There’s an article of interest in the December 2009 National Geographic, “Worlds Apart: Seeking new earths”. Written for National Geographic by stargazer Timothy Ferris, the article discusses, in lay editorial style, the mission of NASA spacecraft Kepler (the launch image on this page).
Also discussed with excellent graphics is a foldout showing new planets that have been found so far. The newsprint magazine also presents thumbnail concepts of current detection techniques, including subtle changes in parent star luminosity, and doppler wobble.
For those of us who don’t have access to the current old-fashioned subscription magazine (which I prefer), here are current links to the National Geo articles:
- Worlds Apart: Seeking new earths – article by Timothy Ferris
- The known Planets – animated scrolling pictorial chart of found planets, sizes and distances.
The chart covers the 373 found planets (as of when the issue went to press). I didn’t realize we had identified orbiting planets out to 10,000 light years distance. At least one “planet” is really a failed star (17 times Jupiter’s mass) – it should have gone thermonuclear.
Since Andromeda is our nearest neighboring galaxy, some 2.5 million light years distant, the article doesn’t report any discoveries there, and most likely none have been observed. For ET hunters it might be somewhat unsettling to realize that there is no way Earth could be seen from Andromeda with what we consider state of the art technology. Newly launched Kepler will peer out 15 times farther than current sightings, that is, 6,000 lights years distance, as opposed to the current 400.
In that case, where exactly are the host stars for our 373 observations to date? They seem to all be in own Orion Spur of the Milky Way’s Sagittarius arm. Even Kepler is confining its search area to this spur.
For the seasoned amateur astronomer, there is perhaps not much content we haven’t read elsewhere, at some time or other, in astronomy magazines and websites. But the National Geo presentation is well-organized, as generations have come to expect from that publication, and well worth our review.