Our Solar System in the distant future may look something like the Helix nebula today. That's because in about five billion years, the Sun will have become a white dwarf, its inner planets swallowed up by its earlier expansion, its outer planets, asteroids and comets surviving in distant orbits and colliding with each other to form a ring of dusty debris. The Sun will undergo, in other words, a kind of rejuvenation, experiencing what scientists call 'late bombardment' in a system that has become dynamically young again. Such a disk has now been found in the Helix nebula, some 700 light years away in Aquarius. It took the infrared tools of the Spitzer Space Telescope to sort out the glow of the dusty disk that circles the remnant white dwarf between 35 and 150 AU out. The assumption is that the disk is the result of smashups in the outer system, presumably involving objects like those in our Kuiper Belt or comets from an Oort-like cloud. Image: Spitzer's infrared view of the Helix...

It's good to see that Greg Laughlin's systemic project is getting some public attention. This article in the Santa Cruz Sentinel goes through the basics, explaining how amateurs can use the systemic console to identify possible planets around other stars. "We want to demonstrate that it's not just public outreach, it's a way of carrying out research," Laughlin adds, and that fusion is what the Net is bringing to exoplanetary studies.

Actually seeing something is so much more rewarding than just inferring its presence. But in the case of exoplanets, looking at the actual light bouncing off a distant planet does more than just satisfying our curiosity. Starshade concepts and other methods of terrestrial planet detection point to an ultimate payoff: We want to analyze the light of a distant world to learn what elements are found in its atmosphere. These become clues to conditions there, and even markers of possible life. Centauri Dreams readers know I'm a great admirer of the starshade concept, not only as developed by Webster Cash in his New Worlds Imager designs but also as widely studied for other possible missions (for more on starshades, see the UMBRAS site). Starshades are all about direct observation -- images, spectroscopy, photometry -- rather than methods like radial velocity studies that find planets through the motions of their parent stars. And I like starshade technologies because they seem to offer...

Want to build a starshade to spot Earth-like worlds around other stars? Start with a Hubble-like telescope a few million miles from Earth. Add a 30-meter wide disk with petal-like extensions, separated by 10,000 miles from the telescope. Watch what happens next. Using lasers, the two parts would line up, with the star shade just blocking out the light from a nearby star from the center of the telescope's view. Calculated mathematically to throw away the light from the star but keep the light from any planets it held (this is the "occulting" part of the occulted), the device would be able to detect planets smaller than Earth orbiting stars within 35 light years of Earth, Cash and his colleagues calculate. The key is the petal shape of the shade, which scatters starlight from the telescope's view. From an overview of planet-finder technologies by Dan Vergano in USA Today. Webster Cash, whose name is frequently found in the Centauri Dreams archives, is a major part of the...

Barrie Jones (The Open University, UK) will have an interesting job in ESA's planned Darwin mission. Darwin's goal is to find Earth-like worlds around other stars. Jones will prioritize planetary systems so the mission's telescopes -- three instruments mounted on separate spacecraft -- can concentrate on those most likely to have Earth-like planets in their habitable zones. He's already done computer modeling on many currently known planets, finding that half of them occur in systems where a stable orbit for a terrestrial world exists in the habitable zone. But much depends on how you deal with planetary migration, says Jones, discussing his computer modeling in a recent interview. A gas giant moving through the inner system to become a 'hot Jupiter' may or may not preclude the presence of an Earth-like planet -- recent work gives us hope that it will not, but the issue is still undecided. Says Jones: If Earths can form after the giants migrate toward the star and become "Hot...

If I were a betting man, I would put some money on this proposition: The first detection of a potentially habitable planet will be made before the end of this decade, and the planet will be found around an M-class red dwarf. The method will doubtless be photometry, picking up the slight drop in light caused by such a planet transiting its star. A planet the size of our Earth will block about one percent of the stellar flux, as a recent paper points out, and a one percent photometric dip is quite detectible. Image: An animation of a stellar transit around HD 209458. Credit: Transits of Extrasolar Planets Network. Although TEP concluded its work in 2001, you can still read about it online. So the key is to find the right M-dwarf, with its planetary system lined up so that the hypothetical terrestrial world passes between its star and us. That's no small challenge, but Paul Shankland (U.S. Naval Observatory), who is lead author on the paper mentioned above, is working with colleagues...