What do you call the pieces of rock and debris that are carried within lava and propelled through the air during an eruption?

What is a reasonable action that provides safe water for communities?

Suggest two reasons why irrigation is important for human development of the desert

One of the brightest comets of the 20th century was comet hyakutake, which passed close to the sun in early 1996. the orbital period of this comet is estimated to be about 30,000 years. find the semi-major axis of this comet’s orbit. compare it to the average sun-pluto distance and to the distance to alpha centauri, the nearest star to the sun, which is 4.3 light-years distant.