Mercurytransit - Blog Posts

Solar System: Things to Know

Help us find the most interesting spots to image on Jupiter, learn how Hubble is helping the Voyager craft find their way and more!

1. Calling All Citizen Scientists!

Join the Mission Juno virtual imaging team by helping us to determine the best locations in Jupiter's atmosphere that JunoCam will capture. Voting is open January 19-23, 2017. Visit www.missionjuno.swri.edu/junocam for more information about JunoCam voting.

2. Leading the Way

Our Hubble Space Telescope is providing a road map for the two Voyager spacecraft as they hurtle through unexplored territory on their trip beyond our solar system. Along the way, the Voyager craft are measuring the interstellar medium, the mysterious environment between stars. Hubble is measuring the material along the probes' future trajectories and even after the Voyagers run out of electrical power and are unable to send back new data, which may happen in about a decade, astronomers can use Hubble observations to characterize the environment of through which these silent ambassadors will glide.

3. Explorers Wanted

Mars needs YOU! In the future, Mars will need all kinds of explorers, farmers, surveyors, teachers . . . but most of all YOU! Join us on the Journey to Mars as we explore with robots and send humans there one day. Download a Mars poster that speaks to you. Be an explorer!

4. Tracking Every Sol

Each sol, or Martian day, the Mars Curiosity Team tracks the rover’s progress. And you can track them too at: http://mars.nasa.gov/msl/mission/mars-rover-curiosity-mission-updates/. 

5. Happy 425th birthday,  Pierre Gassendi

January 22 is the 425th birthday of Pierre Gassendi, French philosopher, priest, scientist, astronomer, mathematician and an active observational scientist. He was the first to publish data on the 1631 transit of Mercury. The Lunar Crater Gassendi is named for him.

Discover the full list of 10 things to know about our solar system this week HERE.

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Mercury In the Spotlight

For more than seven hours on Monday, May 9, Mercury will be visible as a tiny black dot crossing the face of the sun. This rare event – which happens only slightly more than once a decade – is called a transit.

Although Mercury whips around the sun every 88 days – over four times faster than Earth – the three bodies rarely align. Because Mercury orbits in a plane 7 degrees tilted from Earth’s orbit, it usually darts above or below our line of sight to the sun. As a result, a Mercury transit happens only about 13 times a century. The last one was in 2006, and the next one isn’t until 2019.

When: On May 9, shortly after 7:00 a.m. EDT, Mercury will appear as a tiny black dot against a blazing backdrop, traversing the sun’s disk over seven and a half hours. Mercury will cross the edge of the sun (ingress) after 7:00 a.m. EDT. The mid-transit point will occur a little after 10:45 a.m. EDT, with egress around 2:30 p.m. EDT.

Where: Skywatchers in Western Europe, South America and eastern North America will be able to see the entirety of the transit. The entire 7.5-hour path across the sun will be visible across the Eastern U.S. – with magnification and proper solar filters – while those in the West can observe the transit in progress at sunrise.

Safety!

Unlike the 2012 Venus transit of the sun, Mercury is too small to be visible without magnification from a telescope or high-powered binoculars. Both must have safe solar filters made of specially-coated glass or Mylar; you can never look directly at the sun. We’re offering several avenues for the public to view the event without specialized and costly equipment, including images on NASA.gov, a one-hour NASA Television special, and social media coverage.

The Science…Why are Planetary Transits Important?

Transits like this allowed scientists in the 17th century to make the first estimates of Earth’s distance from the sun. Transit observations over the past few centuries have also helped scientists study everything from the atmosphere of Venus to the slight shifts in Mercury’s orbit that could only be explained by the theory of general relativity. Because we know Mercury’s size and location precisely, this transit will help scientists calibrate telescopes on solar observatories SDO, SOHO, and Hinode. 

Transits can also teach us more about planets – both in and out of our solar system. The Venus transit in 2012 provided observations of the planet's atmosphere. Transits are also the main way we find planets outside the solar system, called exoplanets.

The transit method looks for a drop in the brightness of a star when a planet passes in front of it. This method will not find every planet – only those that happen to cross our line of sight from Earth to the star. But with enough sensitivity, the transit method through continuous monitoring is a great way to detect small, Earth-size planets, and has the advantage of giving us both the planet’s size (from the fraction of starlight blocked), as well as its orbit (from the period between transits). Our Kepler/K2 mission uses this method to find exoplanets, as will the Transiting Exoplanet Survey Satellites, or TESS, following its launch in 2017/2018. 

We will stream a live program on NASA TV and the agency’s Facebook page from 10:30 to 11:30 a.m. -- an informal roundtable during which experts representing planetary, heliophysics and astrophysics will discuss the science behind the Mercury transit. Viewers can ask questions via Facebook and Twitter using #AskNASA.

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