Gravitation experiments during the total solar eclipse

The variations of the apparent vertical direction of the gravity field were measured with horizontal gravimeters acting as tilt meters during the total solar eclipse in Turkey in March 29, 2006. Three separated locations within the path of totality were chosen for observations, two spaced apart along the center line, and one off the center line. No anomaly was observed at the furthest location from the center line. Aperiodic oscillations in tilt were recorded at the two locations on the center line. These may be related to the eclipse phenomenon. The average tilt amplitude deviation during the eclipse over all locations and in all directions was 150 nrad, which can be regarded as a mean upper limit for the eclipse related changes in the tilt.

Figure 1

The structure of the magnetically coupled double pendulum. If there is no horizontal gravitation component, the pendulums are in a vertical position (left figure). A small horizontal gravitation component produces large deflection (right figure).

Figure 2

The tilt angles of $x$- and $y$-gravimeters without any trend removing as a function of time at the location III. The first and fourth contacts of the solar eclipse are marked with thick dashed lines and the moment of totality with a thin dashed line. There are short gaps in the data because the data recording was stopped when the batteries were replaced and the devices were started again. The data segments were carefully pieced together and the gaps were linearly interpolated in order to maintain a synchronous time line.

Figure 3

The tilt angles of $x$- and $y$-gravimeters in all three locations as a function of time after removing slow drifts. The first and fourth contacts of the solar eclipse are marked with thick dashed lines and the moment of totality with a thin dashed line. The EQ1 and EQ2 mark two earthquakes.

Figure 4

The ambient pressure and temperature, the magnetic field in $x$- and $y$-directions, and the tilt angles of the $x$- and $y$-gravimeters as a function of time at the location II. The first and fourth contacts of the solar eclipse are marked with thick dashed lines and the moment of totality with a thin dashed line.

Figure 5

Same as Fig. 3 but at the location III.