Earth’s atmosphere’s lowest layers probed during a lunar eclipse

PASJ: Publications of the Astronomical Society of Japan

Hirano, Teruyuki¹  Narita, Norio²  Yamashita, Takuya³  Kawauchi, Kiyoe⁴  Nakamoto, Taishi⁴  Kawashima, Yui⁴  Tamura, Motohide⁵  Sato, Bun’ei⁶ 

[1] Astrobiology Center, NINS, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-0033, Japan;Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan;Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan;National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

关键词: eclipses;    Earth;    planets and satellites: atmospheres;   

DOI  :  10.1093/pasj/psy079

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We report the results of detailed investigation of the Earth’s transmission spectra during the lunar eclipse on UT 2011 December 10. The spectra were taken by using the High Dispersion Spectrograph (HDS) mounted on the Subaru 8.2 m telescope with unprecedented resolution in both time and wavelength (300 s exposure time in umbra and 160000 spectral resolution, respectively). In our penumbra and umbra data, we detected the individual absorption lines of |$\rm O_2$| and |$\rm H_2O$| in transmission spectra and found that they became deeper as the eclipse became deeper. This indicates that the sunlight reaching the Moon passed through lower layers of the Earth’s atmosphere with time, because we monitored a given point on the Moon during the full eclipse duration. From the comparison between the observed and theoretically constructed transmission spectra, the lowest altitude at which the sunlight actually passed through the atmosphere is estimated to be about 10 km from the ground, which suggests the existence of sunlight-blocking clouds below that altitude. Our result can be a test case for future investigations of the atmospheric structure of Earth-like exoplanets via transmission spectroscopy including the refraction effect of the planetary atmosphere.

【 授权许可】

CC BY