Milky Way's Spiral Arms Could Not Have Caused Climate Change

KentuckyFC writes "One of the puzzles of Earth's climate history is an apparent 140-million-year cycle in the climate record. Various astronomers think this can be explained by the passage of the Sun through the spiral arms of the Milky Way, which also seems to have had a period of about 140 million years. The thinking is that in regions of denser star populations, supernovas would have been more common, bathing the Earth in cosmic rays more often. These cosmic rays would then have seeded the formation of clouds that cool the planet. But in recent years, astronomers have mapped out the structure of the galaxy in much more detail. And now a pair of US astronomers have reanalyzed this climate change idea in light of the new evidence. Their conclusion is that the climate change cycle cannot possibly have coincided with the movement of the Sun through the spiral arms. So whatever caused the 140-million-year climate change cycle on Earth, it wasn't the Sun's passage through the galaxy."

Comments

It is difficult to say who is right

[ctrl-alt-canc]

Both Shaviv's and Melott's papers are based upon models of the Milky Way that are built from observations taken from a single point in the universe, and made during a negligible time frame. This model is then kept valid and unchanged for a timeframe of about 1.000.000.000 years, neglecting for example errors in measuring accelerations of the galaxy and of the solar system, the 3D structure of the galaxy, dark matter influence (and existence...) on the motion of the galaxy, etc. Still too much unknowns before reaching a definite answer, isn't it ?!?

Re:Since these comments are going to suck....

[Dr Damage I]

Long term thinking is all very well so long as the short term picture doesn't sneak up and slit your throat before you get there. We can't "get off oil" tomorrow, that would achieve much the same effect as carpet bombing Americas 20 biggest cities would have. Until there is a viable long term alternative to fossil fuels for baseload electrical power, heating, cooking and transportation, it makes sense to pursue short term solutions to energy problems at the same time is we pursue long term renewable sources of energy