Tonight the skies will present a show that won't play again in Westminster until December 2125. If the weather cooperates, observers will see the transit of Venus this evening, when Venus crosses between Earth and the sun.
Jeff Marx, associate professor of physics at , said that the event is significant for several reasons.
First, he said it's simply beautiful.
"Any alignment (or near alignment) of planets, stars, asteroids, whatever, has always captivated people," Marx said. "Events such as these amplify in people’s minds the ideas of harmony, symmetry and order."
Additionally, he said the rarity of the event makes it special. According to Marx, the next transit of Venus that will be seen from Westminster will be in December 2125. Eight years before that, in 2117, people in Asia will be able to see it.
The transits of Venus have helped shape astronomy. Marx said that historically, scientists used the transits of Venus to determine the distance between the Earth and sun. He said it was one of the first ways that astronomical distances were determined.
"That said, I have read that scientists in the 1800s were able to determine the distance to the sun to be 95 million miles," Marx said. "That’s not too bad, considering our best methods today have it around 93 million miles."
Marx said the event also holds historical relevance because it represents one of the first “big science” projects. To make the data more reliable, many people had to make multiple measurements at nearly the same time from distant locations.
"This project was multinational science, requiring dispatching scientists to remote locations, close collaboration and sharing of results," Marx said.
But modern day scientists are also interested in this celestial event. Marx said space agencies will be watching closely.
"This event is significant because space agencies are going to be watching sunlight as it passes through Venus’ atmosphere. We actually already know a lot about Venus’ atmosphere, which is the point," Marx said. "Essentially scientists are going to use what they already know about the venutian atmosphere to calibrate their techniques. Techniques which will then be used to look at the atmospheres of planets outside our solar system."
If the skies remain clear, you will be able to watch the transit of Venus, but Marx warns that you should never look directly at the sun with your bare eyes.
Marx suggested using "eclipse glasses"-glasses that essentially block a large amount of the light from the sun so it doesn't damage your eyes. If you don't have the glasses, you can use a telescope providing you have the right filters. And a third option is to build a pinhole camera.
What will you see? Marx said that as the transit progresses, you should be able to see a very small black disk very slowly move across the face of the sun. That will be Venus. It will take several hours to occur.
In Westminster, it should begin shortly after 6 p.m. and will not finish before the sun sets, so we will not be able to witness the entire event, Marx said.