Venus to appear in once-in-a-lifetime eventMay 01, 2012
On 5 and 6 June this year, millions of people around the world will be able to see Venus pass across the face of the Sun in what will be a once-in-a-lifetime experience.
It will take Venus about six hours to complete its transit, appearing as a small black dot on the Sun's surface, in an event that will not happen again until 2117.
In this month's Physics World, Jay M Pasachoff, an astronomer at Williams College, Massachusetts, explores the science behind Venus's transit and gives an account of its fascinating history.
Transits of Venus occur only on the very rare occasions when Venus and the Earth are in a line with the Sun. At other times Venus passes below or above the Sun because the two orbits are at a slight angle to each other. Transits occur in pairs separated by eight years, with the gap between pairs of transits alternating between 105.5 and 121.5 years - the last transit was in 2004.
Building on the original theories of Nicolaus Copernicus from 1543, scientists were able to predict and record the transits of both Mercury and Venus in the centuries that followed.
Johannes Kepler successfully predicted that both planets would transit the Sun in 1631, part of which was verified with Mercury's transit of that year. But the first transit of Venus to actually be viewed was in 1639 - an event that had been predicted by the English astronomer Jeremiah Horrocks. He observed the transit in the village of Much Hoole in Lancashire - the only other person to see it being his correspondent, William Crabtree, in Manchester.
Later, in 1716, Edmond Halley proposed using a transit of Venus to predict the precise distance between the Earth and the Sun, known as the astronomical unit. As a result, hundreds of expeditions were sent all over the world to observe the 1761 and 1769 transits. A young James Cook took the Endeavour to the island of Tahiti, where he successfully observed the transit at a site that is still called Point Venus.
Pasachoff expects the transit to confirm his team's theory about the phenomenon called "the black-drop effect" - a strange, dark band linking Venus's silhouette with the sky outside the Sun that appears for about a minute starting just as Venus first enters the solar disk.
Pasachoff and his colleagues will concentrate on observing Venus's atmosphere as it appears when Venus is only half onto the solar disk. He also believes that observations of the transit will help astronomers who are looking for extrasolar planets orbiting stars other than the Sun.
"Doing so verifies that the techniques for studying events on and around other stars hold true in our own backyard. In other words, by looking up close at transits in our solar system, we may be able to see subtle effects that can help exoplanet hunters explain what they are seeing when they view distant suns," Pasachoff writes.
Not content with viewing this year's transit from Earth, scientists in France will be using the Hubble Space Telescope to observe the effect of Venus's transit very slightly darkening the Moon. Pasachoff and colleagues even hope to use Hubble to watch Venus passing in front of the Sun as seen from Jupiter - an event that will take place on 20 September this year - and will be using NASA's Cassini spacecraft, which is orbiting Saturn, to see a transit of Venus from Saturn on 21 December.
"We are fortunate in that we are truly living in a golden period of planetary transits and it is one of which I hope astronomers can take full advantage," he writes.
From 12.00pm (Midday) BST, the article will appear online at http://physicsworld.com/cws/article/indepth/2012/may/01/venus-its-now-or-never
Also in this issue:
- Fukushima fallout - Steven Judge from the UK's National Physical Laboratory reports from Japan, where he and co-author Hiroyuki Kuwahara have been monitoring radioactive contamination around the stricken Fukushima Daiichi reactor
- Defeating diffraction - once thought to offer imaging at unlimited resolution beyond that permitted by diffraction, "superlenses" never quite worked in practice, but physicists now have a host of other ideas that could make perfect images, as Jon Cartwright reports
Institute of Physics
Related Venus Current Events and Venus News Articles
Most eccentric planet ever known flashes astronomers with reflected light
Led by San Francisco State University astronomer Stephen Kane, a team of researchers has spotted an extrasolar planet about 117 light-years from earth that boasts the most eccentric orbit yet seen.
New study zeros in on plate tectonics' start date
Earth has some special features that set it apart from its close cousins in the solar system, including large oceans of liquid water and a rich atmosphere with just the right ingredients to support life as we know it.
Astronomers eager to get a whiff of newfound Venus-like planet
The collection of rocky planets orbiting distant stars has just grown by one, and the latest discovery is the most intriguing one to date.
How did plate tectonics start on Earth?
Our planet Earth is the only planet in the Solar System that possesses Plate Tectonics. The Earth's surface is in a constant state of change; the tectonic plates together with the oceans and continents continuously slide along one another, collide or sink into the Earth's mantle.
Plate tectonics thanks to plumes?
"Knowing what a chicken looks like and what all the chickens before it looked like doesn't help us to understand the egg," says Taras Gerya.
Public Release: 29-Oct-2015 UW scientists are the first to simulate 3-D exotic clouds on an exoplanet
Scientists have catalogued nearly 2,000 exoplanets around stars near and far. While most of these are giant and inhospitable, improved techniques and spacecraft have uncovered increasingly smaller worlds. The day may soon come when astrophysicists announce our planet's twin around a distant star.
Earth-like planets around small stars likely have magnetic fields, aiding chance for life
Earth-like planets orbiting close to small stars probably have magnetic fields that protect them from stellar radiation and help maintain surface conditions that could be conducive to life, according to research from astronomers at the University of Washington.
Hot, dense material surrounds O-type star with largest magnetic field known
Observations using NASA's Chandra X-ray Observatory revealed that the unusually large magnetosphere around an O-type star called NGC 1624-2 contains a raging storm of extreme stellar winds and dense plasma that gobbles up X-rays before they can escape into space.
Inspired by venus flytrap, researchers develop folding 'snap' geometry
Inspired by natural "snapping" systems like Venus flytrap leaves and hummingbird beaks, a team led by physicist Christian Santangelo at the University of Massachusetts Amherst has developed a way to use curved creases to give thin curved shells a fast, programmable snapping motion.
NASA simulation indicates ancient flood volcanoes could have altered climate
In June, 1991, Mount Pinatubo in the Philippines exploded, blasting millions of tons of ash and gas over 20 miles high - deep into the stratosphere, a stable layer of our atmosphere above most of the clouds and weather.
More Venus Current Events and Venus News Articles