clear since the middle of the 1970’s
that – in addition to the shining stars and the interstellar
matter – there is also a dark component which perhaps contributes
ten times as much to the total mass of the spiral galaxies as
the stars and the interstellar medium. This Dark Matter is only
noticeable because of its gravitational effect. According to present
models, it is supposed to be located in an extended halo surrounding
the galaxy in the shape of a sphere.
The puzzle of Dark Matter is currently one
of the central subjects of astrophysics. With the help of the
MAGIC infrared camera, a programme is running on the 2.2 metre
telescope at Calar Alto to search for celestial bodies of extremely
weak luminosity in the halos of spiral galaxies. At the same time,
the theoretical group of the MPIA is carrying out numerical calculations
which may provide insight into the spatial distribution and nature
of the matter (Chapter IV.2).
The Solar System
The solar system
is not among the primary subjects dealt with at the MPIA. Only
the zodiacal light has been the subject of detailed studies since
the very beginning. The zodiacal light owes its origins to a fine
dust component which is distributed throughout the entire planetary
system. Thanks to ISOPHOT, it has now become possible to examine
this interplanetary dust at wavelengths of about 200 mm for the
first time. This allows some conclusions to be drawn about the
composition and size of these particles.
However, when important current events have
taken place within the solar system, the telescopes on Calar Alto
have been able to demonstrate their capabilities time and time
again. In 1997, Comet Hale-Bopp was the focus of a great deal
of attention on the part of the public. With the Schmidt telescope
on Calar Alto, it was possible to obtain detailed photographs
showing the rare phenomenon of the striae (Chapter IV.3).