Astronomy/Gamma ray bursts

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Question
Hi,

A recent museum visit introduced me to a theory that Earth's Ice Ages were caused by gamma ray bursts from nearby stars. What's your view of this theory? If you think some other change must have happened to cause them, I'd be most interested in your opinion.

Also I read somewhere that the Earth would have an average temperature of -18 degrees Celsius without the benefit of greenhouse gases like CO2 and water vapour. What is the mean average temperature on Mars?
Thanks, Geoff.

Answer
Hello, Geoff!

To tell the truth, I'm always leery of assorted espoused 'theories' that somehow never made it into peer reviewed journals. Since I have never seen anything concerning GRBs causing Ice Ages, and I peruse the Astrophysical Journal archives regularly, I have to conclude the hypothesis is not really very high profile.

Now, it is true that assorted Google-generated links claim: "Two international science magazines, New Scientist and Nature, have recently reported the researchers' hypothesis." But 'reporting' them is not the same as publishing complete papers on the ideas.

So I'll wait until it makes the Ap. J. (with an exhaustive presentation of analytical models, etc.) before seriously considering it. There are other simpler, more plausible explanations!

Chief among these is lowered CO2 concentrations a la the global climate model now dominating today's climate research landcape. (Of course, I do understand the need for new entry workers to come up with ever mroe far fetched 'theories' and scenarios, like GRBs as a source of Ice ages, since let's face it, as time goes on more and more new ideas have to be advanced to be original!)

Prof. Gale Christianson in his book ‘Greenhouse’ (Penguin, 1999) points out that never has there been an ice age when the CO2 concentration was higher than 200 ppm. This is something that needs exhaustive examination (especially in concert with solar minima that yield less solar irradiance).  This is what I'd consider before gamma ray bursts.

Again, I wouldn't necessarily discount GRBs as a possible contributory agent to ice ages, but these days with more papers published than researchers actually have time to read most astronomers won't waste time on 'reports' or side issues or novel notions that don't at least make it to the 'Bigs' in terms of of publication. It's just the way it is!

As for the mean temperature of Mars, this depends on where you're looking, or where temperatures have been measured. To see assorted answers, as obtained at the solid surface, atmosphere, etc. go to:

http://hypertextbook.com/facts/2001/AlbertEydelman.shtml  

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Philip Stahl

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I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.

Experience

Astronomy: Worked at university observatory in college, doing astrographic measurements. Developed first ever astronomy curriculum for secondary schools in Caribbean. Gave workshops in astrophysics and astronomical measurements at Harry Bayley Observatory, Barbados. M.Phil. degree in Physics/Solar Physics and more than twenty years as researcher with discovery of SID flares. Developed of first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Develop first ever loop solar flare model using double layers and incorporating cavity resonators.

Organizations
American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union.

Publications
Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'. 'Astronomy and Astrophysics: Notes, Problems and Solutions'.

Education/Credentials
B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research (1980), Barbados Astronomical Society Award for Service as Journal Editor (1977-91)

Past/Present Clients
Caribbean Examinations Council, Barbados Astronomical Society, Trinidad & Tobago Astronomical Society.

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