الأجرام السماوية والظواهر المثيرة للنظر

1. Day and night:

Daily note the phenomenon of day and night which is to change our surroundings Zia role of $ 24 an hour. We think the sun shines bright and the morning of this day begins, the evening sets in Morocco, and thus solve the night.

Does this mean that the sun revolves around the Earth?
This is what we think may at first glance seems that this is what may most likely ancestors of our ancestors. However, it appears that two were day and night, not for movement of the sun around the earth, which is after all wrong because the Earth is orbiting the sun, but day and night for two at about the rotational movement of the Earth itself! The earth revolves around itself from west to east in 24 hours. Since the Earth's circumference at the equator with a length of 40,000 km, the speed of rotation of the Earth at the equator more than 1,600 km / hr.






How can we, then, that we feel will diminish over the surface of the earth?
In fact, every object has a property is obliged to maintain the constant movement and called this property Battalh (or inertia). When the object is subject to the acceleration produces a force called the quasi-inertial force resists the force produced by acceleration. And the way that we do not feel any force as long as the pace steady. For example, in a car traveling at 80 km / h are completely silently, but in the case of a slowdown are Bgesmana leaning forward under the force of inertia that article you would like to remain a fixed speed (the opposite occurs when the acceleration, our body tends to back). So no matter how fast the earth, we feel quietly comprehensive!


At the time of what, we note that the linear day and night are changing from place to place from the surface of the earth. And somewhere, we note that these lengths is consistent throughout the year. This result, as we shall see, that the axis of the earth's rotation around itself is not perpendicular to the plane which includes the earth and the sun, it is a diagonal of about 23.5 degrees from plumb (vertical line or vertical).

In the summer (northern hemisphere) the earth revolving around the same interview as a permanent part of the North towards the sun, and so the sun revolves in the sky without losing in the far northern regions of the globe! While the southern part of the globe blocked from the sun and be the most southern areas of the globe in the night, continuously. In the winter (northern hemisphere), when the earth in almost the opposite of where you are in the summer for the sun, the opposite happens: the North Pole at night, while continuing the South Pole during the day in permanently.

If a person traveled in the summer from the North Pole to the South Pole is noted that the length of daylight decreases gradually. In the far north the fact that the full day, then start the sun during his trip to the south access to the horizon and then begin absence of some hours in the day to be equal linear day and night at the equator. After this length of daylight becomes shorter than the length of the night, and become the sun shines a few hours a day only, to become a full night in the far south. In spring and autumn, the axis of the earth's rotation axis perpendicular to the link between the earth and the sun (do not be heading toward the sun), and so long day and night exactly 12 hours all over the globe, and receive all over the globe the same amount of rays of the sun!


Somewhere between the equator and poles, we note that the linear day and night during the year are changing. And at the equator equal to two Ataiwlan throughout the year, while the phenomenon that occurs in extreme poles: the observed passing from night to day and permanent lasting the length of each one of them 6 months! We also note that the virtual movement of the sun in the sky change throughout the year. The sun shines not just in the Middle geographical: This does not only happen in two days a year in spring and autumn. With the exception of these two days, the sun shines between 23.5 degrees (with a maximum deviation to the north in the summer) and -23.5 ° (maximum deviation of its south in the winter) for the East geographical location.


Scientists knew of four distinct circles on the globe are: the Tropic of Cancer (latitude 23.5 degrees), the Tropic of Capricorn (latitude -23.5 degrees), the Arctic Circle (latitude 66.5 degrees) and the Antarctic Circle (latitude -66.5 degrees). And is characterized by the regions between the Tropic of Cancer Tropic of Capricorn north and south on the existence of at least a year the sun passes its zenith (highest point in the sky). And is characterized by areas between the Arctic and the Arctic Circle and south regions between Antarctica and the Antarctic Circle north of the year on the existence of at least 24 hours long his day and last day of the year, at least for the long night of 24 hours. We will see in the next paragraph the cause of the change of seasons.

Chapters:

Earth orbits around the sun in one solar year. And in fact a time of rotation of the Earth around the Sun, 365.25 days (365 days and 6 hours), a period between two consecutive two passes of the Earth from the same location in its orbit. Since the radius of the Earth's orbit around the sun with a length of 150 million kilometers, the speed of Earth in orbit around the sun at about 108,000 km / h!

And the phenomenon of seasons due to change the status of the center of the earth's rotation around its own axis for the link between the earth and the sun during the year and change the amount of heat received by the northern and southern parts of the globe. In about 21 March - March, the Earth's rotation axis perpendicular to the axis for the land - the sun, and this so-called moderate spring. And even through linear day and night in all parts of the globe, as well as the amount of heat that reaches the ground. In about 21 June to June will be Earth's axis at the height of his inclination to the axis for the land - the sun (23.5 degrees) and is heading toward the sun, and Earth's north pole is a counter to the sun. This so-called coup summer. While witnessing the Northern Hemisphere summer and longest day of the year, the Southern Hemisphere in the winter! And about 21 in September - September, the Earth's rotation axis perpendicular to the axis for the land - the sun, and this so-called moderate fall. And even through linear day and night in all parts of the globe, as is the case when the vernal equinox. And about 21 in December - December is the Earth's axis at the height of his inclination to the axis for the land - the sun (-23.5 degrees) and is opposite to the sun, and the land south pole corresponding to the sun. And this is called the winter solstice. While witnessing the Northern Hemisphere winter and the shortest day of the year, the Southern Hemisphere in the summer!







And here we say that the Earth's orbit is not perfectly circular, it is a Elliptical (ellipse), the sun occupies one of the Bartah. And the land as soon as conditions to the sun (ie in Houdeidaha) next to the winter solstice (147 million km), and be far from the sun (ie height) next to the summer solstice (151 million km). Thus, the elliptical "vulnerable" to the Earth's orbit is not the reason for the change of seasons.






And in fact are not characterized by the four seasons, except in areas located between the Tropic of Cancer and the Arctic Circle and areas located between the Tropic of Capricorn and the Antarctic Circle. The areas located between the Tropic of Cancer and the Tropic of Capricorn see the spring and autumn only. While the areas located between the Arctic Circle and North Pole and areas that exist between the Antarctic and Antarctic experience winter and summer only.

. Planets and stars. What is the difference between planets and stars:



Hopes when the sky on a clear night note a few thousand glittering dots, called usually the stars. In fact, among these thousands of stars, it can, with some of the perseverance and standing observation, the discovery that a few of the "stars" do not follow the behavior of the rest of the stars. In fact, these "strange stars" are not only the nearest planets of the solar system to us!






And where that most stars are forms nearly constant (we shall see in the coming quarters in the medium term, which change through these forms or constellations: about a century to note a significant change with the naked eye, although it is possible to see minor changes in a few years the use of the means of minutes), the locations of the planets change in concrete forms for stardom through the surrounding days. And this is what made the ancient distinction between planets and stars since that time, and this despite not knowing that there is a factor as well as a natural distinction between planets and stars!



STARS is a ball of immense size and mass is composed of gas (hydrogen gas per core) and a great producer of energy through nuclear fusion reactions (formation of helium by hydrogen fusion, then the composition of coal, oxygen, iron ...) leakage of this energy is then in the middle of the ocean. Light and the stars seen at night is only part of the optical energy produced in the heart of the stars, because stars radiate this energy in several forms: photons, particles ... And generate temperatures of millions of degrees Celsius in the inner layers.
While the planets is hard objects (such as land, for example) or gas (like Jupiter, for example) do not produce cold energy automatically by nuclear reactions, and for this they are sometimes also called cold objects. And the light that we receive from the planets of the solar system is a product of the reflection of sunlight on the surface! Planets do not have the cluster that can create pressure and temperature adequate to generate nuclear fusion reactions.



And a summary view is that the planets and stars differ in their infrastructure as a result of a difference in mass (mass of the sun is equal to about 1000 times the mass of Jupiter and about a million times the mass of the earth!) And thus STARS produce energy through nuclear reactions while the planets is a rigid objects. It is also no difference between the planets and stars from the observational side, as can be seen significant change in the position of planets for stars within a few days only.

4. Satellite:

Satellite is a small asteroids have shifted around a planet (Earth, for example) Cdoran the planet around the sun. And all the planets of the solar system with the exception of the closest planets to the Sun (Mercury and Venus) satellite has at least one. Our planet Earth has one moon, while the two satellites of Mars and the buyer of about 40 satellite!


And sizes of satellites for Kkbha very different. For example, Earth's moon has a diameter equal to about a quarter of the Earth (and thus is larger than Pluto), and the moons of Mars is almost simple stones (diameter equal to approximately 10 km), while the moon of Pluto has a diameter equal to the radius of Pluto itself!







Currently, astronomers still do not know much about the moons of the planets of the solar, which increases year after year. Every year, almost new is discovered moons of Jupiter, for example. And the output of these small satellites, and therefore weak, and must use the flashing devices and methods of accurate, sophisticated and modern for their detection. The biggest of the four moons of Jupiter have been discovered in the seventeenth century by the Italian scientist Galileo.


And this because he was the first to use the telescope. While the discovery of other satellites in the following centuries with the development of methods of monitoring.


And scientists are trying to find out these satellites by sending unmanned spacecraft to capture images and analyze the samples locally. In other than our moon, people did not visit any planet or moon after another.