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The Sun, and thus the Solar System, is located in the Milky Way's galactic habitable zone. [98] [99] There are about 208 stars brighter than absolute magnitude 8.5 within a sphere with a radius of 15 parsecs (49 ly) from the Sun, giving a density of one star per 69 cubic parsecs, or one star per 2,360 cubic light-years (from List of nearest ...
1920 – In the Great Debate between Harlow Shapley and Heber Curtis, galaxies are finally recognized as objects beyond the Milky Way, and the Milky Way as a galaxy proper. Within it lies the Solar System. 1930 – Clyde Tombaugh discovers Pluto. It was regarded for decades as the ninth planet of the Solar System.
1995 — First detection of small-scale structure in the cosmic microwave background. 1995 — Hubble Deep Field survey of galaxies in field 144 arc seconds across. 1998 — The 2dF Galaxy Redshift Survey maps the large-scale structure in a section of the Universe close to the Milky Way. 1998 — The Hubble Deep Field South is compiled.
Location of the Solar System within the Milky Way. The Solar System travels alone through the Milky Way in a circular orbit approximately 30,000 light years from the Galactic Center. Its speed is about 220 km/s. The period required for the Solar System to complete one revolution around the Galactic Center, the galactic year, is in the range of ...
The Solar System's location in the Milky Way is a factor in the evolutionary history of life on Earth. Spiral arms are home to a far larger concentration of supernovae , gravitational instabilities, and radiation that could disrupt the Solar System, but since Earth stays in the Local Spur and therefore does not pass frequently through spiral ...
Cosmic Calendar. The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its currently understood age of 13.8 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science . In this visualization, the Big Bang took place at the beginning of January 1 at ...
The models of the Solar System throughout history were first represented in the early form of cave markings and drawings, calendars and astronomical symbols. Then books and written records became the main source of information that expressed the way the people of the time thought of the Solar System.
The most widely accepted model of planetary formation is known as the nebular hypothesis. This model posits that, 4.6 billion years ago, the Solar System was formed by the gravitational collapse of a giant molecular cloud spanning several light-years. Many stars, including the Sun, were formed within this collapsing cloud.