Transit of Venus: An amazing lineup

We’ll only get one more chance to see this, and McMaster experts will be on hand to make sure we know what we’re looking at.

On Tuesday, June 5, Venus will pass between Earth and the sun for only the seventh time in recorded history, a celestial event called a transit, and one that will not occur again until 2117.

The first record of a transit dates back to 1639, with the most recent being in 2004. Transits come in close pairs separated by long breaks, due to the uneven alignment of the orbits of Earth and Venus.

During the transit of Venus, the planet will track down the face of the sun as viewed from Earth, with this part of the planet in position to see it for about three hours before the sun sets.

“I think it’s going to be amazing,” says Robert Cockcroft, manager of McMaster’s W.J. McCallion Planetarium. “It’s pretty exciting to know that this is only the seventh time that humans have seen this event.”

For those who use safe viewing methods to watch the event, Venus will look like a small black dot travelling through the upper right quadrant of the sun’s disk, starting at the top centre.

At 4 p.m. on the day of the transit, there will be a special presentation at the planetarium to explain the transit and what it means.

Later, planetarium presenters will welcome the community for a free, guided look at the event. Like an eclipse, the transit is dangerous to watch directly with the naked eye, but the presenters will have a limited supply of special glasses and a telescope with a solar filter for watching the event.

The transit of Venus is not only a rare occurrence. It is also an important opportunity for astronomers, Cockcroft explains. Over history, its movement through Earth’s view of the sun allowed astronomers to make increasingly precise calculations of the sun’s distance from Earth.

Modern scientists will use it as a model for studying similar transits involving more distant planets and stars.

No reservations are required for the guided viewing, which is to take place on campus near the east side of the bridge over Cootes Drive, which offers an unobstructed view of the western sky. The session begins at 5:30 p.m. and ends at sunset. The transit is to begin at 6:04 p.m.