The movement of the solar system in the milky way galaxy. The movement of the solar system in the vastness of the universe

Even sitting on a chair in front of a computer screen and clicking on links, we are physically engaged in a variety of movements. Where are we going? Where is the "top" of the movement, its apex?

First, we participate in the rotation of the Earth around its axis. it daily movement points to the east point on the horizon. The speed of movement depends on the latitude; it is equal to 465 * cos (φ) m / s. Thus, if you are at the north or south pole of the Earth, then you are not participating in this movement. And let's say, in Moscow, the daily linear speed is about 260 m / s. The angular velocity of the apex of daily motion relative to the stars is easy to calculate: 360 ° / 24 hours = 15 ° / hour.

Secondly, the Earth, and we together with it, moves around the Sun. (We will neglect the small monthly wobble around the center of mass of the Earth-Moon system.) Average speed annual movement in orbit - 30 km / sec. At perihelion in early January it is slightly higher, at aphelion in early July it is slightly lower, but since the Earth's orbit is almost an exact circle, the difference in speed is only 1 km / s. The orbital apex naturally shifts and completes a full circle in a year. Its ecliptic latitude is 0 degrees, and its longitude is equal to the longitude of the Sun plus approximately 90 degrees - λ = λ ☉ + 90 °, β = 0. In other words, the apex lies on the ecliptic, 90 degrees ahead of the Sun. Accordingly, the angular velocity of the apex is equal to the angular velocity of the Sun's motion: 360 ° / year, slightly less than a degree per day.

We carry out larger-scale movements already together with our Sun as part of the Solar system.

First, the sun is moving relative nearby stars(so-called local rest standard). The travel speed is about 20 km / sec (slightly more than 4 AU / year). Note that this is even less than the speed of the Earth in orbit. The movement is directed towards the constellation Hercules, and the equatorial coordinates of the apex are α = 270 °, δ = 30 °. However, if we measure the speed relative to all bright stars, visible to the naked eye, then we get the standard motion of the Sun, it is somewhat different, less in speed than 15 km / s ~ 3 AU. / year). This is also the constellation Hercules, although the apex is slightly displaced (α = 265 °, δ = 21 °). But relative to interstellar gas, the solar system moves slightly faster (22-25 km / s), but the apex is significantly shifted and falls into the constellation Ophiuchus (α = 258 °, δ = -17 °). This shift of the apex of about 50 ° is associated with the so-called. by the "interstellar wind" "blowing from the south" of the Galaxy.

All three described movements are, so to speak, local movements, "walks in the yard". But the Sun, together with the nearest and generally visible stars (after all, we practically do not see too distant stars), together with clouds of interstellar gas, revolves around the center of the Galaxy - and these are completely different speeds!

The speed of the movement of the solar system around the center of the Galaxy is 200 km / s (more than 40 AU / year). However, the indicated value is inaccurate, it is difficult to determine the galactic speed of the Sun; we do not even see what we are measuring the motion in relation to: the center of the Galaxy is hidden by dense interstellar clouds of dust. The value is constantly being refined and tends to decrease; not so long ago, it was taken for 230 km / s (this value can often be found), and recent studies give results even less than 200 km / s. Galactic motion occurs perpendicular to the direction to the center of the Galaxy and therefore the apex has galactic coordinates l = 90 °, b = 0 ° or in more familiar equatorial coordinates - α = 318 °, δ = 48 °; this point is in Lebed. Because this is a reversal movement, the apex shifts and completes a full circle in a "galactic year," roughly 250 million years; its angular velocity is ~ 5 "/ 1000 years, one and a half degrees per million years.

Further movements include the movement of the whole Galaxy. Measuring such a movement is also not easy, the distances are too great, and the error in the numbers is still quite large.

Thus, our Galaxy and the Andromeda Galaxy, two massive objects of the Local Group of Galaxies, are gravitationally attracted and moving towards each other at a speed of about 100-150 km / s, with the main component of the speed belonging to our galaxy. The lateral component of the movement is not precisely known, and concerns about collision are premature. An additional contribution to this movement is made by the massive galaxy M33, located approximately in the same direction as the Andromeda galaxy. In general, the speed of motion of our Galaxy relative to the barycenter Local group of galaxies about 100 km / s approximately in the direction of Andromeda / Lizard (l = 100, b = -4, α = 333, δ = 52), but these data are still very approximate. This is a very modest relative speed: the Galaxy is displaced by its own diameter in two to three hundred million years, or, very approximately, in galactic year.

If we measure the speed of the Galaxy relative to distant clusters of galaxies, we will see a different picture: both our galaxy and the rest of the galaxies of the Local Group, together as a whole, move in the direction of the large Virgo cluster at about 400 km / s. This movement is also driven by gravitational forces.

Background relict radiation defines a certain preferred frame of reference associated with all baryonic matter in the observable part of the Universe. In a sense, motion relative to this microwave background is motion relative to the Universe as a whole (this motion should not be confused with the scattering of galaxies!). It is possible to determine this movement by measuring dipole temperature anisotropy irregularity of the relict radiation in different directions... Such measurements showed an unexpected and important thing: all galaxies in the closest to us part of the Universe, including not only our Local Group, but also the Virgo cluster and other clusters, move relative to the background relict radiation with an unexpectedly high speed. For the Local Group of galaxies, it is 600-650 km / s with an apex in the constellation Hydra (α = 166, δ = -27). It looks so that somewhere in the depths of the Universe there is still an undetected huge cluster of many superclusters, attracting the matter of our part of the Universe. This hypothetical cluster was named Great Attractor.

How was the speed of the Local Group of Galaxies determined? Of course, in fact, astronomers measured the speed of the Sun relative to the microwave background: it turned out to be ~ 390 km / s with an apex with coordinates l = 265 °, b = 50 ° (α = 168, δ = -7) at the border of the constellations Leo and Chalice. Then we determined the speed of the Sun relative to the galaxies of the Local Group (300 km / s, constellation Lizard). It was no longer difficult to calculate the speed of the Local Group.

Where are we heading?

Daily: observer relative to the center of the Earth	0-465 m / s	East
Annual: Earth relative to the Sun	30 km / sec	perpendicular to the direction of the sun
Local: Sun relative to nearby stars	20 km / sec	Hercules
Standard: Sun relative to brighter stars	15 km / sec	Hercules
Sun relative to interstellar gas	22-25 km / s	Ophiuchus
Sun relative to the center of the Galaxy	~ 200 km / s	Swan
Sun relative to the Local Group of Galaxies	300 km / s	Lizard
Galaxy relative to the Local Group of Galaxies	~ 1 00 km / s

You are sitting, standing or lying while reading this article and do not feel that the Earth rotates on its axis at a breakneck speed - about 1,700 km / h at the equator. However, the rotational speed does not seem so fast when converted to km / s. The result is 0.5 km / s - a barely noticeable flash on the radar, compared to other speeds around us.

Just like other planets in the solar system, the earth revolves around the sun. And in order to stay in its orbit, it moves at a speed of 30 km / s. Venus and Mercury, which are closer to the Sun, move faster, Mars, whose orbit passes beyond the orbit of the Earth, moves much slower than it.

But even the Sun does not stand in one place. Our Milky Way galaxy is huge, massive and also mobile! All stars, planets, gas clouds, dust particles, black holes, dark matter - all move relative to the common center of mass.

According to scientists, the Sun is located at a distance of 25,000 light years from the center of our galaxy and moves in an elliptical orbit, making a complete revolution every 220-250 million years. It turns out that the speed of the Sun is about 200-220 km / s, which is hundreds of times higher than the speed of the Earth's movement around the axis and tens of times higher than the speed of its movement around the Sun. This is how the movement of our solar system looks like.

Is the galaxy stationary? Again, no. Giant space objects have a large mass, and therefore create strong gravitational fields. Give the Universe some time (and we had it - about 13.8 billion years), and everything will begin to move in the direction of greatest attraction. This is why the Universe is not homogeneous, but consists of galaxies and groups of galaxies.

What does this mean for us?

This means that the Milky Way is being pulled towards itself by other galaxies and galaxy groups in the vicinity. This means that massive objects dominate this process. And this means that not only our galaxy, but all those around us are influenced by these "tractors". We are getting closer to understanding what is happening to us in outer space, but we still lack facts, for example:

• what were the initial conditions under which the universe was born;
• how the various masses in the galaxy move and change over time;
• how the Milky Way and surrounding galaxies and clusters formed;
• and how it is happening now.

However, there is a trick to help us figure it out.

The Universe is filled with relic radiation with a temperature of 2.725 K, which has been preserved since the time of the Big Bang. In some places there are tiny deviations - about 100 μK, but the overall temperature background is constant.

This is because the universe was formed in the Big Bang 13.8 billion years ago and is still expanding and cooling.

380,000 years after the Big Bang, the universe cooled to such a temperature that the formation of hydrogen atoms became possible. Before that, photons constantly interacted with the rest of the plasma particles: they collided with them and exchanged energy. As the Universe cools down, there are fewer charged particles, and the space between them is larger. The photons were able to move freely in space. The relic radiation is the photons that were emitted by the plasma towards the future location of the Earth, but escaped scattering, since the recombination has already begun. They reach the Earth through the space of the universe, which continues to expand.

You yourself can "see" this radiation. Interference that occurs on a blank TV channel when using a simple antenna like hare ears is 1% due to relic radiation.

And yet, the temperature of the relict background is not the same in all directions. According to the results of the Planck mission studies, the temperature is slightly different in the opposite hemispheres of the celestial sphere: it is slightly higher in the regions of the sky south of the ecliptic - about 2.728 K, and lower in the other half - about 2.722 K.

A map of the microwave background taken with the Planck telescope.

This difference is almost 100 times greater than the rest of the observed CMB temperature fluctuations, and this is misleading. Why it happens? The answer is obvious - this difference is not due to fluctuations in the CMB, it appears because there is motion!

When you approach a light source or it approaches you, the spectral lines in the spectrum of the source are shifted towards short waves (violet shift), when you move away from him or he from you - the spectral lines are shifted towards long waves (redshift).

The relic radiation cannot be more or less energetic, which means that we are moving through space. The Doppler effect helps determine that our solar system is moving relative to the relic radiation at a speed of 368 ± 2 km / s, and the local group of galaxies, including the Milky Way, the Andromeda galaxy and the Triangulum galaxy, is moving at a speed of 627 ± 22 km / s relative to the relic radiation. These are the so-called peculiar velocities of galaxies, which amount to several hundred km / s. In addition to them, there are also cosmological velocities due to the expansion of the Universe and calculated according to the Hubble law.

Thanks to the residual radiation from the Big Bang, we can observe that everything in the universe is constantly moving and changing. And our galaxy is only part of this process.

The moon is orbiting at a speed of 1 km per second. The Earth together with the Moon make a complete revolution around the Sun in 365 days at a speed of 108 thousand kilometers per hour or 30 km per second.

More recently, scientists have limited themselves to such data. But with the invention of powerful telescopes, it became clear that the solar system is not limited to just planets. It is much larger and extends over a distance of 100 thousand distances from the Earth to the Sun (astronomical). This is the area covered by the gravity of our star. It is named after the astronomer Jan Oort, who proved its existence. The Oort cloud is a world of icy comets that periodically approach the Sun, crossing the Earth's orbit. Only beyond this cloud does the solar system end and interstellar space begins.

Oort also based on the radial velocities and proper motions of stars, substantiated the hypothesis about the motion of the galaxy around its center. Consequently, the Sun and its entire system, as a whole, together with all neighboring stars, moves in the galactic disk around a common center.

Thanks to the development of science, at the disposal of scientists, sufficiently powerful and accurate instruments appeared, with the help of which they came closer and closer to the solution to the structure of the universe. It was possible to find out where the center of the Milky Way visible in the sky is located. He found himself in the direction of the constellation Sagittarius, hidden by dense dark clouds of gas and dust. If there were no these clouds, then a huge blurry white spot would be visible in the night sky, tens of times larger than the Moon and the same luminosity.

Modern refinements

The distance to the center of the galaxy turned out to be greater than expected. 26 thousand light years. This is a huge number. Launched in 1977, the Voyager satellite, which had just left the solar system, would have reached the center of the galaxy in a billion years. Thanks to artificial satellites and mathematical calculations, it was possible to find out the trajectory of the solar system in the galaxy.

Today it is known that the Sun is located in a relatively calm section of the Milky Way between the two large spiral arms of Perseus and Sagittarius and another, slightly smaller arm of Orion. They are all visible in the night sky as foggy streaks. Te - Outer Spiral Arm, Karin Arm, visible only with powerful telescopes.

The sun can be said to be lucky that it is located in an area where the influence of neighboring stars is not so great. Being in the spiral arm, perhaps life would never have originated on Earth. Still, the Sun does not move around the center of the galaxy in a straight line. The movement looks like a vortex: over time, it is closer to the sleeves, then further away. And thus it orbits the circumference of the galactic disk along with neighboring stars in 215 million years, at a speed of 230 km per second.

Surely, many of you have seen a gif or watched a video showing the movement of the solar system.

Video clip released in 2012 went viral and made a lot of noise. I came across it shortly after its appearance, when I knew much less about space than I do now. And most of all I was confused by the perpendicularity of the plane of the orbits of the planets to the direction of motion. Not that this is impossible, but the solar system can move at any angle to the plane of the galaxy. You ask, why remember long-forgotten stories? The fact is that right now, with a desire and good weather, everyone can see in the sky a real angle between the planes of the ecliptic and the Galaxy.

Checking scientists

Astronomy says that the angle between the planes of the ecliptic and the galaxy is 63 °.

But the figure itself is boring, and even now, when the adherents of the flat Earth are on the sidelines of science, I want to have a simple and visual illustration. Let's think about how we can see the planes of the Galaxy and the ecliptic in the sky, preferably with the naked eye and without moving far from the city? The plane of the Galaxy is the Milky Way, but now, with an abundance of light pollution, it is not so easy to see it. Is there a line roughly close to the plane of the Galaxy? Yes - this is the constellation Cygnus. It is clearly visible even in the city, and it is easy to find it, relying on the bright stars: Deneb (alpha Cygnus), Vega (alpha Lyrae) and Altair (alpha Eagle). The "body" of the Swan roughly coincides with the galactic plane.

Okay, we have one plane. But how do you get a visual line of the ecliptic? Let's think, what is the ecliptic in general? According to the modern strict definition, the ecliptic is the section of the celestial sphere by the plane of the orbit of the barycenter (center of mass) of the Earth-Moon. On the average, the Sun moves along the ecliptic, but we do not have two Suns along which it is convenient to draw a line, and the Cygnus constellation will not be visible in sunlight. But if we remember that the planets of the solar system also move approximately in the same plane, then it turns out that the parade of planets will roughly show us the plane of the ecliptic. And now Mars, Jupiter and Saturn can be observed in the morning sky.

As a result, in the coming weeks in the morning before sunrise it will be possible to very clearly see the following picture:

Which, surprisingly, fits perfectly with astronomy textbooks.

And it is more correct to draw a gif like this:

Source: Rhys Taylor astronomer website rhysy.net

The question can cause the relative position of the planes. Are we flying<-/ или же <-\ (если смотреть с внешней стороны Галактики, северный полюс вверху)? Астрономия говорит, что Солнечная система движется относительно ближайших звезд в направлении созвездия Геркулеса, в точку, расположенную недалеко от Веги и Альбирео (бета Лебедя), то есть правильное положение <-/.

But this fact, alas, cannot be verified "on the fingers", because, even though they did it two hundred and thirty-five years ago, they used the results of many years of astronomical observations and mathematics.

Scattering stars

How can you even determine where the solar system is moving relative to nearby stars? If we can record the movement of a star across the celestial sphere for decades, then the direction of movement of several stars will tell us where we are moving relative to them. Let's call the point we are moving to the apex. Stars that are not far from it, as well as from the opposite point (antiapex), will move weakly, because they are flying towards us or away from us. And the further the star is from the apex and antiapex, the more its own motion will be. Imagine you are driving down the road. Traffic lights at intersections in front and behind will not move too much to the sides. But the lampposts along the road will still flicker (have a large movement of their own) outside the window.

The gif shows the movement of Barnard's star, which has the largest proper motion. Already in the 18th century, astronomers had records of the position of stars over an interval of 40-50 years, which made it possible to determine the direction of movement of slower stars. Then the English astronomer William Herschel took the star catalogs and, without going to the telescope, began to calculate. Already the first calculations according to Mayer's catalog showed that the stars do not move chaotically, and the apex can be determined.

Source: Hoskin, M. Herschel's Determination of the Solar Apex, Journal for the History of Astronomy, Vol. 11, P. 153, 1980

And with the data from the Lalande catalog, the area was significantly reduced.

From the same place

Then came the normal scientific work - clarification of data, calculations, disputes, but Herschel used the correct principle and was mistaken by only ten degrees. Information is still collected, for example, just thirty years ago, the speed of movement was reduced from 20 to 13 km / s. Important: this speed should not be confused with the speed of the solar system and other nearby stars relative to the center of the Galaxy, which is approximately 220 km / s.

Even further

Well, since we mentioned the speed of movement relative to the center of the Galaxy, it is necessary to figure it out here too. The Galactic North Pole is chosen in the same way as the Earth's - arbitrarily by convention. It is located not far from the star Arcturus (alpha Bootes), approximately upward in the direction of the wing of the constellation Cygnus. But in general, the projection of the constellations on the map of the Galaxy looks like this:

Those. The solar system moves relative to the center of the Galaxy in the direction of the constellation Cygnus, and relative to local stars in the direction of the constellation Hercules, at an angle of 63 ° to the galactic plane,<-/, если смотреть с внешней стороны Галактики, северный полюс сверху.

Space tail

But the comparison of the solar system with a comet in the video is completely correct. NASA's IBEX spacecraft was specifically designed to determine the interaction between the solar system boundary and interstellar space. And according to his data, there is a tail.

NASA illustration

For other stars, we can see the astrospheres (stellar wind bubbles) directly.

Photo by NASA

Last positive

Concluding the conversation, it is worth noting a very positive story. DJSadhu, who created the original video in 2012, initially promoted something unscientific. But, thanks to the viral spread of the clip, he talked with real astronomers (astrophysicist Rhys Tailor speaks very positively about the dialogue) and, three years later, made a new video, much more in line with reality, without anti-scientific constructions.

Anyone, even lying on a sofa or sitting near a computer, is in constant motion. This continuous movement in outer space has a variety of directions and tremendous speeds. First of all, the Earth moves around its axis. In addition, the planet revolves around the Sun. But that's not all. We cover much more impressive distances together with the solar system.

The Sun is one of the stars located in the plane of the Milky Way, or simply the Galaxy. It is 8 kpc distant from the center, and 25 pc from the galactic plane. The stellar density in our region of the Galaxy is approximately 0.12 stars per pc3. The position of the solar system is not constant: it is in constant motion relative to nearby stars, interstellar gas, and finally, around the center of the Milky Way. For the first time, the movement of the solar system in the galaxy was noticed by William Herschel.

Moving relative to nearby stars

The speed of movement of the Sun to the border of the constellations Hercules and Lyra is 4 a.s. per year, or 20 km / s. The velocity vector is directed to the so-called apex - the point to which the movement of other nearby stars is also directed. Directions of stars' velocities, incl. The suns intersect at the opposite point to the apex, called the antiapex.

Moving relative to visible stars

Separately, the movement of the Sun in relation to bright stars, which can be seen without a telescope, is measured. This is an indication of the standard movement of the Sun. The speed of such movement is 3 AU. per year or 15 km / s.

Moving relative to interstellar space

In relation to interstellar space, the solar system is already moving faster, the speed is 22-25 km / s. In this case, under the influence of the "interstellar wind" that "blows" from the southern region of the Galaxy, the apex is shifted to the constellation Ophiuchus. The shift is estimated to be around 50.

Moving around the center of the Milky Way

The solar system is in motion relative to the center of our Galaxy. It moves towards the constellation Cygnus. The velocity is about 40 AU. per year, or 200 km / s. It takes 220 million years for a complete turnover. It is impossible to determine the exact speed, because the apex (the center of the Galaxy) is hidden from us behind dense clouds of interstellar dust. The apex shifts by 1.5 ° every million years, and makes a full circle in 250 million years, or 1 "galactic year.