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A UFO will cross the Sun on Nov 11. Or perhaps it will be Mercury.

Notrump

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Notrump
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No, that tiny disc that can be seen racing in front of the Sun on November 11th will not be an ET’s flying saucer.

The innermost planet Mercury will appear to transit the disk of the Sun on 2019 NOV 11 for observers in the Americas, Europe, Africa, Near East and New Zealand. This will be the last Mercury transit until 2032, and until 2049 for North Americans.

As with a Solar Eclipse, great care must be taken to protect eyes. If not accompanied by an expert in solar viewing, it may be wise to simply watch online live videos of the transit.

I’ve created graphics depicting the transit as viewed from various cities. They can be seen at https://www.CurtRenz.com/mertran.html

Photos and descriptions of the transit would be welcome additions to this thread.
 
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11:30 pm to 5:00 am. Great. At least I won't have to worry about eye damage.
 
This looks like a possible chance to use my eclipse binoculars again. Though the magnification may or may not be enough to see the dot that way.
 
One thing I do not understand. Two facts that I cannot reconcile.

1. Mercury and Venus both come roughly between us and the sun several times a year, yet it is rare for them to come directly between us and the sun.
2. We can find planets going around other stars because these planets go between us and their sun. When we observe this we see it happen every time.

Would have thought that planets going around other suns would rarely go between their sun and us for the same reason that Mercury and Venus rarely go between the sun and us.
 
rjh01 said:
One thing I do not understand. Two facts that I cannot reconcile.

1. Mercury and Venus both come roughly between us and the sun several times a year, yet it is rare for them to come directly between us and the sun.
2. We can find planets going around other stars because these planets go between us and their sun. When we observe this we see it happen every time.

Would have thought that planets going around other suns would rarely go between their sun and us for the same reason that Mercury and Venus rarely go between the sun and us.
Click to expand...


It's my understanding that this is because of the the difference in observation distance and relative motion. We can observe planetary transits across distant stars no matter where in our orbit we are, as long as something local doesn't interpose itself, as at that scale we are essentially immobile viewers. In our local system however we are moving quite rapidly relative to and at different orbital periods than our friendly neighborhood rocks.
 
rjh01 said:
One thing I do not understand. Two facts that I cannot reconcile.

1. Mercury and Venus both come roughly between us and the sun several times a year, yet it is rare for them to come directly between us and the sun.
2. We can find planets going around other stars because these planets go between us and their sun. When we observe this we see it happen every time.

Would have thought that planets going around other suns would rarely go between their sun and us for the same reason that Mercury and Venus rarely go between the sun and us.
Click to expand...


Excellent question, rjho1. We can thank TalosMarr for a correct explanation, nevertheless I'll elaborate.

When Mercury or Venus is in inferior conjunction, it is significantly closer to Earth than Sun is to Earth. This is particularly true for Venus. The percentage difference in the case of an exoplanet is insignificant, and the angular perspective is barely variant.

From the perspective of the Sun, when Earth and Venus appear in conjunction, the angular separation can range from 0˚ to 3.4˚. But as viewed from Earth when Venus is in inferior conjunction, the angular separation between Venus and Sun can range from 0˚ to 8.4˚, while the angular diameter of Sun is only 0.5˚.

Transits of Mercury or Venus must occur at not only an inferior conjunction, but also when the planet is near a node, which is on the line of intersection between the orbital planes of that planet and Earth.

Venus averages an inferior conjunction every 1.6 years. and Mercury 0.32 years. Nevertheless, Venus appears to transit Sun an average of less than two times per century, while Mercury does so about 13 times per century. ;)
 
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Notrump said:
No, that tiny disc that can be seen racing in front of the Sun on November 11th will not be an ET’s flying saucer.

The innermost planet Mercury will appear to transit the disk of the Sun on 2019 NOV 11 for observers in the Americas, Europe, Africa, Near East and New Zealand. This will be the last Mercury transit until 2032, and until 2049 for North Americans.

As with a Solar Eclipse, great care must be taken to protect eyes. If not accompanied by an expert in solar viewing, it may be wise to simply watch online live videos of the transit.

I’ve created graphics depicting the transit as viewed from various cities. They can be seen at https://www.CurtRenz.com/mertran.html

Photos and descriptions of the transit would be welcome additions to this thread.
Click to expand...

I think I might still have my eclipse glasses, from 2017, around somewhere.
 
Mercury is smaller than many sunspots. Without magnification, you'll be lucky to see anything. DO NOT THINK of using regular binoculars or telescopes IN FRONT of your eclipse glasses.

Best and safest way to view it for 99.9+ % of people is by watching one of the internet live feeds from the guys with fancy expensive telescopes.
 
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rjh01 said:
Would have thought that planets going around other suns would rarely go between their sun and us for the same reason that Mercury and Venus rarely go between the sun and us.
Click to expand...

You're correct.

1) We *can't* see most planets around other stars this way. But we can do the geometry math and guess that if we can actually see planets around "x" stars, that it means that if the orbits are aligned randomly that there's another "y" stars with planets that we can't see.

2) As you get closer to the sun, the volume of space that you can see due to transits decreases. Imagine a cone with the vertex at your eye, and the base at the sun. You can see transits of any planet that enters the cone. As you approach the sun, the cone decreases in size and there are fewer things you can see. For remote stellar systems, the cone is so tall that it's basically a cylinder within that system.
 
I still have my eclipse binoculars and an eclipse filter for my DSLR. I think I even know where they are!

ETA: Curt, do you have data for the Seattle area? Or shall we just assume it'll be cloudy anyway, which is not a bad assumption.
 
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I've had success mounting my binoculars or a telescope pointed at the Sun and projecting the image coming out the eyepiece onto a white surface. In fact, I showed it to my entire 2nd-grade class at the time.

You want to line it up using the projected image and not through the eyepieces, of course.
 
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rjh01 said:
Would have thought that planets going around other suns would rarely go between their sun and us for the same reason that Mercury and Venus rarely go between the sun and us.
Click to expand...

I'll rephrase other peoples correct explanations in order to add another point.

We don't see transits frequently because the orbits of Mercury, Venus, and Earth are all tilted. For the situation in this solar system, the tilt means that most of the times when Venus or Mercury pass "in front" of the Sun, they will pass either above it or below it. The only times when we'll see a transit is when the Earth is near the one line of intersection that Earth's orbit shares with the other planet (the "node" that was mentioned earlier).

For distant star systems that distance means that the tilt of our orbit doesn't mean much at all and neither does our orbit*. Earth is essentially a stationary point. If Earth is on a line that intersects both that distant star and the planet orbiting it then we are in that planets orbital plane and will be every orbit it makes.

However, "the same reason" that you referred to may also be in play in that distant star system. The planetary orbits in that system may also have different tilts. What that means to us though is that those planets will never transit the star from our point of view. You probably already know that the transit method requires the distant star system be view "edge on" and only works for a small percentage of systems that are properly oriented towards us. However, it also means that even in a system that has some well oriented planetary orbits, not all planets in that system will necessarily have similar opportune orbits.

* There are some edge cases where those factors matter.
 
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Here's my chart showing who's in and who's out for the transit.
 

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I have admitted - and shown - that I am stupid. Will I be able to see this from my location, North of San Francisco? Thanks.
 
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