South Oakleigh College ASTROPHYSICS: The Sun

Friday, June 12, 2009

The Sun

The Sun is the star at the center of the Solar System. The Earth and other matter (including other planets, asteroids, meteoroids, comets, and dust) orbit the Sun. The Sun mainly consists of Hydrogen (74% by mass) and Helium (24%). Its diameter is 109 times as big as planet Earth, and it is 150 million Km from Earth. The surface temperature of the Sun is over 5,500C while the temperature inside the Sun is over 15 million degrees. It is 26000 light years from the center of the Milky way and takes 250 million years to orbit the Milky Way.

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AstroPhysics

Astronomy or Astrophysics is the scientific study of stars, planets, comets and galaxies. Astronomy is one of the oldest sciences when people sought to understand the bright lights in the night sky. The invention of the telescope enabled great progress to be made.

The scientific age began when Galileo Galilei , in Florence, Italy built a telescope similar to the design created by Hans Lippershey In 1610 Galileo published his findings that Jupiter had moons. As a result of Galileo's observations he theorised that the Sun is orbited by Earth and the planets. That the moon is not a planet but orbits the Earth. That Jupiter has its own moons. He challenged the belief that the Earth is the center of the Universe with all the planets, the Sun and the Moon and the Stars in orbit around around the Earth.
Galileo also used his telescope to discover that the Milky Way is composed of stars.

Modern telescopes on Earth have discovered a lot of other galaxies other than the Milky Way, during the 20th Century. It was Edwin Hubble who discovered in 1923, that galaxies exist outside of the Milky Way.

In 1990 a telescope, known as the Hubble Space Telescope, was launched into orbit around the Earth, 600km above the Earth and therefore above the Earth's atmosphere. Being above the atmosphere means that the images captured by the telescope are much clearer than are possible on the surface of the Earth, and therefore much more distant objects can be seen and analysed. Check out these sites [ http://hubblesite.org/ and http://hubble.nasa.gov/ ]