Habitat in Space

Potsdam, 12 August 2003

What would happen if we were to relocate the Earth into another planetary system? Would life still be possible? In the planetary system of 47 Ursae Majoris, which shows strong similarities to our own solar system, there is in fact a habitable zone. These findings were published in the recent issue of the International Journal of Astrobiology by scientists from the Potsdam Institute for Climate Impact Research and the University of Texas.

Siegfried Franck, Werner von Bloh and Christine Bounama of the Potsdam-Institute for Climate Impact Research (PIK), and Manfred Cuntz of the University of Texas at Arlington, examined the planetary system 47 Ursae Majoris (UMa). This system is located approximately 45 light-years from Earth, in the constellation of the Great Bear (Ursae Majoris), and contains a solar-mass central star.

So far, two giant planets, comparable to Jupiter and Saturn, have been discovered in this system. They play an important role, as they shield the inner realm of the planetary system from the impacts of comets and asteroids. Such giant planets, however, can also disturb the orbits of other planets.

The scientists looked at the following problem: In order to be located in the so-called habitable zone, an Earth-like planet in the system 47 UMa has to orbit its central star in a suitable distance. Habitable means that photosynthesis-based life forms can exist on the surface of the planet. Additionally, the orbit of such a planet must remain stable over a long period of time.

The scientists discovered that the chances for a habitable planet are especially good if the planet's surface is covered to a significant extent by water. Such planets are referred to as waterworlds. If it were located within System 47 UMa, the Earth - a waterworld by virtue of its 2/3 surface covered by water - would, at 1.2 times the distance Earth-Sun to its central star, be able to exist in a stable orbit in the habitable zone for several billions of years. These findings have brought scientists a step closer to finding an Earth twin within the Milky Way.

The Potsdam Institute for Climate Impact Research (PIK) was founded in 1992 and employs 121 scientists. Its research on climate change, climate impacts and sustainable development is of international renown. PIK is a member of the Leibniz Association.

Prof. Dr. Siegfried Franck, siegfried.franck@pik-potsdam.de, Tel. +49/331/288-2659
Dr. Werner von Bloh, werner.von.bloh@pik-potsdam.de, Tel. +49/331/288-2603
Christine Bounama, christine.bounama@pik-potsdam.de, Tel. +49/331/288-2659

Press office:
Anja Wirsing, anja.wirsing@pik-potsdam.de, Tel. +49/331/288-2507

Original article:
S. Franck, M. Cuntz, W. von Bloh and C. Bounama (2003): The habitable zone of Earth-mass planets around 47 UMa: results for land and water worlds. International Journal of Astrobiology 2 (1), 35-39.

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