Planes across parts of Europe have been grounded because of a huge cloud of ash in the atmosphere, caused by an erupting volcano in Iceland.
Check out our volcano info by clicking on the questions below...
Where does the volcanic ash come from?
Why is there so much ash coming from this volcano?
Has this volcano erupted before?
Is this eruption one of the biggest we've ever seen?
Why does the volcanic ash in the atmosphere mean that planes can't fly?
Is the ash dangerous to humans?
What is the ash made up of?
Why is the ash plume still rising?
When will it stop?
The volcanic ash comes from an erupting volcano in Iceland.
Clouds of ash are lifted into the sky by huge plumes of steam that come from the eruption.
It began on 20 March this year and it's forced around 500 people in the area to evacuate their homes.
This eruption has produced a lot of ash, and that's because it's happening underneath a massive glacier.
Dr Matthew Roberts who works at the Met Office in Iceland said: "It's the interaction between the molten rock, the magma and the glacial ice which is causing the magma to cool very quickly and turn into tiny fragments of rock."
Experts say the last time this particular volcano erupted was between December 1821 and January 1823.
We don't know how long the cloud of ash stayed around back then.
No, not at all.
It's pretty small when it's compared to other eruptions, but because it's happened in Europe which is a very busy airspace, it's caused lots of disruption.
Volcanic ash can clog up and damage jet engines when it gets inside. The glass in the ash can also melt and block the ventilation holes.
It means the engines can overheat and stop working.
Even though the ash is very fine, it can also damage the windscreen of an aeroplane.
The decision to close British airspace was because the ash cloud was travelling at the same sort of height that planes cruise at.
For most people, the ash will not be dangerous at all.
Sometimes fine ash can affect for people who have breathing difficulties like asthma or lung diseases.
But in the UK it's not likely to be a problem, because such a small amount is falling down.
If it did settle on the ground, the best thing to do is leave it and not scuffle it around. That way you're less likely to breath it in.
The ash is not like ash from a bonfire. It's actually made up of tiny pieces of rock, glass and sand.
The ash plume rises because of steam pushing it up into the sky.
It comes from all the ice in the glacier above the eruption melting and turning into steam.
Experts reckon there must be more water going into the volcano and that's why the ash cloud keeps rising.
Volcanologists (the experts who study volcanoes) have said it's impossible to predict when the eruptions might stop.
They did say that the eruptions could go on for months in Iceland, but that doesn't necessarily mean that planes will be grounded for that long.