April 14/15, 2023 – “(Our) Key moments in AGN research”

An informal, festive mini-symposium celebrating Peter Barthel’s 70th birthday, held April 14-15, 2023, in Groningen.

Peter Barthel was appointed full professor at the Kapteyn Institute in 2004 and Rector of the University of Groningen Pre-university Academy upon its start in 2005. He formally retired in December 2018. On that occasion, he organized a special concert in the large Oosterpoort concert hall, by the student symphony orchestra Mira, for his friends and many university colleagues. He expressed the wish to celebrate his 70th birthday during a festive event in Groningen in April 2023 with a group of invited long-time astronomer friends from all over the world, as well as with interested astronomy colleagues from Groningen and other Dutch institutes. That event, under the title “(Our) key moments in AGN research”, was indeed festive and memorable; the group photograph, taken on the Academieplein, is shown below.

Kapteyn mural and animation

As part of a series of murals devoted to famous Groningen professors, Barthel and colleagues realized an artistic mural for astronomer J.C. Kapteyn (1851-1922), founder of the Groningen Kapteyn Institute. In addition they produced an on-line animation for children on the life and works of Kapteyn; it can be viewed here.

Earth Day 2023

In april 2023, Peter Barthel initiated a project for elementary school children, around the famous image of earth made by the NASA/ESA Cassini mission in 2013. Goal of the project is to educate children about Earth Day (April 22). Three short films were produced, together with Joanna Holt and Marieke Baan of the national astronomy research school NOVA, popular biologist Freek Vonk, and filmer Koen de Koning. The films are essential elements of a lesson about our unique planet, produced and distributed by the national Dutch on-line education platform Nieuwsbegrip. A Challenge, part of the project, was won by the Brederoschool in Groningen.

All information can be found on

Astronomical photographs

Together with his former colleague Mark Neeser, Peter Barthel produced several well-known astronomical photographs, using multi-band exposures with the FORS Camera of ESO’s Very Large Telescope. Three of these appeared together in ESO’s web release Three Dusty Beauties, whereas another one – the Sombrero Galaxy, Messier 104 –  features in the top page of the website you are currently reading. The relevant web release is Fine Shades of a Sombrero. Several of these VLT images appeared as NASA’s APOD, Astronomy Picture of the day, such as Messier66.

The Bethlehem Star

At the occasion of the 4th centenary of Groningen University in 2014, Peter Barthel and his colleague George van Kooten organized the first ever interdisciplinary international scientific conference on Matthew’s story of the Star of Bethlehem and the Magi. The resulting book was published by Brill, and is available as (600-page) hardback and paperback.


Together with his Groningen team Peter Barthel won the 2007-08 national Academische Jaarprijs for science communication, for their project “Discover the invisible universe”, explaining infrared radiation and infrared astronomy to school children and the public-at-large.

In 2014 Barthel won the national Willem de Graafprijs for his efforts in astronomy outreach and education.

On God

Summarizing the views which he developed through many years of publicly discussing the relation between science and religion, and motivated by a question of a 7-year old elementary school pupil, Peter Barthel published his short, unique booklet “Professor, bestaat God?” (“Professor, does God exist?”) in 2017. Its fourth edition appeared in September 2023, and the English version is awaiting a publisher. Reviews can be found here.


Barthel formally retired at the end of 2018, but he plans to continue working part-time.

A festive retirement concert took place in December 2018, in the Groningen Oosterpoort concert hall. The Groningen student symphony orchestra Mira, conducted by Pieter Bosma, played the Academic Fest Ouverture by Brahms, Tchaikovsky’s first piano concerto (with soloist Martin Oei) and Dvorak’s 7th symphony (picture: Elmer Spaargaren).