This image, supplied by Theo Ramakers, shows the path Venus will take as it crosses the Sun on June 5.

The local astronomy club is offering free front row seats to a planetary event which won't occur again until 2117.

On Tuesday, shortly after 6 p.m. Venus orbits directly between the Sun and the Earth, allowing those on the Blue Planet to view Venus as a small dark spot crossing the Sun. The Charlie Elliott Chapter of the Atlanta Astronomy Club is inviting those interested to come take a look through two high-powered telescopes set up at Homer Sharp Stadium, 3109 Newton Drive in Covington.

"It is truly a once-in-a-lifetime opportunity to see this and people will not be able to see this for another 105 years and I think this is the key attraction," said Theo Ramakers, education outreach coordinator for the Charlie Elliott Chapter of the Atlanta Astronomy Club. "We estimate over 1 million people will see this all over the world."

Because the orbit of Venus around the Sun is at a slight incline compared to that of Earth, and its orbit is at a different rate, Venus comes into the line of sight from Earth at infrequent intervals. Venus transits occur in pairs, each eight years apart (it last crossed the Sun in 2004), every 105 and 121 years.

The first person to observe Venus crossing the sun was Jeremiah Horrocks in 1639. He watched the transit by projecting an image of the sun onto a piece of paper via a telescope.

"The thing that really fascinates me about this is that at the time he saw the transit, this fellow was 21 and he was able to calculate when the transit was supposed to take place," said Ramakers.

Ramakers said by observing key transit points and paths from different locations on Earth, scientists have calculated the distance from Earth to Venus and from Earth to the Sun. The distance from Earth to the Sun, 93 million miles, has become the standard measurement -- one astronomical unit -- used by scientists to calculate the size of the solar system.

Ramakers said that he and other astronomy club members will set up their telescopes at 5 p.m. so that visitors can observe the Sun for a while before the transit of Venus.

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Astronomy club offers public the chance to view rare astronomical event