The maximum size of any SMS message is 160 characters for Latin alphabets and 70 characters for non-Latin alphabets like Chinese and Arabic.
Many phones support texting of more than 160 characters. A message consisting of more than this number of characters is simply split up into more than one message. If the recipient has a "long message" feature on his cell phone, the cell phone will join the messages and display them as one. Otherwise, they are received as separate texts
A wild guess about Androids apparent 159 character limit is that either it's an "off-by-one" bug and/or the 160th character is being used to hold the message length.