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Ask an Astrobiologist
Black and white image of ice worm.
This little fellow looks fearsome, but it is actually is only an inch or two long. Scientists were excited to find it because the methane-ice dwelling creatures are proof life can exist in extreme environments (maybe even elsewhere in our solar system).

Is it possible there is life on other planets? Does NASA have any UFO problems? NASA astrobiologists answer your toughest questions. Ask an Astrobiologist is a service to answer astrobiology questions from the public, both about the origin and evolution of life on Earth and looking forward to the search for life on other worlds. This article includes five of the most popular questions from the thousands the team gets each year.

Got a burning question that can't wait? Go directly to the Ask an Astrobiologist Website.

Link to Ask an Astrobiologist
Have a question about life in the universe? Ask an Astrobiologist's Dr. David Morrison has the answers you seek.

What is the possibility of life other planets?
In order for life (in the form that is most familiar to us) to evolve on a planet, scientists believe that the planet must be warm enough to contain at least some liquid water, but not so hot that all of the water turns to vapor, as appears to be the case on the planet Venus. It must also contain certain important elements, like carbon and nitrogen, that are necessary to build living cells, and the environment must be calm enough that life has time to develop - the planets in some star systems may be hit so frequently by giant meteorites (causing all the surface water to boil or vaporize) that life never has a chance to form there.

Earth is a very special place, in that it appears to be the perfect environment for life to form and flourish. In our own solar system, we see that Mars also had water at its surface long ago, and some very primitive life forms (like bacteria) could have developed there - scientists are still debating whether or not one of the meteorites that came from Mars, ALH84001, has fossil evidence of ancient life on Mars. One of Jupiter's moons, Europa, also might contain liquid water deep beneath its surface, which could harbor primitive life forms.

There is also a strong possibility of planets outside of our solar system having the conditions necessary for life. Our galaxy, the Milky Way, contains at least 200 billion (200,000,000,000) stars, and recent observations with very powerful telescopes suggests that many of the stars in the night sky have planets orbiting them. There is a famous equation called Drake's Equation that tries to calculate how many stars contain orbiting planets that have conditions suitable for the development of life. The equation suggests that life forms are very likely to exist on planets in our galaxy or any of the billions of other galaxies in the Universe. Scientists are still working hard to observe earth-like planets around other stars, and to understand the conditions under which life formed and evolved on the ancient Earth.

Prof. Brian W. Stewar
University of Pittsburgh
January 28, 2002

Has NASA any had UFO problems? (I'm doing a school project on them)
No, I can't imagine that NASA would have any problems with something that doesn't exist. The sad thing about UFO reports is that they distract so many people from understanding and enjoying real science. (There is a lot of nonsense on the Internet about UFOs, but I do recommend the website

David Morrison
NAI Senior Scientist
June 2, 2006

Why is water so important for life?
Every known form of life on earth, from the largest mammals to the smallest microbes, relies on water. Why? Because water is an extraordinarily versatile molecule - it's the perfect liquid medium in which to dissolve nutrients for ingestion or wastes for excretion, to transport important chemicals or even be used as one. Water has two particular physical properties that are unique among natural molecules: it remains liquid over an extremely broad range of temperatures, and it decreases in density when converted to solid phase (frozen). While this may seem a relatively minor point, its consequences (that ice floats) are critical to the evolution of life. If ice were more dense than water and the earth cooled slightly, ice formed on the oceans would sink and push the already cold water from the bottom to the surface, where it too would freeze and sink, repeating the cycle until all water on the planet was frozen. Not all scientists believe that the presence of water is "concrete" evidence of life, but liquid water certainly improves the likelihood of life taking hold and finding a hospitable environment. This should not be confused with ice, however, which we know is present in many planets and moons in the solar system. Remember that ice may not be only frozen water, but perhaps vapor from other gases - in either case not as conducive to life.

Check out the following websites:

Finally, take a look at Bruce Jakosky's book The Search for Life on Other Planets, Cambridge University Press, 1998. He devotes a whole chapter to understanding how and why scientists believe water may be an essential requirement for life anywhere.

May 1, 2002

I have a question about the Moon and it's role in life on earth. How important is tidal activity in the formation of life on Earth? Also, does the Moon really act like a shield for the Earth, stopping some impacts that would otherwise hit us? Finally, could life have developed to the extent it has on Earth without the Moon?

Scientists don't agree on the importance of tides for life on Earth. Of course, there are many creatures that live in tidal areas today, but whether the existence of tidal environments was an important factor for the origin of life is not known. The Moon does not shield the Earth from impacts. It occupies only about one millionth of the area of the sky, so it would intercept only one in a million incoming asteroids or comets. The most important way the Moon is important for life is that its gravity maintains an approximately constant tilt for the Earth's rotation axis, so that we have less extremes of climate than does (for example) Mars.

David Morrison
Astrobiology Senior Scientist
June 23, 2010

Is there a planet Nibiru that will pretty much destroy earth in 2012? I watched a video about it last night and I freaked out so bad i was shaking and crying. Is our world coming to an end in 2012? If so... why cant we just blow the thing up and call it a day?
I am really sorry that these crazy Nibiru claims have upset you. I don't want to keep answering these questions about Nibiru, but let me say once more as clearly as I can, for you and the other questioners: Nibiru does not exist. NASA has never discovered or detected Nibiru or anything remotely like it. The handful of dwarf planets that astronomers have discovered beyond Neptune are on stable orbits that will never come into the inner solar system, let alone threaten Earth.

Nothing will happen in 2012. Nibiru is simply a fake, a hoax, the result of a small religious cult that is unfortunately scaring lots of people with totally false stories.

David Morrison
NAI Senior Scientist
January 31, 2008

Note: Ask an Astrobiologist received more than 2,500 questions about Nibiru and 2012, with more than 200 answers posted. Please read a summary of the answers that have already been posted, view a video on these topics, use the search feature and read the FAQs. It is likely your questions already have been answered.

You can also read our compilation of what NASA scientists think about the 2012 doomsday theory.

Last Updated: 24 January 2011

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Last Updated: 24 Jan 2011