Answered Questions

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

How does anyone know for sure what is going to happen in 2012 if the last time it happened was 26,000 years ago? I just want some basic facts about what exactly will be happening astronomically. Aren't our government dollars fueling the program? So why not give us some straight answers, or do you have any?

The simple basic fact is that nothing astronomical is happening in 2012. All the talk about 2012 doomsday is a hoax. The more detailed “straight answers” are in the 20 questions and answers at the top of this webpage. If you haven’t done so yet, please click on the “summary”... More

I was wondering how a planetary alignment is defined? Does it have to be in a straight line to be considered an alignment or does it count if all the planets are in the same portion of the sky, resembling a line but not straight?

I don’t know how “planetary alignment” is defined. This is not a scientific term or concept, so I don’t really care how people use it. Maybe it comes from the pseudo-science of astrology. My message is simply that planetary alignments, or alignments of the Sun with the galactic center, are... More

I have been doing some calculations in regards to an asteroid named (4179) Toutatis. It appears to have a very close intersection with Earth on mid-December 2012. Are you able to detemine with more accuracy how close this asteroid will come to Earth and what chances that it will make contact? AND Comet 45p/honda-mrkos is due to pass within 0.06 AU in 2011. I keep reading about this comet’s erratic orbits. This would appear to be a very close visit by a comet; what are the risks from debris/radiation/flares/asteroids?

While the Earth is subject to rare impacts by comets and asteroids, there are no predictions of any impacts in this century (see the NASA impact hazard website at http://impact.arc.nasa.gov). Concerning asteroid Toutatis, the orbit is very well known because this asteroid has been tracked by radar as well as... More

What exactly are greenhouse gases, how do we get rid of them, and how else can we stop or reverse the global warming process?

Greenhouse gases (also sometimes called heat-trapping gases) are those that are transparent to visible light (like sunlight) but absorb thermal emission (infrared radiation) from the surface and impede its free flow to space. The name “greenhouse effect” comes from the way a glass greenhouse is heated by sunlight, with the... More

Under annual reports 2008 pertaining to A search for primordial water from deep in the Earth's mantle How do you tell the difference between subducted water from tectonic plate shift and primordial water? Is their any truth that radioactive materials in the earths core are helping to keep the earth moleton

I don’t know what you mean by “primordial water”. Much of the water on Earth has accumulated from the impacts of ice-rich comets and asteroids, and this water is constantly recycled through the atmosphere, oceans, and chemical adsorption in rocks. And yes, the Earth’s interior is kept warm from radioactive... More

How do the spacecraft we send past mars avoid the asteroid belt? Are they so spread out that spacecraft is unlikely to be hit or do they have to guide it manually away from asteroids that are close?

The real asteroid belt is nothing like the depictions you see in movies or on TV. Although there are millions of asteroids, they are spread out over a vast distance. You could make many trips across the asteroid belt without even seeing one, let alone having a close encounter. In... More

Are there any plans to take samples of Desulforudis audaxviator or a colony of Tardigrade to another planet and leave it there to see if it survives?

I don’t know of any such plans. There would not be much point them taking these creatures to a hostile world like our Moon. Probably you are thinking of a relatively habitable world such as Mars. But there are international treaties that do not permit any life-forms from our planet... More

As I understand it, the requirements for an atmosphere to form are a gravitational field strong enough to hold onto the gases and a magnetic field to protect them from solar wind. Are there any other factors that determine if a planet can retain an atmosphere?

The factors that determine whether a planet or moon can retain an atmosphere are primarily temperature and gravity (mass). Also, of course, the availability of a suitable gas is critical, and this is related to the chemical interactions between the atmosphere and the crust. Excluding the gas giants, there are... More

What is the point of SETI? If we received a signal from an intelligent alien planet, it would take lets say, 30,000 light years to reach us. By then their civilization would have advanced 30,000 years. After 30,000 years, shouldn't they have the ability to travel to Earth and wouldn't we have made contact?

It is always hard to imagine what intelligent aliens would think or what would motivate them to seek contact. In your example, we could only detect a signal from a distance of 30,000 LY if they were transmitting a very powerful beacon — something intended to advertise their presence. If... More

There are certain people who believe that global warming may in fact be true, but at our current rate it is too late to do anything about it. Suggesting driving more fuel efficient cars will do little to help with the greenhouse gases. From what I’ve learned the main problem with the increase in carbon is methane which comes from cows which is a main source of food for the world. To fix this we would have to cut down on animal population which could cause food shortages. My question to you is, what do you think is the better solution for global warming. Invest billions into trying to find solutions to fix the problem. Or invest the billions of dollars of research into learning to live with global warming?

I am surprised that you refer to “people who think global warming may be true”. Global warming is about as sure as anything in science that deals with a complex system like Earth climate. We know the rapid increase in greenhouse gases is producing a rate of heating that overwhelms... More

I'm from North Africa, and I noticed almost a month ago the emergence of a star in the sky and larger than the rest of the stars. Is it possible for NASA to give information about this strange star? AND I live in southern Maine. Every night I see what appears to be a star that rises in the east and sets in the west. I am curious because it is easily twice the intensity of every other star in the sky. I have many friends that have also noticed it. What is it? AND If nibiru doesnt exist and nothing is going to hit us, what is the thing I can see in the sky that looks like a large orange dot. i want to know what it is I’m seeing. Its like a orange dot that moves quickly; it’s there every night outside my window.

You are all seeing Jupiter, which is the brightest planet in the evening sky this summer and autumn. (For early risers, Venus, which is in the eastern sky before sunrise, is even brighter). I receive many questions like these. Both Jupiter and Venus are this bright every year. Jupiter, in... More

Is the Doomsday 2012 hoax being covered by the newspapers and other traditional media?

Stories about 2012 are beginning to appear, stimulated by the opening of the movie 2012 on November 13, and also my own answers in Ask an Astrobiologist. The entire “20 questions” summary from this astrobiology webpage is printed in Skeptic Magazine this month (as the cover story).

Joel... More

You have mentioned that we passed through galactic plane millions of years ago and wikipedia says that we are now in galactic plane(entered in 1980 and exit at 2016). Whom should I believe?

The Wikipedia article on the Milky way summarizes as follows: “The Sun is currently 5–30 parsecs from the central plane of the galactic disc.” (that is, about 20 to 100 Light Years). There is a substantial uncertainty, because the plane itself is not well defined observationally. In any case,... More

Usually the astrologers use our planets to explain the present, past and the future life of we humans. Is there really any link between the planet alignment and its movement with the human's life or a person's zodiac sign?

No, there is no link — astrology is not science, or prediction, but an ancient religion that is unrelated to modern science. Astrology and the science of astronomy had common origins, however, since much of the motivation for people to observe the skies and figure our how to predict planet... More

My question is about the Yellowstone volcano. I have read that this is a supervolcano, and should it blow, it would cause the destruction of the earth. Apparently, it erupts every 160,000 years or so, and it's been 166,000 years since the last eruption, so we are due - either tomorrow, in a hundred years, or perhaps thousands of years. So, I guess my question is, how truly dangerous is this volcano?

The numbers you heard are off: please use Wikipedia as a first reference to get the facts straight. The last three Yellowstone supervolcano eruptions were 2.1, 1.3, and 0.6 million years ago. The average interval is thus about 0.6-0.7 million years, not 160,000 years. The largest of these, the Huckleberry... More

Why isn't there more media coverage of the 2012 doomsday? Explain to me what I am seeing in the video for HR 8791. Why did you guys finally decide to coordinate with other countries for the global space station or be in such a rush to find a planet that will support life. The biggest news today is the Health Care Reform but if you look at the words at the bottom on CNN they read that NASA has discovered a planet.

There is not more media coverage of the 2012 doomsday because the media realize it is a hoax. Fortunately most of the media prefer to write about real things, and they understand that 2012 is an Internet and UTube cult phenomenon without the slightest bit of evidence to support it.... More