On May 9th Mercury will do something that happens only once or twice every decade: On Monday, May 9th, it will be seen passing in front of the Sun.
Known as a transit of Mercury, this event happens about 13 times per century—the next one will be in 2019. However, it won’t be visible everywhere—Japan and other parts of eastern Asia, and Antarctica will be unable to see it, according to Space.com.
Mercury and Venus are the only planets that circle between Earth and the Sun—meaning they’re the only planets whose transit we can see. However, transits are visible from other spots in the solar system—like in 2014, when the Curiosity rover caught glimpse of Mercury’s transit from Mars. And of course, Earth itself has its own transit. In fact, that’s how aliens might find us.
Venus, which is 24 million miles (38 million km) away at its closest point, has transits that can be viewed through a pinhole projector. But Mercury, which is 48 million miles (77 million km) away at its closest point, is too small to be seen with the naked eye. When its transit happens in the fall, it appears to be 1/194 the size of the Sun; in spring, it’s slightly larger, at 1/158. So instead, you’ll have to use either binoculars or a telescope.
Be Careful!!
But for all that is holy, do not look directly at the Sun without appropriate eye protection—that can cause permanent eye damage or blindness.
When watching the transit, you might be able to see its various stages. The first stage (called contact I) begins at 7:12 a.m. ET (11:12 GMT)—and you’ll see Mercury kiss the edge of the Sun. This will grow for three minutes until contact II (7:15 a.m.), at which point the entirety of Mercury will be in front of the Sun. Then, for several hours, Mercury will cross the Sun, hitting the center at 10:57 a.m. ET (14:57 GMT). Contact IV will be when Mercury touches the other side of the Sun (2:39 p.m.), and contact V will be when Mercury last touches the Sun (2:42 pm).
Many observatories around the country and world, as well as amateur astronomy groups, will host events for the transit—be sure to see what’s going on in your area!
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Image credit: TheBrockenInAGlory
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