We've now learned that our Sun is a Yellow Dwarf,
after it burns for 10 billion years it will turn into a Red Giant,
and after it burns for another 1 billion years it will turn into a White Dwarf.
That white dwarf will burn slowly for a very very long time,
over 10 Undecillion years (One undecillion is a 1 with 36 zeroes after it!),
then it will cool down and turn into a Black Dwarf.
That's such a long time, that no actual black dwarfs exist!
Scientists are just pretty sure that's what is going to happen some day.
(from: wikipedia - outer space)