Moon Definition and 1000 Threads

Happy Moon Day 2016! I was lax in my duties last year and [gasp] missed Moon Day 2015, but that makes Moon Day 2016 all that more important! For those that didn't realize, today marks 47 years since mankind first set foot on the moon. In celebration of this achievement, we are enjoying...

When two bodies orbit each other the entire system rotates about a center of gravity point in the space between them causing a wobble effect of the entire system. Approximately at what distance from Earth is that CG point between the Earth and moon please. tex

I am hopeful that some PF participants can suggest specific plausible future improvements to astronomical instruments sufficient to detect a moon similar in size to Earth's moon revolving around a Earth-size planet revolving around a distant sun.

Homework Statement 1a)How does a ball floating 50% in water move when a LARGE amount of oil is added? 1b) if something denser than water were added, how would the ball move? 1c) if the exp. was done on the moon with different gravity and no atmosphere, how would the ball move?Homework...

I googled this question and found sources which claimed the moon slowly, over about 27 days, rotates on its axis. Yet wouldn't rotating at a speed so that about 40% of the moon never faces the Earth suggest that it is rotating around an axis somewhere inside of the Earth, rather than inside of...

Following scenario: 1) Send a few rockets with large payloads to the moon, carrying various parts of a nuclear reactor to be assembled on the moon 2) Use the nuclear reactor to extract oxygen from various materials found on the moon 3) Use the power of the reactor to harvest resources for...

I was thinking of having the binary planets in my fictional solar system (Kepler Db(Mars like) and Kepler D#(Venus like)) have a moon. Life is on both of these planets in intelligent humanoid forms, but different from the humanoids on the 2 earth-like planets. For 1 the humanoids on Kepler D#...

Why does the moon always have the same side facing earth? Can it be simply that the rotation of the moon just happens to coincide with it period around the earth. If so, how might that happen? Which requires the axis of rotation to be exactly 90 degrees from the plane of orbit. tex

When the the Earth is between the Sun and Moon do the gravitational effects of the Earth and Sun combine to create a stronger pull on the Moon? If so, wouldn't this increased pull draw the Moon closer and closer to the Earth over time? I've looked for an answer to this, but haven't had any luck...

Here's another question for you experts. I screwed in my new Baader Hyperion Zoom in a brief clear period and the Moon looked absolutely blistering. I am so pleased with this lens. It is so much better than the kit lenses that came with the scope. (Dobs 200p). 'Everyone' says that a Moon filter...

Greg Bernhardt submitted a new PF Insights post The Moon Quiz Continue reading the Original PF Insights Post.

Q: Fred is on Earth, and Jane is on the Moon. a) Each lifts a 2.0 kg rock. Who has to apply the larger force? b) Each throws the rock horizontally with initial speed of 6.0 metres per second. Who applies the larger force? For both questions, I wrote: Fred, because the gravity on Earth is...

Hi Community, I have this question and I would like to run thru my theory on working it out. So my approach is to work out the scaling of the jump on Earth and calculate it for the moon by the following. \frac{x}{2.35}=\frac{1.6m/s^2}{9.8m/s^2} solve for...

Even though the moon is much smaller than the Sun, the ratios between their distances to Earth is such that they look the same size in the sky. Further, we have a tidally locked moon with life to observe it all. Now, I'll admit this does raise some superstition in me, especially since religions...

Homework Statement One of Jupiters Moons runs on a circle with the radius r1= 420000km in T1=1,77d. How big is Jupiters Mass? Can you calculate the Mass of the Moon with this as well? γ = 6,672*10-11m3*kg-1*s-2 (gravitational constant) Homework Equations I used following equation...

Why sometimes rings are observed round the moon or sun? My book says When the moon or sun is observed through a thin layer of high clouds,reflection of light from fine icy crystals,present in the clouds,results in the formation of rings. Can someone please elaborate on that so that I can...

***NOTE: The data in my written work & the typed variables under "all known data" are correct. The problem statement has new values for a new submission, but I am trying to correct my work on an old submission. Sorry for the confusion! 1. Homework Statement Problem: All known data: Period (T)...

...so close to the Sun's position? Is this even possible? First two, taken around May 1st, 2015. Last one, taken in October, 2015

From http://www.scientificamerican.com/article/moon-life-tides/ It all started some 4.5 billion years ago when, as theory has it, our nascent Earth was blindsided by a Mars-size planetary embryo, believed to have spun Earth into its initial fast rotation of roughly 12 hours per day. Can...

For some time now I’ve been intrigued by the famous argument between Bohr and Einstein, and which was apparently settled when Bell’s inequality was tested in various experiments carried out by Alain Aspect. After going around and around the whole issue for a while, I don’t think I’m convinced...

Spontaneous negative entropy reactions can occur when the internal energy decrease is greater than the negative dS*T. dG=dU-dST is spontaneous if dG is negative. The moon is receiving at least 1E8 J/s from the loss of rotational energy from the Earth's water and air. A lot more rotational...

I have been looking for an answer for so long. Everywhere I look I find answers to the question how two lunar sized moons would affect the Earth's tides and so on. But I want to know, if we had our own moon, with its normal orbit, and an additional smaller moon, (or just further away from...

So, I have really no background in astrophysics (other than touching on some areas in general physics and calculus). I understand that asking questions such as the one in my title, that I would need to be more specific, and I will attempt to be as specific as I can. I understand that most...

Dear PF Forum, Lunar Satelite orbits the moon, The moon orbits the earth, The Earth orbits the sun, I know that some of you know about this picture You might want to tell me. "No Steven, the Sun also orbits the earth" But for all practical purpose, we'd say that the earth orbits the sun. So...

Suppose that one of the Apollo landings had developed a fuel leak in the lunar ascent module, such that even with a lightened load, the ascent module only had enough delta-v to reach about half of lunar orbital velocity. One possible rescue solution would be to lower the command module's orbit...

Are Newton's three laws all that was needed for the science that got us to the moon? Or did we need Einstein's theories to get there? I just started studying physics last week, so forgive me for my baseness.

From what I've seen on shows like how the universe works and the Wikipedia article on Theia, they are saying that the moon was formed in less than a year after the impact. My question is, how did that happen so quickly? I am simply a fan of watching shows like that or reading articles about...

Homework Statement An object possesses 61.14 kg mass. 1. How much energy in kilojoules would be necessary so as to project the object from the surface of the moon to the Earth's atmosphere at the Karman Line of 100km Earthly elevation, at such a speed that the total travel time between lunar...

Ignoring the fact that the atmospheric friction would probably disintegrate it. I know that to achieve LEO takes around 10km/s delta v. But only 2km/s of that is to overcome the drag and gravity. So you could shoot at 2km/s, get to LEO altitude then it falls back down because it is not at...

Starting to get the hang of it... this is at 25% (1/200 s, 800/5.6, ISO 64)

Homework Statement What is the time of an orbit of a satellite around the moon close to the moon's surface? What quantities do you have to look up to be able to answer this question? Radius of moon is 1736482 meters Homework Equations F = Gm1m2/r^2 and maybe F=mv^2/r 2pir The Attempt at a...

Homework Statement If the distance between the Earth and the Moon doubled, by what factor would the tidal forces felt on Earth decrease by? Homework Equations Not sure if there are any relevant equations F = GM1M2 / r∧2The Attempt at a Solution [/B]G = 1/d^2, if d is doubled, then G =...

I have a question about the moon landing . Wouldn't the solar winds kill any astronaut in space?

If one writes down the Newton's equations of motion for the Earth, the forces that act on the Earth are the gravitational forces exerted by all other massive bodies, such as the Sun, the Moon, the planets etc. The largest of these forces is that of the Sun: keeping into account only the Sun's...

I know that the angular momentum of the moon with respect to the Earth can be calculated by L = Iw but if the L of the moon is k * Learth-sun the there will be way more eclipses, one of each every 28 days. So the momentum of the moon must change over time, how does it work?

On Wolfram Alpha, I get the following values for gravitational acceleration on Earth due to the sun and moon, respectively: gravitational constant * mass of sun / (distance to sun)^2 → 0.005991 m/s2 gravitational constant * mass of moon / (distance to moon)^2 → 3.68×10-5 m/s2 If the...

Someone texted me and asked me if the Earth was half as massive what impact would that have on the rotation period of the moon? I'd think that the moon would rotate slower as it's gravity would more influence on the earth. But I am not sure if that makes sense or not haha

The moon often glows red during a total eclipse because light from Earth's atmosphere is refracted into the Earth's umbra, and Rayleigh scattering filters out blue wavelengths. Who first came up with this idea and how? I'd love to know the history behind that insight.

Head's up, as this scientific finding is making the rounds. http://www.cnet.com/news/the-moon-is-shrinking-and-the-earth-is-shaping-it/ The claim is that the oriented gravitational pull shapes the landscape of the moon. Except for the established effect of tides, it's odd that scientists do...

So I was thinking that radio waves travel at the speed of light, approximately 300,000,000 m/s.I was wondering how much time it would take if the average distance from Earth to the Moon is 384,000 km.

What do you guys think about humans settling on the moon ?

if we fix huge amount of mirrors on surfface of moon...can we obtain light on Earth during night ?

What if we built an electromagnetic track around the circumference of the moon? We could then accelerate a spacecraft to a very high speed. In theory it would only be limited by the strength of the materials holding the craft to the track and the centripetal acceleration that the craft/people...

I'm a writer and I like to play in the science fiction sandbox but keep a firm grasp on what is possible. I recently started working on some notes for a setting in which we have begun to colonise the solar system. To the question at hand. The further you fall into a gravity well, the more you...

So, I recently joined a stargazing club, and for our summer activity, we're supposed to use a telescope, a photoresistor, and a multimeter to measure the luminosity of the moon. I know that luminosity can be calculated with the equation, L = σ AT 4, and that brightness can be measured with the...

I was wondering if somebody could explain to me how does the process of Enceladus being heated up satisfy the laws of thermodynamics, more precisely the conservation of energy. Or should I ask where is the payment for the giant geysers on that moon? In layman terms, please!

Hi all It's a well known fact that the moon is drawing away from Earth by 3.82 ± 0.07 cm/year. I was googling a lot to find the exact distance between Earth - moon that this data was measured. A plain number or a link will be much appreciated. Thanks in advance Elistein

Are there any explanations, theoretical or otherwise, as to why the Earth has a tilt (causing the seasons) while the moon does not?

Could a particle(proton, gold ion, electron) beam reach the surface of the moon, given current technology? Would the beam diffuse too much too scenter the regolith? Or would the beam have to be focused or continually refocused in order to achieve that? If so why can they do it with laser...

Hello, I'm interesting in Earth Moon evolution history. I understand it is very complex problem, and I can find many articles about that. But I would like to start from beginning and add real condition on my model step by step (I hope good way to do something). I would like to start with...