Pecker was the President of the Société astronomique de France (SAF), the French amateur astronomical society, from 1973–1976.

[3] Pecker was a vocal opponent of astrology and pseudo-science[4][5] and was the president of the Association française pour l'information scientifique (AFIS), a skeptical organisation which promotes scientific enquiry in the face of quackery and obscurantism.

[6] The grandson of Joseph Hermann, rabbi of Valenciennes and later Reims, Pecker was born in his maternal grandparents' house, moving later to Bordeaux.

[7] In May 1944 both his parents were transported to Auschwitz where they died, while his grandmother, absent during the raid, was hidden by neighbour Ida Barrett who was later designated by the state of Israel as one of the Righteous Among the Nations for her actions to conceal the old lady until the liberation of Paris.

From early in his career he held many international appointments including fellow of the High Altitude Observatory in Colorado, USA.

He was also known for questioning the standard big bang theory, positing "alternative but partial solutions" (a quasi-static model)[5] and was signatory, with 33 other scientists, to an open letter to the scientific community expressing concern over the dominance of the big bang and expansion of the Universe theories.

[12] In the 1950s Pecker spent a year as associate fellow of the High Altitude Observatory at Boulder, Colorado.

[16] Pecker wrote and co-wrote many books and over 700 academic papers on subjects such as cosmology, astronomy, astrophysics, human rights, pseudo-science, poetry and art.

Pecker spoke out against the governments punitive immigration laws, publicly supporting the National Coordination of Sans Papiers (CNSP) organisation.