This is a monochrome image of the Rosette Nebula (NGC 2237), captured using a narrow-band filter that only passes light centered on the wavelength of Hydrogen Alpha (about 656 nanometer wavelength). Hydrogen is by far the most abundant element in the universe and light at Hydrogen Alpha wavelengths is the the brightest visible light encountered in astrophotography.

The Rosette Nebula is part of the Milky Way galaxy and is a rich star-forming region located about 5200 light-years from Earth. Radiation from the young stars in this region excites the gas in the nebula and causes it to glow.

Capture details:

5 x 1200s Ha,
William Optics Megrez 90FD / Hutech 0.85x field flattener / SBIG ST-8300M
Astro-Physics 900GTO
Processed with CCDStack and Photoshop