What is Lunar: Definition and 113 Discussions

A lunar eclipse occurs when the Moon moves into the Earth's shadow. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy) with Earth between the other two, and only on the night of a full moon. The type and length of a lunar eclipse depend on the Moon's proximity to either node of its orbit.A totally eclipsed Moon is sometimes called a blood moon for its reddish color, which is caused by Earth completely blocking direct sunlight from reaching the Moon. The only light reflected from the lunar surface has been refracted by Earth's atmosphere. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light.
Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse can last up to nearly 2 hours, while a total solar eclipse lasts only up to a few minutes at any given place, because the Moon's shadow is smaller. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon.
For the date of the next eclipse, see § Recent and forthcoming lunar eclipses.

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  1. M

    Possible energy sources that a lunar base might have as an option

    So I am doing research for the different energy sources that might be available for a space base in about fifty years from now. Some of these energy sources would likely be solar, fusion, fission, Nuclear, and I heard of radio - nuclide as well. What else could be used? In addition, does...
  2. M

    What Are the Potential Benefits of a Lunar Base?

    I am curious to know what would be the benefits of a Lunar Base? I know that some benefits include the harvesting and possible use of Helium 3 for nuclear fusion energy. In addition it would help further the progress for space travel that will sometime in the future lead to traveling to other...
  3. T

    Solar vs Lunar Tides: Explaining the Difference

    I have a question about the effects of solar and lunar tides. I know that the effect of lunar tides is twice that of solar. However when I calculated the force of gravity of the Sun on the EArth vs the Moon on Earth using F=GmM/r^2 the force due to the Sun was much greater. Can anyone help me...
  4. L

    Lunar Rover Equipped with HD Video Camera

    I want to know why someone hasn't built a 'rover' of some sort that could easily navigate the lunar surface while recording HD video. I don't think funding would be an issue since you could easily strike a deal with a large company pertaining to product placement i.e. a coca-cola bottle in the...
  5. Philosophaie

    Lunar solstice when the Moon's Equator crosses the Zero Plane of the Earth

    Is there such a thing as a Lunar solstice? When the Equator of the Moon crosses the plane of the tilt equals zero or the plane of the earth. This should occur when the True Anomaly of the Moon is at approximately 90 Degrees or 270 Degrees depending upon the Moon's Eccentricity. The...
  6. K

    Lunar lander in orbit around the moon and how much work the thrusters do

    Homework Statement A 6000 kg lunar lander is in orbit 80 km above the surface of the moon. It needs to move out to a 200 km -high orbit in order to link up with the mother ship that will take the astronauts home. How much work must the thrusters do? Homework Equations...
  7. R

    Does Lunar Gravity Affect Lake Water Levels?

    Does the grav pull of the moon affect the water level in enclosed lakes?
  8. A

    Exploring Lunar Base Design: Need Help!

    Presently, I am working with the "Lunar Habitats" and planning to present all the knowledge I've gathered in an Institute so that some one would probably ignite the fires for building structures on the Lunar surface o:) The thing is ... the date is approaching but I am unable to find material...
  9. M

    Accepted (precise) value for lunar L2 point?

    Does anyone know where I can find one? I've written a program to test the stability of the lunar L2 point by placing a massless test object in orbit there and I've found an optimised value based on the approximation r_{m}(\frac{M_{M}}{3M_{E}})^{1/3} where r_{m} is the radius of the...
  10. Dembadon

    Stargazing How Does Atmospheric Turbulence Affect Lunar Eclipse Shots?

    Here's a shot I took at about 11:40PM Pacific Time I used my new lens! :biggrin: Shot info:
  11. J

    Stargazing Witness a Rare Celestial Event: Total Solar and Lunar Eclipses

    Those of you living on the moon will see a rare sight tonight, a total solar eclipse. Not coincidentally, the entire US, and very little where else will see a total lunar eclipse. This will be one to tell your grandchildren about since there won't be another until June 15, 2011. Don't look...
  12. Philosophaie

    Stargazing Rare Total Lunar Eclipse on Winter Solstice - Dec 21 @12:29AM EST

    There is going to be a Lunar Eclipse on the Winter Solstice. It will start Dec 21 @12:29AM EST. Entering the Earth's Umbra(the shadow of the Earth) @1:33AM. The eclipse will become total @2:41AM EST lasting approximately 72 minutes. The best time to view is 3:15AM EST when the Moon will be...
  13. J

    Lunar orbit question (calculating the mass ratio of earth and moon)

    The problem I am struggling with is this . . The centre of the Earth-Moon system is 4.7x10^3 km from the centre of the earth. Calculate; i.the ratio of the mass of the Earth with the mass of the moon. ii.The acceleration of free fall on the Moon's surface. Constants Distance between...
  14. nukeman

    Why are solar eclipses so short compared to lunar eclipses?

    Is it just because the moon moves in and out of view quicker than the Earth moving in and out of view as to a lunar eclipse? I can't find a simpe definition out there? Thanks!
  15. F

    Landing the Lunar Excursion Module: Astronaut Training Simulation

    You are in training to be an astronaut. In one of your training simulations, your goal is to land a lunar excursion module (LEM) on the surface of the Moon. This LEM has two rocket engines attached to the center of the craft. The engines typically point at angles of 22.0° in opposite directions...
  16. C

    Exploring the Formation of Lunar Silica in Anaerobic Environments

    Perhaps the recent silica found on the Moon highlands resulted from the extreme conditions of temperature and pressure of planetesimal collision with proto-earth. Can covalent bonds be broken at high temperatures, allowing oxygen incorporation in an anaerobic environment? What is the highest...
  17. W

    Lunar gravity assist en route to Mars

    I was wondering how feasible it would be for a spacecraft to use a lunar gravity assist on its route to Mars. Specifically, I was wondering; 1.) Would such a maneuver boost the delta-v en route to Mars? 2.) Would any such boost be possible in terms of its geometry? (i.e., would a lunar...
  18. N

    Designing a MATLAB Lunar Lander: Finding v

    Homework Statement The task is to design a MATLAB program reminiscent of the text-based lunar lander games. Ol, that's not that bad. My problem comes from the research, specifically determining what thrust will be provided from what rate of fuel burned. I know that thrust=(dm/dt)v where v is...
  19. E

    Stargazing About the wave nature theory In the case of Lunar Eclipse

    About the wave nature theory ! In the case of Lunar Eclipse Hello all :) First I'm glad to be a new member of this forum .. Anyway .. as I noticed that if someone thought about a theory or a physics inquiry you share your thoughts and solve the problem .. So what came to my mind months ago...
  20. M

    Exploring the Moon: Discovering Lunar Frequencies and Radiations

    Hy. I want to find a lot of info about the moon. I've read about gravity. I want to know about the frequencies, radiations and whatever there is, and how them interact with earth. Where should i search? Thanks!
  21. Evo

    Stargazing Moon Illusion to Supersize Saturday Lunar Eclipse

    Yay, I'm in central US. http://news.yahoo.com/s/space/20100625/sc_space/moonillusiontosupersizesaturdaylunareclipse
  22. edpell

    Space Elevator on the Moon: Why is Nobody Building It?

    Building a space elevator for the moon seems doable with existing materials (see the wikipedia page). So my question is why is no country or organization interested in building one?
  23. r.vittalkiran

    Exploring the Lunar Laser Ranging Experiment

    Why did they land on the other side of the Moon? And how did they place the Laser reflector (http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment) on the front side of the Moon?
  24. O

    Mysterious Lunar Ring in the French Alps

    I was in the French Alps the other day, high in the mountains (not sure if this is relevant), and, on the night of a full moon, with mist in the sky, there was a circular ring of light around the moon. The ring subtended an angle about 5 times that subtended by the moon (that is to say, it...
  25. S

    Decending Lunar lander velocity

    Homework Statement Lets imagine we are back in 1969 and the Apollo Lunarlander is on approach to the moon. It has a mass of 200 kg and initial velocity of v1 = 6 m/s. The Astrofolks push the big red button in the cabin and engine burst of energy to break the spacecraft where time = 2 sec...
  26. S

    Extraction Methods for Frozen Lunar Water Ice?

    You want to think about technology you can patent? Come up with a way to extract frozen water ice in the shadowed craters on the Moon, which are at temperatures approaching absolute zero. He who controls the lunar water, controls the future of human colonization on the Moon. Given that this...
  27. T

    Lunar effect on weight on earth

    How much does the phase and position of the moon affect the weight of an object on the surface of the earth? For example, if a person at the equator on the equinox weighs 80 kg at noon when the moon is new, how much does he or she weigh at midnight that day? Conceptually, it would seem that it...
  28. O

    Solving for Lunar Landing Craft Thrust

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  29. diogenesNY

    Lunar Reconnaissance Orbiter Photos

    Hey y'all-- Many/most of you may already be aware of and have seen these, but worth checking out are the new photos from the Lunar Reconnaissance Orbiter... particularly of the Apollo landing sites. Amazing detail and really beautiful photos. You can make out details of left behind equipment...
  30. M

    Lunar Crash Trajectory Problem

    Homework Statement As a command module, orbiting the moon passed through a point A (120km altitude), it released a lunar excursion module, which crashed into the moons surface at point B. Knowing the angle AOB was 50 deg (where O is the centre of the moon), determine the velocity of the lunar...
  31. O

    Calculate Delta V for Lunar Orbit Transfer in 2 Maneuver Sequence

    Homework Statement A spacecraft is inserted into a lunar orbit. It varied from 101.5 km to 11,741,8 km above the surface of the moon. Later it was transferred into a circular orbit 96.6 km above the moon. Compute the delta v total for a 2 maneuver sequence to transfer the spacecraft...
  32. B

    Lunar Orbital Angular Momentum

    Homework Statement In lectures and textbooks the lunar orbital angular momentum is given as: A = m/(1 + m/M)xR2x\omegaL But if the distance r of the moon from the centre of mass of the Earth-moon system is given by: mxr = Mx(R-r); so r = MR/(M +m) = R/(1 + m/M) and so the moon's angular...
  33. P

    Descartes, lunar eclipses, and the speed of light

    Hello all. I was doing some research on something or other (i can't rightly remember what right now) and ran across Descartes' claim that the speed of light had to be infinite because if it wasn't the co-linearity of the sun moon and Earth during a lunar eclipse wouldn't exist. (that is to...
  34. T

    MATLAB Matlab 2-D Simulation for TLI (Trans Lunar Injection) Basic Orbital Mechanics

    Matlab 2-D Simulation for TLI (Trans Lunar Injection) "Basic Orbital Mechanics" Hi Everyone, I have been assigned a project in which I am to program in MATLAB the solution to the 3-body problem, but in 2-D with a couple assumptions. 1) Earth and Moon are stationary. 2) Mass of spaceship...
  35. stevebd1

    Jones "Moon Bricks" for Lunar Colonies

    Not quite sure where this would go, hopefully this is the right place. 'Moon Bricks' Devised for Potential Lunar Igloos- http://dsc.discovery.com/news/2009/01/22/moon-brick-igloo.html Lunar rock-like material may someday house moon colonies...
  36. D

    Creating a Computer-Controlled Lunar Lander

    Model "Lunar Lander" How hard do you think it would be to develop a small scale computer controlled vertical take-off and landing machine? Do you think it could be done without using extremely high powered rockets?
  37. L

    Geology of Lunar Rocks: Apollo Moon Landing Reality or Hoax?

    Hi, I am trying to find out about lunar rocks, the ones that came back from apollo. Moon landing hoaxers debunk the whole thing but in my mind, it seems unanswerable the idea that in the 60's and 70's we could have faked the moon rocks brought back. So, I am trying to see if I can close that...
  38. S

    Lunar Surface-to-Orbit Shuttle

    If you had to design a vehicle that would travel from the Moon's surface to lunar orbit and back down again, then what would it look like? What kind of geometry or shape would it have? I'm thinking of a heavy-lift vehicle, which would be able to bring down mining equipment, and lift up ore...
  39. T

    Speed of Light = 12000 Lunar Orbits/Earth Day ?

    Hi everybody ! Hope you're doing fine. I didn't know where to post this so I decided to do it in the general section. I've come across a website which deals with speed of light ... It is said that the speed of light equals 12000 Lunar Orbits/Earth Day outside the gravitational field. So please...
  40. B

    Lunar Space Elevator: Is a Rocketless Trip Possible?

    Lunar space elevator... Based on my limited understanding of the idea. If this system were to omit a rocket or chemical propellant power plant and is not an unbound free traveling vehicle, I would infer, given the distance of the journey the travel time may venture into the realm of the...
  41. Janus

    Stargazing Last nights total Lunar eclipse

    Last nights total Lunar eclipse was probably the first time a great many people even paid any attention to our natural satellite for quite a while. It's kind of taken for granted. After all, except for the passing phases, it usually doesn't change. Its the same face staring at us night after...
  42. Gokul43201

    Stargazing Are You Prepared for the Upcoming Lunar Eclipse?

    Set your alarms, get your cameras ready, clean the lenses on your scopes - it's loony time! http://news.nationalgeographic.com/news/2007/08/070827-lunar-eclispe.html http://news.nationalgeographic.com/news/2007/08/images/070827-lunar-eclipse_big.jpg
  43. L

    Moon Perturbations: Learn Differential Gravitational Forces

    Hi everyone. I was wondering if you know any web sites that describe perturbations on the moon's motion [due to differential gravitational forces] in detail.
  44. O

    How Skepticism Slowed Scientific Progress: The Lunar Laser Ranging Experiments

    Right. Even well-documented observations that do not fit easily into a preconceived notion of how the world should work, may be rationalized away or just neglected. One example of this is the observed mean acceleration {\dot n} of the Moon; from lunar laser ranging experiments this has the...
  45. C

    Lunar Laser Rangefinding: Testing GR's Gravitomagnetic Phenomenon?

    A few weeks ago Physical Review published a Letter (an edited version of http://arxiv.org/abs/gr-qc/0702028" ) that says: "At this time, [Lunar Laser Rangefinding] provides the most precise test of [the gravitomagnetic phenomenon,..] likely better than the ultimate result from the GP-B...
  46. V

    Stargazing A rough calculation on the duration of lunar eclipse

    I guess many have watched the lunar eclipse last night I was just thinking about the duration of a lunar eclipse on my way home sun-to-earth = 1.5x10^8 km, moon-to-earth = 384400 km R(Earth) = 6378 km, R(Sun) = 6.96x10^5 km, R(Moon) = 1378 km Moon's period around Earth = 27.3 days x /...
  47. S

    Lunar Phase Change with Reversed Moon Orbit

    hey guys could anyone help me with this q? q)how would the timing and sequence of lunar phase change if the moon moved at the same speed around its orbit but in a different direction? i thought it would simply reverse the phases of the moon, but I think the answer needs to be more detailed...
  48. Labguy

    Solar and Lunar exposure tables information

    I don't remember if I have ever posted these here before, but if I did it was a very long time ago. Some of these are worth keeping for you astrophoto buffs out there and I have found the exposure tables to be spot-on. For f/ratios not listed, it is easy to see where to start for bracketing...
  49. Astronuc

    NASA What is NASA's Lunar Lander Challenge?

    http://www.newscientistspace.com/article/dn9122-lunar-lander-is-nasas-biggest-challenge.html NASA's Centennial Challeges Program http://exploration.nasa.gov/centennialchallenge/cc_index.html
  50. M

    Structure of the lunar crust and the thumper experiment

    structure of the lunar crust and the "thumper experiment" Hey guys, I know that this is an Earth's forums but I have a question about the moon. On Apollo 14, an experiment was done to determine the structure of the lunar crust down to a certain depth. This was done by detonating explosives...
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