During the VEGA-1 encounter with comet Halley, the magnetometer observed draping and compression of the interplanetary magnetic field (IMF). These are reproduced well by a 3-D MHD simulation of the cometary interaction. Rotations in the magnetic field similar to those at closest approach are also observed 2.75 hours earlier. We suggest that both rotations correspond to the same IMF interval and that the spacecraft had overtaken the plasma and encountered ''older'' magnetic field as it penetrated the coma. Analysis of the MHD model indicates that it should take ~3 to 5 hours for a solar wind parcel to pass from the unperturbed solar wind to VEGA-1 at closest approach. A simulated magnetic field profile composed of nested sections for different IMF orientations closely resembles the observations. This result supports the hypothesis of layered magnetic orientations in the coma. ¿American Geophysical Union 1987