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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... More

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... More

What is the bright planet visible in the evening sky? Is Mars still bright?

There are four planets visible in the evening sky, and this number will increase to five in mid-March when Mercury can also be seen. By far the brightest planet is Venus, high in the western sky at dusk. Mars is near Venus but is much fainter, a big change from... More

What is the importance and significance of Urey and Miller's experiments in the debate on the composition of the primitive atmosphere? Also, what is their contribution to the hypothesis about the origin of life?

The Miller-Urey experiment provides no direct information on the composition of the atmosphere of the Earth. A scientist carrying out a Miller-Urey-type experiment in the lab must assume a composition and use gas of that composition in the experiment. The mix of organic chemicals that is produced in the experiment... More

What would earth look like without water on it? What would be the shape of the 'piece of rock' that would remain?

If you started with the planet as it is today and removed the water suddenly, there would be some rebound in the ocean basins in response to to removal of the pressure of the water. More generally, however, many geologists think that in the absence of water there would be... More

I took pictures several times of UFOs and small crafts not from our planet. If it is of your interest, how can I send you some photos?

Thanks for the offer, but I am not interested in seeing the photos. If the objects you have photographed are unidentified (the U in UFO), how can you know they are from other planets? Previous "UFO photos" have turned out to be birds, airplanes, planets, balloons, meteors, or very often... More

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... More

How long have humans existed on Earth?

Human have existed for roughly half a million years, but this answer depends on the exact definition of "human". Fossil evidence shows that several human-like lineages developed during the past million years or so. >From fossils, the appearance of Homo sapiens is dated at about half a million years, and... More

Have there been sightings of UFO's while you are in space? Also i would like to know if you have ever seen an alien?

The answer to both questions is No. As discussed here previously (check for UFO entries by using the search engine), no astronauts have seen UFOs. Certainly I have never seen an alien, nor have I come across any convincing evidence that anyone else has either. The modern myth of aliens... More

Is area 51 hiding u.f.o ?

No. Area 51 is an obsolete designation for a U.S. Air Force airfield near Las Vegas, Nevada. It is located adjacent to the Nevada Test Range, which was once used for nuclear weapon tests. This area has been used for testing experimental aircraft, which may have been interpreted as UFOs,... More

Have you heard about NIBIRU? Is NIBURU approaching Planet Earth ?

Nibiru is a hoax. There is no such planet. The are a lot of hoaxes on the Internet, but this one is especially strange, because there is no evidence whatever for its existence, and past predictions about it hitting the Earth several years ago were obviously wrong. David Morrison
NAI Senior Scientist

What is Planet Nibiru/Eris ? Is it going to flyby Earth in 2012 ? Are we going to survive the flyby ?

You seem to have fallen for the "Nibiru hoax". Eris is a dwarf planet in the outer solar system, a bit larger than Pluto, discovered in 2003 (see Wikipedia article at http://en.wikipedia.org/wiki/Eris_(dwarf_planet)). Nibiru does not exist; it is a hoax, and certainly it has nothing to do with Eris. Wikipedia... More

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... More

Nibiru Redux: Six recent questions about Nibiru: (1) I have found a lot of stuff about a so called planet. Planet x or nibiru. It anything they say possible like revolving around the sun clockwise and it has been said that its orbit is way far out past Pluto. Also there are statements that it has a 3600 year orbit around the sun an that is is supposed to return in the near future. Is this possible at all? It sounds fishy to me, but there are supposed pics of it and a lot of scientist talk about it. I even wikipedia searched it. I would just like to find out some info please. (2) Nibiru does exist and I can prove it. Nibiru is in the old testament Exodus 6:4. and you are watching Nibiru from a lab on the south pole. also I have images from a telescope of Nibiru. and people from the southern hemisphere can see Nibiru in the daytime. is that proof enough for you? (3) many signs tell that something big is out there coming and why wouldn't it be true about nibiru / planet x there is a lot of fact historical and scientific but i do understand your awnser but why build a telescope at the south pole an photos and such with this redish dwarf star moving fast in 1983 it was 50 billion miles away and 10 years later it is alot closer is it hiding behind the sun i know you all dont want to start a world wide panic. (4) I read were you said that Nibiru is a hoax. My question to you is why would anyone let the american population know about such a catastrophy? Isnt it the governments job to keep the population at ease? (5) You say Nibiru is a hoax, and no such planet exists, but is Nibiru not Eris? (6) What is this a picture of? http://www.greatdreams.com/nibiru-possible.jpg It's said to be Nibiru, but as you say Nibiru is a hoax. so what is this really a photo of?

I hope this is my last comment on the Nibiru hoax, but questions like the above six keep coming in. Most of the entries on the Internet about Nibiru are false. Wikipedia has it correct when they write that "Nibiru is a name in Sumerian, Babylonian astrology associated with the... More

Now if the Nibiru topic is a hoax, then what are the infrared images of the alleged Nibiru??? And i also heard that NASA saw it with IRAS and reported it and all that. Why does NASA deny anything about it instead of telling the public so (if Nibiru is in fact a hoax) they dont take durastic measures such as my family was planning on doing.I need more proof that Nibiru is a hoax because the government and NASA are keeping to much from us for us to make full judgement on it....

I really am sorry that you have taken the Nibiru hoax seriously, and that this hoax is causing you and your family distress. This Nibiru stuff is all pure fiction, without any core of fact or truth. Specifically (1) The are no infrared images of Nibiru -- period. (2) IRAS... More

When most of the planets align in 2012 and planet earth is in the center of the milky way,what will the effects of this be on planet earth? could it cause a pole shift,if so what could we expect.

There is no planet alignment in 2012 or any other time in the next several decades. As to the Earth being in the center of the Milky Way, I don't know what this phrase means, If you are referring to the Milky Way Galaxy, we are rather far toward the... More

What do you make of this theory that the Earth will be in direct alignment with the center of the Milky Way in December of 2012? There are many websites which list a series of events in our solar system, leading up to the alignment which will cause a catastrophic change in the Earth¹s rotation. I went to your Solar System Simulator at http://space.jpl.nasa.gov/ (Which is really cool by the way) and typed in a bunch of these dates. It looked to me like the Earth was still intact. Is this alignment with the center of the galaxy even provable?

You are correct, there is no planetary alignment in December 2012. As to "alignment with the center of the Milky Way" that is a meaningless phrase. It may sound scientific, but it is devoid of content. To put it bluntly, these claims on the Internet of alignments and catastrophe in December... More

why does the Mayan calender say the world will end in 2012?i know you have answered the plant x question....however i have heard that they have been pretty accurate in the past with other planetary stuff ,did they use planets so much to date things? and does that make them better at understanding the solar system? so if they have predicted an end in 2012 will it happen ,how can you be sure you know more than they did?

Calendars exist for keeping track of the passage of time, not for predicting the future. The Mayan astronomers were clever, and they developed a very complex calendar. Ancient calendars are interesting to historians, but of course they cannot match the ability we have today to keep track of time, or the precision of the... More

Can you please explain the polar shift theory? Supposedly the earth's crust does a 180 degree rotation around the core in a matter of days if not hours. Furthermore, this is stated to be a regular occurrence in Earth's geologic history and has to do with our solar system dipping beneath the galactic equator. Is there any merit to it?

I will try to explain. This is one of the craziest lies that is being promulgated by the 2012 conspiracy theorists -- worse in many ways than the Nibiru hoax. It is totally absurd, and completely untrue, but still the story spreads and is frightening people. First, on the matter of a sudden reversal... More

Confused about 2012 "Powerful Solar Storm Could Shut Down U.S. for Months" is a report on the Fox News website. They stated the report was commissioned and paid for by NASA. It was reported by The National Academy of Sciences and includes a comment by Richard Fisher, director of the Heliophysics division at NASA. If nothing is going to happen as a result of the event in 2012, why would NASA allow such nonsense to be reported.

There is nothing wrong with the National Research Council report on heliophysics, and NASA is very pleased with it. As you note, this report includes a worst-case analysis of what could happen today if there were a repetition of the biggest solar storm ever recorded (in 1859). The problem is... More

NASA has denied the existence of Aliens, and NASA claims that there is no proof that the aliens have ever visited the earth, my question will be regarding the egyptian pyramids, do you seriously think that people living thousands of yours BC have build the great pyramids? One more question is how does NASA explain the "face" and the "pyramids" found at Cydonia, in planet MARS.

Unfortunately, quite a few people have fallen for these alien-pseudoscience claims, so I will briefly answer your questions, even though they are not directly related to astrobiology. (1) NASA does not deny the existence of aliens. Most astrobiologists anticipate billions of inhabited planets, including many that are the home to... More

Can Apophis (an asteroid, that will get close to Earth in 2036) destroy or make damage to our planet? If yes, why can't we blow up that thing?!

Apophis, an asteroid about 300 meters long, is very unlikely to hit the Earth in April 2036. We should know for sure by 2013, when it comes close enough for good radar measurements of its orbit. If it did hit it could badly damage an area the size of a... More

If nibiru is a hoax, how did these people got to know about it? where did the idea of nibiru or planet x come from? is it just a product of spontaneous imagination or there are some documents and real evidence that supports it?

The Nibiru hoax has two main sources. First, a man named Zecharia Sitchin, who writes fiction about the ancient Mesopotamian civilization of Sumer, has claimed in several books that he has found and translated Sumerian documents that identify the planet Nibiru, orbiting the Sun every 3600 years. Sitchin has sold... More

Is it true that in August of this year, 2009, Mars and earth will be closer together than ever before and Mars will look as large as the moon?

No, certainly not! Mars is never much closer than 50 million kilometers, so it is always a point source — it looks like a star. And no, Mars is not close to us in August 2009 either. It is actually near its farthest distance from Earth, hidden behind the Sun.... More

If Nibiru is a total hoax, and if NASA and the govt know about the great talk there is everywhere (internet, tv, press, etc) why don't you set a campaign to inform the public about these alleged false stories about Nibiru and the end of the world? ALSO if you feel that its hoax, then why dont from your side make a public announcement that nibiru is a hoax? and announce same through news channels?

It may surprise you, but I have not yet met a single scientist who has heard these stories about Nibiru and doomsday 2012. Similarly, I doubt if more than a handful of people in NASA have heard of this. I would not know about it either if I did not... More

Which planetarium in California allows me to view Planet X?

A planetarium is a device for projecting star fields and astronomical photos on the inside of a dome. It does not allow you to view anything other that the material that has been programmed into the show. I don’t think you will see “Planet X” included in current planetarium... More

i was on the national geographic website and they said that in 2012 we are suppose to have the biggest solar storms in history. In the movie they said a solar flare would incinerate earth. I understand there's solar activity every 11 years ...but in the movie flares from the sun incinerated earth ...could that really happen?

A lot of people are asking about predictions of an unusually intense solar maximum 3 years from now. There is a huge amount of hype on the Internet, most of which (judging by the first 50 listings when I google “solar maximum 2012”) is inaccurate and irresponsible. Let’s look at... More

We all hear exciting news about newly discovered exoplanets every week or so. I was wondering if Nasa plans to point some kind of big ears in the direction of these planets. I know Seti is searching the whole sky, but I guess it would probably be more efficient to search where we know there are planets.

There are now more than 350 known exoplanets, but so far no evidence that any are habitable. Almost all are giant planets, many either close to their star (hence very hot) or on highly elliptical orbits. Thus these are not very likely candidates for SETI searches. Once the Kepler mission... More

I've just found out about something called WR 104, which is worrying me, can you explain this and help me out?

Don’t worry about WR 104; I will explain why in a moment. Your question is like others I receive, often several per day, that express a kind of cosmophobia — a fear of the cosmos. News stories about astronomical events are triggering widespread worry: fear of asteroid impacts, fear... More

As the average 15 year old I find it difficult to understand your answers about the so called 2012 doomsday. I have heard many theories one saying that the U.S project Philladelphia or something traveled into the future and there was nothing left in 2012 the earth was destroyed. Could you give me the simple answer are we or are we not going to die in 2012 I would rather take my own life than suffer a doomsday. ..AND.. hello I am really scared with the news that the world is going to end on 12 21 2012....I have been looking it up to try to find some information that is from a valuable source. Please help me!!!!

I received these two questions within a few minutes of each other, and they make me angry at the liars and fools who keep posting claims of a 2012 doomsday. Nothing will happen in 2012. There is no planet Nibiru, no planet alignment, no crossing the celestial equator, no change... More