Birthdays in Heaven

Today is my mom's birthday. She would be 65. She really liked birthdays, because it was a milestone for another year that she was still with us. Do you think they celebrate birthdays in Heaven? Did Jesus just have his 2005th birthday? If Jesus was born on December 25, was that 1 AD, or 1 BC? Shouldn't Jesus' birthday actually be on January 1st?

Happy Birthday Mom, I miss you.