Residents of the Australian city of Brisbane were treated to spectacular red sunsets during 1991, all thanks to a volcano in the Philippines. The violent eruption of Mount Pinatubo, a volcano situated on Luzon Island, in the Philippines, sent a massive amount of volcanic ash into the air. A side effect of this massive amount of ash in the air and the upper atmosphere was that the ash reflects the light at sunset, causing marvelous red sunsets around much of the Southern Hemisphere.
A volcano is a point on the Earth's crust where magma from the Earth's mantle breaks through to the Earth's surface. The magma in the mantle can become so hot underneath the crust that it starts to melt the rock, allowing the magma to slowly rise through the crust to the surface. Hot gases trapped in the mantle can be released through these points, causing violent eruptions of magma, gas, and volcanic ash. Volcanoes are usually a cone-shaped mould, which is caused by the ash from previous eruptions solidifying around the point where the magma comes through.
Volcanoes can be extinct, meaning that no seismic activity has been recorded at the volcano for a significant period of time. However, this does not mean that the volcano will never erupt again - take the devastating eruption of Mount St Helens, in Washington, USA in 1980. The more recent Mount Pinatubo eruption of 1991 deposited ash over a wide area. Some of the ash fell on the hull of a Australian mining company's iron ore carrier, and samples of this ash were given away through an Australian science club for students.