What if half the earth disappeared?

Jupiter alone stabilizes the axis of rotation of our planet - a large moon can even have a destabilizing effect

Moscow (USA) - Without the moon, no higher forms of life would have been able to develop on earth because it keeps the axis of rotation and thus the climate stable - this was previously thought. But computer simulations paint a different picture. The giant planet Jupiter alone provides a sufficiently stable axis of rotation for our planet, so that the development of complex life forms became possible. As the scientists' calculations show, a large moon can even have an unfavorable effect on an earth-like planet.

"A moon can have a stabilizing or destabilizing effect, depending on what is going on in the rest of a planetary system," explains Jason Barnes from the University of Idaho, one of the three researchers involved, in "Astrobiology Magazine". If, for example, Jupiter were to circle the sun closer to the earth, the great satellite could counteract the stabilizing effect of the giant planet and lead to violent fluctuations in the inclination angle of the earth's axis - with correspondingly dramatic effects on the earth's climate.

The Earth's axis is currently inclined by 23.44 degrees, this angle has only fluctuated by about one degree over the course of decades. Without this stability, complex life would presumably not have developed on our planet. So far, the researchers have assumed that the gravitational pull of our comparatively large moon stabilizes the earth's axis - without the earth's satellite, according to the thesis, the earth's axis could even tilt by up to 80 degrees. The simulations by Barnes and his colleagues now show that this is not the case: the gravitational pull of the giant planet Jupiter alone ensures that the Earth's axis does not fluctuate by more than ten to twenty degrees over the course of half a billion years. This still leads to serious climatic variations, but "should not exclude the development of intelligent life," said Barnes.

According to the scientists, this also increases the chance of intelligent life on planets near other stars. If only one large moon were necessary to stabilize the rotation of an earth-like planet, then only about one percent of these celestial bodies would offer a sufficiently stable climate for the development of complex life forms. The results of the simulations by Barnes and his colleagues now increase this value to 75 percent.