Than the stars are different from the planets: details and interesting moments

A lifeless cosmos is not at all deserted. It unites in itself a huge mass of all kinds of bodies of different nature, sizes and with different names. Among them - meteors, meteorites, comets, fireballs, planets and stars. Moreover, each of the categories of cosmic bodies within itself is divided into species, the difference between which can often only be understood by an astronomer with experience. Let's try to understand basic principles, for example, in what stars differ from planets.

The main difference

The very first, basic and unquestionable difference is the ability to glow. Any star necessarily emits light, the planet does not possess this property. Of course, nearby planets also look like glowing spots - an eloquent example is Venus. But this is not her own glow, she is just a "mirror" in which the light of the true source - the Sun - is reflected.

By the way, this is a very good way of how to distinguish a planet from a star purely visually, without additional optical instruments. If the glowing dot on the night sky "winks", that is, flickers, - be sure, this is a star. If the light emanating from the celestial object is equal and constant, then this planet reflects the light of the nearest luminary. And this is the first and most obvious sign that shows us how the stars differ from the planets.

The second difference, which follows from the first

The ability to emit light is peculiar only to very hot surfaces. As an example, you can consider a metal that does not light up by itself. But if it is heated to the desired temperature, the metal object is heated and emits, even if weak, but light.

So the second, than the stars differ from the planets, is the very high temperature of these cosmic bodies. This is what allows stars to shine. Even on the surface of the coldest luminary, the temperature does not fall below 2000 degrees K. Usually, stellar temperatures are measured in Kelvin, in contrast to the Celsius that we are accustomed to.

Our Sun is much hotter, in different periods its surface heats up to 5000, and even 6000 K. That is, "our way" it will be 4726.85 - 5726.85 ° C, which is also impressive.

Necessary clarification

These temperatures are characteristic only of stellar surfaces. Even more so than stars are different from planets, so it is that inside they are much hotter than outside. Even the surface temperatures on some stars reach 6000 K, and in the center of the luminaries they presumably go off for millions of degrees Celsius! So far, there is neither the possibility, nor the necessary technique, nor even the calculation formula, by which it would be possible to determine the internal "degree" of the stars.

Dimensions and movement

The dimensions of the stars and planets are equally grandiose. Compared with the celestial "lights" of the planet - just grains of sand. And this concerns both weight (mass) and volume. If instead of the sun to put in the middle of the free space apple of medium size, then to indicate the position of the Earth will need a pea, referred to hundreds of meters. Comparison of the sizes of planets and stars shows that the volumes of the second in thousands, and even millions of times, exceed the volume in space that the first ones occupy. With a mass of silent other relationships. The fact is that all planets are solid bodies. And the stars are mostly gaseous, otherwise the thermonuclear reactions, which provide the sky-high temperatures of the luminaries, would simply be impossible.

What is the difference between a planet and a star? The planet by definition has a trajectory of motion, called the orbit. And it necessarily surrounds the star as a heavier heavenly body. The star is still in the sky. If you have patience and a few nights to follow a certain area of the sky, the motion of the planet can be seen even with a weakly armed eye (but at least without an amateur telescope will not work).

Additional signs

The dimensions of the stars and planets can not be determined by eye. But some differences, which accurately characterize the cosmic bodies, require even more specific equipment. So, the chemical composition, which can be determined by spectral analysis, will accurately say, the planet or the star in front of us. After all, the luminaries are gaseous giants, therefore, they consist of light elements. And the planets include mostly solid constituents.

An indirect sign can be the presence of a satellite (or even several). They are only found in planets. However, if the satellite is not observed, this does not mean that we have an unequivocal star - some planets do well without such "neighbors".

Astronomers have one more sign of determining whether the planet is a newly discovered cosmic body. The orbit along which it moves should not contain foreign objects, roughly speaking, garbage. Satellites are not considered as such, they are large enough, otherwise they would fall to the surface. This rule was adopted quite recently - in 2006. Thanks to him Eris, Ceres and - attention! - Pluto is now considered not as full, but as dwarf planets.

Astronomical calculations

Scientists are highly curious. Knowing perfectly how the stars differ from the planets, they nonetheless wondered what would happen when the massiveness of the planet surpassed, for example, the size of the Sun. It turned out that such an increase in the size of the planet would lead to a sharp increase in the pressure in the core of the cosmic body; Then the temperature will reach one million (or several) degrees; Nuclear and thermonuclear reactions will begin - and instead of a planet we will receive a newborn star.