South Oakleigh College ASTROPHYSICS: The nearest stars to the Sun

Friday, June 12, 2009

The nearest stars to the Sun

Proxima Centauri is the nearest star to the Sun. It is about 4.2 light years away [it takes light, which travels at 300,000,000 km every second, 4.2 years to reach us]. Proxima Centauri's mass is about an eighth of the Sun's. The red arrow shows its position in the constellation of Centaurus.

The white arrow below points to Alpha Centaurus one of the pointers to the Southern Cross.

Alpha Centauri is also close to the Sun: 4.37 light years away, and is the third brightest star in the night sky. It is slightly larger than the Sun.

Double-click on the images to enlarge them.

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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/ ]