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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

I have something that may sound ridiculous to write to you but I need to ask you. My friends and I were talking today and they told me that on May 15th, there will be a comet passing the earth, not hitting it, but its gravitational pull will stop the earth from spinning cause all these things to happen and the earth will flood and there will be earthquakes and stuff. This may sound ridiculous but it would be appretiated to get a responce back.

Don't worry, these rumors of catastrophe are not true. For months, weird stories have circulated on the Internet predicting the close passage by Earth this month of a Planet X sometimes called Niburu, or in some versions it is a giant comet or asteroid. The simple answer is that these... 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

Why are O and B stars the brightest in open clusters, and why are red giants the brightest stars in globular clusters?

This question is not really on astrobiology, so I will provide only a brief answer. O and B stars are very young and bright, and they have short lifetimes, so we see them only in very young groups of stars such as open clusters. Globular clusters are very old, and... 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

What is the temperature of Europa (one of Jupiter's moons)?

Like any planet or moon, the temperature depends on where you are. On Europa this can range from as low as -200 C at the surface near the poles to a high in the deep interior that may approach the melting temperature of rocks (above 1000 C). Within its large... 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

What comet is currently visible from some spot on earth?

There are always comets visible, but whether you can see them depends on how big a telescope you have. The only recent naked-eye comet was 73P/Schwassmann-Wachmann-3, which was fairly bright in May but can no longer be seen without a telescope. Generally, a comet, if it is visible at all,... 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

II was on the NASA home page and searched Planet Niburu. Come to find out there actually is a planet beyond Pluto and they are calling it Niburu.Some said Planet Niburu didnt exist but now we know it does! There havent been many straight answers on this subject so I dont really expect to get the total truth,but here I go. Is there ANY chance of a Niburu flyby in 2012? And if there is why dont the public have a right to know so that we can prepare ourselves?

I’m sorry if the NASA webpage confused you. I just checked, and there is no mention of Nibiru other than the various statements that it does not exist and is a hoax. There is a 2005 news story on the discovery of one of the transneptunian dwarf planets, 2003UB313. UB313... 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

Hi, i have a question about the sun alignment in the center of the galaxy in 2012. Will the sun be in the EXACT center of the galaxy? or just lined up/next to the center of the sun. If you can, can you explain this to me. (15 years old) Thank you very much.

I can't explain it because it is just an Internet hoax. There is no alignment with the center of the Galaxy in 2012 or any time. As to the Sun being in the center of the Galaxy, that it impossible; the Sun and solar system will always remain at about 30,000 light years... 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

If Nibiru is a hoax like you state consistently, then why did NASA admit to it on their own web page? Second off, Why did NASA build a Telescope on the southern pole of the earth to where supposively Nibiru will be heading from, if it actually exist.

I am sorry to still be answering questions about Nibiru, especially when the statements in the question are false. NASA has never discovered Nibiru or "admitted it" on their websites. As you can see from previous posted answers, NASA has been involved in discovering many new infrared sources, some initially unidentified, but none of... More

I've read an article suggesting that the entire solar system is experiencing global warming. This fits in with the galactic alignment prediction, I have in fact seen documents about it by scientists. Anyway, so close to the centre of the galaxy some rays are emitted? And if the solar system is moving through the centre of the galaxy, then it would heat up the solar system too, correct?

You have asked a complicated question, so forgive a long answer. (1) There is no general evidence of heating of the solar system; the article you read is wrong if it said so. What is clear is that the Earth is heating rather rapidly due primarily to an increase in greenhouse gases in... More

Hi, I just found this site by typing in 2012 myth on google. I have read multiple posts & it has helped quite alot. Is there any other sites you could refer me to to look at with other people such as yourself that are discussing this, that would give me further peace of mind so I can drop the mental worry on this matter & focus on my family? You mentioned in one post that newspapers & tv were not reporting on this, yet one of the scary sites I clicked on had multiple links to articles from major newspapers & links to short clips from msnbc & fox.

I can't think of any other web-sites that are discussing the 2012 and Nibiru issues from a scientific perspective. I can understand this, since the purveyors of doom are promoting a hoax, with no science behind it. When I was growing up many decades ago in Illinois, we called these fast-buck artists "snake oil... 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

Can you tell me exactly what will happen on December 21st? What will happen in the sky, what will we be seeing? And it's supposed to happen at 11:11am right? Im really curious as to what I'll be seeing. Thank you so much for taking you're time to answer these questions for millions of scared people across the globe.

This is an easy question: Nothing will happen. There is no significance to that date and time. It is near the winter solstice, of course, but that happens every year. If there are millions of frightened people, that is the product of lies by people who hope to scare you so they can make... More

If area 51 isnt doing anything thats top secret than why is the government denying that it excists? p.s everyone knows about it!!!!!

By "Area 51" I presume you mean the Groom Lake military airfield in the United States Air Force's Nevada Test and Training Range, near Las Vegas. There are tens of thousands of such military bases, airfields, bases, and test areas that are closed to the public in almost every nation of the world. I... More

Hi. I was reading up on Wikipedia about this planet Nibiru, as I was trying to do some of my own research to how it all began. I've found out that a man named Zecharia Sitchin had some sort of theory that Nibiru created earth, by smashing into another planet called Tiamat. Sounds absolutely crazy and confusing to me. I was wondering if maybe you could suggest some sites I could read up on as to how it all began.

I mostly answer questions about science, and I am not an expert on pseudoscience. However, one of the earliest sources of the Nibiru hoax is Sitchin's 1976 book "The 12th Planet" based on his claims (fictitious) of translating Sumerian documents. There is also the "psychic" Nancy Lieder who claimed that we were being warned... 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

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

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

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