MANILA and SYDNEY - Clouds broke to let Filipinos catch a once-in-a-lifetime cosmic spectacle on Wednesday morning. They joined sky-gazers around the world to watch the planet Venus slide across the sun - a rare celestial phenomenon that will not happen again for more than 100 years.
"We are very lucky," said Engr. Dario dela Cruz, chief of Pagasa's Space, Science, and Astronomy Section. "The next one will be seen by the next generation."
For astronomists, there were four key "contact" times to observe during a transit: the first contact (at 6:09 a.m., Manila time) when Venus was entirely outside the sun's disk, moving inward; the second contact (at 6:27 a.m.) when Venus was entirely inside the sun's disk and moving inward; the third contact (at 12:31 p.m.) when Venus was moving outward from the sun's disk; and the fourth contact (at 12:49 p.m.) when Venus was moving outward from the sun. The "greatest transit" time was at 9:29 a.m., Manila time, when Venus was directly in the middle of the sun, marking the halfway point in the transit.
Apart from the Philippines, the transit was visible in East Asia and the Western Pacific, although poor weather conditions spoiled the view for some. Filipinos on Wednesday morning were similarly threatened by scattered rain clouds, but the formations cleared enough to give most people a good view of the rare occurrence.
Pagasa, the country's meteorological service, gave media and enthusiasts access to the weather bureau's SkyWatcher Apochromatic camera at the University of the Philippines.
"This is a once in a lifetime thing and if you miss it you have to wait until 2117," said Jong Tze Kian from the National Planetarium in the Malaysian capital Kuala Lumpur.
"So people are very excited to come and see the transit."
Australia - for which the movement of Venus carries a special historical interest - was one of the best places to watch with the nearly seven-hour transit visible from eastern and central parts of the country.
"It's not like an eclipse where you've got something blotting out the sun," Fred Watson, astronomer-in-chief at the Australian Astronomical Observatory.
"Venus is 100th of the diameter of the sun so it's essentially just a black spot superimposed on the disc of the sun, but it moves across from one side to the other."
Europe, the Middle East and South Asia got to see the end of the phenomenon, while North America saw its opening stage.
"Everyone's having a great time," NASA scientist Richard Vondrak said from the Goddard Space Flight Center in the US state of Maryland, where 600 people gathered to observe the fiery planet of love.
The event had special significance to Australia as a previous transit in 1769 played a key part in the "discovery" of the southern continent by the British navy's James Cook.
Captain Cook set sail for Tahiti on HMS Endeavour to record the transit that occurred that year, and after a successful observation he was sent to seek the "great south land" thought to exist in the Pacific Ocean.
During the voyage, he charted the east coast of Australia, staking a British claim in 1770.
Planetary transits have enduring scientific value.
"Timing the transit from two widely separated places on the Earth's surface allows you to work out the distance to Venus and hence the size of the solar system," explained Watson in Australia.
Scientists say it also allows them to learn more about how to decipher the atmospheres of planets outside our solar system as they cross in front of their own stars.
Only six transits have ever been observed - in 1639, 1761, 1769, 1874, 1882 and 2004 - because they need magnification to be seen properly, though the event has happened more than 50 times since 2000 BC.
US space agency NASA promised "the best possible views of the event" through high-resolution images taken from its Solar Dynamics Observatory (SDO), in orbit around the Earth.
The European Space Agency's Venus Express is the only spacecraft orbiting the hot planet at present and will be using light from the sun to study Venus's atmosphere.
ESA and Japan's space agency also had satellites in low-Earth orbit to observe as Venus passed in front of the sun.
And the NASA Hubble Space Telescope, which cannot view the sun directly, used the Moon as a mirror to capture reflected sunlight and learn more about Venus's atmosphere.
source: interaksyon.com
