South Oakleigh College ASTROPHYSICS: Relative distance of Earth and Venus to the Sun

Saturday, October 22, 2011

Relative distance of Earth and Venus to the Sun

When Venus is at its highest in the sky at sunset or sunrise, it subtends an angle of approximately 45° (47.8°) to the horizon. At that time of year (the next time will be on January 3rd 2012), the distance from Earth to Venus is equal to the distance from Venus to the Sun. Using pythagorus theorem the distance from Earth to the Sun is then equal to Earth to Venus multiplied by 1.414.
At that time if a radar pulse is sent from Earth to Venus and if the time is taken to record the echo, it will be found to take about 12 minutes and 6 seconds. Halving the time and multiplying by the speed of light, leads to the determination of the distance from the Earth to the Sun as 152 million km.

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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/ ]