# Sun in hydrogen alpha: Mercury transit, first contact

First contact: Mercury's disc just touching the solar limb at the lower left, a small bite taken out of the edge. In hydrogen alpha, the red line of hydrogen at 656.28 nm, with an active region at the right of the frame. The DayStar Quark passes half an angstrom or less of that line, narrow enough to show the chromosphere, the layer above the visible surface, instead of the surface itself. Photographed with a Skywatcher Esprit 100 at 550mm on an ASI174MM-COOL.

- **Category:** Solar
- **Equipment:** Skywatcher HEQ5 – Skywatcher Esprit 100 F/5.5 Triplet Super APO (550mm) – Daystar Quark Chromosphere HA – ASI174MM-COOL
- **Published:** 2026-08-21
- **Photographed:** 2026-08-21

![Sun in hydrogen alpha: Mercury transit, first contact](https://astro.observer/images/sun-in-hydrogen-alpha-mercury-transit-1st-contact-bottom-lef/sun-in-hydrogen-alpha-mercury-transit-1st-contact-bottom-lef-2400.jpg?v=229d2e1b13)

Prints and merchandise: https://www.redbubble.com/i/photographic-print/Mercury-Sun-transit-1st-contact-by-giancarloerra/21842054/zltf

Copyright Giancarlo Erra, all rights reserved. Licence: https://astro.observer/licence/

Previous: https://astro.observer/image/sun-mercury-transit-mosaic-in-hydrogen-alpha/
Next: https://astro.observer/image/sun-in-hydrogen-alpha-mercury-transit-1/
Gallery: https://astro.observer/