Gliese 710 will become not only the brightest, but also the most dangerous star in the earth's sky.
The star Gliese 710 is now 64 light-years from Earth, but in a million years it will pass very close to the Sun directly through the Oort cloud, which contains many large comets and ice-rich asteroids. Their orbits will be severely disturbed and a significant part should eventually collide with the Earth. The corresponding article was published in the journal Astronomy & Astrophysics.
Gliese 710 is an orange dwarf of spectral type K7. In terms of mass, it is twice lighter than the Sun, and in terms of luminosity it is 30 times inferior. When observing this object, astronomers have long noticed that it has a very small proper motion - the position of the star in the sky changes very little, while there are signs that it is approaching the Earth.
Russian astronomers in 1996 established that as a result of such a convergence, the Sun and Gliese 710 will become the closest stars to each other - they will converge to 260,000 astronomical units or four light years. This is approximately equal to the distance to the planetary system closest to us - Proxima Centauri. The same group of scientists suggested that the orbits of part of the comets of the Oort cloud (up to 1.5-2.0 light years from Earth) may be disturbed by this approach, as a result of which comets may even fall on our planet.
However, over the past 20 years, great changes have occurred in astronomical technology outside our country - powerful space-based telescopes have appeared (in Russia, these are used exclusively for military purposes - for observing the Earth). Using the data of the newest among them European "Gaia", Polish astronomers analyzed the parameters of the motion of Gliese 710 in the direction of the solar system and significantly refined them. As it turned out, in 1.35 million years it will pass 6,250 astronomical units from our star (with a 90 percent probability). This is less than 0.1 light years and significantly less than all previous estimates gave. For comparison, it can be indicated that the average distance of the ninth planet from the Sun is only 10 times less than that of Gliese 710. Therefore, in the earth's sky it will be brighter than any other star, and only slightly inferior to Venus.
More importantly, from this figure it follows that the star will definitely "hit" with its gravity on the stability of the Oort cloud and much stronger than previously thought. In general, encounters with other stars are common in the solar system, and occur every 100,000 years. However, it all depends on the distance. A star at 4.00 and 0.1 light years away from the object acts on it with a force 1600 times different. Accordingly, this passage will affect the bodies of the solar system incomparably stronger than the overwhelming majority of other approaches.
For a million years after the "approach" of Gliese 710, comets from the cloud can strike the Earth. It is believed that 55 million years ago, one cometary hit of this kind was enough to radically and permanently change the climate on the planet. The Oort cloud should also contain large ice-rich asteroids. Therefore, blows can bring more serious consequences - up to those that took place 66 million years ago.