The 2016 Transit of Mercury

On May 9, 2016, they will see a strange spot on the sun–a dark circle moving across the solar disk. This is no ordinary sunspot. It’s the planet Mercury, making a rare transit of the sun.

Mercury passes directly between the sun and Earth about 13 times every century. The last time it happened was ten years ago in 2006, and the next time will be Nov. 11, 2019. This year’s transit will be widely visible from most of Earth, including the Americas, the Atlantic and Pacific Oceans, Europe, Africa and much of Asia. Note it will NOT be visible in Australia.

In the USA it begins on the morning of Monday, May 9, around 7:15 AM EDT. This means it begins before sunrise on the west coast, but that’s no problem. The transit lasts for more than seven hours, so Mercury will still be gliding across the solar disk when the sun comes up over places like California and Alaska. Everyone in the USA can experience the event.

Caution: Take care when viewing the transit. Mercury’s tiny disk—jet black and perfectly round—covers only a tiny fraction of the sun’s blinding surface. Looking at the sun with unprotected eyes on May 9 is as dangerous as ever.

With a proper filter, however, viewing the transit of Mercury can be a marvellous experience. A telescope with a safe solar filter will be required to see the tiny disk of Mercury crawling across the face of the sun. Mercury is too small to be seen without magnification.

Large gatherings will evolve to watch this rare event

You may wish to call your local astronomy club and ask if they have a solar telescope. Amateur astronomers love to show off the heavens. The event will provide volunteers the opportunity to bring their ‘scopes to classrooms for the transit.

If you can’t find access to a good telescope, NASA’s Solar Dynamics Observatory will also witness the entire transit and make it available in real time on its website.

NASA scientist Rosemary Killen and colleagues plan to use the transit to study Mercury’s ultra-thin atmosphere or exosphere. The atoms in Mercury’s exosphere come from the surface of Mercury itself. They are blasted into space by solar radiation, solar wind bombardment and meteoroids. This gives Mercury a comet-like tail stretched out as long as 1.2 million miles. You cannot see this tail during the transit, however.

Killen says, “When Mercury is in front of the sun, we can study the exosphere close to the planet. Sodium in the exosphere absorbs and re-emits a yellow-orange color from sunlight, and by measuring that absorption we can learn about the density of gas there.”

Transit of Venus and Mercury across the Sun seen from Morning Star spacecraft as it slowly comes closer to Venus

She says, “We will be observing the transit from the National Solar Observatory, or NSO, in Sunspot, New Mexico.” Killen, Carl Schmidt of LATMOS at the French National Research Agency, and Kevin Reardon of the NSO will be on site making observations.

The Transit of Mercury offers something to professional astronomers and backyard sky watchers alike—from scientific discovery to simple wonder. Mark your calendar for May 9 and enjoy the show.

Where to See the 2016 Mercury Transit

Regions seeing at least some parts of the transit: Europe, Asia, Africa, North America, South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica.

It is the longest Transit of Mercury transit this century lasting about seven and a half hours. The last one which was longer was in May 1970. In May 2095, there will be another almost as long.

Transit details – May 9

Mercury is in inferior conjunction (passing between the Earth and the sun) and will also transit the sun as seen from Earth. Skywatchers in North America can use a telescope and an approved solar filter to watch the tiny dark dot of Mercury cross the sun today. The transit will be visible to viewers across the globe, except in Australia and easternmost Asia.

The transit begins at 7:12 a.m. EDT (1112 GMT), the midpoint occurs at 10:58 a.m. EDT (1458 GMT) and the transit ends at 2:42 p.m. (1842 GMT). For the western half of North America, the transit will already be in progress when the sun rises. [The Mercury Transit of 2016: Full Coverage] – See more at: http://www.space.com/32786-mercury-mars-rare-celestial-sights-in-may.html#sthash.s8Zljb0P.dpuf

For more news about rare events in the heavens, stay tuned to science.nasa.gov. See more coverage of the 2016 transit of Mercury at http://mercurytransit.gsfc.nasa.gov Source: NASA Science

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