The Earth as an extrasolar transiting planet: Earth's atmospheric composition and thickness revealed by Lunar eclipse observations

Abstract

An important goal within the quest for detecting an Earth-like extrasolar planet, will be to identify atmospheric gaseous bio-signatures. Observations of the light transmitted through the Earth's atmosphere, as for an extrasolar planet, will be the first step for future comparisons. We have completed observations of the Earth during a Lunar eclipse, a unique situation similar to that of a transiting planet. We aim at showing what species could be detected in its atmosphere at optical wavelengths, where a lot of photons are available in the masked stellar light. We present observations of the 2008 August 16 Moon eclipse performed with the SOPHIE spectrograph at the Observatoire de Haute-Provence. Locating the spectrograph fibers in the penumbra of the eclipse, the Moon irradiance is then a mix of direct, unabsorbed Sun light and solar light that has passed through the Earth's limb. This mixture essentially reproduces what is recorded during the transit of an extrasolar planet. We report here the clear detection of several Earth atmospheric compounds in the transmission spectra, such as ozone, molecular oxygen, and neutral sodium as well as molecular nitrogen and oxygen through the Rayleigh signature. Moreover, we present a method that allows us to derive the thickness of the atmosphere versus the wavelength for penumbra eclipse observations. We quantitatively evaluate the altitude at which the atmosphere becomes transparent for important species like molecular oxygen and ozone, two species thought to be tightly linked to the presence of life. The molecular detections presented here are an encouraging first attempt, necessary to better prepare for the future of extremely-large telescopes and transiting Earth-like planets. Instruments like SOPHIE will be mandatory when characterizing the atmospheres of transiting Earth-like planets from the ground and searching for bio-marker signatures.

15 pages, 14 figures, 2 tables. Accepted for publication in Astronomy and Astrophysics

References in corpus (7)

• Rayleigh scattering in the transit spectrum of HD 189733b
• HST/STIS Optical Transit Transmission Spectra of the hot-Jupiter HD209458b
• TiO and VO broad band absorption features in the optical spectrum of the atmosphere of the hot-Jupiter HD209458b
• Determining atmospheric conditions at the terminator of the hot-Jupiter HD209458b
• Rayleigh scattering by H2 in the extrasolar planet HD209458b
• A Spitzer Search for Water in the Transiting Exoplanet HD189733b
• Earthshine observation of vegetation and implication for life detection on other planets - A review of 2001 - 2006 works

Cited by in corpus (45)

• Spectrally resolved detection of sodium in the atmosphere of HD189733b with the HARPS spectrograph
• How to Characterize Habitable Worlds and Signs of Life
• Gran Telescopio Canarias OSIRIS Transiting Exoplanet Atmospheric Survey: Detection of potassium in XO-2b from narrowband spectrophotometry
• Atmospheric Rossiter-McLaughlin effect and transmission spectroscopy of WASP-121b with ESPRESSO
• Detectability of atmospheric features of Earth-like planets in the habitable zone around M dwarfs
• Impact of atmospheric refraction: How deeply can we probe exo-Earth's atmospheres during primary eclipse observations?
• Detection of sodium in the atmosphere of WASP-69b
• Titan solar occultation observations reveal transit spectra of a hazy world
• Glancing views of the Earth. From a lunar eclipse to an exoplanetary transit
• Search for water vapor in the high-resolution transmission spectrum of HD189733b in the visible
• The effect of the stellar absorption line centre-to-limb variation on exoplanet transmission spectrum observations
• Transmission spectrum of Earth as a transiting exoplanet - from the ultraviolet to the near-infrared
• The GAPS programme at TNG XXII. The GIARPS view of the extended helium atmosphere of HD189733 b accounting for stellar activity
• The atmosphere of HD 209458b seen with ESPRESSO. No detectable planetary absorptions at high resolution
• Transmission spectrum of Venus as a transiting exoplanet
• Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars
• High resolution transmission spectrum of the Earth's atmosphere -- Seeing Earth as an exoplanet using a lunar eclipse
• Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy
• High-resolution detection of neutral oxygen and non-LTE effects in the atmosphere of KELT-9b
• The centre-to-limb variations of solar Fraunhofer lines imprinted upon lunar eclipse spectra - Implications for exoplanet transit observations
• The GAPS Programme at TNG. XXXII. The revealing non-detection of metastable HeI in the atmosphere of the hot Jupiter WASP-80b
• Using the Rossiter-McLaughlin effect to observe the transmission spectrum of Earth's atmosphere
• Diagnosing aerosols in extrasolar giant planets with cross-correlation function of water bands
• The Transit Transmission Spectrum of a Cold Gas Giant Planet
• Stellar contributions to the line profiles of high-resolution transmission spectra of exoplanets
• The GAPS Programme at TNG XXXIII. HARPS-N detects multiple atomic species in emission from the dayside of KELT-20b
• The Earth as an extrasolar transiting planet - II: HARPS and UVES detection of water vapor, biogenic O${}_2$, and O${}_3$
• Refraction in planetary atmospheres: improved analytical expressions and comparison with a new ray-tracing algorithm
• Assessing telluric correction methods for Na detections with high-resolution exoplanet transmission spectroscopy
• The GAPS Programme with HARPS-N at TNG. XXXI. The WASP-33 system revisited with HARPS-N
• Applications of a Gaussian Process Framework for Modelling of High-Resolution Exoplanet Spectra
• High-Resolution Transmission Spectra of Earth through Geological Time
• Lowest Earth's atmosphere layers probed during a lunar eclipse
• The impact of the Kasatochi eruption on the Moon's illumination during the August 2008 lunar eclipse
• Characterization of exoplanetary atmospheres with SLOPpy
• The hidden depths of planetary atmospheres
• Trajectory Retrieval and Component Investigations of Southern Polar Stratosphere Based on High Resolution Spectroscopy of Totally Eclipsed Moon Surface
• A precise blue-optical transmission spectrum from the ground: Evidence for haze in the atmosphere of WASP-74b
• High-resolution spectroscopy and spectropolarimetry of the total lunar eclipse January 2019
• HORuS transmission spectroscopy and revised planetary parameters of KELT-7b
• Near-infrared Brightness of the Galilean Satellites Eclipsed in Jovian Shadow: A New Technique to Investigate Jovian Upper Atmosphere
• Doppler-Shifted Alkali D Absorption as Indirect Evidence for Exomoons
• The Hubble Space Telescope's near-UV and optical transmission spectrum of Earth as an exoplanet
• Observability of ultraviolet N I lines in the atmosphere of transiting Earth-like planets
• Polarized Transmission Spectrum of Earth as Observed during a Lunar Eclipse