Posted on 07/03/2002 9:03:47 AM PDT by RightWhale
Scientists estimate 30 billion Earths
By Dr David Whitehouse , BBC News Online science editor
Astronomers say there could be billions of Earths in our galaxy, the Milky Way.
Their assessment comes after the discovery of the 100th exoplanet - a planet that circles a star other than our own.
The latest find is a gas giant, just like all the other exoplanets so far detected, and orbits a Sun-like star 293 light-years away.
Scientists say they are now in a position to try to estimate how many planets may exist in the galaxy and speculate on just how many could be like the Earth. The answer in both cases is billions.
Virtually all the stars out to about 100 light-years distant have been surveyed. Of these 1,000 or so stars, about 10% have been found to possess planetary systems.
So, with about 300 billion stars in our galaxy, there could be about 30 billion planetary systems in the Milky Way alone; and a great many of these systems are very likely to include Earth-like worlds , say researchers.
Better grasp
The 100th new planet circles the star HD 2039. It was found by astronomers using the Anglo-Australian Telescope as part of the Carnegie Institution Planet Search Program.
The Jupiter-sized world circles its star every 1,210 days at a distance of about 320 million kilometres (200 million miles).
Astronomer Dr Jean Schneider, who compiles the Extrasolar Planets Catalogue, told BBC News Online: "The 100th planet is symbolic and important.
"The first discoveries concentrated on short orbital periods because of the limited timebase of observations. Now, we are learning more about the statistics of long orbital periods and know to what extent our own Jupiter is exceptional or not."
New telescopes
With the new world, astronomers say that they have just about finished surveying all the Sun-like stars out to a distance of 100 light-years from Earth.
Current planet detection technology - based on the "wobble" induced in the parent star by the gravitational pull of the orbiting planet - can only detect worlds about the mass of Saturn or larger. Earth-sized worlds are too small to be seen.
But even in this "biased" survey of giants, the smaller worlds predominate - which makes astronomers think that Earth-like worlds do exist. They may even be as common as Jupiter-sized exoplanets.
And if stellar statistics gathered in our local region of space are applied to our galaxy of 300 billion stars, then there may be 30 billion Jupiter-like worlds and perhaps as many Earth-like worlds as well.
Astronomers will have to wait for a new generation of space-based telescopes incorporating advanced detectors before they can detect Earth-sized worlds orbiting other stars.
Then again, given the enormity of the galaxy, there could be many that are extremely similar to earth. If the planet were the same distance to a very similar star, with similar rotation and atmosphere, it could be very possible. I understand there are a lot of factors, but it is very possible, in my opinon.
There could be cream cheese mountains, rivers flowing with beer and a hundred vestigial virgins for every human, no?
What? Did you mean virtual virgins?
The number of stars in OUR universe completely overwhelms your argument...
There may be OTHER universes as well...
TOOT TOOT
Add all the zeros you want. It's still zero.
Funny thing about the moon and Mars. There is no environment unless you count getting irradiated by cosmic rays [moon] or sandblasted all day every day [Mars.]
BUMP
True that housing costs are way too high, but consider moving expenses.
The lower gravity means that any manufacturing has the added bonus of free lift. Set up a rail launcher and just let objects fall on an easy course to the earth's gravity well.
Pretty exciting stuff all in all.
1. Space Interferometry Mission - The beginning of NASA's efforts at space-based interferometry, should detect many terrestrial planets (no images)launch date-2009
2. Next Generation Space Telescope - First direct imaging of Jupiter+ size exoplanets launch date-2010
3. Terrestrial Planet Finder (TPF) - Crude images of Earth-sized planets, will do spectographic analysis of such planets. This one could answer the big question. launch date- 2012-2015
4. Terrestrial Planet Imager - The Uber Telescope, this will give detailed images of exoplanets, almost like flying a Voyager through the system. It will consist of 5-8 meter telescopes in space with a 6000 Km baseline (WOW!)We'll be able to see clouds and continents on Earth like planets probably greater than 50 light years away. launch date-only in planning stages.
Don't know that even the 6000 km diameter telescope constellation would help a lot if it is supposed to give 400x400 pixel resolution to 50 lightyears and if there is only one potential earthlike system within 100 lightyears. They'll have to go to a larger diameter, which is no problem since they are still in the concept stage.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.