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Planetary System Similar to Sol
sgtwilko writes "The BBC News site has an article about how astronomers have found several new planets including some that have a similar distribution to our own Solar System. They are finding planetary systems that are more and more like the one in which the Earth resides. It's only a matter of time until the Terrestrial Planet Finder program gets going and finds another Earth." There's another story on space.com. Update: 06/13 21:51 GMT by M : Space News and Wired have stories as well, with spiffy graphics and artists' renderings and so on.
i don't get the thrust of the article focusing on finding earth-sized planets. is there some theory that necessitates a planet be our size to foster life? if so, why?
(here comes the (-1, Ignorant). bring it on.)
go get it
They have also found the smallest exoplanet yet. It is only 40 times more massive than Earth.
The size of the planet isn't really the issue though,
Detecting Earth-sized planets is probably not possible using current ground-based techniques. That will have to wait for a new generation of satellite observatories, due in the next decade.
The important part is
Calculations made by Greg Laughlin of the University of California at Santa Cruz show that an Earth-sized planet could survive in a stable orbit between the two gas giants.
This of course doesn't mean that we found anything only that when we are able to look for earth-like planets this is our best bet for hitting the jackpot.
I stole this Sig
It's slow and full of pop-up ads..
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A team of astronomers announced today the discovery of the first planet outside our solar system with an orbit similar to Jupiter's, a configuration that has the potential to support an Earth-like planet.
They also found the least massive world ever detected around another star, a planet just 40 times as heavy as Earth.
The primary discovery is a gas giant planet that circles a star called 55 Cancri every 13 years, comparable to Jupiter's 11.86-year orbit. The planet is between 3.5 and 5 times as heavy as Jupiter.
"It's the first extrasolar planet that reminds us of a planet in our solar system," lead researcher Geoffrey Marcy said in an interview with SPACE.com several days prior to the announcement.
Marcy, of the University of California, Berkeley, said he and colleague Paul Butler, of the Carnegie Institution of Washington, have dreamed of this discovery for 17 years as they compiled data using a technique that many scientists said would never work. The two astronomers, whose team has grown in recent years, also announced 11 other worlds today at a press conference at NASA headquarters, bringing the total of known extrasolar planets to 98.
Potential for Earth twin
The new planet orbits 55 Cancri at 5.5 astronomical units (AU). One AU is the distance from Earth to the Sun. Jupiter orbits at 5.2 AU. The same team had already spotted another planet around 55 Cancri, a place slightly less massive than Jupiter. It orbits so close to the star that it makes a complete orbit in just 14.6 days.
Marcy speculated that the two-planet system could harbor more intriguing worlds, possibly even rocky planets like Earth, known as terrestrials.
"A Jupiter at five Earth-Sun distance units might serve as the marquee of a planetary theater located within, where terrestrial bit players are racing around on smaller tracks," Marcy said. "We are left to imagine what geophysical and perhaps biological improvisation is taking place inside this planetary playhouse."
Armed with their new data, Marcy and Butler enlisted theoretician Gregory Laughlin of the University of California, Santa Cruz, to look into whether the 55 Cancri system could also retain an Earth-sized planet in a life-sustaining orbit. Such a region, called a habitable zone, would maintain moderate temperatures suitable to the retention of surface water and the possibility of life.
Laughlin ran the data through computer models of planet formation. The answer is "yes."
"We tried a hypothetical configuration of a terrestrial planet in the habitable zone around one AU from the central star and found it very stable," said Laughlin, who also is associated with Lick Observatory. "Just as the other planets in our solar system tug on the Earth and produce a chaotic but bounded orbit, so the planets around 55 Cancri would push and pull an Earth-like planet in a manner that would not cause any collisions or wild orbital variations."
Marcy and Butler caution, however, that there is no way to detect an Earth-sized planet with present technology. Meanwhile, their data does suggest a third planet in the system, a possible Saturn-sized object. Others could lurk there.
Laurance Doyle, a researcher at the SETI Institute who was not involved in the discovery, told SPACE.com the new finding "is a strong encouragement" that our solar system "may not, after all, be totally unusual."
The Jupiter-like planet has another potential benefit, Doyle points out: Its gravity would lure comets, shielding inner planets from life-threatening bombardment. Jupiter plays this protective role in our solar system.
Pushing the limit
Marcy, Butler and their colleagues also announced today the lightest extrasolar planet ever found, one 40 times as massive as Earth.
This discovery pushes the lower limits of their wobble method, which spots movement in a star induced by the gravity of an orbiting planet. (No confirmed planet outside our solar system has ever actually been photographed.)
This relatively small planet, whose possible presence was first reported in May by SPACE.com, was detected around a star called HD 49674. It is just 15 percent the mass of Jupiter. Theory holds that it would be gaseous, not rocky. Previously, the lightest known extrasolar planet was more than 50 times heavier than Earth.
For comparison, Neptune is about 17 times as massive as Earth and Saturn is about 95 times as heavy.
Marcy has said the wobble method will not be able to find planets weighing less than 10 Earth-masses.
The SETI Institute's Doyle uses a different method for planet hunting, however. He looks for slight dips in a star's light that indicate the passage of a planet. The method has yet to discover a planet, but it has been used to detect the atmosphere of a known extrasolar planet.
This so-called transit method could spot a planet twice as big as Earth, Doyle says, if the planet's path is properly aligned so that it passes in front of the star as seen from Earth.
Such a planet would have roughly eight times the mass of our own. It would still be rocky and could, theoretically, harbor life.
Doyle said the existence of two planets bracketing the habitable zone around 55 Cancri "indicates that planet production may have taken place within the habitable zone of that system."
Next Page: A dream come true, plus what's next
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Dream come true
The discovery of the Jovian twin caps 17 years of planet hunting by Marcy and Butler, who were not deterred by early skepticism in their technique.
"Way back in 1985, Paul Butler and I began sketching the idea for a new instrument, attached to a telescope, that might someday detect planets around other stars," Marcy told SPACE.com. "Some very smart people told us that we wouldn't succeed, that we would never detect the wobble of a star caused by its attendant planets."
They did, beginning in 1995 just months after a European team found the first planet around a star besides our Sun. Marcy and Butler confirmed that finding and went on to become the world's most prolific planet-hunting team.
"We always dreamed that maybe, with a wisp of phenomenal luck and dogged perseverance, we might capture evidence of a Jupiter-like planet," Marcy said.
Prior to today's announcement, all known extrasolar planets orbited more closely to their host stars, some as close as Mercury is to our Sun.
Because the planet around 55 Cancri takes 13 years to make a complete orbit, it took equally long for enough data to accumulate to definitively identify the object. Its orbit is elongated instead of being nearly circular like Jupiter's. "We haven't yet found an exact solar system analog," Butler said. "But this shows we are getting close."
Other recent discoveries have shown that circular orbits do exist around other stars.
Butler said more Jupiter-like planets will likely flow from the data they are collecting on 1,200 Sun-like stars.
What's next
While Doyle or someone else might find a planet twice the size of Earth, the discovery of a true Earth-sized planet won't come for at least a few years, most researchers agree.
But now there is a perfect place to look.
The 55 Cancri system "will be the best candidate for direct pictures" by a next-generation space-based observatory, said Debra Fischer, a UC Berkeley astronomer who is part of the Marcy-Butler team.
Two such missions are planned by NASA, first the Space Interferometry Mission and then the Terrestrial Planet Finder. The discovery of a solar system with elements similar to our own "adds urgency to missions capable of detecting Earth-sized planets," said Charles Beichman, NASA's Origins Program chief scientist at the Jet Propulsion Laboratory in Pasadena.
No firm launch dates are set for either of these satellites, however. Both would follow the less ambitious Kepler mission, set to launch in 2007. Kepler will use the transit method to detect and generate a census of Earth-like planets around other stars, assuming such planets exist, but it won't photograph any.
Details of the research
The star 55 Cancri is in the constellation Cancer. It is roughly 41 light-years from Earth and about 4.7 billion years old, comparable to our Sun.
The new discoveries were funded by NASA and the National Science Foundation. Observations of 55 Cancri were made at the Lick Observatory. The Anglo-Australian telescope was used to find two of the other planets announced today.
Other scientists who collaborated in the new findings: Steve Vogt, UC Santa Cruz; Greg Henry, Tennessee State University; Dimitri Pourbaix, Universite' Libre de Bruxelles; Hugh Jones, Liverpool John Moores University in the United Kingdom; Chris Tinney, Anglo-Australian Telescope; Chris McCarthy, Carnegie Institution of Washington; Brad Carter, University of Southern Queensland, Australia; and Alan Penny of the Rutherford Appleton Laboratory in the United Kingdom.
The wobble method, which is so far responsible for all extrasolar planet discoveries, is also known as the Doppler technique. The researchers employ special filters in a telescope to measure a change in the wavelength in light coming from a star. The change results from the star moving toward the telescope and compressing the waves, and then moving away from the telescope and lengthening the waves.
The effect is similar to the change in sound of a siren from an ambulance rushing toward you and then heading away.
A quote from the CNN article (which seems to be a bit more fleshed out) I didn't see in either of the ones listed at the top:
"We haven't found an exact solar system analog, which would have a circular orbit and a mass closer to that of Jupiter. But this shows we are getting close," said Paul Butler, another member of the planet-hunting team.
But the orbit of the Jupiter-like planet is stable enough to foster a benign, life-friendly environment in the inner solar orbit, Fischer said.
Dark Nexus
"Sanity is calming, but madness is more interesting."
With the money and resources that would be required to move to a new planet in a distant solar system, wouldn't it be far easier and cheaper and quicker to set up a colony on a planet/moon in our own system? They would need some sort of enclosed structure to survive, but could possibly begin terraforming that new world. Given how long it would take to find and inhabit a new earth, we could probably create one here quicker.
As an added bonus, we could send much more people to mars much faster, since in the time it would take to reach even the closest star, let alone one with habitable worlds, we could make many many round-trip voyages to an in-system world. This would certainly help overcrowding here on earth, and also get us started on interplanetary colonization. Once we actually got experience moving to new worlds, each successive one could only get easier, and with people on more than one world, there would most likely be more motivation for development of new technologies to make the trip faster and more efficent, as well as improving communication times.
Maybe it's just me, but I'd rather be on a hostile new world now than a less hostile one in a few million years.
-Space for rent
On the other hand, my uncle said:
I completely agree with both, Spock and my uncle.
This sig is a true statement, but I cannot prove it.
That gives us two things to look for. It tells us how far from a star to look (for the temperature and energy variables), and THAT gives us the likely type of planet to find in that region. From what we know of the physics of planetary formation, those planets would tend to be small and rocky, with the likely working fluid being water.
With a planet with aqueous water, the likely atmosphere would include some oxygen, but too much or too little would tend to work itself out over time (too much, and you tend to support a LOT of combustion, which would take up the excess oxygen. Low oxygen environments are thought to be similar to that in which life developed here on Earth. . . )
In a long and possibly too-technical explanation, that's why we look for "Earth-like" planets when we look for life. . .
This is not a troll -- I'm genuinely very curious.
What do Christians think about stories like this? I ask becuase, in discussions with Christians, I've heard Christians tell me that there is no intelligent life on other planets. This was usually in response to my questions like, "Did Jesus die for aliens on other planets?" Perhaps a silly question for me to ask, but the "There is no intelligent life on other planets" was not an uncommon belief among the Christians I've met.
So I've often wondered what Christians (particularly Christian nerds, who are probably significantly more friendly to science than some of the Christians I've met) think when stories like thit surface and hint at the possibility of finding other "Earth-like" planets that may have intelligent life on them.
Thoughts?
I don't make the rules. I just make fun of them.
What bothers me about this is that while there is a quick mention of "formation models," most of the discussion of the potential existence of a terrestrial planet seemed focused on the stability of an orbit in the present configuration. In fact, it isn't clear to me that they've even considered the formation processes at all. (To be honest, I get the opposite sense.)
Why does this bother me, you ask? Because an orbit at 1 AU might be stable NOW, but if you have a giant planet migrating in through the inner solar system to an 15-day orbit, it'll wreck jolly hell with any planets it passes. The migration is slow enough that you are almost guaranteed a close-enounter of some kind. Once a Earth-sized planet gets near a giant planet, the orbit is in the very least highly perturbed. Odds are fair that it could be ejected altogher or will collide with the giant planet and be effectly lost. But even if it isn't, the eccentricity is probably going to be increases substantially. A planet that changes its distance from its star radically over a year is unlikely to be habitable, if you believe current models.
How likely is that, for any given star?
It's more likely than you might think. It has to do with conservation of angular momentum and it's the planets and even the moons in our solar system are all within a few degrees of the same plane.
Sure there are exceptions, but the chances of seeing a solar system on edge is considerably better than whatever it would be if they were just randomly distributed.
That's not exactly true: in our case, the Sun pushed (light pressure, and another effect I can't think of the name of...) or ate all of the light gaseous material inside the asteroid belt. At least, it did, viewing it from 6 or so billion years later.
Now, the next problem is that we do NOT know how these giant planets near their star formed. People suggest that the planets migrated inwards, which would make an Earth-sized planet unlikely. However, there are some suggestions that the gas giants CAN form that close to their star. In fact, I don't think that we would even KNOW if there had previously been a gas giant inside Mercury's orbit that has long since been devoured by the Sun. Thus we could be looking at a Sol-like system, just much earlier in formation.
It should be noted that Jupiter has some influence on Earth - but it's very minor. Venus has significantly more influence (Venus's rotation is actually in a resonance with Earth's orbit).
A planet that close to the Sun orbiting that quickly would, from Earth's (1AU) point of view, just look like an increase in the Sun's mass. Work out the differential force: With a differential distance swing of 1/40 AU, but the distance going as the cube, it's really going to be quite minor: about 1/200th the tidal force of the Sun, which is less than that of the Moon. It's not like the Moon's influence seriously screws up the planet. (Note that I'm talking about the differential force of the swing of the inner planet: that is, how much does the tug of the inner planet really change from Earth's point of view? Not much at all).
Gravitational perturbations are due to differential gravitational forces, and the forces on Earth due to a planet orbiting at 0.025 AU are trivial. As for asteroid components, it depends on how the planet formed, which we don't understand yet. If it formed far out, and moved in, then yes, it would be a menace. But if it formed close in, it's extremely unlikely to cause any "asteroid bombardment" or anything like that.
Keep in mind that you could consider a slight "bulge" in the sun to be a "giant planet" orbiting the Sun obscenely quick: if it was likely that this would disturb the Earth, the Earth would be in very bad shape: bubbles of different densities appear on the Sun all the time. The differential force just isn't that great.
Should we look there first? Yes. It's an IDEAL target, actually! It's a planetary system where both standard Sol planetary formation processes are occuring, and this "weird' giant planet stuff is happening. If it isn't the first stop for the TPF, I'd be amazed. That's a system worth studying. And would anyone be surprised to see an Earth like planet show up there? Not likely.
By now, I am readily convinced that there is other life in the universe. In fact, it seems that odds are greater that there isn't life in the universe.
But if I'm like most anyone else, the possibility of life on the western spiral of the Andromeda Galaxy just isn't useful. Its simply too far. We would never recieve a radio transmission from there and its too far to travel.
First, lets assume Einstein is correct and we can not travel faster than the speed of light. In addition, lets rid our minds of all this science-fiction crap like wormholes and warp-drive. While I am naive, I'm not *that* naive.
Lets take the nearest star. I've heard it is 4.3 light years away. That means a radio transmission originating their takes 4.3 years to travel here. Honestly, we could live with that. Of course that is not only assuming that that civilization has developed technology, but it also assumes that they haven't been exinct by some means.
But, we're pretty sure there isn't a planetary system around proxima centauri. So we have to look farther out. But how long are we willing to wait for a round of communication from us to them? One hundred years? One thousand years? A hundred-thousand years?
Okay, as a second consideration, how long does a civilization last once it discovers radio? We've only had radio technology for a relatively little time. How much longer will we continue to exist? Take HG Wells Time Machine. Will we unlearn our technology and instead progress towards a native happiness? What about other civilizations?
In all, what are the odds that not only life exists in the universe, but that it is close enough and that it is in their technological prime?
I'd fashion that the odds are astronomical against us.