Answered Questions

I am curious about the relationship between the history of Venus and that of Earth. For instance, it has been mentioned that the reason Venus reaches temperatures of over 500 degrees F is because of the "runaway greenhouse effect " and that Earth may have experienced a similar problem early on in its existence. What is the approximate time when the Earth cooled sufficiently to support life?

Earth, Venus and Mars all experience greenhouse heating, mostly due to the trapping of heat by atmospheric carbon dioxide. The magnitude of the greenhouse heating has changed over time. In the case of the Earth, we think that other gases such a methane also contributed to the greenhouse effect during... More

Understanding the complexities of nuclear and mitochondrial DNA and associated RNA structures, what is the probability that such structures could remain viable during extended exposure to space that would be required to fulfill the concept of panspermia?

Astrobiologists have done a number of experiments exposing organic compounds, tissues, and even individual creatures (mostly one-celled) to space conditions. There is some survival for durations up to several years. These experiments, plus theoretical analyses, suggest that life could survive for long enough to be exchanged between nearby planets, such... More

If you were to construct a sort of green house on mars, with its own temp control and air systems. could the plants grown in the green house sustain themselves since the ground on mars is basically iron particles?

We think we could grow plants in a greenhouse on Mars if we supplied heat, water and air. You are asking more specifically about how fertile the soil is on Mars. My guess is that some plants would do fine in martian soil. It is not made of particles of... More

am a medical student from India, I am persuing final year of my medical study. Can i study astrobiology after my graduation is over? If yes, what is the procedure for admission?

I am glad to hear that you are interested in astrobiology. I don’t know if there are universities in India that offer astrobiology training. Usually prospective astrobiologists have some background in both physical and biological science, and I don’t know if you have already completed appropriate courses in your university... More

Is there an exoplanet that could have life among all the ones who have been already found?

None of the exoplanets discovered so far appears to be habitable, but there are many uncertainties, about both the properties of the planet and the definition of habitability. The great majority of the planets discovered by radial velocity surveys are giant planets without solid surfaces, and many of these are... More

I am very interested in space, stars and astrobiology, i dream of serving humanity by working in NASA. I am currently undergraduating in chemistry, what next should i do to fulfill my dream of becoming NASA Astrobiogist?

I am pleased that you want to become an astrobiologist. Please look at the FAQ on career paths in astrobiology. The main thing is to become proficient in both a physical and a biological science, since astrobiology is an interdisciplinary field. Also, please note that most astrobiologists work in universities,... More

Having read the questions about the asteroid Apophis, I'm curious why it attracts so much attention and why it has, unlike the vast majority of asteroids, its own name? Is it in any way special from a scientific point of view?

The vast majority of the asteroids are in the asteroid belt between Mars and Jupiter. Only the largest are named (2410 Morrison, for example). In contrast, there are only a few thousand known near-Earth asteroids (NEAs), and a large fraction of them are named. NEAs are of much more interest,... More

They say that humans evolved from chimps. Why is then the current chimps are not evolving? Why would we even have chimps at all? Could we have just started out as humans?

I have never heard any scientist suggest that humans are descended from chimps. Humans and the two species of chimpanzees (Pan troglodytes and Pan paniscus) are closely related and apparently shared a common ancestor (now extinct) about 7 million years ago. Evolution involves the development of new species and the... More

Is it true that the comet C/2002 V1 (NEAT) is almost twice the size of jupter?? i saw a video where Nassim Haramein said that nasa was worried about this comet because they thought it gonna hit the sun. quote: they thought we were toast. He also said that the tail of the comet was nearly 1 AU long.

The problem with these statements in the ambiguity of the word “size”. Comets are near vacuums. They have been called the nearest thing to nothing that is still something. The largest comet has a mass a factor of a trillion less than the mass of Jupiter. With such a... 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