Astronomers have used the Hubble Space Telescope to work out when our Galaxy, The Milky Way, will collide with its neighbour Andromeda.
The pair are being pulled together by mutual gravity and the new measurements show they will start to merge in about four billion years.
A further two billion years on and they will appear as a single entity, the BBC reports.
Our Sun's position will be disturbed but the star and its planets are in little danger of being destroyed.
Viewed from Earth, however, the night sky should look fairly spectacular. That is assuming, of course, that a human species is still around billions of years into the future to look upwards.
"Today, the Andromeda Galaxy appears to us on the sky as a small fuzzy object that was first seen by ancient astronomers more than one thousand years ago," lead researcher Roeland van der Marel from the Space Telescope Science Institute in Baltimore in the United States said.
"Few things fascinate humans more than to know what our cosmic destiny and future fate will be. The fact that we can predict that this small fuzzy object will one day come to engulf and enshroud our Sun and Solar System is a truly remarkable and fascinating finding," Dr Van der Marel said.