Magnetron

Magnetrons were devices used to transport massive objects, such as planets. The technology was possessed by both Daleks and Time Lords alike.

The Time Lords used a magnetron to transport the entire Sol system in what became known as the Ravolox affair. (DW: The Mysterious Planet, The Ultimate Foe) The Magnetron was later used to return the Sol system to its original location. (EDA: The Eight Doctors)

The Daleks used a magnetron to move 27 planetary bodies to the Medusa Cascade. The Tenth Doctor later used it to return all but one of them to their original locations. (DW: Journey's End)

The Daleks' version was evidently somewhat more advanced than the Time Lord version, which destroyed most of Earth's surface when it was used on the planet; by comparison, the Dalek version did no apparent damage at all to the planet. While it can be assumed that the Time Lord magnetron probably could have been used to transport objects through time as well as space, only the Dalek technology was explicitly shown to have a temporal aspect, as some of the stolen planets were taken from completely different moments in time. In an alternate timeline, the Daleks used a time vortex magnetron which would cause the human guerrillas who had travelled to the 20th century to be drawn to the Daleks' base the next time they used their time machine. By mistake, Jo Grant was drawn in instead. (DW: Day of the Daleks)

Behind the scenes

 * Magnetrons are, from which their use in Doctor Who can be reasonably extrapolated. Somewhat ironically, they are used in the transmission of television signals and are the source of power in microwave ovens. They allow for the quick production of a great deal of energy.