Tycho and others had observed the supernova of 1572. Ottavio Brenzoni's letter of 15 January 1605 to Galileo brought the 1572 supernova and the less bright nova of 1601 to Galileo's notice. Galileo observed and discussed Kepler's supernova in 1604. Since these new stars displayed no detectable diurnal parallax, Galileo concluded that they were distant stars, and, therefore, disproved the Aristotelian belief in the immutability of the heavens.
The failed Gunpowder Plot of 1605 was a conspiracy among a group of Roman Catholic gentry to re-establish Catholicism in England by assassinating the Protestant King James I and replacing him with a Catholic monarch. To this end, they placed large quantities of gunpowder beneath the House of Lords, which one of the conspirators, Guy Fawkes, would detonate during the State Opening of Parliament on 5 November 1605.
The medieval House of Lords chamber, which had been the target of the failed Gunpowder Plot of 1605, was demolished as part of this work in order to create a new Royal Gallery and ceremonial entrance at the southern end of the palace.