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Top Document: [sci.astro] ET Life (Astronomy Frequently Asked Questions) (6/9) Previous Document: F.02.3 Is there life on Jupiter's moon, Europa? Next Document: F.03 What is the Drake equation? See reader questions & answers on this topic! - Help others by sharing your knowledge This material is extracted from the review article by Chyba & McDonald (1995, Annual Review of Earth and Planetary Science). Titan's atmosphere is a rich mix of nitrogen and methane, from which organic molecules (i.e., those containing carbon, not necessarily molecules in living organisms) can be formed. Indeed, there has been speculation that Titan's atmosphere resembles that of Earth some 4 billion years ago. Complex organic chemistry can result from the ultraviolet light from the Sun or from charged particle impacts on the upper atmosphere. Unfortunately, Titan's great distance from the Sun means that the surface temperature is so low that liquid water is probably not present globally. Since we believe that liquid water is probably necessary for the emergence of life, Titan is unlikely to harbor any life. The impact of comets or asteroids on Titan may, however, warm the surface enough that any water ice could melt. Such "impact pools" could persist for as long as 1 thousand years, potentially allowing life-like chemical reactions to occur. User Contributions:Comment about this article, ask questions, or add new information about this topic:Top Document: [sci.astro] ET Life (Astronomy Frequently Asked Questions) (6/9) Previous Document: F.02.3 Is there life on Jupiter's moon, Europa? Next Document: F.03 What is the Drake equation? Part0 - Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Part8 - Single Page [ Usenet FAQs | Web FAQs | Documents | RFC Index ] Send corrections/additions to the FAQ Maintainer: jlazio@patriot.net
Last Update March 27 2014 @ 02:11 PM
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with stars, then every direction you looked would eventually end on
the surface of a star, and the whole sky would be as bright as the
surface of the Sun.
Why would anyone assume this? Certainly, we have directions where we look that are dark because something that does not emit light (is not a star) is between us and the light. A close example is in our own solar system. When we look at the Sun (a star) during a solar eclipse the Moon blocks the light. When we look at the inner planets of our solar system (Mercury and Venus) as they pass between us and the Sun, do we not get the same effect, i.e. in the direction of the planet we see no light from the Sun? Those planets simply look like dark spots on the Sun.
Olbers' paradox seems to assume that only stars exist in the universe, but what about the planets? Aren't there more planets than stars, thus more obstructions to light than sources of light?
What may be more interesting is why can we see certain stars seemingly continuously. Are there no planets or other obstructions between them and us? Or is the twinkle in stars just caused by the movement of obstructions across the path of light between the stars and us? I was always told the twinkle defines a star while the steady light reflected by our planets defines a planet. Is that because the planets of our solar system don't have the obstructions between Earth and them to cause a twinkle effect?
9-14-2024 KP