Experienced astronomers are well aware that the orbital velocity of the planets is directly related to their distance from the center of the system - the Sun. Well, for people who are just starting to study the amazing science of celestial bodies, it would probably be interesting to know more about this.
What is orbital speed?
Orbit is the trajectory along which a particular planet moves around the Sun. It does not represent an ideal circle at all, as some people who do not understand astronomy think. Moreover, it does not even resemble an oval too much - after all, there are a large number of factors with the exception of the gravitational force of the Sun, which can affect the motion of celestial bodies.
It is also worth immediately dispelling another well-known myth - the Sun is not always located exactly in the center of the orbit of the planets orbiting around it.
Finally, it should be noted that not all planetary orbits lie in the same plane. Some significantly get out of it - for example, if you depict the standard orbits of the Earth and Venus on an astronomical map, you can make sure that they have only a few intersection points.
Now that we have more or less understood the orbits, we can return to the definition of the term orbital velocity of the planets. This is what astronomers call the speed with which a planet moves along its path. It can vary slightly - depending on which celestial bodies pass nearby. This is especially noticeable on the example of Mars: every time it passes in a comparative proximity to Jupiter, it slows down a little, being attracted by the gravitational field of this giant.
Scientists have long established the dependence of the speed of the planets around the sun on the distance to it.
That is, the planet closest to the Sun - Mercury - is moving fastest, while the speed of Pluto is the smallest in the solar system.
What is the reason for this?
The fact is that the speed of each planet corresponds to the force with which the sun attracts it at a certain distance. If the speed is less, then the planet will gradually approach the star and as a result will burn out. If the speed is too high, then the planet will simply fly away from the center of our solar system.
Every astronomer, even a beginner, knows very well that the force of attraction decreases with distance from the Sun. That is why, in order to maintain its place in the solar system, Mercury is forced to rush at a frantic speed, Mars can move more slowly, and Pluto hardly moves at all.
Mercury
The planet closest to the Sun is Mercury. This is where we begin the study of the speed of the planets of the solar system.
It can boast not only the smallest radius of the orbit, but also small size. In our system, this is the smallest full-fledged planet. The distance from Mercury to the Sun is less than 58 million kilometers, due to which the temperature at its equator on a hot day can grow up to 400 degrees Celsius and even more.
In addition, in order to stay in its orbit with such close proximity of the Sun, the planet has to move at great speed - about 47 kilometers per second. Since the length of the orbit due to the small radius is quite small, it completes a complete revolution around the star in just 88 days. That is, the New Year can be celebrated there much more often than on Earth. But the speed of rotation of the planet around its own axis is very small - Mercury makes a full revolution in almost 59 Earth days. So, a day here is not much shorter than a year.
Venus
The next planet in our system is Venus. The only one on which the sun rises in the west and sets in the east. The distance to the center of the system is 108 million kilometers. Due to this, the speed of the planet in orbit is much less than that of Mercury (only 35 kilometers per second). Moreover, this is the only planet in which the orbit really represents an almost perfect circle - the error (or, as experts say, the eccentricity) is extremely small.
True, the length of the orbit (compared to Mercury) is much larger, which is why Venus completes the full path in only 225 days. By the way, another interesting fact that distinguishes Venus from all other planets of the solar system: the rotation period around the axis (one day) here is 243 Earth days. Consequently, the year here lasts less than a day.
Land
Now we can consider the planet, which has become the home for humanity - the Earth. The average distance to the Sun is almost 150 million kilometers. It is this distance that is usually called one astronomical unit - they are used in calculating small (by the standards of the Universe) distances in space.
It’s hard to believe, but while you are reading this article, you are moving with the Earth at a speed of almost 30 kilometers per second. But even at such an impressive speed to make a complete revolution around the Sun, the planet spends more than 365 days or 1 year on this. But it rotates around its axis rather quickly - in just 24 hours. However, these and many other facts about the Earth are obvious to everyone, therefore, we will not begin to examine our native planet in detail. We proceed immediately to the next.
Mars
This planet is named after the formidable god of war. In all respects, Mars is as close to Earth as possible. For example, the speed of a planet in orbit is 24 kilometers per second. The distance to the Sun is about 228 million kilometers, which is why it is rather cool on the surface most of the time - only in the afternoon it warms up to -5 degrees Celsius, and at night it gets colder to -87 degrees.
But the day here is almost equal to Earth - 24 hours and 40 minutes. To simplify, a new term was even coined for the Martian day - sol.
Since the distance to the Sun is quite large, and the trajectory of movement is much longer than that of the Earth, the year here lasts quite a long time - as much as 687 days.
The eccentricity of the planet is not too large - about 0.09, so the orbit can be considered conditionally round with the Sun located almost in the center of the circumscribed circle.
Jupiter
Jupiter received its name in honor of the most powerful ancient Roman god. It is not surprising that this particular planet can boast the largest dimensions in the solar system - its radius is almost 70 thousand square kilometers (the Earth, for example, has only 6,371 kilometers).
The distance from the Sun allows Jupiter to rotate quite slowly - only 13 kilometers per second. Because of this, it takes almost 12 Earth years to make a full circle!
But the day here is the shortest in our system - 9 hours and 50 minutes. The inclination of the axis of rotation is extremely small - only 3 degrees. For comparison - on our planet this figure is 23 degrees. Because of this, there are absolutely no seasons on Jupiter. There is always the same temperature, changing only for short days.
Jupiter's eccentricity is quite small - less than 0.05. Therefore, he uniformly winds circles strictly around the sun.
Saturn
This planet is not too inferior to Jupiter in size, being the second largest cosmic body in our solar system. Its radius is 58 thousand kilometers.
The speed of the planet in orbit, as mentioned above, continues to fall. For Saturn, this figure is only 9.7 kilometers per second. And to travel at such a low speed is a really great distance - the distance to the Sun is almost 9.6 astronomical units. In total, this path takes 29.5 years. But the day is one of the shortest in the system - only 10.5 hours.
The eccentricity of the planet is almost the same as that of Jupiter - 0.056. Therefore, the circumference is quite smooth - perihelion and aphelion differ by only 162 million kilometers. Given the huge distance to the sun, the difference is very small.
Interestingly, the rings of Saturn also revolve around the planet. Moreover, the speed of the outer layers is much lower than the inner ones.
Uranus
Another giant of the solar system. Only Jupiter and Saturn are superior in size. True, Neptune also bypasses it in weight, but this is due to the high density of the nucleus. The average distance to the Sun is really huge - as many as 19 astronomical units. He moves rather slowly - he can quite afford it at such a great distance. The speed of the planet in orbit does not exceed 7 kilometers per second. Due to such a slow pace to go a huge distance around the Sun, Uranus takes as many as 84 Earth years! A very decent time.
But around its axis it rotates amazingly fast - a complete revolution takes place in just 18 hours!
An amazing feature of the planet is that it rotates around itself not vertically, but horizontally. In other words, all the other planets of the solar system make a revolution “standing” at the pole, and Uranus simply “rolls” in its orbit, as if lying on its side. Scientists explain this by the fact that during the formation of the planet collided with some kind of large cosmic body, because of which it simply fell on its side. Therefore, although in the generally accepted sense, the day here is very short, at the poles the day lasts 42 years, and then the night lasts the same number of years.
Neptune
The ancient Roman ruler of the seas and oceans gave its proud name to Neptune. No wonder even his trident became a symbol of the planet. In terms of size, Neptune is the fourth planet in the solar system, only slightly inferior to Uranus - its average radius is 24,600 km against 25,400.
From the Sun, it is kept at an average distance of 4.5 billion kilometers or 30 astronomical units. Therefore, the path that he goes through the orbit is really huge. And if we take into account that the circular velocity of the planet is only 5.4 kilometers per second, then there is nothing surprising in the fact that one year here is equivalent to 165 Earth.
An interesting fact: there is a rather dense atmosphere (though it consists mainly of methane), and sometimes there are winds of amazing strength. Their speed can reach 2100 kilometers per hour - on Earth, even a single rush of such power would instantly destroy any city without leaving stone unturned there.
Pluto
Finally, the last planet on our list. More precisely, not even a planet, but a planetoid - it has recently been deleted from the list of planets due to its small size. The average radius is only 1187 kilometers - even our moon has this figure of 1737 kilometers. Nevertheless, his name is rather formidable - he was assigned in honor of the god of the underworld of the dead among the ancient Romans.
On average, the distance from Pluto to the Sun is about 32 astronomical units. This allows him to feel safe and move at a speed of only 4.7 kilometers per second - Pluto will still not fall on a red-hot star. But to make a complete revolution around the Sun with such a huge radius, this tiny planet spends 248 Earth years.
Around its axis, it also rotates very slowly - it takes 152 Earth hours or more than 6 days.
In addition, the largest eccentricity in the solar system is 0.25. Therefore, the Sun is far from the center of the orbit, but shifted by almost a quarter.
Conclusion
This can end the article. Now you know about the speed of the planets of our solar system, and also learned many other factors. Surely now you understand astronomy much better than before.