NASA Goddard Space Flight Center Sun-Earth Day
An illustration of the Venus transit from James Ferguson's book Astronomy Explained.
By Assistant managing editor
updated 6/1/2012 12:25:46 PM ET 2012-06-01T16:25:46

A rare opportunity to see the planet Venus cross in front of the face of the sun is coming up next week.  

On June 5 to 6, Venus will "transit" the sun for the last time until 2117, joining the ranks of the handful of planetary transits that have occurred since the dawn of modern astronomy.

From our vantage point on Earth, we occasionally have the chance to see two planets — Venus and Mercury — pass in front of the sun, as these are the only two planetary bodies between us and our star.

Transits of Mercury are more common than Venus transits, with an average of 13 occurring each century. Venus transits come in pairs separated by eight years, with more than a century usually elapsing between one pair and the next. [ Gallery: Transits of Venus Throughout History ]

"The first transit ever observed was of the planet Mercury in 1631 by the French astronomer (Pierre) Gassendi," Fred Espenak, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., wrote on the NASA Eclipse website. "A transit of Venus occurred just one month later, but Gassendi's attempt to observe it failed because the transit was not visible from Europe. In 1639, Jeremiah Horrocks and William Crabtree became the first to witness a transit of Venus."

Planetary transits through history
Historically, planetary transits have offered a rare chance for scientists to learn about the solar system.

In the 18th century, transits of Venus provided astronomers with the first way to measure the absolute size of the solar system, including the distance from the Earth to the sun, which wasn't known at the time. Astronomer Edmond Halley first came up with the method of comparing measurements made from various locations on Earth to triangulate the distances to Venus and the sun.

This technique was successfully put into practice during expeditions to observe the Venus transits of 1761 and 1769 from around the world.

And even as recently as 2006, the transit of Mercury was used to measure the size of the sun. A group of astronomers from Hawaii, Brazil and California used NASA's Solar and Heliospheric Observatory (SOHO) to time the transits of Mercury across sun in 2003 and 2006, enabling the most precise measurement yet of the diameter of the sun.

"Transits of Mercury occur 12 to 13 times per century, so observations like this allow us to refine our understanding of the sun’s inner structure, and the connections between the sun’s output and Earth’s climate," one team member, University of Hawaii astronomer Jeff Kuhn, said in a statement.

And the science being planned for the upcoming Venus transit is a step ahead of research done during the 2004 Venus transit, as instrumentation and research goals have advanced, said Matt Penn, lead scientist at the McMath-Pierce Solar Telescope at Kitt Peak observatory in Arizona. [ 2012 Venus Transit Observer's Guide (Infographic) ]

Much of the research during the past Venus transit focused on using spectroscopy — a technique to divide light into its constituent wavelengths — while looking for polarized light will be the thrust of many researchers' aims this time around, he said.

  1. Space news from NBCNews.com
    1. KARE
      Teen's space mission fueled by social media

      Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

    2. Buzz Aldrin's vision for journey to Mars
    3. Giant black hole may be cooking up meals
    4. Watch a 'ring of fire' solar eclipse online

"The opportunity to read what other people did in 2004 and to build on their work is a unique opportunity," Penn told Space.com. "We're hoping that one of the experiments will allow us to detect polarization through Venus' atmosphere."

Venus ties to alien planets
The upcoming transit will be used not just to study the architecture of our own solar system, but that of others as well.

"Astronomers in the 18th and 19th centuries observed transits of Mercury and Venus to help measure the distance from Earth to sun," said Frank Hill, director of the National Solar Observatory’s Integrated Synoptic Program. "We have that number nailed down now, but transits are still useful. This one will help us calibrate in several different instruments, and hunt for extrasolar planets with atmospheres."

The transits of alien planets in front of their stars, from the point of view of Earth, are one of the key ways scientists discover such planets' existence. As planets pass in front of their stars, they briefly dim the stars' light, signaling their presence.

And just as with Mercury and Venus, the filtering of stars' light through planets' atmospheres can reveal clues regarding the presence and composition of gaseous atmospheres around these distant worlds.

Since scientists know quite a lot about Venus' atmosphere by now, they can use observations of its transit to calibrate their instruments and set a benchmark for studying the atmospheres of new planets beyond the solar system.

You can follow Space.com Assistant Managing Editor Clara Moskowitz on Twitter @ClaraMoskowitz.Follow Space.com for the latest in space science and exploration news on Twitter  @Spacedotcom  and on  Facebook.

© 2013 Space.com. All rights reserved. More from Space.com.

Photos: Month in Space: January 2014

loading photos...
  1. Southern stargazing

    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

    The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps. (NASA) Back to slideshow navigation
  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  4. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

Discuss:

Discussion comments

,

Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments