October 22, 2004

H-Alpha Moon

Image Credit: Frank Barrett

H-Alpha Moon Most images of the Moon are taken in visible light, which is where human eyes are most sensitive. But here (right) is one taken through a hydrogen-alpha filter which is normally used to image the Sun in a narrow red part (656.3 nm) of the visible spectrum. I compare this image to Frank's previous LPOD (and APOD!) image on the left which was taken in visible light. I enhanced both images, making comparison a little uncertain. Nevertheless, there are a few interesting comparisons. first, the two images look quite similar - probably because the Sun is quite bright at H-alpha wavelengths, contributing significantly to its total visible brightness. Second, there are some differences. In H-alpha, Mare Nectaris is more muted - the rays that cross it are more strongly depicted. The same seems true for maria Fecunditatis and Crisium - both are low in titanium. Additionally, the dark mare patches south of Mare Serenitatis have more contrast on the H-alpha image. Frank's image suggests that amateurs may want to experiment imaging the Moon thru different color filters to explore compositional differences in the maria. — Chuck Wood Technical Details: Right image: Sept 25, 2004. Orion 80 mm ED + SBIG ST7E camera + Schuler 10nm H-alpha filter. Mosaic of two 110 ms exposures. CAW ehhanced with unsharp mask. Left image: Dec 9, 2003. Celestron C8 SCT with a SBIG ST-7E ccd camera and an Orion Moon Filter to capture 18 frames at 110 ms each which were mosaicked into this image. Related Links: Frank's Celestial Wonders Yesterday's LPOD: 60 of Tycho Tomorrow's LPOD: Imaging the First Lunar Photographer

Author & Editor: Charles A. Wood COMMENTS? Register, Log in, and join in the comments.