How stars differ from planets: details and interesting points
The sky has always attracted people, so distant and mysterious. For some time now we have been successfully comprehending the mysteries of space, we learn more and more new information about the stars, planets and other objects of the Universe. With today's development of astronomy and cosmology, the difference between a planet and a star is basic knowledge.
Planet Is a rotating astronomical object with a spherical shape, which has an average mass in space. A star is a celestial body, the main feature of which is thermonuclear chemical reactions taking place inside it. Thus, the stars glow due to these reactions. Naturally, all stars "during their lifetime", that is, while the reactions are going on, are much hotter than the planets. The planets do not emit light, they can only reflect it. Usually the stars are much more planets by mass, although this depends on the stage of the star's life. This usually means a larger diameter (size). A planet is distinguished from a star by the fact that it is not a field for thermonuclear reactions (occurring massively and naturally), since the planets do not have sufficient mass for this. With a mass of thirteen times the mass of Jupiter, the planet turns into a star. Both those and other objects rotate around their own axis. In this case, the planet also rotates relative to its star. However, this fact is currently being disputed by scientists, as objects very similar to planets that do not revolve around the stars were noticed.
Surface stars not solid, since a star is a mixture of gases and dust. As we know, the planets in this regard are not so homogeneous: gas planets are known, as well as planets with a solid surface, like our Earth. The planets have a magnetosphere, that is, a "magnetic atmosphere" created by the planet's own magnetic moment. A weak magnetic field is unable to hold the planet's atmosphere, although such cases are rare. Stars have no atmosphere. And in chemical composition stars are dominated by "light elements" - with a small atomic number (for example, carbon, helium).
To summarize, TheDifference.ru highlights the following differences between a planet and a star:
The star is supported by thermonuclear reactions taking place in it.
The planet is much lighter than a star and also smaller in diameter.
Planets and stars have different chemical compositions and temperatures - the planets are much colder.
Stars have no atmosphere
The stars emit light, the planets are not capable of this.
The planets revolve around the stars.
All space objects are called celestial bodies and they are divided into 4 groups: stars, planets, asteroids, comets.
a natural celestial body that:
Has a certain density
- rotates around its axis
- revolves in orbit around the star
- massive enough to become rounded under its own gravity, but not massive enough to start a thermonuclear reaction
The planets of the solar system
All the planets of the solar system rotate in their orbits in the direction in which the sun rotates. The sun rotates counterclockwise as viewed from its "north pole". Most of the planets in the solar system rotate around their axis in the same direction in which they orbit, that is, counterclockwise, with the exception of Venus and Uranus, which rotate in the opposite direction.
A natural celestial body in which, under the influence of the forces of its own gravity, the matter is compressed, sufficient for the start of a thermonuclear reaction.
The temperature inside the stars is determined by millions of degrees, but it is measured, however, not in degrees, but in a special unit of measurement - Kelvin. Kelvin is equal to the degree Celsius + 273, that is, the counting is carried out practically from absolute zero. The main elements of stars are hydrogen and helium. The average density of the Sun is 1.4 g / cm. cubic.
During a thermonuclear reaction, a huge amount of light, wave and thermal energy is released into space. So, the temperature on the surface of the Sun is 5000-6000 Kelvin. Our "battery" is a typical G2V star - a "yellow dwarf".
Star classification
By radiation spectrum
all stars are divided into 7 classes: O, B, A, F, G, K, M. Classes are divided into subclasses from 0 (hottest) to 9 (coldest).
Main sequence stars
these are stars in which the energy losses due to radiation are compensated by thermonuclear energy. Our Sun also belongs to them.
Brown dwarfs
the conditional name for stars in which nuclear reactions do not compensate for the energy loss due to radiation.
White dwarfs
these are dense compact stars, the mass of which is comparable to the mass of the Sun, but the diameter is 100 times less than the Sun, and 10,000 times less luminosity. These stars do not have their own sources of thermonuclear energy; they originate as "degenerate cores of red giants" that have thrown off their shell.
Red giants
these are stars of late spectral types; they all have a hot dense core and a very sparse and extended envelope.
New stars
Stars are called novae whose luminosity suddenly increases more than 100 times. All new stars are close binary systems, consisting of a white dwarf and a companion star - stars from the "main sequence" or a red giant. There is an overflow of matter from the outer layers of the "companion" star onto a white dwarf.
Supernovae
these are stars, the brightness of which during a flare increases by tens of magnitudes during several days. At maximum brightness, a supernova is comparable in brightness to an entire galaxy.
The term "supernovae" refers to stars that flared up much brighter than the so-called "new stars". In fact, neither one nor the other is physically new: already existing stars "flash".
Neutron stars
this is celestial bodies consisting of a neutron core and a relatively thin (up to one kilometer) crust of heavy atomic nuclei. I wonder what mass neutron star comparable to the mass of the Sun, but the radius is only 10 km.
Double stars
Double star, or double system- two gravitationally bound stars revolving in closed orbits around common center masses. Black hole candidates are found in binary systems.
Star clusters
A star cluster is a group of stars that have a common origin, position in space and direction of motion. The members of such groups are interconnected by mutual attraction. Most of the known clusters are found in our Galaxy.
How are stars born?
First, it is a cold, rarefied cloud of interstellar gas, which is compressed by its own gravity. In this case, the energy of gravity is converted into heat. When the temperature in the core reaches several million Kelvin, the process of formation of nuclei of chemical elements heavier than hydrogen begins and the compression stops. The star remains in this state for most of its life, until the reserves of fuel in its core run out.
Terms and Definitions
Galaxy
a large cluster of stars, interstellar gas and dust, and "dark matter"
Dark matter
a form of matter that does not emit electromagnetic radiation and does not interact with it.
Magnitude? - shine
This is a dimensionless numerical characteristic of the brightness of an object, which characterizes the flow of energy from a luminary per unit area. The apparent stellar magnitude depends both on the physical characteristics of the luminous object (luminosity) and on the distance to it. The lower the magnitude, the brighter the object.
Gravity
the property of objects to attract each other, gravity. The force of attraction, according to Newton's law, is directly proportional to the mass of objects and inversely proportional to the square of the distance between them.
Gyroscopic effect
the property of the axis of a rotating body to remain parallel to itself. A good example is a children's whirligig. The earth and other planets are big gyroscopes. Due to the gyroscopic effect, the angle of inclination of the planets to the orbital plane always remains unchanged, for the Earth ~ 23.5 degrees.
Briefly to remember
A natural celestial body in which, under the influence of the forces of its own gravity, the matter is compressed, sufficient for the start of a thermonuclear reaction. Radiates energy into space in the form of heat, light and electromagnetic fluxes
A natural celestial body that is massive enough to become round under its own gravity, but not massive enough to start a thermonuclear reaction. Rotates along a specific trajectory around its star
The sun is like a red giant
The Sun is currently a middle-aged star, approximately 4.5 billion years old. The sun will remain on the "main sequence" for about 5 billion more years, gradually increasing its brightness by 10% every billion years, after which the hydrogen in the core will be depleted. Then the temperature and density in the solar core will rise so much that helium will begin to burn, and the helium will begin to turn into carbon. The size of the Sun will grow by about 200 times. Mercury and Venus will be swallowed up by him. The earth will heat up so much that all living things will simply burn out, and the oceans will evaporate. At the stage of the red giant, the Sun will be about 100 million years, after which it will turn into planetary nebula, and then becomes a white dwarf.
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The star is a huge ball of gases. What is the difference between stars and planets?
People have long begun to observe and study the celestial bodies that surround the Earth. Even ancient researchers noticed that in the sky, apart from fixed stars, there are also moving objects, and they are called "planets" (translated from Greek means "wandering"). Of course, it may seem that stars and planets are very similar, but observing through telescopes, people have identified the main differences between them.
Brightness and luminosity
To the human eye, the planet in the sky is represented by a small light circle, which glows with an even calm light, and the stars are luminous points. This fact is explained by the fact that the planets do not have their own light, they are visible to the eye due to sunlight, which, falling on the surface, is simply reflected.
The planets differ in color from each other: Mars - red, Venus - white, Saturn - yellow, Earth - blue.
The glow of stars occurs as a result of certain processes (nuclear and thermonuclear reactions) that occur in the interior of a star.
These celestial bodies are incandescent gaseous balls with a very high surface temperature (up to 40,000 degrees, and in the center it even reaches several tens of millions of degrees). An enormous amount of energy (light that can be observed) is released during the conversion of light elements (mainly hydrogen) to heavy ones. It is due to the large amount of released energy that a sufficiently high temperature is maintained, which will ensure the passage of the further process of a nuclear reaction and, accordingly, the release of a new amount of energy. The closest star to be observed is the Sun.
Weight
Stars differ from planets in their mass and size. Usually the mass and size of the planet is comparatively less than that of the stars. For example, the Sun is several hundred thousand times larger than the planet Earth. Only one planet, Jupiter, can be approximated in terms of its mass and size characteristics to the so-called dwarf stars.
Movement in space
All planets move relative to stars, such as, for example, the Earth around the Sun, and the movement necessarily takes place along an elliptical trajectory, this explains the continuous change in the apparent diameter and brightness of the Sun. Unlike stars, planets show phases similar to the moon.
Planets, unlike stars, can have one or more satellites. The stars remain stationary relative to the planets, you can see this if you look at the starry sky for several nights in a row.
Internal structure of a typical star
Chemical composition
The difference between stars and planets is also significant in their chemical composition. The star mainly contains light elements, with the so-called small atomic number (more hydrogen, helium, small amounts of carbon, nitrogen, oxygen). A planet can contain both solid and light elements. All terrestrial planets have hard shells in which almost all of their mass is concentrated. Venus, Earth, and Mars all have gaseous atmospheres, while Mercury, for example, has virtually no atmosphere. And only the Earth has a hydrosphere and a biosphere; the cryosphere present on Mars can be called an analogue of the hydrosphere.
Admiring the brightest star in the evening sky, we often don’t realize that this is not a star, but a planet. Yes, exactly - the planet Venus, although it is brighter than almost all visible stars... Almost - because our sun is also a star.
What is the difference between stars and planets?
Already in ancient Babylon and Egypt, a thousand years before our era, the priests who watched the sky learned to distinguish stars from planets. True, it is unlikely that they understood what exactly shines in the sky, and what stars or planets are - in general!
- Therefore, they called the planets wandering stars.
- What we can see without a telescope: the planets change their position in the sky, move.
- Also, we can see that the planets are not flickering. Venus, for example, burns with an even white light, Mars - reddish.
- The stars twinkle, especially on a frosty or windy night, just above the horizon. Shimmer in different colors, constantly changing the brightness of the glow.
- This is how, without optical instruments, you can distinguish a star from a planet. But, of course, the differences do not end there, but begin.
- The answer to the question - how do stars differ from planets can be put into five points.
The first difference, explaining why the stars twinkle, and the planets glow with an even light - the stars are much farther from us. The distance to the nearest star is measured in parsecs, this is such an astronomical unit of measurement, 30.8568 trillion kilometers. From our sun to the very close star- 1.3 parsecs, proximal to the constellation Centaurus. The light of a star travels a colossal distance, refracting in gaseous layers, inhomogeneous media of different densities, because space is not a complete vacuum!
The planets, accordingly, do not flicker, because, much closer, within our solar system... The distance from the Earth to the same Venus varies from 40 to 259 million kilometers.
The second difference
A star, for example - our Sun, is a huge ball of gases, incandescent to unimaginable temperatures, up to 40 thousand degrees on the surface, and even more - in the center. The glow of a star is the result of a nuclear reaction that constantly occurs in its interior. A nuclear reaction turns light elements into heavy ones, and a colossal energy is released, including the short-wave radiation that we see, light.
A planet is much smaller than a star, for example, the mass of the Earth is 332,958 times less than the mass of the Sun. How do stars differ from planets? The fact that thermonuclear reactions do not take place in the bowels of the planets, therefore, the planets are dark bodies.
Why, then, we admire such a bright Venus in the sky? Because our Sun illuminates it, and we see the reflected light.
Third difference
The star rotates on its axis. The planet also revolves around its axis, so we see how the night replaces the day. But, the planet still revolves around its star. And, therefore, we see the changing of the seasons.
Fourth difference
The planets have a magnetic field that is capable of holding the atmosphere. Therefore, we can live on our Earth.
The difference between stars and planets is that they have no atmosphere. Huge temperatures and chemical composition, mostly hydrogen and helium, i.e. - light elements, do not allow the formation of the atmosphere.
Fifth difference
The chemical composition of the planets of the so-called first four, close to the Earth - silicon, iron, aluminum, magnesium, titanium, and also compounds of silicon (silicates) and iron. The chemical composition of the giant planets contains methane and ammonia. If you look at the atomic weight according to the periodic table - heavy and medium elements.
The chemical composition of the Sun, like most stars, is hydrogen and helium, light elements that support nuclear reactions.
There are five such differences. And now - just admire the starry sky!