The vastness of the sky within everyone’s reach… this is the promise of a moment with one of the greatest space scientists, astronomer and planetologist at the Côte d’Azur Observatory, and holder of the “Planetary Formation” chair at the Collège de France: Alessandro Morbidelli. Do we know, today, how planets are formed?We are starting to have ideas, but obviously, the models are never perfect. So, we have known since Laplace, in the 19th century, that when a star forms, it is surrounded by signs of gas and dust. Laplace had deduced it, today when we look at young stars, they are all surrounded by these disks”, he explains.
“In these disks of gas and dust, the dust begins to aggregate by electrostatic force to form larger dust which interacts with the gases, forming lumps. These lumps are held by gravitation, so they form small bodies called planetesimals, a bit like asteroids or comets“, and these bodies collide with each other.
Life elsewhere than on Earth, “imaginable that it does not exist”
While today some people are considering going into space to look for materials on other planets that would be rare on Earth, Alessandro Morbidelli says he does not believe in this option.We talk a lot about “space mining” to recover minerals that are rare on Earth, but they are also rare elsewhere or are widely dispersed elsewhere. It’s not El Dorado“, he judges. “The Moon, certainly not, because it has an even more depleted soil than the Earth in the elements that interest us”, even if certain elements like helium could serve as fuel. “But using resources in space for our daily lives, I really don’t believe in that.“.
What about life elsewhere than on Earth? “It is unimaginable that life appeared only on Earth. There are 100 billion stars in the galaxy, there are 100 billion galaxies in the universe, we would not think that the only place in the entire universe with such a number of stars and galaxies is the Earth !“
