Answered Questions

What are the theories about life on europa? is it that the ice is melting and therefore there is water so there must be life? and also i have seen drawings of what the europa rover would be like. have they made an actual model?

Europa has an ocean of liquid water larger than the oceans of Earth (with less area but much deeper), covered with a crust of ice at least several kilometers thick. The water is liquid because Europa has an interior heat source caused by stress from Jupiter tides. This is much... More

On reversal of the Earth's magnetic polarity, you wrote "the magnetic polarity of Earth, which does change irregularly with a magnetic reversal taking place every 400,000 years on average. As far as we know, such a magnetic reversal doesn’t cause any harm to life on Earth. A magnetic reversal is very unlikely to happen in the next few millennia, anyway." If the last shift of the Earth's polarity occured 780,000 years ago, how can you say that it will not occur within the next few millenia, because you are indeed correct in that it does occur an average every 400 millenia. Furthermore I question your statement about the effect such a reversal will have on the life of our planet. While we are not certain about the extent of the effect, most scientists agree that when a reversal event occurs the Earth's magnetic field is all but non-existent, and then severely weakened for some time afterward. The magnetic field surrounding us is our primary shielding from a bombardment of cosmic and solar radiation.

In answer to your first question, the Earth’s polarity reversal is not a periodic phenomenon. While the timing may not be random either, that assumption is consistent with the data. If it is random, and happens on average every 400,000 years, then the probability of it happening in the next... More

Does SETI look for light pulses as well as radio signals from the stars? Is there any other group that searches for any signals from space besides SETI?

SETI means the search for extraterrestrial intelligence, so by definition any such search, looking for radio signals or light pulses, is a part of SETI. There are quite a few SETI groups around the world. One of the oldest and largest is at the SETI Institute in Mountain View, California... More

I want to thank you. At 26 I am a mother of 2. The last few weeks I have been loosing sleep over this 2012 doomsday issue that the media promotes to make a dollar, and frankly I think it is sick. I spent the last few hours reading your answers. I hope i can sleep better tonight; I dont want to loose my children to some awful disaster. I hope everyone out there believes NASA and not the conspiracy theory. But as i read your answers I see you get irratated with people for asking the same questions; please try to understand these people are like me waking up at night wondering if they should start trying to figure out how to survive a disaster or if they are being crazy. My only question is if the Earth poles were due to change as well as the sun, can we expect anything at all to happen? or would we notice nothing?

I am sorry if I sometimes get irritated, but so many people who write don’t bother to read any of my previously posted answers, yet they check the box that says “I have used the search feature (blue box to the right) to verify that a question similar to mine... More

WHY, do you and some others say that there shall be no alignment of Earth, the Sun, and the center of the universe, when there are other scientist that say there shall be?

The people who say there will be alignment of Earth, the Sun, and the center of the universe are not scientists. They are hoaxers.

David Morrison
NAI Senior Scientist

On global warming, I gather you are a believer in man made warming as opposed to natural climate cycles. C02 is increasing but makes up a very small percent of greenhouse gases with the most abundant being water vapor. Here are a few questions I have. One I have read that the temperatures in the medevil times were warmer than today (pre fossil fuels); how can this be explained if not for cyclical temp patterns? Secondly with the C02 we are producing, why would the gov't just outlaw the production of it by 2030 as opposed to saying it is bad and proposing a cap-and-trade system? Sounds like a tax scheme.

I am sorry to see you repeating the disinformation that is being circulated by the global warming deniers. Specifically, you suggest that we should not worry about carbon dioxide, since the main greenhouse gas is water vapor. This is partly true, but it is the carbon dioxide that controls the... More

When we discover extra-terrestrial life, how will this information be distributed to the public?

Thanks for asking “when” not “if” we discover extraterrestrial life. If we found either extant or fossil life in meteorites or on the surface of a planet like Mars, there would probably be several months of intense scientific work before an announcement was made. NASA already had this sort of... More

My question concerns the significance of life's existence on Earth and whether its simply an accidental byproduct of the Universe and could easily have not occurred, or if the Universe was designed to produce life.

Yours is a difficult question because astrobiologists do not understand exactly how life formed on Earth or elsewhere. In a trivial sense yes, the universe must be friendly to life or we would not be here to ask the question. But that would indicate that the universe allows life, not... More

Don Yeomans from NASA, July 2008 writes an article "Why Study Comets" saying: "It is not a question of whether a comet will strike the Earth, it is a question of when the next one will hit." At what interval do you believe a "comet hitting Earth" event will occur? being the last one took place 65 million years ago?!

First, we don’t know when the next comet hit will take place. The astronomical evidence is that there are few if any comets smaller than about 2 km diameter, and in the size range of a few kilometers, comets represent only about 1 percent of the impact risk, with the... More

I am a 28-year veteran English teacher and I would like permission to print a copy of your page of 20 questions about the 2012 doomsday scare for distribution to my colleagues. While reading on another site about some of the letters you received from teenagers, it occurred to me that we teachers have an obligation to be informed on this issue in order to address fears that our students may have. The topic could also be used for study units on propaganda techniques and/or manipulation of language, critical thinking skills, free-speech issues, media studies, the importance of thorough research, and on and on. Mostly, though, we might save a life, or, at the very least, calm someone down. The whole 2012 thing for me has gone from mild amusement to disgust to real alarm over our nation's ignorance. The doomsday scare has potential to do real harm, and reading of the kids who wrote to you considering suicide woke me back up to one of the important things we have to deal with besides our curricula, and that is the mental, emotional, and physical well-being of our students.

Thank you for your note. You are very welcome to use the 20 questions and any other information from this website. I especially recommend this 4-minute video for the students who are more comfortable getting their information from Youtube than written texts. Good luck! For video: http://astrobiology.nasa.gov/ask-an-astrobiologist/intro/nibiru-and-doomsday-2012-questions-and-answers

David Morrison More

I have always wondered if it is possible that there could be a planet in a synchronis orbit with earth but on the opposite side of the sun from us. We can't see the other side of the sun and our long range probes are looking away into deep space as they leave our solar system.

No, there cannot be a “counter-Earth” — any such planet would be immediately detected by its gravitational effects on the orbits of other planets.

David Morrison
NAI Senior Scientist

More reader feedback on the 2012 hoax:

Hi, I work in astronomy education outreach at University of Texas and wanted to thank you for putting together the 2012 Q&A site. We get similar questions all of the time and it really helps to have a site to refer people to. One thing I think you might want... More

How much longer can take the Earth take all the human damage we are causing?

Earth, the planet, is hardly affected by what humans do. Whether we survive or rapidly go extinct, the planet will continue much as before. The main threat of humans is to the biosphere, where we are causing severe damage, especially in loss of habitat, producing what is looking more and... More

I want to ask how did NASA lose the rocket blueprint to go to the moon. I always wonder since today rocket technology is far more advanced then it was 40 years ago, and has there been research on anti gravity

AND

You wrote that we no longer have the capability to send astronauts to the Moon. Does this mean that the Apollo Program was a hoax too?

Losing the Moon rocket blueprints is an urban legend. The reason we could not duplicate the Saturn rockets that took astronauts to the Moon in the Apollo program is that the parts are no longer available, and many of the companies that built the Apollo hardware are no longer in... More

I read Ask an Astrobiologist and enjoy your posts weekly. I am a recovering "Cosmophobe" and your answers have put my mind to ease more than once. I was reading an article that the Sun is acting very strangely and not following the average sunspot amount in the solar minimum. Is this something to be concerned about?

No one knows why the start of the new sunspot cycle has been delayed, but I can’t see any reason to be concerned. There is very little variation in solar luminosity with the activity level. What is interesting to me is sociological. A few months ago I received many messages... More

Is it true that in roughly 5 billion years or so if not more that scientists have said one way for the end of the universe would be if the sun was to exhaust itself by becoming a red dwarf and destroying everything with too much heat, or a white dwarf even.

The Sun is about half-way through its 10-billion year lifetime. In about 4 billion years it will increase in both size and brightness and become a “red giant” star. Eventually it will evolve into a “white dwarf”, small and faint. See the Wikipedia article on stellar evolution for details. These... More

I read recently that the planet Venus experienced a "runaway greenhouse effect" and that if this was to happen on Earth, the temperature would high enough for the oceans to boil. Is any of this "runaway warming in this century" stuff on the Internet plausible? And are the rumors true that the Earth has stopped warming and is now cooling (maybe headed for an ice age)?

The current global warming on Earth is extremely unlikely to lead to a runaway greenhouse effect, although to be honest scientists are not sure exactly what triggered the runaway greenhouse on Venus. But that does not mean that we can ignore the more modest warming that is happening now. What... More

What is the radiation background on Europa?

Charged particles trapped in the magnetosphere of Jupiter create a high radiation environment when they strike the surfaces of the two inner Galilean satellites, Europa and Io, or when they hit a spacecraft operating in these parts of the jovian system. The most extensive study of Europa was carried out... More

Is there a planet alignment going on right now? I was told the planets were lined up which was affecting gravity, causing eggs to stand up, brooms to stand up, etc. If there is a planet alignment, is this a dangerous thing? AND My partner at work today was trying to describe something he'd read about the earth dropping below the milky way. He said scientists are predicting an increase in gravity? Have you of heard this?

I thought that by now I had heard every weird idea about 2012, but these are new. First, there is no planet alignment now or in the next few decades. Even if there were, it would have no measurable effect. The public interest in alignments comes from astrology; this is... More

Can you tell me if there was any night sky activity by any agency that could provide a plausible explanation for a white, inverted cone shaped light emitting over Franklin WV about 8 - 9 pm on September 19th, 2009. It was clearly visible with the naked eye and slowly raised straight up out of sight. I have researched the date online without success. Thank You.

On September 19 there was a research rocket launch from Wallops Island (on the Eastern Shore of Chesapeake Bay) that released a luminous cloud into the upper atmosphere. This was widely reported in the press. For instance, Newsday wrote "Staff at several National Weather Service offices in the Northeast received... More