On the morning of Monday, November 11, 2019, the planet Mercury will transit the Sun for the first time since 2016. The transit of a planet across the face of the Sun is a relatively rare occurrence since, as seen from Earth, only transits of Mercury and Venus are possible—those being the only two planets within the inner solar system and closer to the sun than our own. There are only about 13 transits of Mercury each century, and while it’s only been three years since the last transit, the next one isn’t for another 20!
Why is there such an irregularity and scarcity to being able to see these transits? The answer has two parts. First is that Mercury’s orbit is very fast—just 88 (Earth) days compared to our 365. As it whips around the sun, we lumber along, which makes it hard to align our orbits. Second is a larger part in the answer, and that is because the planets in our solar system don’t follow the same orbital plane, meaning the solar system isn’t flat like a plate, as many illustrations suggest. Relative to our orbital plane, Mercury’s is pitched at an angle. When you combine these two factors, you have a fast-moving planet that comes in at an oblique angle to ours, so it’s very rare that our position lines up with the sun both in our orbits and in our orbital planes.
Now that we’ve piqued your interest, you must be asking yourself, “How do I view it, and what will it look like?” Great questions!
You will need an optic like a spotting scope or telescope with approved solar filters in place. These can be basic white-light Mylar or glass solar filters that fit over the objective lens, all the way up to dedicated optical tubes like Meade’s Coronado SolarMax III family of solar scopes. Additionally, the consensus among astronomers is that to be able to discern the transit, you’ll need magnification of at least 50x, so your binoculars will probably need to stay home for this one. As far as mounts are concerned, the transit takes a few hours, so while Mercury will move fast, you will be able to get away with most alt-azimuth telescope mounts or a stable tripod with a sturdy head (if you’re using a spotter). We here at B&H will be using at 70mm double-stacked SolarMax III set on an LX85 GoTo equatorial mount—but we’re pretty extra over here, so that shouldn’t be a surprise. (Plus, we’re planning a Special Event around the transit and we’re going to need some cool gear to pull it off, so look out for details on our social media in the coming weeks).
As far as what it will look, like… well, I wish I had a spectacular string of words that would paint a mind-bending picture of a fantastical astronomical phenomena. But I can’t. It’s going to look like a small black dot moving diagonally across the face of the sun. I know. I know. But think of it this way: You can look through an eyepiece and SEE ANOTHER PLANET. As an amateur astronomer myself, I can tell you that experiencing this for yourself is extremely cool. To be able to say that you saw it with your own eyes, as opposed to a picture on a smartphone, is something that will stick with you.
So, stay tuned for our cool Transit Event to be announced soon, and while you’re waiting check out all things space-related out our dedicated B&H in Space Page here (it’s also where you’ll see new content we’re feverishly writing for the Transit) and, if you have any questions or suggestions, you can drop them down below and we’ll get right back to you.
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