Astronomical searches for Earth-like planets and signs of life

Neville Woolf, J Roger P Angel

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

If Earth-like planets orbit nearby stars, they could be detectable with specially designed telescopes. Direct observations would be very revealing, particularly low resolution infrared spectra, which could establish habitability on the basis of temperature and atmospheric water. Abundant, primitive life based on organized molecular structure might reveal itself, as on Earth, by an atmospheric composition modified in ways unlikely to be from inorganic processes. The technical challenge is to detect and obtain spectra of an object with Mbol∼28 that is very close to a star and some 5 × 109 times less luminous. Indirect methods, used to detect Jupiter-mass planets, do not seem to offer an easy intermediate step to finding Earth-like planets. However, the direct detection techniques needed for spectroscopy also offer a viable method for discovery by imaging. Thermal infrared wavelengths, in which a planet emits most energy, are the most favorable. A robust search for planets of ∼100 nearby solar-type stars, with spectroscopic follow-up of Earth-like candidates, could be made with an interferometer ∼75 m in length. In visible light, the Next Generation Space Telescope (NGST) could, with the addition of a high resolution correction instrument, see Earth-like planets around a dozen or so of the nearest stars. Both infrared and optical instruments are possible within the range of current space agency plans.

Original languageEnglish (US)
Pages (from-to)507-537
Number of pages31
JournalAnnual Review of Astronomy and Astrophysics
Volume36
Issue number1
StatePublished - 1998

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planet
planets
stars
telescopes
habitability
infrared instruments
atmospheric composition
optical instrument
Jupiter (planet)
interferometer
molecular structure
Jupiter
infrared spectra
interferometers
orbits
spectroscopy
high resolution
wavelength
wavelengths
water

Keywords

  • Exobiology
  • Extrasolar
  • Origins
  • Terrestrial

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Astronomical searches for Earth-like planets and signs of life. / Woolf, Neville; Angel, J Roger P.

In: Annual Review of Astronomy and Astrophysics, Vol. 36, No. 1, 1998, p. 507-537.

Research output: Contribution to journalArticle

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