A galactic tide is defined in the international astronomical community as a tidal force that is generated by a galaxy on surrounding dwarf companions, or even its own solar systems and their asteroid belts. The Milky Way, being the massive galaxy that it is, produces large amounts of tidal forces of its own, which also act on our solar system, and especially on the Oort Comet Cloud, a hypothesized spherical cloud of comets and other space rocks that lies roughly 50,000 AU from the Sun. Some experts have even recently proposed that these interactions may have prompted life on Earth.
An AU, or astronomical unit, represents the mean distance between the Earth and the Sun. The Oort Cloud is believed to lie very far away from Pluto's orbit, but its influences are felt even within the inner solar system, astrophysicists say. Just recently, Slovak expert Jozef Klacka, from the Comenius University, managed to complete his calculations of the Milky Way's tidal forces, as well as its quantification of how these forces might have affected the outer asteroid belt. He believes that our galaxy exerts enough tidal forces on it to alter the path of comets.
This discovery could have far-reaching implications, considering the fact that recent studies have revealed that the Earth's atmosphere and oceans, as well as some of its minerals, may have had an extraterrestrial origin. If so, then the chemicals that now foster life were brought to our planet by comets coming in from the outer fringes of the solar system, more precisely from the Oort Cloud. This piece of news, if confirmed, could change the way we look at space exploration and astrobiology for good, analysts say, quoted by Technology Review
Klacka still has some more work to conduct on these issues, but he believes that his findings are in tune with what some astrobiologists have been saying for a long time, namely the fact that, for the most basic chemicals needed for life to emerge – hydrogen and oxygen – there most likely exists an extraterrestrial origin. The images showing the primordial soup boiling with chemicals ejected from early volcanoes on Earth is currently beginning to crumble. However, this also means that not only do the conditions of a solar system need to be taken into account when looking for extraterrestrial life, but also those of the galaxies that our telescopes are scanning in their search for other living things.