Answered Questions

Will pluto and neptune ever collide since thier orbits seems to cross, if so when? and if so what would that collision be like?

No, Neptune and Pluto cannot get close to each other. They are in what astronomers call resonance orbits. Pluto lies in the 3:2 mean motion resonance of Neptune: for every three orbits of Neptune around the Sun, Pluto makes two. This is a stable configuration, so they will remain "safe" from any future collisions. More

Regarding the methane plumes discovered on Mars--given that we know that there are trapped Martian atmospheric gasses in some Martian meteorites--is it possible that detectable levels of methane could be extracted from any of these, and if so would the isotopic composition of this methane allow us to clearly determine a biogenic vs. geologic origin?

The discovery of methane in the martian atmosphere is potentially one of the most exciting recent results from astrobiology research. The new determination that there are three specific locales on Mars where much of the methane originates adds to the interest among astrobiologists. Your question is fascinating. Yesterday I discussed it with three of... More

In sci-fi, "silicon based life" is always depicted as hard-bodied or metallic. I assume this is because silicon is hard, and nobody stops to think that soft and squishy humans are made of all kinds of hard things like iron and the carbon that silicon is supposed to replace. Is that correct, or is there some scientific basis for the way hypothetical "silicon based life" should be depicted?

Good point. I have no idea what silicon-based life would be like, although it would probably operate at higher temperatures than carbon-based life. But I suppose science fiction authors have to make a guess. The other kind of "silicon life", of course, is based on computers. Such artificial life is probably more likely than... More

Hello - Is it possible an asteroid could hit the Earth and cause global devastation? I heard reports last year in January that a large asteroid was on a collision course, but didn't hit after all. Also, one asteroid (or was it a meteor?) came the closest to Earth of any in the past. Thanks for any insight.

Yes, it is possible, as we know from the mass extinction 65 million years ago caused by a collision with an asteroid (or comet) about 15 km in diameter. However, such large hits are extremely rare. Smaller objects hit more often, but they do not have enough energy to cause global devastation. You can... More

Instead of sending a series of manned missions to Mars in the search for life, wouldn't it be less expensive to use nuclear weapons to deorbit Deimos? The resulting impact would throw billions of tons of debris into interplanetary space, and we could collect some of the resulting Mars-origin meteorites here on Earth for study.

NASA and the astrobiology community hope to carry out the search for life on Mars robotically, before any commitment is made to land humans. There is no plan for a series of manned missions to look for life (although investigating martian life could become a major motivation for human flights). Concerning your interesting suggestion... More

Will the sun ever explode? I was told in class that the sun was a big ball of fire that is getting bigger and bigger and will eventually explode? Is this true? If so, when is it estimated that it would happen?

The Sun won't explode. Only massive stars explode as they near the end of their lives. The Sun us now about half way through its "main sequence" lifetime (when it is deriving energy from the fusion of hydrogen to helium). Over this lifetime it gradually increases in luminosity (rate of energy production), but not... More

Are there planets that you believe could possibly sustain life? In the past, could any other planets in our solar system have sustained life? Since Mars has polar ice caps, the planet has water, so it could have had life on it at one point, perhaps? I have also heard that Europa could possibly sustain life.

Your questions are central to astrobiology. Ultimately, our most important challenge is to find evidence for life -- past or present -- beyond Earth. Mars has (or at least it once had) the most Earth-like environment, including liquid water on the surface; it is the one other place in the solar system where we... More

What domain and kingdom are viruses placed in?

Viruses don't fit within the usual classification system for life. Indeed there has long been a dispute whether a virus is really a form of life at all, since they require a living cell as host in order to metabolize and reproduce. However, most astrobiologists today do consider viruses to be alive, and the... More

Solar flares, how dangerous are they? is there evidence of them being dangerous to the earth in the past? I'm always seeing stories on these sites that a major solar flare is coming and it will burn up half the earth. Also is our solar system moving closer together or further apart? For instance, is there any evidence that once in the early days of our solar system that earth was possibly as Venus is now, and Mars was as earth is now.

Solar flares eject high-energy plasma (atomic particles) into space, which could be very dangerous (for a few hours) to any astronauts outside the the Earth's magnetosphere. In the future, astronauts who spend long periods of time on the Moon or traveling to asteroids or to Mars will need protection against occasional large solar flares.... More

If the Earth emits noise in a derranged musical scale, couldn't that be used as a signature amongst planets in the universe to detect similar environments?

The Earth does not emit noise, of a deranged musical scale or in any other way. Also, sounds cannot be transmitted through the near-vacuum of space. Sorry.

David Morrison
NAI Senior Scientist