What will you be doing on June 5? If you don’t have plans, you might want to make some… to stand outside and look up into the sky.
The planet Venus will spend about six hours passing across the sun, like a tiny ant crawling across a huge bright melon, and it won’t happen again until the year 2117.
Earthlings can only see Venus’s tiny shadow traverse the sun when Venus, Earth and the sun are all aligned rather than Venus passing just above or below the sun because of its orbit being slightly tilted from ours.
When it does happen, the Venus sun-trek happens twice in an eight-year period, and this year’s trek will be the second half of that pair since the first trek happened in 2004.
The cycle of these pairs is every 105.5 to 121.5 years, and centuries’ worth of professional and amateur astronomers, from Johannes Kepler to Edmond Halley to James Cook have watched the skies for these opportunities.
This year will be no different as astronomers like Jay Pasachoff, who describes the history of Venus’s path across the sun in the current issue of Physics World here, will be watching the planet’s transit.
Astronomers can learn from observing this phenomenon and apply what they learn to their search and study for other planets and solar systems. In fact, they hope to watch Venus’s path across the sun from other vantage points in the solar system as well, such as from the moon and from Jupiter, using the Hubble Space Telescope.