As our Earth and Venus orbit the Sun, only rarely does Venus cross between the Sun and the Earth.
The so-called Transit of Venus occurs only twice about every 120 years.
In 2004, Venus made its first transit of the Sun since 1882 -and viewed from Earth, passed across the Sun's southern hemisphere.
8 years later, on June 5th, 2012, Venus transited the northern hemisphere of the Sun.
From NASA's Solar Dynamics Observatory, the nearly 7 hour transit was recorded and speeded up, so that we can view a 15-second time lapse of the complete Venus Transit, in 171 wavelength of extreme ultraviolet light.
Described by some as comparable to seeing a pea move across a dinner platter, Venus only obscured the sun's light by less than 1/100th of one percent.
Only seven transits of Venus have been observed since the invention of the telescope in 1608.
It won't happen again for 105 years-in 2117.
Historically, this rare alignment of the planets is how astronomers accurately measure the size of a planet and its solar system.
While observers on Earth could view the Transit of Venus with simple optical assistance, to see transits of planets outside our own solar system, researchers enlist more sophisticated help. And NASA's Kepler spacecraft provides that.
Kepler has been circling the Sun since 2009 to get a closer and less obstructed view of planets orbiting other stars in our galaxy. When an object transits its star at regular times, a planet has been discovered. And from the brightness change of the star, scientists can tell the size of the planet.
As of the 2012 Venus transit, Kepler has helped scientists confirm more than 60 new planets. And the mission is hoped to last at least through 2016.
