'Chasing Venus' is thrilling adventure story

In this book cover image released by Alfred A. Knopf, "Chasing Venus: The Race to Measure the Heavens," by Andrea Wulf, is shown. (AP Photo/Alfred A. Knopf)

"Chasing Venus: The Race to Measure the Heavens" (Alfred A. Knopf), by Andrea Wulf: On June 5 or 6, depending on the time zone, millions of people around the globe will watch Venus glide across the sun in a rare celestial event that won't happen again until 2117.

Because the planet is just 1/32nd the diameter of the sun, its silhouette will appear as a black speck during its six-plus hour passage. Observers must guard their eyes from dangerous solar rays lest they go blind in an instant.

So why go to the trouble, you ask? Because not that long ago, the Transit of Venus was the key to unlocking the distance between Earth and the sun — and by extension, the size of our solar system.

And also because the strenuous efforts of 18th-century astronomers to measure the exact time and duration of this singular event represent one of the most thrilling chapters in the history of science.

In a fitting homage to those courageous and dedicated souls, British design historian Andrea Wulf has written an absorbing account of their expeditions to do so in 1761 and 1769. (Transits come in pairs that are eight years apart and separated by over a century.)

She begins the story with legendary astronomer Edmond Halley, namesake of the comet, who issued a call in 1716 for scientists to fan out across the globe to witness the unusual alignment that would not recur until some 20 years after his death.

You would be hard-pressed to find a more colorful cast of characters than those who answered the call, including British explorer Capt. James Cook, whose randy crew slept with as many Tahitian women as they could while setting up observation sites on the island paradise.

Wulf's marvelous eye for detail and talent for simplifying complex science make the book, timed for release a month before the last transit of this century, well worth reading before June.

But a word of caution if you decide to partake in the spectacle: Protect your eyes. Dozens of websites including www.transitofvenus.org and www.transitofvenus.nl offer tips on how to do so.

And you might also thank your lucky stars you were born when you were. For even if the weather is a washout, you can watch the transit from the comfort of your living room via NASA's live remote webcast from atop Mauna Kea, Hawaii.