I. Kant (1775) — P. Laplace (1796)
The hypothesis of D. Jeans (the beginning of the XX century)
The hypothesis of academician O. P. Schmidt (40s of the XX century)
Guy poteza a kale mika V. G. Fesenkova (30s of the XX century)
The planets were formed from gas dust matter (in the form of a red hot nebula).
Cooling is accompanied by compression and an increase in the speed of rotation of some axis.
Rings appeared on the equator of the nebula.
The substance of the rings collected into incandescent bodies and gradually cooled down
A larger star once passed by the Sun, and its attraction tore a jet of incandescent matter (a prominence) out of the Sun.
thickenings were formed, from which later planets
The gas dust cloud orbiting the Sun had to take a solid form as a result of the collision of particles and their movement.
The particles combined into thickenings.
The attraction of smaller particles by thickenings should have contributed to the growth of the surrounding matter.
The orbits of the clusters were supposed to become almost circular and lying almost in the same plane.
The thickenings were the embryos of the planets, absorbing almost all the matter from the gaps between their orbits
The Sun itself emerged from the rotating cloud, and the planets emerged from secondary thickenings in this cloud.
Further, the Sun has greatly decreased and cooled down to its present state
Fig.
3. Composition of solar systems
THE SUN The sun is a star, a giant red hot ball.
Its diameter is 109 times the diameter of the Earth, its mass is 330,000 times the mass of the Earth, but the average density is small — only 1.4 times the density of water.
The sun is located at a distance of about 26,000 light years from the center of our galaxy and orbits around it, making one revolution in about 225-250 million years.
The orbital speed of the Sun is 217 km / s — thus, it passes one light year in 1400 Earth years.
4. The chemical composition of the Sun The pressure on the Sun is 200 billion times higher than at the Earth's surface.
The density of the solar matter and the pressure are rapidly increasing deeper; the increase in pressure is explained by the weight of all the overlying layers.
The temperature on the surface of the Sun is 6000 K, and inside it is 13 500 000 K.
The characteristic lifetime of a Sun type star is 10 billion leg.
Table 1.
General information about the Sun Weight, kg
2 * 1030
Diameter, m
1.392 * 109
Average density, kg / m3
1400
Rotation period, days
25,380
Age, billion years
About 5
The chemical composition of the Sun is about the same as that of most other stars: about 75 % is hydrogen, 25 % is helium, and less than 1 % is all other chemical elements (carbon, oxygen, nitrogen, etc.)
The central part of the Sun with a radius of about 150,000 km is called the solar core.
This is a nuclear reaction zone.
The density of the substance here is about 150 times higher than the density of water.
The temperature exceeds 10 million K. (on the Kelvin scale, in terms of degrees Celsius, 1 °C = K 273.1) (Fig. 5).
Above the core, at distances of about 0.2-0.7 of the Sun's radius from its center, there is a zone of radiant energy transfer.
The energy transfer here is carried out by the absorption and emission of photons by separate layers of particles (see Fig. 5).
Fig.
5. The structure of the Sun Photon (from the Greek phos light), an elementary particle that can exist only moving at the speed of light.
Closer to the surface of the Sun, a vortex mixing of plasma occurs, and the transfer of energy to the surface is performed mainly by the movements of the substance itself.
This method of energy transfer is called convection, and the layer of the Sun where it occurs is called the convective zone.
The thickness of this layer is approximately 200,000 km.
Above the convective zone is the solar atmosphere, which constantly fluctuates.
Both vertical and horizontal waves with lengths of several thousand kilometers propagate here.
Fluctuations occur with a period of about five minutes.
The inner layer of the Sun's atmosphere is called the photosphere.
It consists of light bubbles.
These are pellets.
Their dimensions are small 1000-2000 km, and the distance between them is 300-600 km.
About a million granules can be observed on the Sun at the same time, each of which exists for several minutes.
The granules are surrounded by dark gaps.
If the substance rises in the granules, then it falls around them.
The granules create a general background on which such large scale formations as torches, sunspots, prominences, etc. can be observed.
Sunspots are dark areas in the Sun, the temperature of which is lowered in comparison with the surrounding space Solar torches are called bright fields surrounding sunspots.
Prominences (from Lat. protubero swell) - dense condensations of relatively cold (compared to the surrounding temperature) matter that rise and are held above the surface of the Sun by a magnetic field.
The appearance of the Sun's magnetic field can be caused by the fact that different layers of the Sun rotate at different speeds: the inner parts rotate faster; the core rotates especially fast.
Prominences, sunspots and torches are not the only examples of solar activity.
It also includes magnetic storms and explosions, which are called flashes.
Above the photosphere is the chromosphere — the outer shell of the Sun.
The origin of the name of this part of the solar atmosphere is associated with its reddish color.
The thickness of the chromosphere is 10-15 thousand km, and the density of matter is hundreds of thousands of times less than in the photosphere.
The temperature in the chromosphere is growing rapidly, reaching tens of thousands of degrees in its upper layers.
At the edge of the chromosphere, spicules are observed, which are elongated columns of condensed luminous gas.
The temperature of these jets is higher than the temperature of the photosphere.
The spicules first rise from the lower chromosphere at 5000-10, 000 km, and then fall back, where they fade out.
All this happens at a speed of about 20,000 m / s.
The spicula lives 5-10 minutes.
The number of spicules existing on the Sun at the same time is about a million (fig. 6).
Fig.
6. The structure of the outer layers of the Sun The chromosphere is surrounded by the solar corona — the outer layer of the Sun's atmosphere.
The total amount of energy emitted by the Sun is 3.86 • 1026 watts, and only one two billion part of this energy is received by the Earth.
Solar radiation includes corpuscular and electromagnetic radiation.
Corpuscular main radiation is a plasma stream that consists of protons and neutrons, or in another way - the solar wind, which reaches near Earth space and flows around the entire magnetosphere of the Earth.
Electromagnetic radiation is the radiant energy of the Sun.
It reaches the Earth's surface in the form of direct and scattered radiation and provides a thermal regime on our planet.
In the middle of the XIX century, the Swiss astronomer Rudolf Wolf (1816-1893) (Fig. 7) calculated a quantitative indicator of solar activity, known worldwide as the Wolf number.
Having processed the materials of observations of sunspots accumulated by the middle of the last century, Wolf was able to establish the average and summer cycle of solar activity.
In fact, the time intervals between the years of the maximum or minimum Wolf numbers range from 7 to 17 years.
Simultaneously with the 11 year cycle, a century old, or rather 80-90 year old, cycle of solar activity takes place.
Inconsistently overlapping with each other, they make noticeable changes in the processes taking place in the geographical envelope of the Earth.
The close connection of many terrestrial phenomena with solar activity was pointed out as early as 1936 by A. L. Chizhevsky (1897-1964) (Fig. 8), who wrote that the vast majority of physical and chemical processes on Earth are the result of the influence of cosmic forces.
He was also one of the founders of such a science as heliobiology (from Greek. helios the sun), which studies the influence of the Sun on the living matter of the geographical envelope of the Earth.
Depending on the solar activity, such physical phenomena occur on Earth as: magnetic storms, the frequency of auroras, the amount of ultraviolet radiation, the intensity of thunderstorm activity, air temperature, atmospheric pressure, precipitation, the level of lakes, rivers, groundwater, salinity and efficiency of the seas, etc.
The periodic activity of the Sun is associated with the life of plants and animals (there is a correlation between the solar cycle and the duration of the growing season in plants, the reproduction and migration of birds, rodents, etc.), as well as humans (diseases).
Currently, the relationship between solar and terrestrial processes continues to be studied with the help of artificial Earth satellites.
In addition to the Sun, the planets of the EARTH GROUP are distinguished as part of the Solar System (Fig. 9).
According to their size, geographical indicators and chemical composition, the planets are divided into two groups: the planets of the earth group and the giant planets.
The planets of the Earth group include Mercury, Venus, Earth and Mars.
They will be discussed in this subsection.
Fig.
9. Planets of the Solar system Earth is the third planet from the Sun.
A separate subsection will be devoted to it.
Let's generalize.
The density of the planet's substance depends on the location of the planet in the Solar System, and taking into account its size, its mass also depends.
The closer a planet is to the Sun, the higher its average density of matter is.
For example, for Mercury it is 5.42 g / cm\ Venus 5.25, Earth 5.25, Mars 3.97 g/cm3.
The general characteristics of the planets of the Earth group (Mercury, Venus, Earth, Mars) are primarily: 1) relatively small size; 2) high temperatures on the surface and 3) high density of the matter of the planets.
These planets rotate relatively slowly around their axis and have few or no satellites at all.
There are four main shells in the structure of the planets of the Earth group: 1) dense core; 2) covering his mantle; 3) 4) a light gas water shell (excluding Mercury).
Traces of tectonic activity have been found on the surface of these planets.
Now let's get acquainted with the giant planets, which are also part of our Solar system.
These are Jupiter, Saturn, Uranus, Neptune.
Giant planets have the following general characteristics: 1) large size and weight; 2) rotate rapidly around the axis;
3) have rings, many satellites; 4) the atmosphere consists mainly of hydrogen and helium; 5) in the center there is a hot core of metals and silicates.
They are also distinguished by: 1) low temperatures on the surface;
2) low density of the matter of the planets.
Natural Science The concept of Natural Science Biology — Astronomy
Related subjects History
Astronomy The solar system, its model and structure.
Planets of the solar system Planet Mercury: description, characteristics, atmosphere and radius Planet Venus, its description, characteristics and photos Planet Mars: description, characteristics, satellites and photos Planet Jupiter Planet Saturn Planet Uranus Planet Neptune Moon satellite of the Earth, its phases and rotation around the Earth
The Earth's motion in orbit and around the Sun The Earth's magnetic field
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