Venus, a Planetary Portrait of Inner Beauty

MEDIA RELATIONS OFFICE
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DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

News feature: 2012-150 May 31, 2012

Venus, a Planetary Portrait of Inner Beauty

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-150&cid=release_2012-150

A Venus transit across the face of the sun is a relatively rare event -- occurring in pairs with more than a
century separating each pair. There have been all of 53 transits of Venus across the sun between 2000
B.C. and the last one in 2004. On Wednesday, June 6 (Tuesday, June 5 from the Western Hemisphere),
Earth gets another shot at it – and the last for a good long while. But beyond this uniquely celestial
oddity, why has Venus been an object worthy of ogling for hundreds of centuries?

"Venus is a fascinating yet horrendously extreme place all at once," said Sue Smrekar, a scientist at
NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Although the surface is hot enough to melt lead
due to its runaway greenhouse atmosphere, in many respects it is Earth's twin [size, gravity and bulk
composition]."

Venus is not only nearby, but its orbit brings it closest to Earth of all the planets. Which along with its
bright atmosphere goes a long way toward making it the third brightest object in the sky (the sun and
moon are one and two). Along with Smrekar and many other equally intrigued planetary scientists, you
can add to the list of those studying the second planet from the sun the ancient Babylonians, who noted
its wanderings in texts as far back as 1600 BC. And anyone who has ever sweated out a Pythagorean
Theorem in school (a^2 + b^2 = c^2) might find some solace in knowing that Greek mathematician
Pythagoras sweated out the orbits of Venus, eventually becoming the first to determine that what had
been believed to be unique and separate evening and morning stars (as believed by the ancient
Egyptians and Greeks), was actually just one object – Venus.

But for all that these ancient astronomers and their medieval contemporaries (including the Aztecs back
in the 1500s) were able to deduce, no human had ever laid eyes on Venus as more than a bright dot in
the sky until Galileo Galilee, who in 1610 was the first human to actually see Venus in various kinds of
light. With his telescope, Galileo started cranking out Venetian discoveries, including how the planet
changed its illumination phase just like the moon as it circles Earth. Galileo's telescope provided strong
evidence that Venus goes around the sun, and not Earth, as most of his contemporaries believed.

After Galileo, Venus came under even more intense scrutiny, both scientific and fanciful. More than one
astronomer (and science fiction author) theorized it was home to some type of life form. The thick,
impenetrable clouds allowed them to imagine tropical environs with steady rainfall and lush vegetation.

With the dawn of robotic space probes, America's Mariner 2, built by JPL, became history's first
interplanetary traveler when it flew past Venus on Dec. 14, 1962. All told, 45 missions targeting Earth's
twin have been launched by the United States, Russia (and former Soviet Union), and Japan. All this
probing by astronomers and robotic explorers has found Venus to be replete with 900-degree-
Fahrenheit (500-degree-Celsius) temperatures in a carbon-dioxide-rich atmosphere with pressures
equivalent to being half a mile below the ocean surface. It is not a particularly hospitable environment.

"If our research tells us anything, it is that while Venus is devoid of life, it should be anything but
avoided," said Smrekar. "Throughout history, Venus has been one of the most studied and speculated-
about celestial bodies in our sky, and the same truth will hold well after this transit is over. Venus is a
remarkable world with many lessons for us about the climate and interior of Earth and Earth-like planets
in other solar systems."

For those who want to know more, check out NASA's web page for all things Venus transit:
http://venustransit.nasa.gov/transitofvenus/ .

If you're in the western Pacific, eastern Asia and eastern Australia, you'll get a great view of the entire
event. North and Central America, and northern South America get the beginning of the transit (on June
5), but the sun will set before the event ends. Conversely, Europeans, as well as those watching in
western and central Asia, eastern Africa and western Australia will get a glimpse at the tail end.

For information about NASA and agency programs, visit http://www.nasa.gov .

-end-



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