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Questions tagged [moon]

A smaller body orbiting a larger, primary body, where the primary body is not a star.

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Energy from nothing [duplicate]

How come Titan gets hot from being dilated and contracted by Saturn gravity? Does this mean that gravity creates energy? What is the primal cause for this?
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How would humans with appropriate equipment navigate the surface of Saturn's moon Titan on foot? [on hold]

I'm not sure if this is the proper stackexchange sub-community to post this, but here goes... Taking into account the physical characteristics of Titan (e.g. surface gravity, atmospheric pressure), ...
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Why do some scientists want a moon base for further space travel? What are the advantages of a moon base if compared with an earth base? [migrated]

The distance between moon and earth is just 384,400 km. So, if we can travel (from moon) to another planet, we also can travel (from earth) to the same planet. But I've read that some scientists want ...
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Convert Irradiance to Radiance

I need to remove lunar radiance from a satellite image. I have a satellite image (VIIRS DNB) which contains radiance in $$\rm W\,{cm}^{-2 }\,{sr}^{-1}$$ I also calculate lunar radiance with: $$L_m=(...
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If the Earth would change into a ball of water, how wil its form develop, considering only the Sun's and Moon's influence? [duplicate]

Let's fantasize that the Earth changes in a non-rotating ball of water. And let's assume the only gravitational influences on it are those of the Sun and Moon. What will happen to the form of the ...
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What happens to the water on the surface of the Earth if the Earth is not rotating about its axis in the Earth-Moon system?

Suppose the Earth is not rotating. As usual, the Moon follows its normal path around the Earth. Let's assume it's a circular motion and that there are no other gravitational influences. A test ...
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How severe would the consequences be if the earth's moon were wrenched from orbit?

The old TV series Space 1999 from the early 1970s seems to have resurfaced on Youtube reminding me of something I watched as a child. It is one of those obviously ridiculous SciFi series (from the ...
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Confusion about angular momentum of earth moon system

My assumed definition of angular momentum is the sum over $i$ of $L_i =r_i\times{\omega_i}\times{r_i}$ for each particle about some origin. We have two spheres rotating about the centre of orbit. For ...
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Watts in the brightness of a Full Moon

I heard that there is a order of magnitude of brightness/luminosity for a full moon, roughly 398110 times less than the luminosity of the sun. And the luminosity of the sun to watts is 3.846 x 10^...
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Can amateurs use the retroreflector on the moon? [duplicate]

There is a retroreflector on the moon, placed there, I believe, by astronauts in the 1970s. I think there is at least one station (in France?) that continuously beams a laser at it to measure the ...
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How to tell if the moon is waxing or waning?

Imagine you are placed in an unknown location in the middle of the ocean. You see the moon at its half. Which are the different "sets of information" which, if provided to you, would allow you to ...
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Can a planet have multiple significant sized moons?

The Earth has one moon at about 1/80 of Earth's mass. Is it possible to have two moons large enough each to subtend a >30 minute disk as viewed from the surface? I have tried with various ...
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78 views

What would happen to the Earth, if the moon was a black hole? [closed]

Would it be a feasible scenario? I have read this question: What would happen to the Moon if Earth is turned into a black hole? Where Lubos Motl says: The extremal Kerr J=GM2/c∼RbhMc. Now, the ...
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How did the Moon get into orbit?

It's the accepted theory that Moon was formed when an object collided with Earth, throwing off a lump of matter which became the Moon. But also, an object cannot be launched into orbit from a planet ...
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1answer
28 views

Difference in gratitational field due to lunar apogee/perigee

I am trying to answer this Phys.SE question but got an unreasonable answer: In making laboratory measurements of $g$, how precise does one have to be to detect diurnal variations due to the moon's ...
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2answers
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Delta-V of Earth to Moon mission using Moon orbit

I have read this article here and it talks about the delta-v cost of travelling to and from the Moon. Importantly it says that getting to an orbit round the Moon, and docking with a space station, and ...
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72 views

Is there any moon without its planet?

Is there any planet without its star? Is there any moon or any planet wandering in outer space without a definite orbit? (The name moon or planet used here serves only for size and spherical shape ...
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Does water height in mixed semidiurnal tide systems change in a sinusoidal pattern between peaks?

I'm writing a bit of plotting software that takes the time of high tides and low tides and interpolated what the height should be between these times. I know that diurnal tidal systems follow a ...
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1answer
26 views

Would a Lunar space elevator only be stable if it passes through Earth-Moon L1 or L2?

I understand that space elevators are extremely hypothetical (bordering on pure fiction), but they are supposed to be theoretically possible. My questions is about what longidtudes a lunar space ...
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In which direction is orbit around the moon easiest to achieve?

Suppose a conventional spacecraft is launched from Earth with the intention of establishing an orbit around the Moon. In the context of this question, the Earth/Moon system is viewed from far above ...
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1answer
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What's keeping the Moon in its orbit when the Sun's gravity is greater? [duplicate]

Just as the title says, what's keeping the moon in its orbit around the earth while sun's gravity is greater, why doesn't it deviate and take an orbit (purely elliptical without moving around the ...
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1answer
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Why does not the Moon escape from the Earth? [duplicate]

We know that Gravitational Force that is applied by the sun on the moon is greater than that by the earth on the moon. My Question is then why does not the moon escape from the earth and go towards ...
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What caused the curve in the Apollo transearth trajectory?

In reference to the below image, The thin black curved line is the Apollo 11 trans-lunar trajectory (outbound) The dark blue line is a tangent to the trajectory just after the TLI burn (as best as I ...
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Lunar angular frequency

I have this question from my teacher which quite confuses me. It asks to calculate lunar angular speed, when we know that the Moon circles Earth in 27.3 day. Why is number (27.3) significant here? ...
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Why doesn't the moon appear yellow?

The sky is blue (I'm told) because nitrogen in the atmosphere scatters short blue wave lengths of light from the sunlight, which is also why the sun appears somewhat yellowish rather than white, as it ...
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If the moon also fall then why can the astronaut moonwalks?

imagine astronauts inside the ISS while everything are in free fall, the astronauts are floating around. Now if the moon are also in free fall then how come astronauts can perform moonwalk on the ...
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Energy from tidal waves [duplicate]

We all know that the Moon orbits around the Earth, and that this happens because the kinetic energy from the Moon is enough to "deny" Earth's gravity but not enough to escape its orbit. If I'm not ...
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1answer
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Can the collision of asteroids form another moon?

In the lifetime of the earth, is it possible for sufficient collisions to occur in the asteroid belt to form a prototype moon?
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Is it possible to achieve a stable Low Lunar Orbit? [duplicate]

I have been researching on Lagrangian points, and also Low Lunar Orbits. However, following what I have read, LLO is unstable and can easily be perturbed from its orbit. On the other hand, I have also ...
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How big a lens would you need to light a fire with moonlight? [duplicate]

Randall Munroe posted an interesting what-if in which he claims that you can't use moonlight to light a fire, because it is impossible for reflected light to raise the temperature of an object higher ...
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Why does the full Moon appear?

I know that the full Moon appears when Sun, Moon and Earth are in a straight line, but if we consider that they are in straight line, why is the Moon illuminated? I mean to say that Earth should ...
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1answer
66 views

Does the moon rotate around the earth-moon axis?

It is well known that the moon always shows the same side to the earth. But does the orientation of this side change? I.e. does the moon rotate around the moon-earth axis?
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Buoyancy on the Moon

A body is floating partly immersed in a liquid. The body and the liquid are taken to the Moon. What will happen next? Will its immersed part come out of the liquid? Will it sink? Will it continue to ...
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3answers
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Why is a bright night sky dark?

The sky in the day is colored blue because molecules in the air scatter blue light from the light of the sun. The sky during a some nights of having a full moon is very bright, as it shines the dark ...
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2answers
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Increasing distance between Earth and Moon [closed]

I have a problem where a planet's rate of rotation is decreasing due to tidal effects of the moon. I know that the angular momentum of the system will be conserved. So, in order to conserve that the ...
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152 views

Distance from the center of earth to Lagrange point L1 (Earth-Moon system)

I have derived an equation for the distance from the center of earth to the L1. I have then used python to solve this equation (approximately). I have obtained a value of 326045071m (326045km). I ...
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2answers
212 views

If gravity can be disrupted by larger forces, why does the moon orbit the Earth instead of the Sun? [duplicate]

I read an thread on this site about how a larger gravitational pull can overpower a smaller gravitational pull. I took this to mind, and I started wondering why the moon orbits the Earth instead of ...
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329 views

Does escape velocity require you to cross Moon's orbit?

Escape velocity is the velocity required to project an object from an object's (here, the Earth's) surface so that it "escapes" the gravity of that object (or in our case, the Earth's gravity). Now, ...
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why do total solar eclipses vary in length?

Quoting https://www.mnn.com/earth-matters/space/blogs/why-2024-total-solar-eclipse-may-outshine-2017, For the 2017 eclipse, the duration of totality will last between 20 seconds (over Kansas City,...
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1answer
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What speed should I maintain on land or in the air in order to experience the whole path of total solar eclipse?

What speed should I maintain on land or in the air in order to experience the total path of total solar eclipse? And What other factors are taken into account for calculating that speed? For e.g. ...
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1answer
106 views

Total eclipses becoming rare soon?

Given that the moon is receding from the earth and that the average angular size of the moon is approximately equal to the angular size of the sun at the moment, what is the current rate at which ...
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How can a full moon be seen south of an observer's location?

I know this seems like a simple question, but I'm trying to debate with a flat earth theorist. I asked him to explain why can the ISS visibly be seen orbiting the Earth with the naked eye, and he put ...
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1answer
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“Global” orientation of an inclined orbital plane

I'm pretty much trying to figure out, whether an inclined orbital plane rotates with its parent or not. To make my problem understandable an equivalent question would be, whether the longitude of ...
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1answer
303 views

Expanding Moon's orbit and newtonian mechanics

the 2 body problem of earth and moon is suppose to be perfectly described by Newtonian mechanics / Kepler's laws. How ever the moon's orbit is been moving away from earth in contradiction to the ...
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1answer
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Someone walking on near side vs. far side of Moon - are weights different? [duplicate]

Running a thought experiment, I considered someone's weight when they were standing on the Earth with the Moon directly overhead. My initial thought was that the person weighs less because the Moon's ...
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2answers
569 views

Gravity on the surface of Io

Something about this seems a little incorrect to me but I can't quite put my finger on it. The moon closest to Jupiter is Io, with a diameter of $3650$ km and a mass of $8.93 \times 10^{22}$ kg, and ...
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1answer
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Orbital pendulum (librating moon dumbell model)

Consider a moon orbiting its planet on a circular orbit. The moon is tidal locked to its planet, and has two permanent bulges, not exactly aligned with the planet. According to Newton's theory of ...
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What are ShadowBands during SolarEclipse and how can it be reproduced?

I recently got to know about different phases of a solar eclipse and its impact on Earth and its living creatures.., but one of the most interesting and not well explained phenomenon is the ...
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1answer
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If Earth spun the other way, would the Moon be pulled closer by tides?

I read this answer and thought “that’s not right”. But thinking that the moon would continue to receed and the Earth torqued in the same direction (speeding up) doesn’t balance kinetic energy. I ...