Science Advances, the researchers discussed how rocky planets might have formed from small water-bearing dust particles that could give rise to the formation of oceans and continents. How water emerges on planets Scientists are still trying to figure out how water emerged on Earth. One of the prominent theories points to water-bearing comets or icy asteroids that slammed the planet in its infancy. But the researchers are calling that theory into question, positing that water has been present since a planet’s birth. This is true not only for Earth but also for Venus, Mars and many other rocky planets in the galaxy.