250.000 Visitors on my Blog - Thank You

Today, my blog reached 250K visitors. Thanks for reading my blogposts.

Release of Solar book by Christian Buil and Valerie Desnoux

Christian Buil and Valerie Desnoux will publish shortly a book on how to observe the Sun with a spectroheliograph. 

Selfie with Valerie and Christian

 

Solar Observation Indices: White Light vs. H-alpha

 

I was inspired by the VVS Solar Working group organised last Sunday, March 8, 2026 on the determination of H-Alpha activity on the Sun using indices. Going through some of my books like "Die Sonne beobachten" from Beck and Völker (see aswell link to my books) and a couple of websites I made following list on potential use of H-alpha indices. I made a reference towards white light observation.

Corona

The corona is the outermost layer of the solar atmosphere, consisting of extremely tenuous and very hot plasma.

- Plasma: H⁺ and e⁻
- Follows magnetic structures
- Temperature anomaly:
        - Magnetic reconnection provides the basic heating

        - Alfvén waves (wave heating) transport energy further out into space
- Radiation spectrum: X-rays (RX), EUV, and white light due to electron scattering
- Density: ~10⁻¹² of the photosphere
- Charged particles escape from the corona and move through our solar system as the solar wind.

We can destiguish different regions:

E Corona (L Corona – Line Corona)
Emission from highly ionized metals (Fe XIV, Ni XII, Ni XIII, Ca XV).
Ionization occurs at t = 2 million K.

K Corona
Thomson scattering by high-energy electrons.
The scattering does not affect the wavelength itself, but the electrons’ velocities cause a Doppler effect, which smears out the wavelengths and thus forms a continuous spectrum (continuum).

F Corona
Caused by dust that scatters photospheric light.
No change to the spectrum shape, and it shows an absorption spectrum; hence the Fraunhofer-line spectrum.

MoonSwatch - Omega Speedmaster Mission to Earthphase Moonshine Gold

Not only I was interesested in the Speedmaster as a Moonwactch but also the fact the MoonSwatch shows the phases of the Moon. And in the case of the MoonSwatch Mission to Earthphase, the watch shows aswell the phase ot the Earth from the Moon. At the 10 o’clock position, the earth phase indicator shows the Earth with oceans that glow blue under UV light. Beneath the earth phase indicator is an illustration of Snoopy and Woodstock on the Moon, marveling at the enchanting spectacle of Earth. The illustration showcases a phrase that appears only under UV light. At the 2 o’clock subdial, is a moon phase indicator with two radiant full moons, both coated with OMEGA’s Moonshine™ Gold. One of the moons is designed in the distinctive style of the world of Snoopy, while the other features a unique snowflake design. The design is unique for every model, ensuring that, just like snowflakes in nature, no two timepieces are ever the same.

I bought the watch last week in Brussels, together with my daughter.

Differential velocity - H-beta - JSolex

 

Differential Velocity of the Sun - JSolex 4.5 release

With the release of JSolex 4.5, it's now possible to calculate the differential velocity of the sun's disk using doppler effect of H-alpha.

I used some of my better Sol'Ex images and the result is very good compared with the theoretical one.