Jef Ongena lecture on Georgens Lemaître

Jef Ongena's lecture on Georges Lemaître sheds a clear light on the origins of the Big Bang theory. He explains how the Belgian priest and astronomer was the first to realize that the universe is not static, but constantly expanding from a primeval atom. In doing so, Ongena corrects the historical narrative in which Edwin Hubble often receives all the credit for this discovery. During his presentation, he clarifies how Lemaître kept science and faith strictly separate to protect the integrity of both fields. The speaker further connects these historical insights with modern astronomical observations of cosmic background radiation. The result is a compelling account of intellectual courage and the Belgian contribution to our fundamental knowledge of the cosmos. Thanks to Ongena's accessible style, this complex subject becomes understandable for a broad audience. This ensures that Lemaître's legacy remains alive in contemporary scientific discussions about the beginning of everything.

Selfie with Jef Ongena

Some references:

The difference between f/1.8 and f/3.5

Since a couple of months I own a Sigma 18-35mm f/1.8 lens. I know this lens captures more light but how much more and what about comparing with my Nikon 18-200mm f/3.5-5.6 lens.

I captured the same scene with same settings:

- Nikon D7500

- Exposure time 1.3s

- ISO 800

The difference, which is significantly can be seen in the picture below.

The Sigma lens f/1.8 captures 4 time more light as my Nikon 18-200mm lens on 18mm f/3.5.

So f/numbers do matter :)

Comet C/2025 R3 (PanSTARRS)

It was a very early start this morning. I got up at 4:30 AM and hopped on my bike, heading inland in search of darker skies. About 4 km from the Nieuwpoort coast, I found a clear view of the eastern horizon. After setting up my gear, the waiting game for the comet to rise began. By 5:30 AM, an orange-red glow started to creep over the horizon.

I couldn't spot the comet with the naked eye, or even on my camera screen, so it was a bit of a gamble whether I’d captured it—especially with those high clouds lingering near the horizon. Back at the apartment, after some post-processing, I finally saw it: Comet C/2025 R3 (PanSTARRS). There’s even a small tail visible!

At the moment of capturing, the Comet was about 7° above the horizon.

Venus - Moon

Venus and Moon at Nieuwpoort (B) with Nikon D7500 and 18-35mm Sigma f/1.8 lens.

Venus during blue hour

Image of Venus above the North sea @ Nieuwpoort at the end of the Blue hour. When editing my picture I found a couple of issues. First, the aperture was still set on the Sun (f/29) and my lens is really dirty.

Belgium's Lost Solar System: a tour around Belgoum and now completed with Neptune

See my previous blogpost back in January 4th 2019.
In this blogpost I gave an overview of the sun and planets located in Belgium at a scale of  1 to 40 million.

I found the entire solarsystem around Belgium: 

- Sun in Oudergem

- Mercury in Oudergem

- Venus in Watermaal Bosvoorde

- Earth and Moon in Uccle

- Mars in Hoeiilaart

- Jupiter in Kempenhout

- Saturn in Gembloux

- Uranus in Tongeren

- Neptune was missing in Oostende

- Pluto in Florenville

Finally this year, the statue of Neptune showed up again. Before it was installad at the seashore of Oosternde, now it is installed at Astropolis, Space Science Center of Oostende.

This morning I was in Oostende and made a detour to visit the statue. And finally, yes, I could finish my Belgium tour around the sun and planets.

H-alpha and FeI(c) with Solex

Two images using my Sol'Ex of H-alpha and FeI(c).