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84

When looking at the first image, you need to take into account perspective distortion in images with a narrow field-of-view. This is the same effect that makes people look closer together than they actually are when photographed through zoom lenses (which is useful to bear in mind when reading the news these days!). Mercury is not as close to the Sun as the ...


38

From where we stand on Earth, Mercury is pretty small about 13 arcseconds across at most. The sun, by comparison is about 1800 arcseconds across, so if you are to see Mercury as a disc, you need to magnify your image a lot. And that makes the sun appear very very big. It only appears very big because it has been magnified. But if you are on Mercury, you ...


33

[The real answer is in @James K's answer (it's to do with the field of view of your top image being tiny, but the second one is quite wide). This is to translate the situation into one that might be easier to intuitively reason about.] Let's assume the top photo was taken when Earth-Mercury-Sun is a straight line (this will be very close to true in the top ...


18

I can make a similar image using Stellarium, where the Sun seems huge compared to Saturn. Yet when on the surface of Saturn, the Sun seems much smaller in the sky than it does from Earth. Or in other words, the Sun's angular diameter is much smaller as seen from Saturn. So that first picture doesn't really tell you much about the angular diameter of the ...


13

For intuitive understanding: if Mercury were a lot bigger, but in the same orbit, the view of the sun from the surface of the planet (2nd photo) would be the same, but from our perspective (1st photo), Mercury would look a lot bigger relative to the sun. So from the first photo, you can not derive anything as to how the sun would look from the surface of the ...


13

A magnetic field is only one of the requirements for an aurora (and given the signs of emissions from excited oxygen on Venus after solar flares, it may not actually be a requirement). There needs to be an atmosphere, too. In Mercury's case, there isn't much in the way of an atmosphere. The magnetic field still channels solar wind to the polar regions, where ...


8

And we know that many of astronomers know that mercury orbit does not precess ... Mercury's orbit does precess, by a good amount. The greatest amount is explained by Newtonian mechanics. Venus, Jupiter, and to a lesser extent, all the other planets, make Mercury's orbit precess by over 500 arcseconds per century. A key problem of the latter half of the 19th ...


5

Thanks to the Mercury transit, you can measure the parallax from the Earth. That happens due to TRACE , which tracks the transit of Mercury along the polar diameter of the Earth. During that tracking, the transit of Mercury goes like that: [ Now notice that, if TRACE remained stationary, the transit would be a straight line. So, if you calculate the ...


5

See these questions on photo.stackexchange.com. If you use a telephoto lens so that the sun fills your field of view, it will magnify the size of other objects depending on how far away they are from the lens. So while Mercury looks very close to the sun in that photo, in reality it is between 46 and 70 million kilometers away from it (closer to Earth). ...


5

The size of the object (i.e. Sun) on the Sky doesn't depend on how big is the body you are sitting on (i.e. Mercury). It only depends on a distance from you to this object and its size. So the size of the Sun when viewed from Mercury depends on the distance from Mercury to the Sun, and size of the Sun. Similarly when viewing Mercury and Sun from some ...


4

What effects does the motion of the Sun have on the perihelion precession of Mercury? A better way to phrase that question is "What effects do the planets have on the perihelion precession of Mercury?" When calculating the perihelion precession of a planet, one is implicitly working in a heliocentric frame, one in which the Sun is viewed as fixed. ...


4

There's an optical illusion at play here (click here for video): This scene, from the film Jaws, popularized the "dolly zoom," in which the camera is moved toward the subject while simultaneously zooming out. The result is that the subject's apparent size remains the same, while the apparent sizes of background objects change dramatically. This effect is ...


4

If you hold a marble at arm's length, it's about 1cm wide at 100cm away. The moon and sun are also about 100 times further away than they are big, so they are as big as the marble. If you bring the marble at 20cm away from your eye, that's like being on planet mercury the marble is 6 times bigger. If you shoot the marble at the big sun and take a photo of ...


2

The measurements discussed weren't done by Messenger, they were done by round-trip delay-doppler radar ranging using the coherent transponder of Messenger's Radio_science_subsystem. Park et al. (2017) discuss separating the effects of the solar quadrupole moment from the partially degenerate effects of the post-Newtonian $\beta$ and $\gamma$ parameters (...


2

Much has been covered in the previous answers (especially @Witold's answer), but here's another way to think about the original question: In order to "fill the sky" on Mercury, such that you "can't see the edges of the sun", you would need to be able to look "west" and see the sun, and also "east" and see the sun. Thus, the sun would take up more than 180 ...


1

The cause of the motion of the Sun is the gravitational effects of primarily the outer, massive planets. These also perturb the orbit of Mercury. So rather than "orbiting around a barycentre" you might think of the motion of Mercury and the other inner planets and the Sun as moving in an irregular and constantly changing gravitational field. When ...


1

There is almost no data available on the internet as such. Though, the theory that they (Mercury and Venus) are stabilised by the Sun's Tidal Force seems very likely as they are much closer to the sun than any other planet. The Sun very easily dwarfs these planets in both size and gravitational and tidal attraction. I found this Wikipedia page that I think ...


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