by iamlucky13 » Tue Feb 27, 2007 7:14 pm
Some interesting comments. I have a few thoughts to offer.
TimeTravel123456789 wrote:Water vapor could be present and somehow not visible in a Spitzer image because of interference with other chemicals in the spectra.
To the best of my knowledge, this is true. It's also possible (I think probable) that there were trace amounts of water vapor to faint to detect by Spitzer. However, these planets are extremely close to their stars, and I don't think a strong water signal was expected in the spectra. Over time it would be ionized by heat and blown away by the solar wind or be sorted by mass toward the center of the gas giant.
NoelC wrote:Is it just me, or does it seem HIGHLY unlikely that an extrasolar planet and its star would align well enough with us so that we could measure light from them during an eclipse?
I'm no statistician, but it seems to me the chances of viewing an eclipse of a pair of distant bodies is infinitessimal. How often do we see any of our planets eclipse another?
It's not as rare as you might think. The key is that the system's eccliptic plane must be well-aligned with us, and the period has to be short enough that we can see it happen in the time we can devote to looking at it. Conveniently, these are the easiest planets to find because their stars show the greatest Doppler-shift for a given star/planet mass ratio, and they do so in short time frames. The bonus is planets that eclipse their stars can be found by the transit method, which was recently tested by the Hubble. This atmospheric investigation method will probably be utilized quite extensively after the launch of the Keplar mission, which will use the transit method to find planets. If a planet does eclipse, it will probably happen again, as the wobbles in an orbit are pretty small.
I don't know how often planets in our own solar system align with each other, but their orbits are relatively long. The planets in the APOD have orbits of days. Our neighbors also swing an entire 360 degrees around us (except Mercury and Venus, which occasionally transit the sun), as opposed to extrasolar planets, whose orbits represent only arc-seconds of sweep. The relative distance is to our advantage. If this isn't clear, I think I can come up with a drawing illustrating it.
ipaqgeek wrote:I'm curious about whether there is a deeper underlying motive for the search for extraterrestrial life - that is to make money.
I don't doubt that the people most involved in SETI are genuinely interested in their work and honestly trying to find evidence. I don't think they're trying to cheat us, but the value and potential return is certainly debatable. When scientists went looking for quarks, they had really good theoretical evidence they should exist. The motivation for SETI is purely speculative.
Some interesting comments. I have a few thoughts to offer.
[quote="TimeTravel123456789"]Water vapor could be present and somehow not visible in a Spitzer image because of interference with other chemicals in the spectra.[/quote]
To the best of my knowledge, this is true. It's also possible (I think probable) that there were trace amounts of water vapor to faint to detect by Spitzer. However, these planets are extremely close to their stars, and I don't think a strong water signal was expected in the spectra. Over time it would be ionized by heat and blown away by the solar wind or be sorted by mass toward the center of the gas giant.
[quote="NoelC"]Is it just me, or does it seem HIGHLY unlikely that an extrasolar planet and its star would align well enough with us so that we could measure light from them during an eclipse?
I'm no statistician, but it seems to me the chances of viewing an eclipse of a pair of distant bodies is infinitessimal. How often do we see any of our planets eclipse another?[/quote]
It's not as rare as you might think. The key is that the system's eccliptic plane must be well-aligned with us, and the period has to be short enough that we can see it happen in the time we can devote to looking at it. Conveniently, these are the easiest planets to find because their stars show the greatest Doppler-shift for a given star/planet mass ratio, and they do so in short time frames. The bonus is planets that eclipse their stars can be found by the transit method, which was recently tested by the Hubble. This atmospheric investigation method will probably be utilized quite extensively after the launch of the Keplar mission, which will use the transit method to find planets. If a planet does eclipse, it will probably happen again, as the wobbles in an orbit are pretty small.
I don't know how often planets in our own solar system align with each other, but their orbits are relatively long. The planets in the APOD have orbits of days. Our neighbors also swing an entire 360 degrees around us (except Mercury and Venus, which occasionally transit the sun), as opposed to extrasolar planets, whose orbits represent only arc-seconds of sweep. The relative distance is to our advantage. If this isn't clear, I think I can come up with a drawing illustrating it.
[quote="ipaqgeek"]I'm curious about whether there is a deeper underlying motive for the search for extraterrestrial life - that is to make money.[/quote]
I don't doubt that the people most involved in SETI are genuinely interested in their work and honestly trying to find evidence. I don't think they're trying to cheat us, but the value and potential return is certainly debatable. When scientists went looking for quarks, they had really good theoretical evidence they should exist. The motivation for SETI is purely speculative.