A Tale of Two Telescopes

A Tale of Two Telescopes

by Whabbear

Owls, have you heard of the Search for Extra-Terrestrial Intelligence (SETI) institute in my hometown of Mountain View? The institute used to be part of NASA until Congress de-funded it back in the 1990s. Today, it is thriving through public donations and public support.

SETI’s biggest benefactor is Paul Allen, the Microsoft billionaire. Allen’s donated over 25 million dollars to built the Allen Telescope Array (ATA), a new suite of radio telescopes that will do radio astronomy and search for signals or broadcasts from extra-terrestrial civilizations.

Last week, I read an article about where in the galaxy they were deciding to aim the ATA to do their first search, and their reasoning was absolutely fascinating (well, at least I thought it was)! They’re going to search in the band around our solar system that’s formed by the ecliptic, the narrow region of the sky that contains our astrological “sun” signs.

Now why on earth (LOL!) would they search there? The answer is associated with another telescope that’s going to be launched into space next year by NASA, not the SETI institute. This remarkable instrument, called Kepler, will aim itself at one section of the sky and monitor about 100,000 stars continuously. Why? Kepler will be searching for tiny periodic dips in these star’s brightness levels that would reveal the presence of an earth-sized planet “transiting”, moving across the face of, the star. Only about 2% of the solar systems around these stars should be oriented right along our line of sight, so that their planets pass directly in front of their stars from our vantage point. If every one of those 2000 stars has an earth-like planet orbiting it, Kepler will discover 2000 earths (in fact, the actual number of earth-like planets is likely to be much smaller than that… just how much smaller is the million dollar research question. If Kepler detects no earth-sized planets
at all, we will have for the first time hard evidence that our home planet is very unusual indeed).

There is pretty good reason to believe that all the planets in other solar systems are like ours, in that they all inhabit a narrow band around their stars. Now suppose alien beings in other star systems have been doing the same thing we are about to do with Kepler, trying to detect transits of Earth-like planets across the stars in their survey area. The only regions in space where they would detect the Earth itself are those aligned with our ecliptic, that is, stars in the direction of Capricorn, Aquarius, Pisces, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, or Sagittarius! Accordingly, that’s where the Allen Telescope Array is going to look first!

Stay tuned, owls! If there are any ET civilizations out there that have discovered life-bearing planet Earth through the transit method, they may be phoning us right now!