The sun is located in a very quiet place: 27,2 thousand light-years from the center of the galaxy, on the edge of the sleeve of Orion. And in the framework of human life – on the sky visible to the naked eye, nothing happens (except for the motion of the planets). But even in the history of human civilization, it was not always so. And this situation is not standard even for our Milky Way (and other galaxies too).
And when we go to the scale of millennia – even in the disk of our Milky Way there are places (with a dense cluster of stars) Something happens: so say the globular cluster M71 (pictured in the photo) has about 10,000 stars in diameter just 27 light years (in the same radius from us is less than 250 stars). Such a density of stars leads to the fact that for a few thousand years, the starry sky is completely transformed, and the stellar maps become hopelessly outdated (due to the rotation of individual stars, their groups, and groups of their groups around the common center of mass).
But since we are "stuck" here, let's talk about the most noteworthy events that will take place in our district in the future, and occurred in the past:
After 4 billion years. Possible variant developments: the collision of the Milky Way and Andromeda. Given that our counter-speed is about 110 km / s, and the transverse speed is not more than 100 km / s – the galaxies can both collide and only slightly converge during rotation around the common center of mass: the current accuracy of determining the angular position of the object is limited by technical The possibility of telescopes and the necessary accuracy will be obtained only during the data collection by the Gaia telescope.
Anyway, we will not be able to observe this process from the surface of the Earth: the temperature at the surface of the Earth by that time the mill so high that all the oceans will evaporate, and
the known forms of life on it simply can not exist.
After 1.35 million. years. The Glise 710 star must pass at a distance of only 0.205 ± 0.07 light years from the Sun (according to the first data of the same Gaia). This distance (in 13 thousand AU) will allow this star to gravitationally affect objects in the Oort cloud (located at a distance of 50-100 thousand AU), and cause the flow of comets. The magnitude of Gliese 710 will be -2.7 (which is higher than the brightness of Mars, but below Venus).
The direction of the north …
… and the southern poles of the Earth (the cycle is about 26 thousand years)
12 thousand years later The precession of the earth's axis will cause the place of the Polar Star to occupy Vega (as it was already 14 thousand years ago). For the same reason, the ancient Greeks – could with all justification call Tuban the "Polar Star."
9,800 years later To us for the nearest distance (3.75 light years), the Barnard star should come up – having the biggest angular velocity in the sky. However, a double approach, for astronomy enthusiasts will give a little: the star value will decrease by one unit (but still will be 8.5 units, which is beyond visibility to the unaided eye), and the speed that has grown to ≈20 arc seconds per year is still not Will allow to fix this process (without large telescopes or yearly observations).
2854 AD This year there will be a big parade of planets (all 8 pieces + excluded from them Pluto). The last time this happened in 561 AD. E.
1006 year of the year. E. May 1 this year marked the appearance in the sky of a new star – it was a supernova SN 1006 (SN in this case a reduction from supernova, 1006 – the year of its formation, in the years when they are found more than one – the name is added one or two letters, like in this case). This supernova was the brightest, recorded from the whole history of mankind, and it could be observed even during the day.
66 mln years ago. If the dinosaurs have telescopes and astronomers – a supermassive black hole in the center of our galaxy, they would not call the Sagittarius A * (like us), but Cygnus A *: during this period, the Sun traveled 99 ° around the Earth around the galactic center (about 23.5 Thousands of light years).
4.6 billion years ago In place of the solar system – a protoplanetary disk with the nascent Sun in the center. Protoplanets are warmed by the process of collapse from the gas-dust cloud, and by collisions (the process of formation and cooling of the Earth took almost 100 million years). The sun by the time of formation of the Earth already takes its place on the main sequence (for him the formation process took only 1 million years). Such a spread in the rate of formation is due to a difference of 332.9 thousand times in mass and the gravitational influence of other protoplanets.
560 Ma from the Big Bang. Period of formation of the first stars (population III). In connection with the lack of metals (by which astronomy means all substances heavier than helium) in the young universe, stars with a mass of at least 10 solar (blue giants) could form in it. The star that generated the molecular cloud from which the Sun was formed does not yet exist (but a star is already being formed that will become a donor of matter for it).
150 million years from the big bang The so-called "Dark Ages" – the relic radiation has already managed to shift to the infrared zone of the spectrum, and the stars have not yet formed (the average temperature in the Universe falls to -210 ° C for the appearance of the first stars). Time of formation of the first galaxies.
Relic radiation taken from the Planck Observatory: the temperature difference between the coldest and hottest point in this photo is 800 times lower than the average temperature.
377 thousand years from the big bang Recombination stage: The universe becomes transparent to light, everything around it is filled with a uniform yellow color (the relict radiation temperature is 4 thousand K). Extrapolation of time further – gives an increase in temperature further into infinity, when approaching a singularity (in the zone of gamma radiation through X-rays and ultraviolet). But we can not look so far physically (no matter how good our telescopes are).
Afterword. Human life does not allow us to fix most of the astronomical processes directly: the time of existence of anthropoid apes is comparable to the lifetime of the largest (and shortest-living) stars. And even the age of existence of all life on Earth is measured by 15 galactic years, and human civilization – and at all there are some 22 "galactic minutes" (or 0.0002% of the time of existence of the Sun).
However, this does not prevent Astronomers literally collect from thousands and millions of "puzzles" (ten-year observations of stars of different ages, but of the same composition and mass), a picture of their development for hundreds of millions and billions of years.
Even greater effort, had to resort to astronomers of the Renaissance Nikolai Copernicus – spent 40 years writing the work "On the rotation of the celestial spheres," Tycho Brahe – spent 20 years observing the planets, and Johannes Kepler – spent 22 years calculating the orbits of the planets on the basis of these observations, and the heliocentric system of Copernicus (for Transformation of the "circular" system of Copernicus into an "elliptical" system, used up to now, with a small addition.)