Luke 21:25-27

Luke 21:25-27

[25] And  signs  in  the sun,  and  in the moon,  and  in the stars;  and  upon  the earth  distress  of nations,  with  perplexity;  the sea  and  the waves  [26] Men's  hearts failing them  for  fear,  and  for looking after  those things which are coming on  the earth:  for  the powers  of heaven  shall be shaken.  [27] And  then  the Son  of man  coming  in  a cloud  with  power  and  great  glory. 

What is the context of Luke 21:25-27?