Space.com (December 14, 2009)
"Four newfound planets orbiting two nearby stars1 add weight to the promise of detecting habitable worlds within the next few years, researchers said today.
"Two of the extrasolar planets are considered super-Earths, more massive than Earth but less massive than Uranus and Neptune. Spotting true Earth-sized planets is challenging with current technology, but the presence of super-Earths suggests finding a world like ours is just a matter of time, researchers say.
" 'These detections indicate that low-mass planets are quite common around nearby stars,' said study team member Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz. 'The discovery of potentially habitable nearby worlds may be just a few years away.'
"The astronomers are not sure if the super-Earths are rocky like our own world or if they have some other composition...."
I remember when an alien world was considered exotic if the space princess had a green complexion.
That was science fiction, of course, but serious speculation about planets around other stars went from the assumption that there might be a few other stars in the universe with planets - and that those were probably pretty much like the set we knew about - to the idea that planets might be fairly common: but still, pretty much cookie-cutter copies of what we were familiar with, in the Solar system.
Then, not too many years ago, astronomers worked out ways to detect planets circling other stars.
Today, it's a little hard to keep up with what's been discovered recently, and what they're like.
And, although there are some systems with a sort of family resemblance to our Solar system, it's getting fairly obvious that there are a whole lot of variations possible on the theme of 'planets.'
As I quoted in another blog:
"Not only is the universe stranger than we imagine, it is stranger than we can imagine."
Sir Arthur Eddington English astronomer (1882 - 1944)
(Drifting at the Edge of Time and Space (November 1, 2009)
- "Earth May Not Be a 'Class M' Planet"
(December 5, 2009)
- "Gliese 581: Lightest Known Expoplanet (Caution! Geeky Content!)"
(April 21, 2009)
Related posts, at
1 Three of the new exoplanets orbit one star: Three of the exoplanets orbit the star 61 Virginis, which another source says that this star "stands out as being the most nearly similar to the Sun in terms of age, mass, and other essential properties...." (UC Santa Cruz, (December 14, 2009))
At a distance of only 28 light-years, it's (on a galactic scale) a close neighbor of Earth.
Let's put it this way: this diagram on the Milky Way Galaxy (with "Sun" as a sort of "You Are Here" label) is 648 pixels across. That makes each pixel well over 100 light years across - not quite four times the distance from here to 61 Virginis.
Or, let's say a graduate student sent a message to the 61 Virginis system - and someone (something?) replied immediately. The response would come 56 years later. By then the one-time student would be around 80 years old: but these days, quite a few people live that long - and stay interested.
(from Department of Physics, University of Oregon, used w/o permission)
If you've got good eyes and clear skies - and are awake a few hours before the sun comes up - you should be able to pick out 61 Virginis in the constellation Virgo, a bit south of Spica.
The 61 Virginis system, as currently known:
- The star, 61 Virginis
- 61 Vir b, 5.1 x Earth mass
- 61 Vir c, 18 x Earth mass
- 61 Vir d, 23 x Earth mass
- "New planet discoveries suggest low-mass planets are common around nearby stars"
UC Santa Cruz (December 14, 2009)
- "Virgo Constellation"
Observational Astronomy: David Haworth