Logo IMG
HOME > My Amsci > Restricted Access

Restricted Access The content you've requested is available without charge only to active Sigma Xi members and American Scientist subscribers.

If you are an active member or an individual subscriber, please log in now in order to access this article.

If you are not a member or individual subscriber, you can:


Figure 1. Searching for Earthlike worlds...Click to Enlarge Image

Astronomers have discovered nearly 200 planets orbiting distant stars. The vast majority of these bodies are considerably more massive than Earth, perhaps because of the inherent bias in the methods used to detect such extra-solar planets. Distant worlds that are more Earthlike in size and composition are likely to be abundant too—just harder to detect. Astronomers have thus been intent on developing the means to find Earthlike planets and to obtain spectra of their atmospheres, which could show whether conditions are amenable to life—and may even yield indirect evidence of life itself. Of particular import in that regard is the planning now going on for two space missions, both called Terrestrial Planet Finder. One, slated to be launched in a decade or so, will involve a single telescope outfitted with a coronagraph, a set of occulting masks designed to reduce the glare of a distant star enough to reveal planets that may be in the vicinity. The other, to be launched a few years later, will use multiple telescopes configured as an interferometer, which can suppress light from a star using the phenomenon of destructive wave interference, while allowing light from a planet near that star to be detected.

Connect With Us:


Subscribe to Free eNewsletters!

Read Past Issues on JSTOR

JSTOR, the online academic archive, contains complete back issues of American Scientist from 1913 (known then as the Sigma Xi Quarterly) through 2005.

The table of contents for each issue is freely available to all users; those with institutional access can read each complete issue.

View the full collection here.

RSS Feed Subscription

Receive notification when new content is posted from the entire website, or choose from the customized feeds available.

Write for American Scientist

Review our submission guidelines.

Subscribe to American Scientist