Looking at the Milky Way from above, we see four giant spiral arms. Our solar system is currently located within a small armlet called Orion, between the two large spiral arms, Sagittarius-Carina and Perseus. However, it doesn't stay there. It rotates at a speed of about 830,000 kilometers per hour around the galactic center, completing a full rotation every 250 million years. This rotation period is called a galactic year. This means that, on average, every 65 million years, our solar system moves through one of the major spiral arms of the Milky Way.
» The Sun controls the Earth's cloudiness. The climate is controlled by the clouds.
The clouds are controlled by cosmic rays. And the cosmic rays are controlled by the Sun. «
The clouds are controlled by cosmic rays. And the cosmic rays are controlled by the Sun. «
The Solar System's passage through the Milky Way (HERE)
During such a passage, the average temperature on Earth is about 5-10°C colder than outside the spiral arms, where more clouds can form, causing cooler climatic conditions. Within a spiral arm, more cosmic rays reach the Earth because there are more supernovae in the immediate vicinity of our solar system. These dying stars emit cosmic rays—subatomic particles with enormous energy rushing through the galaxy at almost the speed of light. Some of them shower down and bombard the Earth. In our atmosphere, the cosmic rays serve as nuclei for the condensation of water vapor and cloud formation. The clouds then reflect sunlight, cooling the Earth.
The Sun, of course, also plays an important role in cloud formation. When there are many sunspots, the Sun's magnetic fields emit more charged particles, called the solar wind. The solar wind counteracts and neutralizes cosmic rays, controlling how many reach the Earth. During the 20th century, the Sun's magnetic activity almost doubled. As a result, fewer cosmic rays reached the Earth, the cloud cover thinned, and the Earth's climate warmed.
The Sun, of course, also plays an important role in cloud formation. When there are many sunspots, the Sun's magnetic fields emit more charged particles, called the solar wind. The solar wind counteracts and neutralizes cosmic rays, controlling how many reach the Earth. During the 20th century, the Sun's magnetic activity almost doubled. As a result, fewer cosmic rays reached the Earth, the cloud cover thinned, and the Earth's climate warmed.
» Within a spiral arm, more cosmic rays reach the Earth. Cosmic rays serve
as nuclei for the condensation of water vapor and cloud formation. «
as nuclei for the condensation of water vapor and cloud formation. «
A ‘lazy’ Sun would produce less magnetic activity, less solar wind, and more cosmic rays would reach the Earth’s atmosphere, where they could build up clouds and cool the planet’s climate. The Sun controls the Earth’s cloudiness. The climate is controlled by the clouds. The clouds are controlled by cosmic rays. And the cosmic rays are controlled by the Sun.
The Cloud Mystery - Henrik Svensmark on Climate Change, 2007.
The Great Global Warming Swindle — Martin Durkin, 2007.
Sources:
Henrik Svensmark and Eigil Friis-Christensen, astrophysicists, Danish National Space Institute (DTU Space), Copenhagen | Nir Shaviv, astronomer, Racah Institute of Physics, Hebrew University of Jerusalem | Jan Veizer, geologist, Department of Earth Sciences, University of Ottawa and Institute for Geology, Mineralogy and Geophysics, Bochum Ruhr University | Jasper Kirkby (2011): The CLOUD experiment at CERN [65 m] | Lars Oxfeld Mortensen (2007): The Cloud Mystery - Henrik Svensmark on Climate Change [53 m] | Martin Durkin (2007): The Great Global Warming Swindle [76 m]