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Questions tagged [mercury]

Questions about Mercury, the first planet from Earth's sun. Also the smallest major planet in the Solar System.

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κ₀ for Mercury—Formula (another definition)

Following my other question about a specific “hidden” formula in Ptolemy’s model for Mercury, I am now looking for yet another “hidden” formula, this time the one used to find $\bar\kappa_0$ so that $...
Pierre Paquette's user avatar
1 vote
1 answer
242 views

Why is Mercury visible

How is it possible that Mercury can be seem from Earth if it is such a small planet, it has the lowest albedo of any planet, and it is so close to the Sun?
Stephen's user avatar
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15 votes
1 answer
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Why is Mercury's orbit so unusual?

Mercury's orbit has the most eccentricity, 0.2, of all the planets. And this orbit is also the most inclined relative to Earth, 7 degrees. Edit: And to the invariable plane, it is inclined 6.35 ...
DrZ214's user avatar
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21 votes
6 answers
5k views

Why doesn't the IAU definition of "Planet" disqualify Mercury and Venus as planets?

Here's the IAU definition of a planet (source): A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ...
Schroeder's user avatar
  • 511
1 vote
1 answer
70 views

At what exact date and location does Mercury appear at the highest altitude from Earth in history?

I have been messing around with the elongation for Mercury, and I have been getting 27.8 degrees at maximum in https://www.heavens-above.com/PlanetSummary.aspx. Is there any history record that ...
InfinitySwordofDiamond's user avatar
3 votes
1 answer
163 views

Does the observed Perihelion precession of Mercury still deviate from prediction?

In Wikipedia section about the Perihelion precession of Mercury, we have the follwing table titled "Sources of the precession of perihelion for Mercury": Amount (arcsec/Julian century) ...
d_e's user avatar
  • 1,667
12 votes
1 answer
2k views

What rotational speed would Mercury need to have to achieve a temperature comfortable for humans

I wondered what rotational speed would Mercury need to have to achieve a temperature comfortable to humans, let's say 20 °C. EDIT: My idea was that if Mercury is so cold on the night side and so hot ...
Piotr Golacki's user avatar
5 votes
2 answers
932 views

Will Mercury ever become locked to the Sun?

The Mercury year is between 1 and 2 days. Has it ever been greater, and will it eventually become "tidally locked" with the Sun?
John Canon's user avatar
7 votes
1 answer
907 views

What are the "weather" (and other) implications of long "days" and short "years" on Mercury?

On earth, it takes a "day" for it to rotate on its axis, and 365 of these days for it to revolve around the sun. On Mercury a "day" that encompasses a rotation represents 59 earth ...
Tom Au's user avatar
  • 349
5 votes
2 answers
266 views

Can Mercury be seen from the 60th parallel north on Earth? Shetland, Faroe, Norway, St Petersburg, Alaska

I'm originally from a city in Spain which is 40 degrees north, and I used to watch Mercury (naked eye and telescope) every time I had the opportunity, that is, when Mercury was at maximum elongation ...
we'll see's user avatar
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3 votes
1 answer
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Where can I build my house on Mercury so that I can see double sunsets (and sunrises)? Can I do it near the poles where it's cooler?

CNN'S Mercury mission flies by closest planet to the sun for the first time says at the end: Mercury's unusual rotation and oval-shaped orbit around the sun (sic) means our star seems to quickly rise,...
uhoh's user avatar
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3 votes
2 answers
763 views

Could Mercury be a some kind of Chthonian?

A recent news article mentioned that Mercury has an unusually large core - meaning it is denser than the other rocky planets in the solar system. It made me wonder if Mercury could have started as an ...
codeMonkey's user avatar
2 votes
0 answers
55 views

Surface composition of Mercury?

I've been doing research on the surface composition of Mercury, but it doesn't seem that there are many helpful results online from ArXiv. One article from PNAS describes the composition of Mercury as ...
WarpPrime's user avatar
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1 vote
0 answers
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Is the asteroid belt made up of Mercury's former crust?

Mercury has an unusual composition: It seems to consist mostly of metal, which is otherwise common in the cores of planets. Also, Mercury's rocks are rich in volatile materials, which could not have ...
AlgebraicsAnonymous's user avatar
0 votes
1 answer
220 views

When will Mercury have rotated an extra round around its axis?

It is well known that Mercury orbits slightly differently from a pure Newtonian orbit. Every year a slight deviation is found. Now if we observe a lot of these orbits then Mercury should at one point ...
Deschele Schilder's user avatar
3 votes
1 answer
90 views

Planetary tails: How many have we observed yet?

Just recently I learned that Mercury has a sodium tail and it is actually well studied since long: As a result, the planet has the appearance of a comet, with a tail that's been observed streaming ...
B--rian's user avatar
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1 vote
0 answers
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Calculating Angle Between Two Planets In Heliocentric Orbit

My goal is to calculate the retrograde of Mercury. What I've been working from is the book, Practical Astronomy With Your Calculator 3rd edition. I've made some progress, but I seem to be stuck with ...
Misfit's user avatar
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6 votes
1 answer
1k views

Why is Mercury's Density So Low?

I know the title sounds odd. You might be thinking "Doesn't Mercury have the highest uncompressed density of any terrestrial planet? Much higher than a planet its size normally should have?&...
Xi-K's user avatar
  • 403
4 votes
2 answers
300 views

What are the Time Zones on Mercury?

I normally post on worldbuilding, but this question is merely about facts of a planets orbit and spin. I am trying to figure out how time periods work on Mercury to possibly make a worldbuilding guide ...
skout's user avatar
  • 309
4 votes
2 answers
188 views

What are those long, smooth, longitudinally-opposing areas from pole to pole on Mercury?

Look at this model and spin it - Mercury 3d model Are those artifacts of stitching together images, or does Mercury really have these opposing, huge pole to pole lines of smoothness?
richard's user avatar
  • 203
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1 answer
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What is the naming convention for craters on Mercury?

The two largest craters on Mercury are names Caloris (meaning "hot") and Rembrandt (for the painter). So there doesn't seem to be a pattern. By convention, craters on Mars are named for ...
usernumber's user avatar
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3 votes
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86 views

Measured values of the solar irradiance at other values than 1 AU?

It is straight forward to estimate the total solar irradiance of a planet using the Earth's solar constant, and scaling it according to the (mean) distance of the planets. But for which planets have ...
B--rian's user avatar
  • 5,616
6 votes
0 answers
218 views

Did simultaneous transits of Mercury and Venus actually last occur in 373,173 BC?

According to the Wikipedia article for Transit of Venus, the last time a transit of Mercury and a transit of Venus occurred at the same time was 22 September of 373,173 BC. This is a Featured Article ...
Johansson McFleppers's user avatar
9 votes
1 answer
199 views

Mercury's spin-orbit resonance

When was it confirmed that Mercury has a 3:2 spin-orbit resonance and by whom (research group/radio observations...)? The first suggestion was made by Giuseppe Colombo in 1965. Its proximity to the ...
theWrongAlice's user avatar
3 votes
1 answer
161 views

What would the Earth's peri- and aphelion have to be in order to have the same seasons due to its orbit?

Imagine the Earth had no axial tilt but had seasons due to a very elliptical orbit. How elliptical would the Earth's orbit have to be in order to have about the same seasons as it has now (just with ...
Greenhorn's user avatar
  • 397
22 votes
4 answers
5k views

Does anything orbit the Sun faster than Mercury?

Mercury's orbital period around the Sun is about 88 days. Comets and other things have gotten closer to the Sun than Mercury does. But has there ever been an asteroid or some other body discovered ...
Connor Garcia's user avatar
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5 votes
2 answers
637 views

After what time interval do the closest approaches of Mercury to the Earth repeat?

The sidereal period of Mercury's revolution is 88 days and the synodic period — 116d. my solution, but in the question featured "the greatest rapprochement." And this is no longer so easy. ...
марат's user avatar
4 votes
1 answer
642 views

What is the highest point on Mercury?

Continuation of "Gravity on Mercury's highest elevation?" Because when you Google that, you see "Caloris Montes" which is actually a mountain range consisting of mountains 1-2km ...
Nilay Ghosh's user avatar
  • 4,462
3 votes
0 answers
118 views

Gravity on Mercury's highest elevation?

This post answers what is Mars' gravity at its highest point (Olympus Mons) compared to the Earth's and Mars' standard, it's 0.3736 g (Mars standard is 0.3794 g). This also seems to be the lowest ...
John's user avatar
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6 votes
1 answer
217 views

What effects do CMEs have on planets like Mercury?

Some Background? Coronal Mass Ejections, or CMEs for short are the topic of this question. Anyone new to this topic is sure to find some really interesting facts (and consequences) of CMEs and Solar ...
Infinity Milestone's user avatar
1 vote
1 answer
90 views

Is it still the case that the transit of Mercury can't be measured with sufficient accuracy to determine the Sun's distance?

The book Transits -- When planets cross the Sun, Maunder & Moore, page 44 states that Legentil [was] one of the first to realise that transits of Mercury could never be observed with sufficient ...
usernumber's user avatar
  • 17.5k
5 votes
4 answers
596 views

How can Mercury's sodium tail be imaged?

I recently learned that Mercury has a sodium tail. Can this sodium tail be imaged with a ground based telescope? Is so, what is the minimum setup required to be able to take a picture of it? Do you ...
usernumber's user avatar
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12 votes
1 answer
871 views

Are there auroras on Mercury?

Auroras on Earth are caused by interactions between the solar wind and the magnetosphere. I've also seen a few pictures of auroras on Jupiter and Saturn. Mercury has a global magnetic field. Does it ...
usernumber's user avatar
  • 17.5k
2 votes
2 answers
234 views

What effects does the motion of the Sun have on the perihelion precession of Mercury?

According to the wikipedia page, there are multiple effects contributing to the perihelion precession of Mercury. Of course, according to this link and this link we know that the Sun is itself ...
Maximal Ideal's user avatar
5 votes
1 answer
433 views

Does the axial tilt of Mercury and Venus vary?

The axial tilt of Mars varies greatly over time, with a tilt varying between 15 and 25° over the last million years, and varying even more over the last 5 million years. The Earth's tilt on the other ...
usernumber's user avatar
  • 17.5k
35 votes
10 answers
14k views

Why doesn’t the Sun fill the sky on Mercury?

I’ve seen a lot of photos showing Mercury in front of the Sun when it passes by and you can see just how tiny it is in comparison. Here’s a great example: So I’d expect if I was travelling towards ...
Cameron's user avatar
  • 469
5 votes
1 answer
237 views

How could one use the transit of Mercury to try and find the Astronomical Unit?

I am trying to use the transit of Mercury to estimate the distance between the Earth and the Sun, or 1 AU. I know that I need to observe mercury from two antipodes, but I do not understand any of ...
Khanrad's user avatar
  • 63
2 votes
1 answer
160 views

How was the Messenger spacecraft used to measure Mercury's orbital precession to such accuracy? Could this have been done using radar?

This comment under an answer to Path of Mercury and general relativity mentions that the Messenger spacecraft was used to measure the precession of Mercury's orbit to such accuracy that the tiny ...
uhoh's user avatar
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-1 votes
1 answer
168 views

Path of Mercury and general relativity [duplicate]

I have read that many physicists challenge the theory of general relativity, and it has been proved many times that it is correct; my question is on Mercury's orbit. And we know that many of ...
आर्यभट्ट's user avatar
5 votes
2 answers
449 views

What is wrong with this measurement of the synodic period of Mercury?

I'm measuring the synodic period of Mercury using Stellarium. When measuring the synodic period one needs to choose a reference point to start the measurement, and I choose the point when Mercury is ...
Allure's user avatar
  • 4,544
2 votes
0 answers
78 views

How to write a normalized, dimensionless form of Binet's relativistic equation?

$$\frac{\delta^2 u}{\delta \theta^2} + u = \frac{\mu}{h^2} + 3 \mu u^2$$ This is Binet's relativistic equation. Here $u = 1/r$ where $r$ is the radial distance, and $\mu$ is the reduced mass of the ...
zircon's user avatar
  • 139
3 votes
0 answers
140 views

How did Arecibo make radar images of ice on Mercury's poles?

update: I still haven't been able to get my hands on the Icarus paper linked below (I'll try other libraries) but these are newer and quite interesting!: Constraining the thickness of polar ice ...
uhoh's user avatar
  • 30.8k
2 votes
1 answer
117 views

Where can I find data on Mercury's orbit to fit a model to? [duplicate]

I have a project in which a Monte-Carlo method is used to find the optimal parameters for some model that is fit to a data set. I want to fit a model for the orbit of Mercury using this methods, but I ...
DeNLau's user avatar
  • 21
4 votes
3 answers
1k views

What could possibly save an atmosphere other than a magnetic field? Why can't a magnetic field save the atmosphere in certain cases?

Similar question here. We know as a fact that the magnetic field protects planets from Solar Wind, a damaging, continuous, atmosphere-stripping wind of charged ions. Thus, a magnetic field protected ...
Max0815's user avatar
  • 1,862
2 votes
1 answer
318 views

Historical Distance of Planets to Earth [duplicate]

I'm curious if there is a readily accessible tool available, or simply a reliable way to find out what the distance of the planets in the solar system were on a given date. For example, if I am ...
kmehta's user avatar
  • 123
1 vote
1 answer
1k views

If Mercury and Venus where to collide would it make a habitable planet? [closed]

I have been wondering for a while now about a scenario of where if you combined Venus & Mercury would it be habitable if located in the goldy locks zone? I have found in my little research that ...
Kolby L's user avatar
  • 77
5 votes
1 answer
886 views

Explanation of resonance stability and instability

I'm having some trouble grasping the idea of planetary resonances due to what seems to me like an ambiguity. It is known that the asteroid main belt is sculpted by the Kirkwood gaps, corresponding to ...
mysterium's user avatar
  • 811
8 votes
1 answer
151 views

Can Mercury's core "boil over" if it gets to close to the Sun?

I was reading about how Mercury's core makes up most of the volume of the planet. I'm guessing this is both because of the small size and the distance to the Sun. If Mercury got too hot could it ...
Magic Octopus Urn's user avatar
2 votes
1 answer
233 views

Why does in-the-sky.org say that Mercury is not visible from Taipei these days?

I know that viewing Mercury is a challenge, but I'm fairly close to the equator and Mercury was at greatest elongation just a week ago. In-the-sky.org says: All around the world, Mercury is visible ...
uhoh's user avatar
  • 30.8k
3 votes
0 answers
402 views

What is the temperature under the surface of Mercury?

What is the temperature under the surface of Mercury? I know at the surface the temperature varies greatly (-297 F to 801 F). I also realize that the answer would likely depend on depth. Do we know ...
Jonathan's user avatar
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