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TagFine-tuning (Earth for life)

The Earth from space. This image elements furnished by NASA.

Astronomer: We Can’t Just Assume Countless Earths Out There

He points out that the Principle of Mediocrity is based on faulty logical reasoning

Dartmouth physicist and astronomer Marcelo Gleiser wrote recently that the Copernican Principle has been misused to imply that Earth is somehow insignificant. That, he says, is a philosophical attitude, unrelated to the science. We don’t know where Earth stands in relation to other planets because we do not yet have telescopes capable of getting much detail about planets outside our solar system. Gleiser, author of The Island of Knowledge (2014), has also tackled the Mediocrity Principle (because Earth is nothing special, there must be countless intelligent civilizations out there). According to Britannica, “Widely believed by astronomers since the work of Nicolaus Copernicus, this principle states that the properties and evolution of the solar system are not unusual in any important Read More ›

Venus against the background of the sun. Elements of this image furnished by NASA

Carl Sagan Institute: Who Can See Us From Outer Space?

Most exoplanets are spotted when they dim a star’s light while crossing it. Earth does the same thing

We’ve all heard of astronomer Carl Sagan’s pale blue dot (Earth from a billion miles away, 1990). But Jaimie Green reminds us at Slate that Sagan (1934–1996) also published a paper in 1993 that looked at Earth from that distance as if it were an exoplanet. What signals would prompt them to suspect life here? That approach is still followed by astronomer and director Lisa Kaltenegger at Cornell University’s Carl Sagan Institute. One question is, where would an intelligent, technologically advanced civilization need to be to see us? Kaltenegger and her collaborators used new data from the European Space Agency’s Gaia mission to figure out which stars have, have had, or will in the next 5,000 years have the right Read More ›