Here's what erupts from Io:

* Lava flows: Io has hundreds of volcanoes, and the most common eruption is molten rock, or lava, flowing from these volcanoes. The lava is extremely hot, reaching temperatures of over 1700° Celsius (3100° Fahrenheit).

* Sulphur dioxide gas: The eruptions also release vast amounts of sulphur dioxide gas, which creates a huge plume that can stretch thousands of kilometers into space. This gas is what gives Io its distinctive yellow color.

* Other materials: Besides lava and gas, eruptions can also release other materials like sulfur, sodium, and potassium.

Io is the most volcanically active body in our solar system, due to its unique position and the gravitational pull of Jupiter. This constant volcanic activity creates a dramatic and constantly changing landscape on the moon.