Transit Method Reveals Many Extrasolar Planets

eldavojohn writes "You might recall not too long ago the first photo of an extra solar planet or, more recently, the mapping & speculation on these planets that lie outside our own solar system. Long since those first few spotted in the 90s, we're now starting to find them in droves due to the popularity of a method that relies on the planet passing directly between the viewer on earth and the star that it orbits. Be sure to check out Space.com's list of the most interesting extra-solar planets. Will we ever find Earth 2.0 candidates?"

Comments

Pegs that variable in the Fermi equation...

[It doesn't come easy]

Considering the statistically unlikely percentage of planetary orbits that would naturally line up so that the planet would transit its sun from our point of view, planets must be pretty much common as dust. Either that or God was nice enough to line them up so it's easy for us to find them (possible, I hear God is a very nice person)...

Re:Pegs that variable in the Fermi equation...

[jobsagoodun]

This is the whole argument that Stephen Hawkins uses to "believe in God."

Quite the opposite actually...

"You cannot prove that I exist", says God, "For Proof denies faith, and without faith I am nothing!"
"Ah", says man, "But the planets lining up nicely like that so that we can see them is a dead give away isn't it. It proves you exist, and therefore by your own logic you don't. QED"
"Oh bugger I hadn't thought of that" says God and disappears in a puff of logic.


Sorry Mr Adams.

Ummm....It's The Wobble Method That's Tops

[cybrpnk2]

Read the article. Discovering planets via the transit method (eclipse dimming of the star) is rare. Around 80% are instead discovered using the so called wobble method, which measures changes in starlight doppler shift.

Bowman 2.0

[Rob T Firefly]

All these World 2.0s are yours except Europa 2.0. Attempt no landings there.

Re:Will we ever find Earth 2.0 candidates?

[omeomi]

Will we ever find Earth 2.0 candidates?"

I certainly hope it contains the same easy-to use ergonomic AJAX functionality as Web 2.0...I hate having to reload an entire Earth page every time I want to do something...

perhaps not so lucky

[goombah99]

Considering the statistically unlikely percentage of planetary orbits that would naturally line up so that the planet would transit its sun from our point of view, planets must be pretty much common as dust. Either that or God was nice enough to line them up so it's easy for us to find them (possible, I hear God is a very nice person)... Maybe not so lucky. Most of the planets in our solar system (not all) have their rotational axes mostly parallel to their orbital axis. I assume there's some reason for that, perhaps simply if they are spun off of the sun then they acquire it's angular momentum. Or like the moon where tidal forces lock the orbit. In any case then, the next question is if the solar systems in our galaxy mainly orbit in the plane of the galaxies rotation. I'd assume so.

Given all that then it's not too surprising that there be a preference for this favorable occultation geometry.

Finally I note that we are not really interested in planets that don't rotate in their orbital plane since otherwise they'd be roastingly hot on one side and freezing on the other.

Re:perhaps not so lucky

[Chris Burke]

Yes, but wouldn't there be a certain ring that is exactly 70 degrees?

I'm no expert, but I'd be willing to bet that what you'd really get is a ring that fluctuates violently between the hot and cold extremes of the two sides of the planet and is constantly bombarded by gigantic storms. I mean we're basically talking about a permanent clash between hot and cold weather fronts.

Huge temperature deltas do not result in nice smooth gradients between them.

Re:perhaps not so lucky

[jae471]

It should be noted that out the Sun's axis of rotation (and that of the major planets) is NOT with the galactic plane. We can see them, but they can't see us...

Re:perhaps not so lucky

[mp3phish]

Your statement seems misleading but it may just be incomplete (IMO).

"Finally I note that we are not really interested in planets that don't rotate in their orbital plane since otherwise they'd be roastingly hot on one side and freezing on the other."

The rotation of the planet has nothing to do with the detection of planets in this method, only the orbit determines the ability to detect it. So while some planets may or may not be rotating on the correct axis to support multiple seasons, it isn't accounted for in this type of study because they can't detect this with the transient method.

Also, there are actually a large variation of planes that can be detected with this method. Imagine our solar system as a disk. Then imaging looking at it from the top view. This view does not allow the planet detection using the transient method. However, angle your view down until you can see just one of the planets cross over the sun. From this angle on, and twisted up to 360 degrees, is where this transient method works. So actually, there are many planes of orbit which can be used to detect planets with this method. And assuming that a percentage of these planets are within the habitable distance from their star, and that a percentage of these rotate on a reasonable axis, then they could contain life. But nothing in these studies is determining that any of this is the case. Right now they are just looking for ANY planets. so we can detect extrasolar planets even if their orbital planes are perpendicular to the galactic disk, so long as they are close to parallel to our viewing line of site. With this in mind, you can imagine that if you can view stars in our galaxy from 360 degrees around our planet, that we would be able to detect every orbital plane angle available in the galaxy, depending on which direction we are looking from the earth. So while we can't see all of them, we can see a very large subset of them with this method.

Also, the reason that all the planets in the solar system follow close to same typical plane of orbit is because of the way solar systems form. They start as a gaseous body collapsing. As the rotation of the gas nears closer and closer to the center of the nebula, the rotational inertia causes the forming of a disk due to inertia. The same thing happens to drag car tires when they spin fast (they turn more disk-like). From this disk-like nebula the planets form. The center typically ends up with something larger than a gas giant (the sun, or a couple of suns) and the other planets turn into gas giants (Jupiter) or solid planets (i forgot the name, but they gain gravitational pull and pull in particles from the nebular disk)

So this is why the planets are all in one plane of orbit. If all star systems are formed in this general method (something that is assumed) then it is fairly easy to say that they should all be in a single plane. But each system does not necessarily have to be in the same plane relative to each other just because they are in the same galaxy. Each nebula forms independently and collapses typically from an outside force, but not necessarily on the same rotational plane.

Also, the planets have their own disks associated with them. The moons and rings of Uranus and Saturn and Jupiter follow different planes. They don't necessarily need to follow the same plane as the solar system. This is because each of those planets also formed independently of each other. The spin of those depends on the angular momentum of the local mass as it formed, which would be different than the parent nebular disk especially when you take into account collisions of forming bodies. The same could be said to happen on the galaxy level, if you compare the galaxy formation to solar system formation.

These are just my points of view of what I have studied. Many people will have different points of view formed from the same observations.

I'm not sure how serious you're being

[benhocking]

However, they do plan on looking for signs of molecular oxygen in the atmospheres of some of these planets. Molecular oxygen is chemically unstable, so its presence is usually considered to be an excellent indicator of life. Not perfect, as it might not be necessary or sufficient, but it's the best method we have right now for detecting M-class planets.