Planetary orbits
Planetary orbits
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It gives vertigo to know how long the path around the Sun is for each planet, how long each one takes and at what speeds.Recently I found a very cute and interesting animated gif. I was looking for who did it, but I did not find the original source. It was used on Instagram by the astronomer Neil DeGrasse Tyson and many others reused it, but the corresponding credit is not clear. If someone can tell me, I will indicate it accordingly.
I mean this:
It's cute, is not it? But...Is it to scale?
It is clear that on a planetary scale, no. It is not necessary, since what is tried to show is the time of orbit of each planet.
But time, is it to scale? Can time be scaled without being to scale?
To know it is easy: we focus on the Earth and count how many times it reaches the starting point, that is, how many turns it gives. In that time, Neptune (the last planet of the gif) will take a turn. I count 6 orbits of our planet in the gif. As you will see below, in the astronomical reality, at the time when Neptune completes an orbit to the Sun, the Earth gives 164 turns. I can be sure that it is not to scale.If we wanted to do it at scale we would have some problems, namely:
According to Kepler's Laws, the time it takes the planets to circle the Sun (their "years") depends on the length of the orbit: For any planet, the square of its orbital period is directly proportional to the cube of the length of the planet. Semi-major axis of its elliptical orbit (Kepler's Third Law).The speed is not always the same, since the orbits are ellipses, not circles, with the Sun in one of the foci. Therefore, when the planets are close to the Sun they move faster and when they are farther away, they do so at a lower speed.
The vector radius that unites a planet and the Sun travels equal areas in equal times (Kepler's Second Law).From this it follows that there are three data linked to the time it takes the planets to orbit the Sun:
1-The average speed (between the highest and the lowest, in km / s)
2-The length of the orbit (in km)
3-The time it takes to orbit (in Earth years)Well, if we want to visualize the three variables, we must consider that they are different units of measurement and that the discrete values are very different. Doing this at a distance scale, considering the semimajor axis or directly drawing the ellipse to scale, as in the gif, would be impractical, since the inner planets would hardly be seen. And if the separation between the inner planets were greater, the total size of the image would be ... astronomical.
What can be done?
There are two other ways to visualize this data. The simplest is to indicate the information for each body in an image, as in this case:
The good thing about this image is that, if we know how to read numbers, we will easily notice that the average speed decreases from Mercury to Pluto; that the length increases and consequently, the time increases even more.
The image was taken from the JPL page, accredited below. I took the data from some NASA pages, except for the length of the orbits that is hard to find. I found them on the site of a university, in miles. I passed them to kilometers and divided them by 10 ^ 9, so that the number is smaller.As the data was written down in a spreadsheet, it is also possible to make a typical bar graph with the three variables for each planet. As we will see, you hardly notice a line instead of a bar on the inner planets, since the difference in values between Mercury and Pluto are large.
The blue bar is the speed, which is clearly lower than the Sun. The orange bar is the length of the orbits, which is not seen in the inner planets and also grows as we move away. And the green bar is the orbital time in Earth years, which grows exponentially.
Length of the orbit
Note that the length of the orbit is not the same as the length of the semimajor axis. The distance from the Sun to the planets (average) is usually taken from the semimajor axis, but if we want to evaluate the time of travel, then we must consider the perimeter of the ellipse, although you can also apply Kepler's third law and use the semimajor axis to calculate the period algebraically, at the rate of ttwo = a3, where t is period and a, semi-major axis.On the hyperphysics site it is explained as follows:
As seen in the graph, logarithmic scales are used, expressed in Astronomical Units (cubed) on the axis of the coordinates, while in the horizontal (axis of the abscissas) terrestrial years are expressed (squared).Graphic v.2
I decided to make a second version of the graph, incorporating the distance, the Semi-Axis Major (S.E.M.) expressed in Astronomical Units (AU). In the NASA page, however, the length is indicated in millions of km, so I took that data and in other cells I divided them by 150 to obtain a good approximation of the distance in UA and I added those data.
Now the reader can do, if he wants, a simple exercise: take the data t (period) and raise it to power two; and take the data D and elevate it to the cube. You will see that they are similar values.
You can even use Google's calculator, either to calculate both figures or directly subtract the first to the second. If they are similar values, the result of subtraction should be close to zero.
Eppur si muove
Some time ago I suggested to do in Buenos Aires Capital, also in La Plata, a path, walk or solar walk, that is, a route during which there are posters with information about the planets located at a distance to the Solar System. In such a journey, we would have to add some images like these, since they allow us to better understand and visualize not only distances, but also speed. It is not necessary to clarify that the speed used is of translation. I did not include the rotation movement data so as not to confuse with more numbers.
It is interesting to note that if people live more than 80 years and not much more than 100, then throughout a human life, neither Neptune nor Pluto (now considered Dwarf Planet) will have made a complete return to the Sun.
And it gives a bit of vertigo to know that, even if you are motionless, you actually move at almost 30 kilometers per second, something like 108 thousand km / h !.Nerdital ideas
Curiosity: I saw this graph at the beginning of the week. I warned that it could not be to scale. I kept thinking. And I went back over the subject again and again, as if my brain orbited the idea incessantly. Today, after work, I started taking data to make both the image and the bar graphs. I think this deserves Nerd's yellow belt!Sources and related links
What are the orbital lengths and distances of objects in our solar system?
http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/3-orbital-lengths-distances.htmlHyperphysics: Kepler's Laws
http://hyperphysics.phy-astr.gsu.edu/hbasees/kepler.htmlSpace Facts
https://space-facts.com/planet-orbits/POT
https://nssdc.gsfc.nasa.gov/planetary/factsheet/NASA JPL Solar System Dynamics
https://ssd.jpl.nasa.gov/?planet_phys_parNASA Solar System Exploration
https://solarsystem.nasa.gov/planets/mercury/by-the-numbers/About the images
Planetary Photojournal Home Page Graphic
https://www.jpl.nasa.gov/spaceimages/details.php?id=pia06890GIF on Pinterest
https://www.pinterest.es/pin/237705686565091878/?lp=trueIn G +
https://plus.google.com/+JavierVadilloVicente/posts/iRLuadnfTkWOn Instagram
https://www.instagram.com/p/BRCis3RlRMQ/?utm_source=ig_embed
SOURCE LINK THE BEST ONLINE UFO WEBSITES https://www.beviral.online
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