Atmospheric Dust Causes Darkness to Fall Rapidly on Mars
Abstract
On mission sol 783 (at Martian solar longitude (LS) of 217°), Mars Science Laboratory's MastCam instrument imaged a faint glow, extending upwards from the horizon (Figure 1(a)). The images were acquired from 18:58 to 19:01 LTST, nearly an hour after sunset occurred at 18:05 LTST, providing an opportunity to examine illumination in the Martian sky around sunset. The radiance of the observed glow is small when compared to daytime sky brightness values, with an average value between 20 and 35 μW m-2 Sr-1, and appears brightest in the blue filter (the average B/R ratio is 1.25). The total flux at the time of the measurement was calculated to be 4.2 × 10-4 W m-2, nearly three orders of magnitude dimmer than what would be expected for an Earth-like Atmosphere. An observer on the surface of Mars would thus find twilight becoming deeper much more rapidly than on the Earth.
- Publication:
-
Research Notes of the American Astronomical Society
- Pub Date:
- November 2020
- DOI:
- 10.3847/2515-5172/abc6ae
- Bibcode:
- 2020RNAAS...4..196K
- Keywords:
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- Mars;
- Planetary atmospheres;
- Optical observation;
- Twilight;
- 1007;
- 1244;
- 1169;
- 1722