Astronomers say the best — and safest — place to view Mercury passing directly in front of the sun tomorrow is on your computer screen.

Hawai'i is in a prime location for watching the relatively rare event, which happens an average of about 13 or 14 times a century. But it will not be visible to the naked eye since the planet is so much smaller than the sun — an estimated 194 times smaller.

The Mercury transit will start at 9:12 a.m. and last about five hours. Officials warn the public should not try to watch the transit on their own unless they are proficient with telescopes and solar filters.

University of Hawai'i astronomers will use special telescopes at the summits of Haleakala and Mauna Kea to transmit live images of the event over the Internet as a "Mercury Transit Hawaiian Style" webcast. Viewing also is available on the Bishop Museum grounds, where solar telescopes will be set up and the webcast also can be seen.

The webcast will include real-time images of the transit from professional and amateur astronomers in a variety of wavelengths of light, including white light, hydrogen-alpha, and calcium-K, that will provide "wonderful details," said Gary Fujihara of the UH Institute for Astronomy. Sets of images will be compiled into time-lapse movies of the transit and will be updated every half-hour.

Although some scientific knowledge has been gained from planet transits across the sun, such as providing a better grasp of the scale of the solar system, tomorrow's event is perhaps more noteworthy to amateur astronomers and casual skygazers.

"It's the romantic and historical perspective that still appeals to a great many humans here on Earth," Fujihara said.

The last Mercury transit in 2003 couldn't be seen from Hawai'i, and the next one in 2016 will be visible here only minutes before sunset. After that, the next transit that to be seen in its entirety from the Islands will occur May 10, 2062.

The images of the transit will be supplemented on the webcast by interviews with UH astronomers across the Islands. The webcast is a collaboration between the Institute for Astronomy, the UH-Hilo Physics and Astronomy Department, and the Haleakala Amateur Astronomers.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.