Mr Lemaître proposed on theoretical grounds the universe was expanding, which was later confirmed observationally by Edwin Hubble, in what is known as Hubble’s Law.
He is also acknowledged with proposing the concept the universe expanded from an initial point, which he called the “primeval atom” or “the Cosmic Egg, exploding at the moment of the creation”.
His theory was presented in one of his academic papers in 1931, and is now widely accepted and known as the “Big Bang” theory.
The astronomer and professor was born on July 17, 1894, in Charleroi, Belgium, and began studying civil engineering at the Catholic University of Leuven at the age of 17.
His academic studies were interrupted when he signed up to serve as an artillery officer in the Belgian army during World War One.
Following the conflict he studied physics and maths at university along with preparing for the diocesan priesthood.
He completed his doctorate in 1920 and was ordained as a priest in 1923.
He became a post-graduate student in astronomy at the University of Cambridge in 1923, before spending the following year at Harvard College Observatory in the US.
Mr Lemaître returned to Belgium in 1925 and became a part-time lecturer at the Catholic University of Leuven, where he started to work on his groundbreaking research.
He published his cutting-edge theory that the universe was expanding in his famed report in 1927, but it did not specifically link to the notion of the Big Bang theory.
He later suggested the universe had expanded from a single point, which he referred to as the “Primeval Atom”.
In 1933 Mr Lemaître attended a series of seminars at the California Institute of Technology along with world-renowned scientists including Albert Einstein.
After outlining his theory of the universe’s creation to the scientist, Mr Einstein is reported to have said: “This is the most beautiful and satisfactory explanation of creation to which I have ever listened.”
Mr Lemaître received a number of accolades during his life, including the Prix Jules Janssen in 1936, the highest award from the French astronomical society.
He was also elected a member of the Royal Academy of Sciences and Arts of Belgium in 1941, and was awarded the Eddington Medal from the Royal Astronomical Society in 1953.
Pope Pius XII declared in 1951 that Lemaître’s theories offered a scientific validation for Catholicism, which Lemaître himself strongly rejected.
He claimed his theory was neutral and refused to acknowledge whether there was a connection between religion and his research.
Mr Lemaître died on 20 June 1966 at the age of 71.