Right now, Mercury is making its transit across the Sun, and every second of that journey can be witnessed online.
The Transit of Mercury is a once in a decade phenomenon, according to NASA, and on Monday between about 7 a.m. and 3 p.m. on the east coast, the planet will appear as a “tiny black dot crossing the face of the sun.”
This journey will take about seven and a half hours to complete. It emerged early this morning, was at its midway point at around 10:45 a.m., and will starting drifting away from the Sun by around 2:30 p.m.
The last time this happened was 2006, and the next one isn’t until 2019; the Transit of Mercury happens only 13 times a century.
This transit can be seen from Western Europe, South America, and eastern North America, however, it’s too tiny to be seen without magnification from a telescope or binoculars. In addition, you’ll need solar filters since you can’t look directly at the sun. For skywatchers out west, the Transit of Mercury can be seen with the sunrise.
Mercury goes around the Sun every 88 days (four times quicker than our planet), but this trip is rarely seen, “because Mercury orbits in a plane 7 degrees tilted from Earth’s orbit” and “usually darts above or below our line of sight to the sun,” NASA explained.
The planet makes its transit usually in May or November, and spring transits happen only a third of the time, NBC News reported.
The transit of Mercury 2016 begins at 4:12 a.m. Pacific. Watch it live, right here: https://t.co/EZO82zEcFM— Los Angeles Times (@latimes) May 9, 2016
“During May transits, Mercury’s closer to us, so it appears larger than in November,” said David Rothery, a planetary geoscientist. “You can make more precise measurements in May.”
While everyday stargazers will just enjoy the view, scientists will use the Transit of Mercury to study the planet. These events helped 17th-century scientists figure out the Earth’s distance from the Sun, and in the centuries afterward, they’ve taught us about the atmosphere of Venus (which makes its own transit) and slight shifts in Mercury’s orbit.
Transits like this one also help astronomers find planets outside the solar system, called exoplanets. In the “transit method,” scientists look for a dimming in a star’s brightness as an indicator of a planet passing in front of it. This is considered a “great way” to find “small, Earth-size planets,” and can determine planet’s size and orbit.
During the transit of Mercury, scientists will study the planet’s thin atmosphere in a search for sodium. Its atmosphere reaches a little bit above its surface, so starlight can pass through and illuminate it. The hope is that this analysis will reveal how sodium is released from Mercury’s surface.
The transit will also help calibrate the instruments of spacecraft. While Mercury crosses past the Sun, scattered light from instruments turned toward it may cause it to look illuminated. The transit will help fix this.
“It’s like getting a cataract — you see stars or halos around bright lights as though you are looking through a misty windshield,” said NASA’s Solar Dynamics Observatory project scientist Dean Pesnell. “We have the same problems on the instruments.”
Mostly, however, the Transit of Mercury is an excellent way to educate the public about space, said Rothery.
“This event is a chance to tell people about Mercury — it’s a very perplexing planet for a geologist. It’s important for outreach, to inspire the next generation of scientists.”
The Transit of Mercury also comes at the same time the planet is in retrograde, which astrologists believe influences human behavior and luck on Earth but is technically an optical illusion, CBS News reported.
“Retrograde” refers to a “perceived reversal” in the west-to-east movement of the planet. When Mercury’s orbit and Earth’s catch up to each other, it looks like Mercury is backtracking. This has been blamed on some bad luck — refuted by scientists — back on Earth, from “overspending on new purchases, poorly planned work pitches and unimpressive first dates.”
[Photo by Dmitri Lovetsky/AP Images]