Answered Questions

i heard u guys r sending a drill/submarine thing to one of the moons around jupiter, is this true?if so when?

No, we are not sending any probe or lander to Europa. Astrobiologists would very much like to study Europa because of its huge liquid ocean. But we have no missions in preparation now, and to drill through several kilometers of ice to reach the liquid water is at best a...

August 5, 2008 More

I have watched documentaries on tv that explain the cause of global warming isn't actually anything to do with humans producing CO2, in the documentary it explains that CO2 makes up around 0.7% of the greenhouse gases that are blamed for global warming and less than half of that (0.3%) is caused by humans, 95% is water vapor. it suggests that the suns fluctuations in activity are to blame i.e sun spots, and before the industrial revolution the earth's average temperature was actually higher than after which backs up the claim. i would like your opinion on this matter please as it is confusing for me, thankyou.

Climate change is a complex but critically important issue. Not every scientist agrees on the details of what us happening to our planet. However, from your description of the program you saw, it does not seem to have even tried to get the science right. The thing that gives this away as non-scientific is...

August 4, 2008 More

I want to know about earth like planets. what does it exactly means? Atmosphere, size, temperature, liquid water or from which circumstance can we say that that planet is earth like? and as i know, from now nasa has detected 169 earth like planets and some of them are tenth of light years away, so how are we going to determine that life exists on one of them if we can't travel there even in the life time period?

One of the triumphs of astronomy over the past decade is the ability to find planets orbiting other stars. Approximately 300 have been found so far, mostly at distances of tens to hundreds of light years. However, none of these planets is earth-like, meaning that it has a size (mass) similar to that of...

August 1, 2008 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...

July 31, 2008 More

I listen to a podcast called AstronomyCast. This is a credible insightful show, perhaps you have heard of it. On it, Dr Pamela Gay of Southern Illinois University said recently that NASA is not allowed to look for "life" by official Congress mandate. Is this true and if so why would we do this? It seems the most intriguing question of Astrobiology is the question of whether life exists outside of the Earth. I'm puzzled by this comment, especially from an accredited person and am looking for more insight. Thank you.

Answer: No, the statement that NASA is not allowed to look for life is absolutely false. One of the primary long-term objectives of NASA astrobiology is to find evidence for life on other worlds. One of the three themes of astrobiology is to study the distribution of life in the universe. Perhaps the person...

July 30, 2008 More

I share your view on Nibiru causing a catastrophe. It has to be a hoax which has been around for a lot of time. However, the only thing that generates curiousity in me is the fact that the area dimensioned (5h 53m 27s, -6 10' 58") has been blackened out in Google Sky and Microsoft Telescope. People suggest that these have been blackened out because those are the co-ordinates where Nibiru is located at present. Please clarify.

Several people have asked me about this blank rectangle in Orion in Google Sky, which is a presentation of images from the Sloan Digital Survey. This can't be a "hiding place" for Nibiru, since it is a part of the sky that could be seen from almost everywhere on the Earth last winter...

July 29, 2008 More

Ancient calendars (pre-8th century B.C.E) used a 360 day year (12 months/30 days ea.) but our Earth year is now 365.2 days. Why is our Earth year longer now?

Calendars are complicated, and many different calendars have been (are are still being) used. Some are based on the Sun (and the seasons), some on the Moon, and at least one (the Mayan) on the position of Venus. Common solar calendars in use today (the Gregorian calendar or modifications of it) are approximately 365.2...

July 28, 2008 More

The article "Target Earth" in Feb 2002 magazine Astronomy, cites Gene Shoemaker's estimate of Tunguska sized events as 1 per century. Now the size of Tunguska is lowered and the estimate of events should increase in frequency to more than 1 per century, but is stated to be one per few centuries. Could you please clarify this apparent contradiction?

Two things contribute to uncertainty about how often the Earth is struck by an impactor the size of Tunguska. One is the impact rate itself, which is derived primarily from astronomical surveys. Since Gene Shoemaker's work, the surveys have progressed significantly, and the current estimate for impact frequency for a 60m asteroid is less...

July 25, 2008 More

Why was it significant that the Phoenix lander found ice on Mars? Haven't we known for some time that Mars has ice caps at its poles?

At the Phoenix landing site in the martian Arctic, we expected to find ice-cemented ground beneath dry permafrost. This kind of ice can form from condensing vapor just as do the polar caps on Mars. However, the small chunks of what appear to be pure ice (segregated ice) were a surprise. On Earth segregated...

July 24, 2008 More

I understand that the earths magnetic field periodically winds down to zero, then reverses North to south and that we are overdue the next reversal. Since the magnetic field plays a part in protecting the Earth from solar radiation, is there any evidence that environmental disasters/extinctions (possibly evolutionary bursts) have occoured at the periods when the magnetic field was zero.

No, there is no indication in the rock records of mass extinctions at times when the Earth's magnetic field changed polarity. However, the last polarity change took place nearly a million years ago, so we don't have much data on any possible smaller environmental effects. Probably the change takes place over thousands of years,...

July 23, 2008 More