<Tr> <Td> purple </Td> <Td> Norma and Outer arm (Along with extension discovered in 2004) </Td> </Tr> <Tr> <Td> green </Td> <Td> Scutum--Centaurus Arm </Td> </Tr> <Tr> <Td> pink </Td> <Td> Carina--Sagittarius Arm </Td> </Tr> <Tr> <Td_colspan="2"> There are at least two smaller arms or spurs, including: </Td> </Tr>

Where are gas and dust found in the milky way