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

learn more… | top users | synonyms

1
vote
0answers
22 views

How does the Giant Impact Hypothesis resolve impulse for orbital insertion?

The Giant Impact Hypothesis describes that Earth's moon was formed from collision between a proto-Earth and another Mars-sized object. This collision ejected mass from the Earth into orbit, whereupon ...
0
votes
1answer
36 views

From where do tides get their energy [duplicate]

We all know that tides are caused by the Moon's gravity. In this process the water in the ocean gains energy (in the form of tides, which can be harnessed to get tidal energy). Where does the ...
52
votes
4answers
5k views

Why does the sun have to be nearly fully covered to notice any darkening in an eclipse?

I was looking at eclipse footage and I noticed that it doesn't get any noticeably darker until the very end when it suddenly all the light is gone. As the moon blocks out the Sun, I would expect that ...
37
votes
8answers
30k views

Why CAN we see the new moon at night?

I understand that the Moon's phases are determined by its position in orbit relative to the Sun. (See: Full Story on the Moon). The "shadow" is not cast by the Earth (a common misconception - this is ...
4
votes
3answers
2k views

How can we see the moon while it's between the Earth and the Sun? [duplicate]

I know this sounds like (and probably is) a stupid question, but I can't figure it out. As far as I know, the crescent shape of the moon is when the moon is on the sunny side of the Earth, but that ...
17
votes
6answers
5k views

Why can we see the moon when it is between the Earth and the Sun? [duplicate]

A rather stupid question, why can we see the moon when it is between the Earth and the Sun?
-4
votes
1answer
28 views

What changes in the moon light (spectrum, intensity, etc…) after the spring equinox? [closed]

There must be a correlation between the earth moon system and the sun during spring, just after the spring equinox.
0
votes
0answers
39 views

What is the difference between the light coming from Moon and the Sun? [duplicate]

The moon surface is reflective so, we should have the same light spectrum. And yet there is a difference in the quality of these two lights.
5
votes
2answers
63 views

How much mass must Earth lose to lose its Moon?

Maybe I am wrong about the basic concept here, but for my curiosity: how much mass would need to leave the Earth (like satellites and rockets) to create an imbalance between the Earth and Moon so that ...
7
votes
3answers
2k views

Why does the light side of the moon appear not to line up correctly with the evening sun?

I live at roughly $(52.4^\circ,-2.1^\circ)$. On sunny evenings I've often looked at the Moon and the Sun and noticed that the light part of the Moon does not appear to line up with the Sun. For ...
2
votes
1answer
49 views

Tidal effect on planet with two moons

If an Earthlike planet had two moons, one relatively smaller and closer while the other was bigger and farther away, and one had a prograde orbit while the other had a retrograde orbit, in what ways ...
5
votes
2answers
475 views

Why is the Earth's moon so big?

It could just be me, but it seems like our Moon is WAY bigger than it should be for a planet of our size. If you look at satellite-to-planet mass ratios for the largest moons of Jupiter, Saturn, ...
0
votes
1answer
32 views

Where does gravity get it's energy to cause tides? [duplicate]

The moon's orbital radius is fixed as a function of its velocity (I know it is actually drifting..). Since there is nothing in space to resist this velocity, it will continue orbiting "forever". Now ...
0
votes
0answers
32 views

Heliocentric Cartesian position of moons

I have a working Kepler orbit system that is GPU accelerated to allow precision, speed and parallelism and more importantly allow as many factors as possible in calculation. For various reasons I ...
35
votes
4answers
15k views

Why is a new moon not the same as a solar eclipse?

Forgive the elementary nature of this question: Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse (...
0
votes
1answer
64 views

Gravity Sun Earth Moon [duplicate]

The gravitational pull the Sun has on the Moon is roughly two times greater than the pull the Earth has on the Moon. If this is the case, why does the Sun's gravity not pull the Moon away from the ...
-1
votes
2answers
86 views

Is Moon too hot?

I find it puzzling that Moon's maximum "daily" equatorial temperature is almost 400K. Earth's theoretical black body temperature would be 279K at 1AU, and Moon is the same distance from Sun, yet its ...
0
votes
0answers
45 views

Can we calculate the point on Earth nearest to the Moon?

We have the ability to calculate the Moon's orbit in order to predict Lunar and Solar eclipses precisely. Using our known calculations of the Moon's orbits, can we calculate the closest point (city ...
3
votes
1answer
48 views

Which force transfers angular momentum in tidal locking?

The moon is in tidal lock with the earth, but a long time ago it was not. As the moon became tidally locked with the earth, its angular momentum changed and the delta went into it's orbit and possibly ...
6
votes
5answers
7k views

Why is the sky of the moon always dark?

Why is the sky of the moon always dark compared to the sky of the earth, doesn't it have day and night like earth?
3
votes
2answers
147 views

How does the Moon influence atmospheric pressure?

I have just read in the Telegraph an article entitled Moon overhead makes rainfall lighter, scientists conclude. In that article there is the following statement: When the moon is overhead, its ...
2
votes
0answers
44 views

How to find out diameter of some crater on moon using meteorite size and velocity?

I am looking for a formula to find out the diameter of a crater using meteorite size and velocity.
51
votes
4answers
4k views

Why does moonlight have a lower color temperature?

Moonlight has a color temperature of 4100K, while sunlight has a higher color temperature of more than 5000K. But objects illuminated by moonlight don't look yellower to the eye. They look bluer. ...
0
votes
2answers
907 views

Pendulum on the moon, (Highschool)

A simple pendulum used as a clock, set with the correct time at earth, was sent to moon, it was noticed that it is late 36mins for each hour on earth. Calculate the ratio between acceleration of ...
9
votes
2answers
1k views

Why don't we see solar and lunar eclipses often?

Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Earth during the evening ( and as far as I know if this happens during the day, you'll get to see a ...
1
vote
1answer
48 views

Will the Earth ever show synchronous rotation? Why and when?

In this answer to the question "why does the moon have the same rotation and revolution periods?", we read: The mass and speed of rotation of the Earth influence the moon in that some of its ...
2
votes
0answers
33 views

Why is the moon white? [duplicate]

Why is the Moon white? What is it's geological composition and how does that relate to it's apparent "color"?
5
votes
1answer
83 views

Strength of moonlight

So I read this xkcd, and thought it was kind of cool. However, I showed it to my engineer father and physics undergrad brother and neither seem to find the explanation very convincing (though they ...
0
votes
1answer
17 views

By which factors are tides and waves affected?

To my understanding, the tides and waves on Earth's oceans are caused by various factors such as the moon's gravity, the water cycle (rains, storms, evaporation), Earth's rotation, etc. Although the ...
1
vote
2answers
75 views

Why are Lunar Eclipse more common than Solar Eclipse?

Why are Lunar Eclipse more common than Solar Eclipse? Chapter from Light My thoughts; Eclipse can only occur at new moon and moon orbit is inclined at an angle of about 5 degrees to the earth's ...
0
votes
1answer
65 views

Optimal time for satellite rocket launch considering moon gravity [closed]

As per this The Gravitational Force of the Earth and Moon on Each Other Moon is pulling us with a force equal to 1/300,000th of our weight. I have read this Is the fuel burn for a satellite launch ...
1
vote
1answer
114 views

How much force would it take for you stop the Moon from crashing into the earth once it has started to fall?

In my previous question, I asked how much force it would take to destabilize the Moon's orbit enough for the moon to start falling into the Earth and collide. Assume this has already happened. Now, ...
1
vote
1answer
89 views

How much force would be required to destabilize The Moons orbit enough for it to crash into the Earth?

It is known that the moon slowly drifts away from the Earth. How much force would be required to destabilize it in the opposite direction enough for it to accelerate and crash into the Earth? What ...
0
votes
0answers
14 views

Tidal Bulge on Earth due to Line of Action [duplicate]

I am in an intro to Statics course, and we briefly went over why tidal bulges occurred due to vectors in the line of action between the earth and the moon. I am confused because I do not understand ...
2
votes
0answers
52 views

How deep would a moonbase have to be dug for radiation protection?

The atmosphere of the earth protects us from cosmic rays and other kinds of space radiation. On the moon there is little to no atmosphere so anyone on the surface of the moon is directly exposed to ...
1
vote
2answers
2k views

True or false: the Moon was touching the Earth 1.2 billion years ago

A creationist website makes this argument for the 6,000 year old earth. I'm embarrassed to say I don't know how to do the math to evaluate the claim myself. However, the time scales involved seems ...
10
votes
2answers
2k views

What happened to Apollo's Saturn-third-stage rockets?

I read recently the original Apollo 11 press release and it mentions that the Saturn V's third stage (used for Trans-Lunar Injection) was deployed into a solar orbit of some kind: (Source: Press ...
2
votes
2answers
1k views

How many hours will there be in a day 5,000,000,000 years from now?

It is known that the moon is moving away from Earth 2cm a year, and in doing so makes the days longer. I want to know how many hours will have one day, when our planet is near its end.
1
vote
1answer
57 views

Reconciling geosynchronous orbits and why the moon is moving away

First time on PSE, and forgive me if the question doesn't make sense. Everything I've read, and the explanations make perfect intuitive sense, for why the moon is moving away from the earth is ...
-1
votes
2answers
2k views

How does the Moon stay in orbit? [duplicate]

How does the Moon stay in orbit? The Moon has not reached escape velocity from the Earth, then how does the Moon stays in orbit?
-17
votes
3answers
43k views

If there is no gravity on the moon why is the american flag waving?

If there is no gravity on the moon, how could this flag be flapping in the wind? (see link) http://www.stumbleupon.com/su/2wD6eg/hea-www.harvard.edu/~fine/images/desktops/Armstrong.jpg
6
votes
1answer
1k views

If the Moon had gravity as good as the Earth and a magnetic field could it have supported life?

If the Moon had gravity as good as Earth and a magnetic field could it have supported life? Because if the Moon had gravity, it could have retained water more than is present today on the surface. ...
25
votes
3answers
115k views

Why does the moon sometimes appear giant and a orange red color near the horizon?

I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
5
votes
3answers
5k views

Why is moonlight less colourful than yellow light?

Just what the title states; and this isn't an original question: On full-moon, moonlight is almost as bright as mid-dawn; yet there is hardly any colour visible. This is not the case with sunlight. ...
2
votes
2answers
76 views

Could self-powered human flight be possible in a pressurized dome on the moon? [closed]

Given on the moon (or other place with 1/6th the gravity of the earth, though let's use the moon to keep this anchored in a real scenario) a "flying room" within which to fly, such as a large enough ...
4
votes
2answers
2k views

What kind of cooling mechanism could be used in outer space?

This question arises out of this question on Quora - Apollo 11: 1969 Moon Landing: Did Neil Armstrong really land on the moon? I'm convinced with most of the explanations provided in the first ...
0
votes
0answers
16 views

Weight difference on full moon and no moon day [duplicate]

Since Moon has an impact of gravity, would same piece of mass be heavier on a no moon day (since moon is at opposite side, thus pulling downwards) and lighter on full moon day (since the moon is at ...
2
votes
1answer
7k views

Why does the Moon or the Earth revolve anti-clockwise?

The question is very simple: Why does the Moon or the Earth or any another planet revolve anti-clockwise? And can any planet (or satellite) revolve clockwise? What is the physical law for this ...
2
votes
0answers
21 views

The moon affects the motion of the oceans, but can the motion of the oceans affect the moon? [duplicate]

Obviously the earth's oceans have mass and therefore they have an attractive force upon the moon. However, let's say that we were to cover most of earth with tidal power generators that extract some ...
2
votes
2answers
483 views

Which will collide first, the moon and Earth, or Sun and Earth?

As time progresses, which scenario will happen first? The moon colliding with Earth, or the Earth colliding with the Sun? I figure the Moon and Earth will happen first, based on proximity, but the sun ...